Untreated Domestic Waste Research Articles

Spatiotemporal and vertical variability of water quality in lentic small water bodies: implications of varying rainfall and land use conditions.

Lentic small water bodies (LSWBs) deteriorate owing to anthropogenic activities, such as untreated domestic and agricultural waste disposal. Moreover, different turnover mechanisms occur during different seasons, contributing to nutrient enrichment and consequent degradation of LSWBs. However, understanding their spatial, temporal, and vertical variations during different seasons is understudied. In addition, studies on the variation in water quality under varying rainfall and land-use conditions are limited. Therefore, in this study, three LSWBs located in Northern India were studied during the pre-monsoon and monsoon seasons (December 2022 to October 2023). Total nitrogen (TN), chlorophyll-a (Chl-a), total phosphorus (TP), temperature, pH, dissolved oxygen (DO), total dissolved solids (TDS), chemical oxygen demand (COD),secchi disk depth (SDD), and water level (WL) were measured monthly. Sentinel-2 and CHIRPS pentad data were used for land use, land cover classification, and rainfall analysis. The spatial analysis indicates that the seasonal shift affects the water quality distribution, especially near the inlets and at the edges. The overall concentrations of TN and TP decreased during the monsoon season; however, they increased significantly at the inlets of the LSWBs. On the other hand, the Chl-a concentration shifted towards the edges due to the inflow during the monsoon. Temporal analysis also suggests that the arrival of the monsoon lowers pH, DO, and TDS. However, the concentrations of TN and TP increased because of agricultural runoff. Chl-a and COD show distinct variations due to the individual LSWBs' local conditions. Vertical variability analysis demonstrated pH, temperature, and TN stratification during the pre-monsoon period. However, during the monsoon, stratification is less significant due to intermixing. Redundancy analysis (RDA) showed that land use and rainfall patterns affected the water quality of LSWB 1, 2, and 3 by 53.49%, 81.62%, and 92.64%, respectively. This shows that land use, land cover, and rainfall changes affect the water quality of LSWBs. This study highlights the negative impact of runoff from agricultural land use as the main factor responsible for increased nutrient levels in the LSWBs.

Evaluating Surface Water Quality of Euphrates River in Al-Najaf Al-Ashraf, Iraq with Water Quality Index (WQI)

The present study illustrates the rapid pollution of Euphrates River, inwards Al-Najaf Al-Ashraf governance (Al-Kufa River) in Iraq, which is one of the most important rivers in the region. The river faces formidable pressure due to encroachments, discharge of untreated domestic and industrial waste, drainage water from cultivated orchards, and dumping of solid waste. This study was conducted to assess the temporary and locative organic pollution in the region. Water Quality Index (WQI) of the Al-Kufa river was determined according to the Canadian Council of Ministers of Environment (CCME) method by calculating seven parameters (water temperature, DO, COD, EC, TDS, turbidity, and pH) in two sampling stations. Surface water samples were collected in a period of four months (September to December) in 2023. WQI level, correlation analysis between parameters, and Iraqi and CCME drinking water specification standards were employed to classify the surface water status. The results show that the ecological condition can be classified as marginal with WQI= 49 and poor with WQI= 42 in stations 1 and 2, respectively.

Chemometric heavy metal contamination in tropical Indian estuaries: Implications for source identification

