Iris Publishers-Open access Journal of Complementary & Alternative Medicine| Gut Microbiome: A Potential Controller of Androgen- Modulated Disease

 

Authored by Chunxiao Yu* and Qingbo Guan*.

Abstract

Hypoandrogenism in males and hyperandrogenism females are both androgen disorders, which can adversely impact a variety of physiological factors. Recent studies provide that one of the principal regulators of circulating androgen is the gut microbiota. In this review, we elaborate on how gut microbial imbalance (dysbiosis) may lead to dysfunction of androgen synthesis, thereby contributing to androgen-driven disease. Some of the most common metabolic diseases namely obesity, metabolic syndrome, polycystic ovary syndrome and hypogonadism have been discussed and delineated along with recent findings. Then, suggestions for future research concerning the study are put forward as well.

Keywords:Androgen; Obesity; Gut microbiota; Complications

Introduction

The co-evolution of human microbial communities with human hosts is critical to human health [1]. The human gut have the greatest numbers of microbiota in the body [2], indeed, there is growing evidence that the gut microbiota and its bacterial genome (the microbiome) affect energy harvesting, fat storage, controlling satiety, modification feeding behaviour and regulating inflammatory responses within the host [3]. Under normal circumstances, gut microbiota in adults is dominated by members of three bacterial divisions, the Firmicutes (Gram-positive), Bacteroidetes (Gramnegative) and Actinobacteria (Gram-positive) [4]. The imbalances of its composition are related to homeostasis and lead to several non-in testinal pathologies [4]. Actually, recently studies proposed that the gut microbial can affect androgen levels. As reported, transfer of gut microbiota from adult males to immature females altered the recipient’s microbiota, leading to elevated testosterone and metabolomic change [5]. In reality, it involves a variety of molecular mechanisms which can be divided to several aspects: directly infect androgen levels through specific bacterial communities [6], and bacterial products [7], or modulate the enterohepatic recirculation of androgens and participate in redox reaction [8,9]. It is widely accepted that androgen plays a significant role in many diseases, such as obesity and metabolic syndrome, type 2 diabetes mellitus, polycystic ovary syndrome and hypogonadism. This review will introduce the influence of the gut microbiome has on androgen, discussed the role of gut microbiota in androgen-driven disease. Then, we proposed two related research prospects: developing gut microbiota-based intervention and diagnostic criteria for female androgen excess (AE) and male androgen deficiency (AD).

Changes in Gut Microbiota Influence Homeostasis

Gut microbes are constantly interacting with intestinal epithelial cells. Gut microbiota are physically separated from mucosal immune system by a single epithelial cell layer, mucosal immune system can avoid the development of chronic inflammation and the subsequent loss of the intestinal epithelium integrity [10]. Changes of bacterial composition influence intestinal homeostasis. In the case of gut microbial imbalance, the permeability of the intestinal barrier increases, which promotes bacterial products, especially LPS synthesis [11], and as we know, LPS is believed as a key factor to cause low-grade inflammation and related to reactive oxygen species(ROS)-induced oxidative stress which contributes to insulin resistance, endotoxemia and so on [12,13]. On the other hand, altered of gut microbiota can also affect short-chain fatty acids (SCFAs) synthesis [14], which can regulate immune function, induce ROS and prevent passage of macromolecules such as endotoxin between intestinal epithelial cells by enhance the production of epithelial tight junction proteins [15,16]. As reported, administered sodium butyrate to mice significantly alleviated high fat dietinduced obesity and restored plasma glucose, insulin and leptin to control levels [17]. Secondly, Firmicutes/Bacteroidetes (F/B) ratio also correlates with disease, for example, obese mice have more of Firmicutes and less of Bacteroidetes in their gut compared with lean mice, similar findings were observed with obese people [18]. At last, the gut microbiota can communicate with the brain through the microbiota-gut-brain axis, which is mainly composed of the nervous pathway, endocrine pathway, and immune pathway, so it is a crucial part of the gut-brain network [19]. Actually, gut microbiome also plays an important role in cognitive conditions such as anxiety, depression and memory impairment, which has been described extensively beyond the scope of this review, furthermore, the microbiota maintains central nervous system homeostasis by regulating immune function and blood brain barrier integrity [20]. In a word, imbalance of the gut microbiota not only leads to inflammatory response and detrimental to gut epithelial health, but also affect emotion and physiological stress. Therefore, gut microbiome diversity is important to gut homeostasis and health.

Gut Microbiota Can Affect Androgen Levels

As above, gut microbiota is essential for protecting from pathogens, maintaining of the physiology of immune homeostasis, and promoting of digestion and absorption of dietary nutrients for energy production [21]. Recently, studies shows that gut microbiota also closely related to androgens, which has different effects on metabolic diseases in men and women [22]. Compared to conventionally raised counterparts, Germ-free non-obese diabetic (NOD) male mice have lower systemic testosterone levels [5]. Additionally, transfer of gut microbiota from adult males to immature females altered the recipient’s microbiota, resulting in elevated testosterone and metabolomic changes [5]. This evidence proved the interactions between testosterone and the gut microbiome. In fact, gut microbiota can directly infect androgen levels through specific bacterial communities and bacterial products. We have known that products of ‘estrobolome’ are capable of metabolizing estrogens [23], specifically, hepatically conjugated estrogens excreted in the bile can be conjugated by bacterial species secretion of β-glucuronidase in the gut, leading to their reabsorption into the circulation [8,24,25]. Similarly, the bacteria -glucuronidase excises glucuronide from conjugated androgens and releases free androgens for reabsorption [8].

Gut microbiome also modulates androgens through reductive and oxidative reactions [9]. Androgens, such as androstenedione and testosterone, are C-19 steroids derived from C-27 cholesterol through reductive reactions. Further, as we know, gut microbiota can convert primary bile acids (BAs) into secondary BAs through deconjugation, dehydrogenation and hydroxylation. Sex steroid hormones and bile acids (BAs) has similar structure and they can both be recycled through enterohepatic circulation, enterohepatic circulation is partially regulated by the gut microbiome, so gut microbes determined whether they are excreted or recycled in a way [8]. It has known that a human gut microbe named Clostridium scindens can convert glucocorticoids into androgens by side-chain cleavage [8], which is associated with a cortisol-inducible operon (desABCD). Ridlon JM, et al. [6], proposed that desABCD could encode enzyme involved in anaerobic side-chain cleavage. The desC gene have found to encode 20α-hydroxysteroid dehydrogenase (HSDH), which is an enzyme that catalyzes a chemical intermediate in the biosynthesis of androgens 17α-hydroxyprogesterone (OHP) production. This operon also encodes desAB which may have steroid-17,20-desmolase/oxidase activity, and desD, a possible corticosteroid transporter. Additionally, there are some other special microbiomes (e.g. SPF microbiota, segmented filamentous bacteria, Escherichia coli or Shigella–like) is positively correlated with high blood testosterone levels in male mice [26]. Insenser M, et al. [27], proposed that women with PCOS has an increased abundance of the Catenibacterium and Kandleria genera which shows positive correlations with serum androstenedione concentrations. Another report shows that Bacteroides vulgatus was also elevated in the gut microbiota of individuals with PCOS, transplantation of fecal microbiota from women with PCOS or B. vulgatus-colonized recipient mice resulted in increased insulin resistance and infertility [28].