The impact of urban and industrial effluents in the tropical Indian estuaries (Ariankuppam backwater and Chunnambar River), east coast of India have been investigated in the present study by determining the degree of heavy metals contamination of the estuarine sediments. A total of 30 surface sediment samples were collected from both estuaries and were analyzed for trace metals, grain size and organic matter. The granulometric analysis reveals that both the estuaries are predominated by silty sand to sandy silt. The significant amount of organic matter (OM) in the Ariankuppam estuary sediment is due to natural (mangroves) and anthropogenic (pollution) organic input. Pearson correlation analysis reveals that there was a strong negative correlation of sand fraction with other sediment variables (silt, clay, and organic matter) and heavy metals, whereas a positive correlation was observed between silt+clay, organic matter, and heavy metals. The significant positive correlation of Fe with Ni, Cu, Pb and Zn presents Fe-Mn oxyhydroxides are the main controlling factor of heavy metals in both estuarine sediments. Cluster analysis and PCA helped to discriminate the station groups along both estuaries according to their sediment components and heavy metals. This study also revealed that sediment grain size is a key factor influencing organic matter and heavy metal accumulation in surface sediments. The calculated pollution indices such as Contamination factor (CF), Geoaccumulation Index (Igeo) and Pollution Load Index (PLI) values indicate that both estuaries are moderate to highly contaminated by Co and low to moderately contaminated by Pb and Zn. Based on the factor analysis, it is presumed that river runoff and industrial and untreated domestic wastes from lands are responsible for increased heavy metal concentration in both estuaries. Increased levels of metal contamination along the Union Territory of Puducherry coastline may increase the risk of human exposure to metals through the consumption of seafood, making the need for tougher regulations on the discharge of metals into the environment even more important.

The relationship between water quality and the microbial virulome and resistome in urban streams in Brazil

Urban streams that receive untreated domestic and hospital waste can transmit infectious diseases and spread drug residues, including antimicrobials, which can then increase the selection of antimicrobial-resistant bacteria. Here, water samples were collected from three different urban streams in the state of São Paulo, Brazil, to relate their range of Water Quality Indices (WQIs) to the diversity and composition of aquatic microbial taxa, virulence genes (virulome), and antimicrobial resistance determinants (resistome), all assessed using untargeted metagenome sequencing. There was a predominance of phyla Proteobacteria, Actinobacteria, and Bacteroidetes in all samples, and Pseudomonas was the most abundant detected genus. Virulence genes associated with motility, adherence, and secretion systems were highly abundant and mainly associated with Pseudomonas aeruginosa. Furthermore, some opportunistic pathogenic genera had negative correlations with WQI. Many clinically relevant antimicrobial resistance genes (ARGs) and efflux pump-encoding genes that confer resistance to critically important antimicrobials were detected. The highest relative abundances of ARGs were β-lactams and macrolide-lincosamide-streptogramin. No statistically supported relationship was detected between the abundance of virulome/resistome and collection type/WQI. On the other hand, total solids were a weak predictor of gene abundance patterns. These results provide insights into various microbial outcomes given urban stream quality and point to its ecological complexity. In addition, this study suggests potential consequences for human health as mediated by aquatic microbial communities responding to typical urban outputs.

Spatio-temporal evaluation of the impact of anthropogenic stressors on physico-chemical characteristics and water quality of the River Ganga using GIS-based approach in the middle Gangetic Plains at Patna, Bihar, India.

The present study aimed to assess the impact of anthropogenic stressors on the physico-chemical characteristics and water quality of the River Ganga employing a GIS-based approach in the middle Gangetic Plain at Patna, India. After the survey, sand mining, bridge construction, and disposal of untreated domestic and sewage wastes were selected as major anthropogenic stressors. A total of 48 samples were collected in pre-monsoon and post-monsoon seasons of 2022 and were analyzed for 16 physico-chemical parameters, namely water temperature (WT), pH, electrical conductivity (EC), total dissolved solids (TDS), turbidity, dissolved oxygen (DO), biological oxygen demand (BOD), total hardness (TH), Ca2+, Mg2+, Na+, K+, Cl- and SO42- ions, following standard protocols. The WQI was calculated using the Weighted Arithmetic Water Quality Index (WAQWI) method and spatial maps were created using ArcGIS software. The result revealed significant seasonal variation in several physico- chemical parameters except for Ca2+, K+ and TA (p > 0.05). ANOVA revealed significant variation for BOD and COD at Ghagha and Triveni, whereas for nitrate at Gai Ghat reference and impact sites, respectively. The Water Quality Index (WQI) revealed a deterioration in water quality by 60% in post-monsoon season. HCA revealed that the WQI was mostly governed by TDS, TH, TA, and EC.