Gut Microbiota Dysbiosis Influence Androgen- Modulate Disease

Obesity and metabolic syndrome

The prevalence of obesity is increasing worldwide [29], the growing incidence of obesity and obesity-associated complications, including diabetes, cardiovascular disease, and stroke is rapidly becoming a major public health problem [30]. As we kown, Male androgen deficiency raises the risk of abdominal obesity and cause metabolic syndrome [31]. Generally, androgens can directly stimulate the androgen receptor (AR) or indirectly aromatizate androgens into estrogens and, thereafter, stimulate the estrogen receptors to regulate the adipose tissue metabolism in men [32]. After androgen deprivation therapies, such as either castration or a luteinizing hormone-releasing hormone analog for prostate cancer patients, also promote the development of obesity [33]. Aromatization of testosterone into 17β-estradiol (E2) is also critical to energy homeostasis in males [34]. In fact, hypogonadism after castration caused abdominal obesity in high-fat diet (HFD)-fed, but this phenotype was not induced in mice treated with antibiotics that disrupt the gut microflora [33]. As described above, a crucial reason that androgen deficiency lead to obesity is altered by the gut microbiome. In fact, androgen deficiency also can alter the gut microbiome and induce abdominal obesity in a diet-dependent manner [33], it has been found that the Firmicutes/Bacteroidetes ratio and Lactobacillus species increased in the feces of HFD-fed castrated mice [33]. At present, modulation of the gut microbiota through probiotics has been shown to ameliorate obesity and associated metabolic disorders both in animals and in humans. The two most commonly used probiotic which can enhance gut health are bifidobacterium and lactobacillus [35]. Bifidobacteria and A. muciniphila have been shown to improve high-fat dietinduced metabolic disorders, including fat-mass gain, metabolic endotoxemia, adipose tissue inflammation, and insulin resistance [36-38]. Treating PCOS rats with Lactobacillus and fecal microbiota transplantation (FMT) from healthy rats can decrease androgen biosynthesis [39].

Type 2 diabetes mellitus

Obesity and insulin resistance are major predisposing factors to type 2 diabetes, actually, androgen is also a main driver to it [40]. For example, androgen receptor knockout mice developed significant insulin resistance rapidly [41]. A polish study of gonadotropininduced hypogonadism (HH) in type 2 diabetes mellitus (T2DM) males showed a negative association between HbA1c and cfT [42]. A meta-analysis showed a significant decrease in testosterone levels in men with type 2 diabetes mellitus [43]. Similarity, for female, AE has been suggested as risk factor for T2DM [43]. However, it has already described in the above that androgen levels are not solely mediated through their level of endogenous secretion, it is also related with gut microbiome [44]. Patients suffering from T2DM have significantly lower gut microbiota diversity compared to healthy controls [45]. Evidence of an increase in testosterone levels due to gut microbiome transfer coupled with direct evidence of testosterone synthesis from bacteria highlight the interaction between microbiome composition and testosterone levels. These testosterone-associate microbiotas may influence sex hormone driven disease states such as T2DM. In addition, inhibition of testosterone through SCFA and blockade of androgen receptor for female in late gestational can alter AE condition and reverse glucose dysregulation [24]. All of this result demonstrates that not only testosterone is important in the development of T2DM, the appropriate gut microbiota composition associate with androgen also plays a crucial role.

Polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common cause of androgen excess in women, affecting 5-10% of women of reproductive age [46], characterized by hyperandrogenism, hyperandrogenism, anovulation, and ovarian cysts [47], which contributes to infertility and metabolic problems. The pathogenesis of PCOS remain unclear, some researchers shows that it is related with dysbiosis of gut microbiota. As above, gut microbiota influences the level of testosterone. Patients suffering from PCOS tend to have less diverse gut bacteria than women who do not have the condition [48,49]. In germ-free mice, fecal microbial transplant from letrozole (a nonsteroidal aromatase inhibitor) induced PCOS model indicated that gut microbiota has a close relationship with its host’s sex hormone levels and estrus cycles [50]. According to another mouse model experiment, female recipients of male cecal microbiota displayed increased testosterone levels, compared with unmanipulated females and female recipients of female cecal micriobiota [51]. Many of the conditions such as metabolic syndrome, infertility, polycystic ovary syndrome (PCOS) and cancer have been shown to be alleviated via bariatric surgery [52]. Besides, alteration of the gut microbiota through bariatric surgery has been shown to alter many of the negative metabolic signatures indicative of metabolic syndrome [52]. However, alleviate the symptom of PCOS not only through weight loss but also modulate hormone levels which may through changes of gut microbiota condition. Fecal transplantation from healthy rats to a rat PCOS model as well as lactobacilli transplantation has been shown to improve estrous cycles and decrease androgen biosynthesis [53]. PCOS has also been shown to be resolved through administration of metformin [54], which can regulate compose of gut microbiota [55] and used in treatment of type II diabetes.

Male hypogonadism

Late-onset hypogonadism is characterized by low serum testosterone levels and associated symptoms of poor morning erection, low sexual desire, erectile dysfunction, inability to perform vigorous activity, depression, and fatigue [56].These symptoms can have a major impact on men’s quality of life, especially when they affect relatively young men [57]. The two-prevailing theory of low testosterone levels in hypogonadism is due to a combination of reduced pituitary LH drive and a direct impairment of testicular function [58]. Currently, there are some researches indicated that gut microbiota may reduces leptin sensitivity and lead to leptin resistance. For example, a study of gut microbiota and leptin sensitivity showed that leptin treatment significantly reduced the body weight of germ-free mice compared to conventionally fed mice [59], at the same time, the hypothalamic expression of leptin resistance-associated suppressor of cytokine signaling 3 (Socs-3) was increased in conventionally fed mice more than germ-free mice [60]. Generally, leptin directly stimulate the anterior pituitary [61], and increasing hypothalamic GnRH pulsatility [62], to increases LH and FSH release. At a state of leptin resistance, leptin action impaired and hypothalamic pituitary axis function declined, which lead to low serum testosterone.

There is also other abundant evidence linking gut microbiota with a direct impairment of testicular function leads to low testosterone. Absence of the normal microbiota influences the formation and the integrity of the blood-testis barrier (BTB) as well as the intra-testicular levels of testosterone [63]. Leptin also can reduced tight junction-associated proteins in Sertoli cells to impair blood test is barrier integrity [64]. In addition, the lysis of gram-negative gut microbiome leads to the continuous production of lipopolysaccharide (LPS) [65]. There are some studies indicated that oxidative stress due to LPS-induced inflammation related to apoptosis of Leyding cells [66-69]. Through recognizing LPS, Tolllike receptor 4 (TLR4) activates innate immunity and promotes the secretion of proinflammatory cytokines [70]. The cytokines such as TNF-α, IL-1β, and IL-6 directly inhibiting testicular function, for instance, inhibit the Leydig cell function by regulate steroidogenic acute regulatory protein and regulate function of Sertoli cell to impair testosterone production [71,72]. Probiotics have a positive role in improving testicular function. For example, bifidobacteria positively correlated with leptin levels in mice [73]. Fed the purified L. reuteri to mice presented significantly larger testicles and dominant male behavior compare with common controls [74]. Indeed, rats fed a high-fat diet fed probiotic mixture containing lactobacillus and other probiotic bacteria also can prevent sperm oxidative stress and associated sperm quality decline [75].