Identifying the controls on nitrate and metabolic state within the Red River delta (Vietnam) with the use of stable isotopes

In many places around the world, anthropogenic activities have resulted in nitrate (NO3−) pollution and changes in the metabolic state of aquatic ecosystems. Here we combined stable isotope and physico-chemical monitoring to assess the sources of NO3− and the overall metabolic state within the Red River delta, Vietnam. River water stable isotope compositions (δ18O-H2O) ranged between −11.2 and −2.7 ‰, δ18O-NO3− between −7.1 and + 29.7 ‰ and δ15N-NO3− between −3.9 and + 14.0 ‰. We identified the dominant NO3− sources as: 1) soil leachate, 2) domestic waste flushed from urban areas, and 3) NH4+ fertilizers washed from paddy fields. The relative impact of each source depends on geographical location within the delta and the time of year, due to dilution and concentration effects during wet and dry seasons. The primary NO3−source upstream is natural soil leachates, predominantly from tributaries connected to the Red River’s main stream. Within the middle-lower section of Red River delta, urban pollution from manure and septic waste reaches as high as 50 % of the total NO3− load during dry season. NO3− leached from fertilizers is also high at sites in the middle of the delta, related to agricultural activities. Dissolved oxygen isotope (δ18O-O2) values calculated from δ18O-H2O and δ18O-NO3− values indicate that the aquatic metabolism is net autotrophic (oxygen from primary production exceeds consumption by respiration), but high inputs of biodegradable organic matter from untreated domestic waste and high rates of sediment oxygen demand (SOD) and chemical oxygen demand (COD) have resulted in the whole river system becoming undersaturated in oxygen. High NO3− loads and low DO saturation are of critical concern and require mitigation practices to improve water quality for millions of people.

Multi-index assessment of sea bottom sediments of the Izmir Gulf, Aegean Sea: A study of interrelation between anthropogenic and hydrodynamic effects

This study aimed to investigate the sediment transport pathways and geochemical parameters in the Izmir Gulf to determine the heavily impacted areas by natural and anthropogenic parameters. The grain size trend analysis was used to determine sediment transport patterns and, statistical methods were employed to identify the sources and distribution of chemical elements in sediments. The main factors that were affecting the area were identified as lithogenic, anthropogenic, maritime traffic, biogenic and shipyard activities. The tannery industry (Cr), maritime traffic and shipyard/dock activities (Cu and Zn), road traffic run-offs (Pb and Zn), and untreated domestic waste discharges (TOC and S) were identified as the sources of metals. Contamination rankings based on metal concentrations indicated higher pollution levels in the Inner Gulf compared to the Central Gulf. Zinc and chromium were found to pose significant risks to benthic organisms. The pollutants tended to accumulate in deposition zones, following sediment transport directions.

Urbanization and population resources affect microplastic concentration in surface water of the River Ganga

Microplastic (MP) pollution has received increasing attention as a serious threat to aquatic ecosystem. The River Ganga is one of the longest rivers in India and supports an enormous species diversity. The major Indian cities situated on its bank discharge untreated domestic and industrial waste in River Ganga and are largely responsible for generating MPs. Every day millions of people use the river recreationally, for bathing and for drinking water. This study is the first to elucidate the distribution of MPs according to their shape, size and type in River Ganga from the Rishikesh to Farakka in India. Surface water samples of the river were obtained at 22 locations of the riverbank. Microplastic particles were identified using binocular microscope and categorized by shape, size and type. MPs were found in all surface water samples along the River Ganga and highest concentrations of MPs were found within Kanpur city (average 206 ± 31.9 particles m−3). The average MPs concentration was 92.85± 50.69 (SD) particles m−3 (-0.1 particle L−1) of surface water. In addition, MPs distribution was dominated by filament particle (polyester and nylon fibre). The MPs concentration was positively correlated with population density in the vicinity (r=0.65; p<0.001) and sewage volume discharged (r=0.5; p<0.01) in the river. The MPs in Ganga water may pose potential risk to the devotees through direct consumption of Ganga water on the occasions of ritualistic bathing. The present work adds new knowledge and understanding of MPs pollution in the Ganga River and the effects of highly urbanized cities on MPs pollution, which may be used as baseline data to evaluate precise mitigation.