Future Areas of Study

Given the mounting evidence of the effects of the gut microbiome on androgen-related disease, these results provide important implications for two research directions in future: gut microbiota-based intervention and gut microbiota-based diagnostic criteria for AD or AE. Firstly, elucidating the mechanisms underlying the associations between AD (or AE) and gut microbiota will be instrumental in the development of this target to combat it. The molecular mechanisms are expected to be multiple. For instance, as discussed above, gut microbiota dysbiosis could affect SCFA metabolism which is associated with gonadotropin levels, blood-testis barrier and phosphorylation of CREB. In addition, gut microbiota can regulate androgens through secretion of β-glucuronidase, an enzyme that can cleaves off glucuronide from androgen conjugates. Future research may be targeted to finding efficient ways of promoting a healthy microbiota. Although the role of modulate gut microbiota to regulate androgen levels has been gradually confirmed, randomized control studies are needed to better define the therapeutic efficacy of treatment of androgen-modulated disease. Characterization of the microbiota and metabolome composition before and after bariatric surgery, take probiotics or FMT may help elucidate microbial and metabolic components of healthy and disease states which could have further therapeutic and diagnostic applications [76-79].

Earlier diagnosis is effective in the treatment of androgenrelated diseases. Identification and validation of specific bacterial taxonomic groups sensitively altered in AD (or AE) patients can be developed as gut microbiota associated biomarkers may help predict or detect AD (or AE) and improve detection accuracy. Certainly, the idea that gut microbiota serves as a biomarker of these diseases is premature with the currently available data, and comprehensive comparison of changes in bacterial species in patients with other diseases should be performed first to examine their specificity. Therefore, a lot of work needs to be done to verify the feasibility of this strategy, and then large-scale trials need to be conducted to develop diagnostic criteria based on gut microbiota and validate its accuracy, before it can be adopted in clinical practice.

Conclusion

In decade years, infertility caused by AE in female and AD in male is increasing and it has become an increasing public health problem. There is growing evidence shows that modulate the gut microbiota can affect androgen levels, which offers exciting future therapeutic applications. Modulation of the gut microbiome through bariatric surgery, fecal microbiome transfer, probiotics and pharmaceutical (metformin) methods also shows promise for combating the metabolic aspects of disease states, which subsequently contribute to resolving related disease. Beyond to that, gut microbiota could also be used to diagnostically in unison with serum and urinary to identify risk factors for these diseases or as a biomarker. However, the impact of specific microbiota composition on the metabolic profile is an emerging area of research. With the development of technology, the relationship between microflora and androgenrelated diseases will be more and more discovered. Regulate gut microbiota may provide an attractive diagnostic and therapeutic target for future research to improve the associate infertility.

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Iris Publishers-Open access Journal of Textile Science & Fashion Technology| Recent Developments in Textile Materials Based on the Piezoelectricity Concept

 

Authored by Fernanda Steffens*,

Abstract

Textile materials stand out for presenting various characteristics that allow them to be used in technological solutions in the most diverse areas. In this sense, one may emphasize the growth in studies that cover the piezoelectric technology inserted in the textile area. This study aimed to gather the main and current innovations surrounding piezoelectric textile materials to highlight the various possibilities that this theme offers. For such, a search was carried out with keywords that relate piezoelectricity to textile materials, presenting 132.409 scientific papers published in the last five years. Lastly, this bibliographic review contributed positively to a view of opportunities inserted in the large textile area. Moreover, it was possible to observe some innovations and the ascension of the theme in terms of new developments.

Keywords:Piezoelectricity; Textiles; Technological products

Introduction

Textile materials stand out more and more due to their technological characteristics, and one may evince the piezoelectric technology inserted in the area of textile materials [1]. Piezoelectricity is the ability of a material to generate electrical energy from a mechanical stimulus and vice-versa [2]. This property was first found in natural crystals and later discovered in ceramic and polymeric materials [2,3].

The use of this technology in textile materials is praised, especially due to the flexibility and lightness that the textile products offer, allowing the necessary movement for the piezoelectric textile product to generate electricity in a simple manner [4].

The use of piezoelectric textiles is found in various areas such as the medical and health fields [5], with materials able to generate an intravenous electrical field used for electrotherapies, brain stimulation, and skin tissue regeneration, among others [3].

With this, developments concerning the mentioned theme are on the rise, and this may be determined through searches on platforms such as Google Scholar and Science Direct, considering keywords related to the theme. For such, a search on the platforms mentioned before was carried out considering the following terms: piezoelectric AND textile, piezoelectric AND fabric, piezoelectric AND “knitted fabric”, piezoelectric AND yarn, piezoelectric AND nonwoven, piezoelectric AND filament, AND piezoelectric and manufacturing. This search considered only scientific papers, excluding patents and/or books, and the state of the art defined for the search was five years, from 2017 to 2021.

Based on the search results, regardless of the words selected, an increase in publications was noticed since, in total, 132.409 scientific papers were published in the last five years that relate piezoelectricity to textile materials. The data may be observed in Table 1. It is possible to observe that the search keyword covering piezoelectricity and knitted fabric has the lowest number of publications. In this sense, it is verified as a potential area of the textile industry to be explored in terms of products with piezoelectric properties. This ends up being quite interesting since knitting technology provides materials with elastic characteristics, which are important for developing the piezoelectric behavior. Among the words selected, the highest numbers in terms of publications were verified for the term that covers the manufacturing of piezoelectric materials, once again confirming the great potential of this technology.

Table 1:Publications from 2017 to 2021 about the theme of piezoelectric textiles.

From this study, some examples of applications of piezoelectric textile materials were verified in the literature, confirming the various possibilities that this theme offers.

Applications of Piezoelectric Textile Materials

Textile products with piezoelectric characteristics are inserted in the most diverse areas. For example, one may mention the development of piezoelectric and flexible acoustic sensors [6], devices built in layers based on piezoelectricity concepts to capture electrical energy [7], and materials for use in the medical area with the ability to release drugs [3], among others.

Monitoring of human conditions

A study by Naeem et al. [1] evinced the development of a piezoelectric textile device built from polyvinylidene fluoride (PVDF) nanofibers obtained from the electrospinning method incorporated into a knitted fabric with the aid of a sewing technique for use in monitoring the angles of the human body during a given activity. The results confirmed the piezoelectric behavior of the device, given that its electrical response increased as an increase in the curvature (angle variation) of the human body occurred [1].

High-tech piezoelectric products

Yu et al. [8] presented a waterproof piezoelectric textile device with good breathability properties, characteristics still challenging for a piezoelectric material due to the need to incorporate electrodes at the ends. In this study, the authors developed a material built in layers, with the outermost layers being of conductive woven fabric with zinc oxide (ZnO) nanoparticles and a central layer formed of electrospun PVDF nonwoven fabric. The final device presented an average voltage of 1.6 ± 0.08 V and maintained this result even after being submitted to 3600 cycles of a pressure test. Regarding the hydrophobicity test, the material corresponded to a contact angle ranging from 119.87° to 107.41°, thus confirming its waterproof characteristic [8].

Textile machinery components

The so-called “Piezo technology” is present in components for manufacturing textile products. An example is the selection of piezoelectronic needles for use in both weft and warp knitting machines in circular Jacquard and Raschel machines, respectively, developed by Johnson Matthey Piezo Products GmbH®. The set of needles operates electronically and contains piezoelectric technology based on ceramic materials. This technology provides an increase in the productivity of the mentioned machinery since the actuators based on piezoceramics have high quickness in their process compared to the selection of needles. Moreover, it offers a cost reduction, given that it consumes less energy, in addition to not requiring a cooling system because the actuators do not heat up during the operation. Other beneficial characteristics of the technology are the innovative designs, ability to produce different patterns, and long lifespan [9].

Challenges and Perspectives

Piezoelectric materials find challenges regarding their development and the definition of standardized tests to verify the piezoelectric effect, especially when the textile device in question is built in layers, with each layer possibly being formed by a different textile technology, such as weaving, knitting, and nonwoven fabric, among others [2].

However, reinforcing the data presented in Figure 1, in which different textile technologies associated with the term piezoelectricity were selected, one may confirm that the mentioned theme is on the rise and covers various areas within the textile chain.

Conclusions

This work gathered innovations surrounding piezoelectric textile materials, highlighting some areas of application of such products. Through a search on scientific paper platforms, this study evinced the growth in publications regarding the keywords that cover piezoelectricity and the textile area.

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Iris Publishers-Open access Journal of Neurology & Neuroscience| An Unusual Cause of Dizziness: Persistent Ground Sickness in Duane Syndrome

 

Authored by Marco Poloni*,

Case Presentation

A young man, 30 years old, was submitted to a neurologic examination due to the persistence of rocking and swaying sensations with unsteadiness which raised after a boat excursion of one afternoon duration in the sea around Maddalena archipelago in Sardinian area. The persistence of dizziness aroused as ground sickness - mal de debarquement (MdD) in presence a second rare disease such as Duane Syndrome (DS) raises the question of a possible relation between these two diseases. Interestingly these are two coexisting “rare diseases”. The case here described showed a pure absence of abduction in OD without a restriction of palpebral fissure on abduction, nor reduced visual acuity at binocular vision; he didn’t notice any manifestation of amblyopia in OD and didn’t showed a turning compensation of the head. He was fully compensated and never had dizziness or similar disturbances until the boat excursion four years ago. The clinical overall visit as well as the neurological examination revealed entirely normal with the exception of oculomotion alteration, present since the birth and diagnosed as Duane Syndrome (DS); with this exception Oculist and ORL examinations were normal; blood controls, imaging and electrophysiologic examination were at the same without any abnormal findings. In conclusion, the Oculist examination diagnosed a Duane Syndrome; The MR imaging of the brain was entirely normal. After the boat trip of half day duration, he begun to feel instability and body oscillations and overall sensations similar to those he felt when he was on board; this vertigo and dizziness, were present for 4 years and became really uncomfortable, with anxiety, depression, joined to job and daily life difficulties.

Background

• Duane Syndrome (DS) or Duane Retraction Syndrome: Also known as (Stilling-Turk-Duane Syndrome) is a congenital strabismus occurring in isolated or familial forms, described by Alexander Duane in 1905 [1]: in the complete form it consists of -complete or partial loss of abduction, -retraction of globe on abduction, -narrowing of palpebral fissure on abduction, -partial deficiency of adduction, - oblique involvement with attempts on abduction, - upshoot pr downshoot of globe with abduction (Leash Phenomenon), - widening of palpebral aperture with abduction, - deficiency of convergence; it has a prevalence of about 1/1000, slightly more common in females, accounts for up to 4% of strabismus cases, is the most common form of congenital abnormal innervation, appears isolated in most cases (70% )or in 30% of them associated with other congenital alterations as we will see later; it is mainly unilateral in 90% and sporadic, while in 10% is bilateral and associated vertical movement abnormalities with a left eye preference. The most commonly accepted pathophysiology in the neurogenic theory suggests the presence of absent or dysplastic nuclear motor neurons with aberrant innervations of the lateral rectus muscles by the oculomotor nerve. The differential diagnosis for DS include any condition that demonstrates strabismus or limitations of extraocular movements. These includes: Okihiro’s syndrome (DS plus radial ray defects), Goldenhar syndrome (DS and malformation of the jaw, cheek and ear, on one side), Wildervanck syndrome (DS plus Hlippel-Feil anomaly and deafness), Moebius Syndrome (DS plus facial paresis), Holt- Oram Syndrome (DS plus upper limbs abnormalities and heart), Morning Glory Syndrome (DS plus optic disk abnormalities), Abducens Nerve Palsy, Brown Syndrome (limited elevation of the eye by malfunction of the superior oblique muscle), Marcus Gunn Jaw Winking Syndrome (blepharoptosis with synkinetic movements of eyelid elevation during mastication), and Congenital Esotropia (a form of strabismus). There are familial cases: Type 1: Autosomal Dominant (locus 8q13); Type 2: Autosomal Dominant (mutation of CHN1 gene at DURS 2 locus 2q31-q32.1) and Type 3: Autosomal Recessive. Molecular genetic testing of CHN1 is recommended only in familial cases. Management includes the use of spectacles or contact lenses or refractive glasses to improve the compensatory head position; the treatment of amblyopia with standard therapy; the use of Botulinum Toxin decreases the amount of deviation and leash phenomenon (upshoot or downshoot of globe with adduction. Surgery cannot cure Duane Retraction Syndrome, but it can correct for the deviation in the primary position, thereby improving a compensatory head position that can occur in some individuals; It can also improve the Leash phenomenon [2].

• Motion sickness and Mal de Debarquement: Acute motion sickness (MS) arises during passive transportation and resolves spontaneously within 1-3 days at the most after the disappearance of the inducing stimulus. The full picture of acute severe motion sickness evolves with symptoms of lightheadedness, physical discomfort, tiredness, periodic yawning, pallor and light dizziness with apparent surround motion and self-motion. An increase in facial pallor is followed by cold sweats, increased salivation, hypersensitivity to smells, occipital head pain, and feelings of pressure in the upper abdomen. Finally, the central symptoms of nausea, retching, and vomiting develop with motor incoordination, loss of drive and concentration, apathy, and fear of impending doom. MS is not only provoked by vestibular “overstimulation” during strong accelerations of the body, but by unfamiliar (i.e., nonadapted) motion stimuli and particularly by intersensory perceptual incongruencies among the visual, vestibular, and somatosensory systems. The most important concept explaining the pathogenesis of MS is the so-called mismatch theory; the decisive trigger is the incongruence of the signals of motion from various sensory channels or the incongruence between expected and actual sensory stimulation. On a ship we can suffer by seasickness, but we can adapt with time; when we return back walking, we can suffer again of a disturbance similar to sea sickness which take the name of groundsickness or MdD, at least until the vestibulum adapt to the new stationary network conditions: . The MdD is a stance and gait unsteadiness with postural vertigo that develops on land after longer ship travel [3,4]. Moeller and Lempert [5] speculated that it has to do with pseudo hallucinations of the “vestibular memory.” Such complaints can occur at short notice in the form of sensorimotor aftereffects even in healthy subjects after a long-persisting motion stimulus (e.g., “seamen’s legs”). Patients suffering from this condition exhibit impaired postural stability, kinesiophobia [6], and fatigue [7]. This syndrome lasts for months or years with a substantial economic burden [8] and recalls the development of somatoform vertigo similar to that of phobic postural vertigo. Physical means of prevention of MS is adaptation (habituation) by intermittent exposure to the stimulus. This adaptation, however, is only temporary and specific for each type of acceleration, i.e., resistance to seasickness does not protect from flight sickness. If “vestibular training” does not make the subject resistant, his/her head should be kept still during the stimulus, and additional accelerations that are complexly coupled with the vehicle motion should be avoided. Susceptibility is less when lying than when sitting. MS develops above all in closed vehicles or while reading on the back seat of a car, when the body is being accelerated, but a stationary environment is being viewed, which contradicts the labyrinthine stimuli. By maintaining adequate visual control of the vehicle movement, one can significantly reduce MS from that experienced under eyesclosed conditions. Conversely, susceptibility is significantly increased if primarily stationary contrasts fill the field of vision. Anti-vertiginous drugs such as dimenhydrinate (Dramamine) or scopolamine (Transderm Scop) can inhibit the spontaneous activity of the neurons of the vestibular nuclei, thus reducing the susceptibility to MS and to MdD.