Comparison of Grain Size Trend Analysis and Multi-Index Pollution Assessment of Marine Sediments of the Gülbahçe Bay, Aegean Sea

In this study, 46 elements plus total carbonate and total organic carbon contents were measured in 48 sea bottom sediments to determine the pollution levels in the study area and their source to understand better the natural and anthropogenic processes in the study area. Also current flows and sediment transport pathways inferred using multidisciplinary methods by interrelation between grain size trend analysis, shallow seismic and acoustic doppler current profiler analysis to unravel the hydro-sedimentary processes in a micro-tidal environment. Four main factors that were affecting the study area were identified as lithogenic factor (50.6%) anthropogenic factor caused by untreated domestic waste (13.2%), anthropogenic factor caused by marine traffic/port activities (9.3%) and anthropogenic factor caused by small-scale industrial activities (with 6.9% of the total variance). The main source of metals in the study area were determined as untreated domestic waste discharges (total organic carbon and sulfur), maritime traffic/harbor activities (copper and zinc), and discharges of other wastes caused by urbanization. The main metal element that poses the most significant risk for benthic organisms was determined as nickel in the study area. All environmental indices showed non to moderate pollution existing in Gülbahçe Bay. It has been observed that most prominent feature of the distribution of elemental concentrations and assessment of pollution indices were that the pollutants carried inwards to Gülbahçe Bay from Izmir Central Bay with inflows, following the sediment transport directions.

Performance Evaluation of Al-Rustamiya Wastewater Treatment Plant

Al-Rustamiya sewage treatment plant (WWTP) serves the east side of Baghdad city (Rusafa) and is considered one of the largest projects.It consists of three parts (old project F0, first extension F1, and second extension F2) that treat wastewater and the effluent is discharged into Diyala river and thus into the Tigris River. These plants are designed and constructed with an aim to manage wastewater to reachIraqi effluent standard for BOD5, COD, TSS and chloride concentrations of 40, 100, 60 and 600 mg/L respectively. The data recordedfrom March till December 2011 provided from Al-RustamiyaWWTP, were considered in this study to evaluate the performance of the plant. The results indicated that the strength of the wastewater entering the plant varied from medium to high. The average concentrations of the effluent of BOD5, COD, TSS and chloride were within Iraqi effluent standards. The overall efficiency removalswere: For BOD5: 92.1, 90.31, and 92.96% for F0, F1, and F2 respectively COD: 88.23, 87.9, and 87.95% for F0, F1, and F2 respectively TSS: 86.98, 80.72, and 89% for F0, F1, and F2 respectively Chloride: 14.79, 15.37, and 15.31% for F0, F1, and F2 The mean value of BOD5/COD ratio of the raw wastewater was 0.67 as for typical untreated domestic wastes. The mean BOD/COD ratios of the treated sewage from F0 was 0.48, from F1 0.50 and from F2 0.38. These ratios did not confirm with the typical ratios indicating that the wastewaterneeds more treatment