• Vertigo: vertigo is a very unpleasant symptom for the patient. Vertigo may be defined as a distorted perception of the position and/or movement of head in the space, accompanied by nausea, vomiting and other vegetative symptoms at times; other supplementary signs may be nystagmus and postural deviations with falls. If we consider the structures which give a contribution to our perception of the position and shift of our head in the surrounding and that maintain our balance in the space, we must look to: - vestibular receptors, located in the inner ear and providing the brain with afferents about head position and movement, - visual system which has a dominant position through sight, - proprioceptors, in the spine, legs and feet which send ascending information on position and movement of body segments; we have to remember the contribution of the cerebellar afferents carrying unconscious information and, in a subsidiary way, the exteroceptive sensitive system too: remember the contribution to the stance of walking in the sand and sea!. When sight, vestibular, proprioceptive, cerebellar and exteroceptive afferents give a concordant information to the nervous system everything sounds well with feeling of balance; when the information along the channels is discordant, something wrong happens, and we feel unhappy and have a sensation of unbalance and dizziness [3].

Discussion

As concerns the MdD in a patient affected by DS, it seems to much easy to explain the appearance of vertigo through psychogenic solution and I prefer to seek for an abnormality of physiologic mechanisms. Dizziness is present in various conditions of visionrelated problems, including eyestrain, incorrect prescription of eyeglasses or lens, binocular vision disturbances, double vision and nystagmus. It is well known that several conditions favour physiologic dizziness and unbalance: 1) If we are looking to a large object engaging to a wide extent our visual field when it moves, we feel uncertain if what is moving is the object or ourselves, and we feel unstable; we are steady, but the sight give a movement information; 2) When we are carried by a car or by train or plane we are moving, and our vestibular system is stimulated, but our sight and our proprioception give information of absence of movement, above all if we are reading or concentrated on a particular job; we begin to suffer motion sickness (MS) and feel nausea and vomiting; 3) If you go to skiing in a bad weather day with fog, cloudy sky and snow, you really don’t have any reference and everything around you is white and you leave completely the orientation in the space and feels very badly with nausea and vomiting; in these situations, is necessary to concentrate on proprioception and seek the aid of exteroceptive stimuli to gain information. Vestibular receptor is very sensible but fortunately has the characteristics of being plastic and adaptable too: the correct name of this propriety is habituation. We have illustrated just few examples of what we can call physiological vertigo, or pseudo-vertigo, simply due to a variant information through the different afferents responsible to integrate our steadiness in the space in normal situations. There are, also, examples of habituation and training: certain boys have fun revolving on themselves until they fall; the Darvish dancers revolve giddy for 10-20 min or more during their exhibitions; who practices the circular bound flight is used to flight in this way an aero model. Now, if you put attention to the different and very intricate modalities through which the pertinent information reaches our brain you can even find the key to solve the problem of your patient: something went wrong in vestibular apparatus and the pattern of stimuli became discordant between the two sides? Or, due to the numerous connections and intricate pathways of vision, vestibular, cerebellar, proprioceptive and exteroceptive afferents you can consider the variety of dysfunctions and diseases which affects this extremely complex network: I wish just recall a couple of strange and unexpected causes of vertigo which I had the chance to observe: one was a colleague who felt dizziness in the morning at the beginning of own work; no information was gained by careful history and objective examination, until he remembered that had changed the lenses of the spectacles! Another patient felt dizzy when he exceeded the speed of 100 Km/h on the highway towards Milan; here, I was uncertain if the problem was sight related due to the rapid change of images or if it was psychogenic and fear connected, a sort of already cited kinesiophobia; another particular case was a retired man who had a mastoid fistula rear to the right ear; he felt vertigo when he had a dive or a dip in the sea: here the problem was most probably linked to a vestibular stimulus induced by a sudden drop of temperature near the semicircular channels with consequent convective motion of the endolymphatic fluid; It was like a real life Barany Test! Last case was that of two brothers, a female and a man, who were always disturbed by sensations of instability and unsteadiness; both were found affected by familial hemochromatosis and that was the origin of derangement of labyrinthic function; the successful treatment was based in these cases on periodic blood-extraction. DS should lead to dizziness and vertigo, due to the visual disturbances of double vision, and we have seen how much important appears the sight in the symptom of vertigo; moreover, anisometropia and amblyopia were highly prevalent in DS, with the latter generating the former in a significant association [7]. The duration of MdD has been described lasting from 6 months to 10 years (mean 3,5 years) in a survey [10]. Cases of motion triggered (MT) DS and non MT DS have been described [11] with a duration variable, with a mean of 35,4 months (mean 12; range 1-204) for MT and. 82,8 (mean 62,9; range 18-255) for non MT. Interestingly, metabolic and functional connectivity changes have been described [12] in MdD syndrome characterized by an association between entorhinal cortex and amygdala providing both a clearly objective brain modification in an entirely subjective discomfort and both a natural model to study neuroplasticity of the motion adaptation system in humans. The troubling symptoms may find a compensatory action by counterbalanced head turn and by the gradual onset of amblyopia; in this case nor diplopia neither amblyopia were present, most probably due to a compensation. In occasion of the onset of vertigo and dizziness due to MdD the symptoms of dizziness might be unmasked; in other words the equilibrium achieved since the presence of this problem from birth was breached off by the boat trip and the appearance of MdD with its peculiar sensorial manifestations; the introduction of a further mismatch between the different factors responsible of balance on a saturated ground lead to the impossibility to find a further compensatory solution. Obviously, it is well known that panic attacks of phobic-obsessive neuroses may generate vertigo, a condition called Kinesiphobia, and that psychosomatic disturbances in patients affected by different forms of anxiety, depression and unhappiness may give a significant contribution to the onset of vertigo and dizziness [13]; nevertheless, a similar contribution without the comprehensive characteristics of mood and personality in the patient here described seems quite unlikely. A dynamic of this type or the coexistence of different factors in the origin of this peculiar disturbance can’t obviously be ruled out.

Conclusion

The Oculist examination diagnosed a Duane Syndrome; The MR imaging of the brain was entirely normal. After the boat trip of half day duration, he begun to feel instability and body oscillations and overall sensations similar to those he felt when he was on board; this vertigo and dizziness, were present for 4 years and became really uncomfortable, with anxiety, depression, joined to job and daily life difficulties.