TRANSFORMATION OF THE NORMALIZED DIFFERENCE CHLOROPHYLL INDEX TO RETRIEVE CHLOROPHYLL-A CONCENTRATIONS IN MANILA BAY

Abstract. Manila Bay is one of the most significant harbors in the region, enabling commerce and trade between the Philippines and other countries. Its abundant natural resources have provided for generations of its inhabitants and have driven socio-economic development for centuries. Like other water bodies adjacent to highly urbanized cities, the increased organic and nutrient loading from untreated domestic, industrial, and agricultural wastes resulted to further degradation of its water quality. While frequent water quality monitoring is ideal, data from traditional field sampling methods might not be sufficient to assess the spatial and temporal variations of water quality in Manila Bay. Remote sensing fills the need for a frequent and full overview of the bay’s water quality. Sentinel-3 images were initially processed through the Case 2 Regional CoastColour (C2RCC) model to retrieve the remote sensing reflectance. The Normalized Difference Chlorophyll Index (NDCI) was computed for the images and were modeled against the C2RCC-derived chlorophyll-a estimates. From this, we were able to get a general equation (TNDCI – transformed NDCI) to retrieve chlorophyll-a concentrations from two reflectance bands (Oa8 and Oa11). TNDCI gave an R2 of 0.9 and RMSE = 5.12 µg/L as compared to C2RCC values, and an R2 = 0.85 and RMSE = 2.44 µg/L with field data.

ASSESSMENT OF HEAVY METALS IN SABARMATI RIVER: A CASE STUDY BEFORE AND DURING THE LOCKDOWN

Sabarmati is one of the largest rivers in Gujarat and passes through cities like Gandhinagar and Ahmedabad. The municipal pollutants in the river comprise untreated domestic and sewage wastes. In contrast, industrial pollutants constitute the discharge of heavy metals into the river, responsible for increasing metal load in the water. Increasing heavy metal concentration in the water can cause severe problems. In this work, Cu, Mn, Fe, Cr, Zn, Pb, and Cd heavy metals were analyzed from the five selected sites for two years, 2020 and 2021, in Two seasons pre and post-monsoon. In 2020, there was a lockdown situation because of Covid-19, so all industrial the activities were shut down. Therefore pollution levels were decreased, and the environment was clean. Our study indicates that in the pre-monsoon season in 2020, Iron metal was highest, and in post-monsoon, Chromium was the highest. In the Post-monsoon season 2020, Iron metal was the highest, and Lead was the highest in the post-monsoon season. Because of the covid-19 lockdown, the result of post-monsoon 2020 shows the low concentration of heavy metals.

ENVIRONMENTAL PROBLEMS OF THE CASPIAN REGION, CAUSES AND WAYS OF SOLUTION

The article considers the environmental problems of the Caspian region, the causes of their occurrence and the necessary solutions. For a long time, the sea has suffered from pollution from oil extraction and refining activities, radioactive waste from nuclear power plants and huge amounts of untreated domestic and industrial waste brought by the Volga River, which provides about 80% of all fresh water inflow into the Caspian. Currently, this issue is very relevant, because the negative impacts on the environment are increasing every day. Accordingly, there is a need to develop and adopt scientifically sound ways to solve the environmental problems of the Caspian region.

Bird Communities and the Rehabilitation of Al Karaana Lagoons in Qatar

Qatar, a peninsular country in the Persian Gulf, is significant to avian species due to its location along the African–Eurasian Flyway, a key migratory path. Receiving untreated domestic and industrial liquid waste from Qatar in the past, Al Karaana Lagoons have since been reconstructed as an artificial wetland to address the growing environmental concern posed by contamination build-up. This study documents the changes in biodiversity at Al Karaana Lagoons following their environmental remediation. Data collected (2015 and 2017) by Ashghal (Public Works Authority) prior to project implementation was analyzed alongside data collected independently following project completion (2019–2021). There was a marked increase in bird biodiversity following remediation, including substantial use by migratory species and resident breeders. Further analysis of water quality data of the TSE (treated sewage effluent) ponds shows that they are eutrophic but still support substantial bird life. The project’s success demonstrates how reclaimed lands can provide important habitats to local and migratory birds and encourages similar restoration efforts in the future in both Qatar and elsewhere. We call for the continued monitoring of the site and the implementation of guidelines for the use of the site that balance human activities and habitat quality.