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Iris Publishers-Open access Journal of Hydrology & Meteorology| Remote Sensing Analysis of Water Quality in Reservoirs at Water Fund Locations

 

Authored by Fernando Miralles-Wilhelm*,

Abstract

This investigation introduces remote sensing (RS) methods for monitoring of water quality in support of measuring, understanding, and managing impacts in sensitive water bodies that are part of the Water Funds portfolio. The water bodies focus of this work are as follows: the Jaguari-Jacarei Reservoir in the Cantareira reservoir system (Sao Paulo Water Fund); the Ribeirao das Lajes Reservoir in the Guandu River systems (Río de Janeiro Water Fund); the Rio Grande Reservoir in the Medellin reservoir system (Cuenca Verde Water Fund); and the Thika Reservoir in the Nairobi reservoir system (Upper Tana-Nairobi Water Fund). This study focuses on the development and application of a RS data processing pipeline that detects phytoplankton abundance as a proxy for pollution by nutrients, as well as sediments, which are the major water quality issues identified across the Water Funds portfolio. This pipeline is tailored to specific reservoir systems of interest to Water Funds stakeholders and thus provides a comprehensive dataset for a suite of water quality parameters. Additionally, this pilot leverages remote sensing data archives to provide a baseline assessment of how these metrics behave over time and in space. Remote Sensing applied to monitoring of water quality in lakes, rivers and reservoirs is a valuable emerging technology that can provide geospatial information about water clarity, nutrient, bacterial and industrial pollution from urban and rural sources. The methodology presented in this paper using cloud computing allows rapid monitoring deployment and scalable coverage across numerous watersheds and geographies. Although this paper presents a comprehensive analysis of this entirely new source of water quality data across the sites and locations of interest, a more detailed analysis can be performed by looking at different timeframes (e.g., entire data set or monthly aggregates) within these watersheds. Additional insights may be unraveled by further combining the water quality data sets of this work with other sources of information including local sensors, information from water and sanitation utilities and a more detailed analysis of the timing of location conditions and their local impacts.

Introduction

This investigation introduces remote sensing (RS) methods for monitoring of water quality in support of measuring, understanding, and managing impacts in sensitive water bodies that are part of the Water Funds portfolio [1]. More specifically, this study pilots the use of a satellite-imagery-based data processing pipeline that operationalizes the creation of location-specific water quality data products. Such products provide conservation scientists, organizational decision-makers, and other stakeholders in the Water Funds community with a comprehensive measurement basis to complement future monitoring efforts and inform investment planning to improve water quality in the Water Fund. This study provides detailed, site-specific RS products for water quality that are relevant for management and planning, as well as examples of how these products can support management planning and restoration implementation. Moreover, this study provides a methodological baseline for the use of RS across the Water Funds portfolio. Importantly, this approach allows for asynchronous and systematic monitoring that can aid Water Funds with impact monitoring of conservation and restoration actions and increasing efficiency in tactical and strategic decision making.

The methods used allow for easy-to-scale and systematic monitoring, analytics, and reporting for water quality stakeholders, increasing efficiency in tactical and strategic decision making. The specific focus of this study is to develop an automated RS data processing chain enabling detection of phytoplankton abundance (chlorophyll-a) as a proxy for pollution by organic and inorganic nutrients, as well as sediments (and turbidity or water ‘clarity’). These water quality parameters are typically driven by land-erosion and runoff processes and also often contain other pollutants from urban environments such as untreated or partially treated sewage or effluent. Excess nutrient loading, and urban runoff and wastewater pollution due to inadequate sanitation are representative of major water quality issues worldwide.

The water bodies focus of this work are as follows: the Jaguari- Jacarei Reservoir in the Cantareira reservoir system (Sao Paulo Water Fund); the Ribeirao das Lajes Reservoir in the Guandu River systems (Río de Janeiro Water Fund); the Rio Grande Reservoir in the Medellin reservoir system (Cuenca Verde Water Fund); and the Thika Reservoir in the Nairobi reservoir system (Upper Tana- Nairobi Water Fund). This study focuses on the development and application of a RS data processing pipeline that detects phytoplankton abundance as a proxy for pollution by nutrients, as well as sediments, which are the major water quality issues identified across the Water Funds portfolio. This pipeline is tailored to specific reservoir systems of interest to Water Funds stakeholders and thus provides a comprehensive dataset for a suite of water quality parameters. Additionally, this pilot leverages remote sensing data archives to provide a baseline assessment of how these metrics behave over time and in space. It is the hope that data pipeline, water quality products, and analyses will assist in more targeted monitoring, risk mitigation and eventual prevention of sediment and nutrient pollution and subsequent eutrophication.

Methodology

Remote sensing datasets

At the core of this pilot study is a dense satellite time series dataset continuously collected over each of the four sites since early 2016. The two Sentinel 2 satellites orbit asynchronously to provide a new image of a location on the earth’s surface every 5 days at the equator (2-3 days at the mid-latitudes). Each image has 13 unique spectral bands available in a resolution of 10-60m, depending on the band.

These multi-spectral images provide a snapshot of the earth’s surface beyond the visible red, green, and blue spectral bands available from a typical consumer-grade digital camera image. For example, the amount of water present in vegetation canopies can be calculated using spectra invisible to the human eye, the near infrared, and shortwave infrared bands on Sentinel 2A (8A, 11, and 12).

Satellite imagery datasets are acquired from the European Space Agency’s Sentinel 2 A & B platforms, which can produce a high-resolution (10-20 m) multispectral (490-865 nm) image at the same location on Earth every 5 days. These imagery data are distributed free for public use and are used as the starting point for the satellite data processing methodology. This methodology ingests the raw top-of-atmosphere imagery, corrects for atmospheric effects, calculates a suite of WQ metrics, and creates a data repository for use across different display and analysis platforms. For this study, three different WQ metrics are calculated and used for the assessment of each water body.

Chlorophyll-a measures the concentration of phytoplankton growing in the water and is expressed in milligrams per cubic meter (mg/m³). Water quality problems associated with changes in this water quality parameter are typically caused by nutrient pollution.

Turbidity measures the optical clarity of the water and is supplied in Formazin Nephelometric Units (FNU).

Suspended Matter measures the concentration of fine particles, both inorganic and organic, that are suspended in the water and is supplied in units of grams per cubic meter (g/m³). Water quality problems associated with changes in this water quality parameter are typically caused by sediment pollution.

All resulting WQ product datasets are georeferenced, cloudscreened, and adjusted to account for localized water extent changes over time.

Adaptation of NASA’s Ocean color radiometry

Figure 1 illustrates the basis of the methodology used for processing of remote sensing observations into water quality estimates. NASA and other space agencies have established protocols for how this is done and following NASA nomenclature these top-of-atmosphere corrected images are referred to as processing level “L0”.

To make these images useful for calculating water quality parameters, the images must undergo a process that removes the effects of the atmosphere present between the satellite sensor and the earth or water surface. This process, termed atmospheric correction, implements a series of algorithms to reduce or eliminate the effects of atmospheric absorption and backscatter on the image, yielding a more accurate representation of the earth’s surface. The resulting images contain values for the remote sensing reflectance (abbreviated as Rrs) of the water body, which are referred to as “L1” in the commonly adopted NASA nomenclature. These processed images can then be used to derive a variety of data products.

Reflectance data processing approaches commonly rely on atmospheric correction processes based on open-source methods developed for inland and coastal water applications, such as the Royal Belgian Institute of Natural Sciences’ (RBINS) Acolite processor, the National Aeronautics and Space Administration’s (NASA) SeaDAS processor. The full image collections, also referred to as archives, containing the atmospherically corrected imagery and Rrs values, are used to calculate the three water quality (WQ) products in this pilot study; Chlorophyll-a, suspended matter, and turbidity concentrations.