Integrative Study of Coastal Land-Based Pollution and Effects: Focus on Soil Properties

The discharge and dumping of untreated domestic and industrial wastes into estuaries, rivers, and nearshore waters are the principal sources of coastal pollution in the current study area. Ten soil samples were collected near the industry pollutant exit point near the seashore and towards Mangalore city and were undergo chemical and physical analysis. Also, both distilled water and seawater were used to determine the strength characteristics of the samples. SEM, XRD and EDS were used to determine the surface morphology, chemical compositions of samples. From the results, it was found that most of the samples collected were more or less not met the sufficient range for the agricultural activities. When soil samples undergo Compaction and UCS tests in the presence of seawater and distilled water, MDD and UCS values were decreased in the presence of seawater. From the SEM study, the majority of samples have crystalline texture. Carbon, Oxygen, Aluminium, Silicon, Iron and Mercury were major elements abundantly found in the collected soil samples when it undergoes EDS Analysis. From the XRD analysis, it was known that Quartz, illite, kaolinite, orthoclase, mica, halloysite are the major mineral compounds found in the collected soil samples.

Evaluation and Correlation Analysis of Surface Water In and Around Mangalore Coastal Belt, Karnataka, India

Urbanisation, industrialisation, population growth and various agricultural activities in and around coastal areas have led to a significant amount of pollutants into the surrounding aquatic ecosystem such as estuary, river, sea, seashore and coastal wetlands. This causes ecological degradation. Pollution is one of the major challenges to the sustainability of coastal areas. In the study area, major industries are located on the Gurupur river bank which joins the Nethravati river to form a common estuary before entering the Arabian sea. The major activities that are responsible for coastal pollution in the study area are discharge and disposal of untreated domestic and industrial wastes to estuaries, rivers, nearshore waters and harbour activities. Gurupura and Nethravthi are two west flowing rivers of the Mangaluru coastal region. They receive a large amount of pollution load from the nearby industries causing the deterioration of the water quality. In this study, 10 surface water samples which include stream water, river water and sea water, were collected during the pre-monsoon and post-monsoon and analysed for various water quality parameters by adopting standard methods. The study reveals that the electrical conductivity, total dissolved solids and chlorides concentration of most of the surface water samples were met above the standard limits in both seasons. From the correlation analysis, it was found that a very strong correlation was observed between chlorides and hardness (0.9691), TDS and conductivity (0.9227) during post-monsoon season of 2018 and TDS and conductivity (1.00), COD and chlorides (0.8922), DO and chlorides (0.8810) during pre-monsoon of 2019.

Assessment of Water Quality in Safilguda Lake, Hyderabad using Water Quality Index

In the present study,Water Quality Index (WQI) was used to assess the quality of water in Safilguda lake. Safilguda lake was the source of drinking for the Nawabs and British authorities and was also the source of irrigation to the farmers. But today the agricultural fields have turned into housing colonies and multistorey complexes which led to the deterioration of lake water by direct entry of sewage into the lake. Three sampling stations were selected within the lake for the collection of surface water samples at monthly intervals for a period of one year. The water samples were analyzed for various physico-chemical parameters by following the standard procedures. For calculating WQI, ten physico-chemical parameters were considered such as pH, alkalinity, chlorides, total hardness, calcium, magnesium, nitrates, sulphates, total dissolved solids and dissolved oxygen. From the water quality index, the lake water quality was determined. On the basis of WQI classification, the water quality status ratings clearly indicates that the Safilguda lake has poor water quality due to the discharge of untreated domestic waste water from the surrounding residents and religious activities like immersion of Ganesh idols made up of plaster of paris and the lakewater is unsuitable for drinking, domestic and recreational purposes. The water quality rating study also exhibits eutrophic condition of the lake.