We derived the following WQ products are obtained by applying relatively standard algorithms developed in the open scientific literature specifically for detecting the makeup of inland coastal waters.

a. Chlorophyll-a concentrations, which are measured in milligrams per cubic meter (mg/m³), are calculated using normalized difference chlorophyll index (NDCI) developed by [2].

b. The NDCI algorithm can be used to detect algae concentrations and blooms using the red and red-edge spectral bands.

c. Suspended matter and turbidity concentrations are measured in grams per cubic meter (g/m³) and Formazin Nephelometric Units (FNU), respectively, and are both derived from the methodology developed by Nechad B, et al. [3] for detecting total suspended matter (TSM) concentrations on the water surface.

It is important to note that the data in this research is not calibrated or validated against ground measurements, due to inconsistent availability of water quality data across the four study sites. The analyses used in this pilot study relied on the pixel-wise time series data extracted from the entire water surface across each site. Having datasets that were dense in both the spatial (10 m pixels) and temporal (1 new image roughly every 5 days) dimensions facilitated analyses that could focus on establishing WQ baselines, quantifying changes in temporal trends, and illustrating patterns in spatial distributions. Trends over time and within seasons were established using simple time series plots constructed from the average or median WQ data product value across the entire water surface or else constrained to Virtual Gage locations. Moving average filters were applied to time series data to both smooth spikes and interpolate across small gaps.

Spatial and temporal data analyses

Virtual gages: A Virtual Gage is a specific geographic region of interest in which water quality parameters are temporally assessed in greater detail than viable across the entire water body. The goal of establishing Virtual Gage locations is to extract data that enables rapid, flexible, and relevant investigation into areas where known WQ issues exist. Virtual gages are well defined points or areas of interest on a data map.

To establish a Virtual Gage location, we first collected information from local experts and the scientific literature about where WQ issues originate or tend to occur. Examples of this information include official WQ sampling locations, citizen science reports, known point source polluters, areas where rivers are input into a reservoir, or locations of critical infrastructure (e.g. drinking water or hydropower intake locations). Then, a spatially referenced area is created that reflects both the research and a statistically relevant pixel sample size. In this way, virtual gages allow us to generate time series for any point or area that is of interest on the data maps, as if we had placed a gage there physically. Virtual Gage locations were placed in areas close to densely populated regions and at least 50 meters across in rivers.

Seasonal trends: To better understand the seasonal effects on water quality parameter values, we created maps illustrating the average seasonal changes across the entire water body. This approach is illustrated in Figure 2. First, water quality values across the full archival time series were grouped into three-month intervals: December through February, March through May, June through August, and September through November. Then values were averaged through time to produce maps that highlight the seasonal differences. This allows for identifying periods during the year or location within the water body where trends are noticeable, providing a method to link hydrological and land processes, or prevailing meteorological conditions. Seasonal and meteorological drivers not only impact the urban and rural runoff but can influence the hydrodynamics (water mixing) including flooding, storm surge, sewage flows and light available for photosynthesis, and more generally photochemical processes within the watershed.

To further illustrate the differences within seasons and across years, we plot water quality time series data split by each year. Plots are produced for the entire water body as well as for each Virtual Gage location. Such plots can be produced for sub-regions of a waterbody or specific Virtual Gage locations, as shown in Figure 3.

Long term trends (Mann-Kendall trend test): Quantifying the direction and magnitude of trends in the time series data is important to contextualizing any significant annual fluctuations [4]. To do so a seasonally adjusted Mann-Kendall trend test was used to assess the presence, direction, and magnitude of a trend in the larger time series. Mann-Kendall tests are used to look through an entire dataset and quantify whether there is a significant fundamental change in the trend, regardless of the nature of the data distribution (i.e., no assumptions for a normal distribution) or linearity of the trend (i.e., it could be a non-linear trend). Seasonally adjusted Mann-Kendall trend tests were applied to each WQ dataset averaged across each Virtual Gage location. The results quantified the long-term behavior at each Virtual Gage location and helped differentiate the dynamics at locations where water inputs and outlets occurred.

The procedure used and its results is illustrated in Figure 4. First, the median water quality parameter value is calculated across a Virtual Gage location for each image date. Then, a Mann-Kendall test is applied to the full archival time series which provides the direction, magnitude, and statistical significance of potential trends at that location. The outcome indicates whether the time series data at that location has a consistent increasing or decreasing trend. This statistical assessment is particularly useful to understand the underlying variability and longer-term trends at specific locations.

Spatial variation maps

To quantify where water quality values are consistently high, low, and have high variability over time, we created spatial variation maps for each water body and water quality parameter (see Figure 5). This process calculates the median, standard deviation, and coefficient of variation on a pixel-wise basis through time. The product is a map that shows the spatial distribution of these summary statistics through time. These maps can be used to locate areas that stand out with consistently different water quality patterns or areas with high variability. Either of these areas could be locations that are valuable indicators of important processes or can be used as locations for more detailed monitoring.

Spatial trend maps

Next, extending the concept of spatial variation maps, we create spatial trend maps to visualize where temporal trends in water quality parameters are occurring (Figure 6). First, data across the entire water body is spatially binned by averaged to approximately 100m resolution. Then, a linear regression is applied along the temporal axis for each bin; a three-sigma outlier filtering process is used to remove outliers. Finally, the linear trends are visualized on a map where statistically significant (p-value below 5%) values are colorized based on direction and intensity. Similarly, to the Spatial Statistics maps, colorized areas can be used to understand areas or locations where long-term trends indicate a linear trend in underlying water quality over multiple years showing increasing environmental pressures on the ecosystems, or successful implementation of policies, land-use practice or water and sanitation projects.

Results and Discussion

Rio de Janeiro Water Fund (Riberao das Lajes Reservoir)

This is a part of a highly controlled reservoir system, with all developed inputs and outputs managed for hydropower generation and drinking water supply for the City of Rio de Janeiro [5]. The Ribeirão das Lajes reservoir itself is relatively shallow, has steep sides under water, and long water retention times Guarino AWS, et al. [6], which may contribute to the relatively high Chlorophyll-a levels observed across the entire reservoir and at the Virtual Gage locations 1-3 (Figure 7) [7]. The reservoir is at its highest levels at the end of the rainy season in April (~ day of year 100), during which both turbidity and suspended matter levels are at their highest (Figure 8). The reservoir is at its lowest levels in November (~ day of year 300), during which the Chlorophyll-a levels are among the highest (Figure 9). The seasonal algal blooms could be enhanced by generally lower sediment concentrations and turbidity and also by higher solar radiation during these months.

Across the entire site, higher turbidity and suspended matter levels are observed during the months of the Austral summer-fall (Dec-May) (Figure 8). This is particularly apparent in the adjoining downstream reservoirs, Reservatorio Vigario and Reservatorio Fonte Coberta, which correspond to Virtual Gauge locations 4 and 5 (Figure 10). The opposite signal is observed in Chlorophyll-a levels, with the highest levels occurring into the Austral winter-spring (Jan-Nov) and overall higher values observed in the main Ribeirão das Lajes reservoir (Figure 7). The considerably higher suspended matter and seasonally consistent concentrations at Virtual Gage locations 4 and 5 are likely associated with the control of pumping and hydropower at nearby facilities. Here, there is a notably higher increase in suspended matter for Virtual Gage location 5 compared to location 4, which is likely related to gradual changes in water flows at the two inputs.