Studies on Marine Pollution Caused By Litters in the Marmara Sea on the Coast of Turkey

It is aimed to contribute to the marine litter problem by revealing the main sources of marine litter. In this study, the current situation regarding the marine litter problem in the Marmara Sea has been presented and solutions have been proposed for the problem. Industrial development and population explosion are the roots of pollution in the Marmara Sea. The Marmara Sea hosts the two banks of the Bosphorus and is the home to a metropolis, Istanbul, founded in the North Eastern region of the Sea of Marmara and having the most crowd ed population of Turkey, and is the receiver of industrial and domestic wastes of this metropolis. Solid litters in the seas have land-based and marine origins. Marine litters, originate from waterfronts containing shores, piers, ports, marinas, docks and riverbanks, and regions with internal sources. In order to determine the terrestrial sources of marine litter, waste yards, untreated domestic waste water, the load of waste carried by rivers, industrial and tourism facilities operating near the shoreline must all be mapped out. It is necessary to implement integrated waste management components on marine litter and coastal cleaning and to prevent the current confusion of authority based on this. Studies on the prevention of industrial microplastics at source should be initiated and training activities should be provided for fishermen on the management of ghost nets and the capacity of the system should be developed. Keywords : The marmara Sea, Marine litter, Microplastic, Population,Waste water DOI : 10.7176/JSTR/7-10-11

MAPPING COLOURED DISSOLVED ORGANIC MATTER IN MANILA BAY USING SENTINEL-3 AND WASI

Abstract. Manila Bay is one of the most significant bodies of water in the Philippines; it has abundant natural resources that have been the source of livelihood and center of socio-economic development for centuries. However, Manila Bay is affected by multiple environmental problems and challenges. These include increased organic and nutrient loading from untreated domestic, industrial, and agricultural wastes and deterioration of marine habitats threatened by anthropogenic activities. Regular water quality monitoring is ideal in these situations, however, sampling by traditional field methods would not be enough to assess the spatial and temporal variation of water quality in Manila Bay. Gathering field data for the whole bay can also be very challenging due to its extent and logistic constraints. Remote sensing fills the need for a frequent full view of Manila Bay’s water quality. This study makes use of existing bio-optical models to estimate colored dissolved organic matter (CDOM) in Manila Bay. CDOM is the mixture of organic molecules from decayed higher plants, algae, and bacteria, and is the colored portion of the total dissolved organic matter. Sentinel-3 images with concurrent field sampling on 19 July 2021 was used to calibrate and validate the bio-optical models implemented in WASI. The parameterization output showed an R2 = 0.579 and RMSE of 1.274 m−1 from lab-measured CDOM fluorescence converted to absorption. The same parameter set was used on a different image with a concurrent water quality survey on 19 May 2021 and resulted to an R2 of 0.72 with the spectrofluorometer yellow substance concentrations.

Indian coastal waters: a concoction of sewage indicator bacteria! An assessment on recreational beaches.

Coastal water quality assessment is important to maintain a healthy environment for various uses including fisheries and recreation. Microbial populations are used as biological indicators of contamination to monitor water quality and are considered by the government to be one of the critical features for issuing safety guidelines. Different bacterial groups (pathogenic, vibrio and faecal) from five major recreational beaches of Chennai, India, were monitored for the assessment of coastal water quality. Faecal coliforms (FC) were high at all the beaches, with up to 4.2 × 105CFU/mL and exceeding the normal standard limits of 100CFU/100mL set by the Central Pollution Control Board (CPCB) of India. Rainfall was found to have a role in the variability and distribution of indicator and pathogenic bacteria. The seasonal dry period witnessed elevated FC, while dilution in the wet period reduced Escherichia coli-like organisms (ECLO). High microbial counts were detected near the beach situated close to the river mouth, mainly due to discharges of untreated domestic sewage and industrial wastes. Similarly, the biological oxygen demand (BOD) was also high, 0.32 to 10.32mg/L. Dissolved inorganic nitrogen (DIN) ranged from 2.21 to 134.53μmol/L and inorganic phosphate (IP) ranged from 0 to 57.53μmol/L. These values indicated the presence of significant untreated sewage in the coastal water. This study revealed that Chennai coastal waters carry high levels of faecal and pathogenic bacteria, detrimental for recreational and other contact activities. The quantitative and qualitative analyses will be useful for modelling and prediction of coastal water quality and management of other recreational beaches in India.