Focusing on regions of interest, we find that at Virtual Gage locations 1, 2 and 3 there are consistently high Chlorophyll-a levels which follow clear seasonal trends. This is particularly the case at the dam structure and intake locations (Virtual Gage 2). The direction and magnitude of Chlorophyll-a concentration trends over time are relatively neutral since 2016, except for a slightly decreasing trend at Tocos tunnel outlet (Virtual Gage location 1). However, both turbidity and suspended matter levels are gradually increasing over the same time period (Figure 11).

Sao Paulo Water Fund (Jaguari reservoir)

The Jaguari-Jacarei reservoirs are interconnected and the first main reservoirs in the Cantareira System supplying drinking water to the City of Sao Paulo. The reservoirs receive input from a number of surface water sources, the primary being the Jaguari and Jacarei Rivers. While there are large inputs of organic pollutants from these increasingly eutrophic rivers, the large capacity and low residence time in the reservoirs has kept the overall water quality stable [8]. This is evident from consistently high Chlorophyll-a concentrations at the locations where both rivers enter the reservoirs (Virtual Gages 1 and 4) (Figure 12). Interestingly, at these same locations there is no observable trend of Chlorophyll-a levels throughout the entire time series (Figure 13).

While most of the Mann-Kendall trend analyses showed little or no changes in the trend of all the water quality metrics throughout the entire time series, the northern portion of the site, where the Jaguari Reservoir is located, had consistently higher median values in all water quality parameters over time. For example, this translates to a discrete geographic area in which Chlorophyll-a values have been consistently higher compared to those across the entire site (Figure 14).

Cuenca Verde Water Fund (Río Grande reservoir)

The Rio Grande Reservoir lies at the confluence of the Grande and Chico Rivers outside of Medellin, Colombia. The reservoir is an integral part of the regional drinking water and hydroelectric power generation system and faces sedimentation challenges from both river inputs [9]. Additionally, increased industrial activities at and upstream of the reservoir are leading to greater nutrient concentrations and occurrences of algal blooms. Time series of turbidity and suspended matter show strong seasonal trends that correspond to the two distinct rainy seasons that occur between April-May and September-November (Figure 15).

High turbidity and suspended matter concentrations tend to occur at the main river inputs, with the Rio Grande River providing consistent sediment inputs year-round (Figure 16). This trend is also evident across the entire time series dataset, with consistently high median turbidity values occurring at both the northern and western portions of the reservoir where both rivers input (Figure 17).

There are consistently high Chlorophyll-a concentrations at all virtual gage locations across the entire time series dataset (Figure 18), however the overall trend is decreasing since 2016 (Figure 19). Figure 20 shows the spatial distribution of Chlorophyll-a concentrations across the entire water and highlights the far western portion of the reservoir to have persistently higher concentrations over time, this area also corresponds to Virtual Gage location 1.

Upper Tana- Nairobi Water Fund (Thika reservoir)

The Thika Reservoir supplies 75% of the drinking water to the city of Nairobi and faces increases in sedimentation rates as land-use changes continue to reduce forest cover in the upper watershed ([10,11]. Time series of turbidity and suspended matter concentrations show seasonal patterns consistent with the wet (November to May) and dry (June to October) seasons. Higher values during the wet season presumably correspond with increased runoff during that time (Figure 21). These seasonal patterns are evident across the entire site without much variation due to the relatively small size of the reservoir (3 sq. km) (Figure 22).

Each surface depicts the mean pixel value across the entire site throughout a three-month period. While there is some localized spatial variation, the small size of this site leads to rather consistent values across the entire area indicating good spatial and vertical mixing and limited prevalence of consistent hydrological or meteorological forcing inputs.

Summary

Remote Sensing applied to monitoring of water quality in lakes, rivers and reservoirs is a valuable emerging technology that can provide geospatial information about water clarity, nutrient, bacterial and industrial pollution from urban and rural sources. The methodology presented in this paper using cloud computing allows rapid monitoring deployment and scalable coverage across numerous watersheds and geographies.

This significantly lowers the costs of obtaining water quality information compared to laborious water sampling and collection methods. Furthermore, satellite data acquisition and processing are automated and available continuously across the globe, and new data are automatically analyzed and contextualized within seasonal or historical trends. This allows investments in water and sanitation infrastructure to be valued based on realized regional and community benefits and allows operators of water systems to reduce risks and lower operational and management costs.

Although this paper presents a comprehensive analysis of this entirely new source of water quality data across the sites and locations of interest, a more detailed analysis can be performed by looking at different timeframes (e.g., entire data set or monthly aggregates) within these watersheds. Additional insights may be unraveled by further combining the water quality data sets of this work with other sources of information including local sensors, information from water and sanitation utilities and a more detailed analysis of the timing of location conditions and their local impacts.

There is significant growth in available low-earth orbit satellite imagery or aerial imagery platforms used for observation from private companies such as Planet Labs and public agencies such as NASA, ESA, and others. Significant improvements are expected in how often new images are generated. Daily revisits for larger > 5~10 km water areas are already possible. Satellite imagery from commercial platforms is available at 1-meter spatial resolution, enabling access to narrower rivers (>10~20-meter width) and smaller ponds and lakes. These can be easily integrated for specific applications where daily data or high-resolution products are needed. Additionally, autonomous optical sensors provide coverage for smaller streams, and important surfacewater locations continuously, enabling improved accuracy of data obtained from satellite imagery and continuous information when satellite imagery is not available. Continuous monitoring of smaller river, stream, canal and could particularly be helpful to pinpoint sanitation and waste-water treatment hotspots, which in turn could inform more localized spatial extents where water quality impacts could be more concentrated.

These results and remote sensing technology in general, can be a useful addition to the toolkit used by infrastructure, and water and sanitation teams in general or more specifically to understand the impacts due to water quality interventions. The new datasets generated through this pilot can help provide insight in three key areas:

a. Inputs on where to measure and optimal in situ sampling rates: Remote sensing results pinpoint locations of high activity and variability throughout the year, helping to optimize the effectiveness of on the ground sampling by ensuring sampling is happening in the most interesting places.

b. Where to plan and develop future remediation or investment efforts: These data can also be used to identify locations where problems are most frequently occurring, as well as understanding the mitigation or remediation measures that should be applied. In addition to location, the scale of the needed intervention can be determined based on modeled or predicted impacts, and then verified during project implementation.

c. Inputs to help understand the ecological impact of construction, civil engineering, or other infrastructure projects: This remote sensing dataset on water quality gives us insight on what seasonal fluctuations are to be expected, and how levels of different water quality parameters are shifting over the long term. By combining this dataset with the timing and location of engineering projects, or interventions, meteorological and specifically rainfall data, as well as land use change information more generally, we can reach a more complete understanding of the downstream water quality and other environmental impacts from various projects.

This analysis of the water quality data sets can be extended by integrating local in-situ water quality data, or additional data on meteorological and hydrodynamics, as well as quantified geospatial datasets describing specific changes resulting from socioeconomic conditions (e.g., land use changes) across the locations, or other data sets as they become available. Local water-quality in situ data would allow validating and calibrating the satellite-based retrievals to get more quantitative results and the meteorological and hydrological data sets could provide additional context on the relationships between water quantity and quality. Additionally, geospatial information about wastewater infrastructure quality, waste outflow locations and changes in population movement during the lock-down could be used to identify locations for study further upstream within the urban system before significant mixing or dilution occurs. These additional datasets and analysis would allow these findings to be applied towards more quantitative and finer resolution scales in time and space.

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