Assessment of temporal and spatial water quality in international Gomishan Lagoon, Iran, using multivariate analysis.

Coastal lagoon ecosystems are vulnerable to eutrophication, which leads to the accumulation of nutrients from the surrounding watershed over the long term. However, there is a lack of information about methods that could accurate quantify this problem in rapidly developed countries. Therefore, various statistical methods such as cluster analysis (CA), principal component analysis (PCA), partial least square (PLS), principal component regression (PCR), and ordinary least squares regression (OLS) were used in this study to estimate total organic matter content in sediments (TOM) using other parameters such as temperature, dissolved oxygen (DO), pH, electrical conductivity (EC), nitrite (NO2), nitrate (NO3), biological oxygen demand (BOD), phosphate (PO4), total phosphorus (TP), salinity, and water depth along a 3-km transect in the Gomishan Lagoon (Iran). Results indicated that nutrient concentration and the dissolved oxygen gradient were the most significant parameters in the lagoon water quality heterogeneity. Additionally, anoxia at the bottom of the lagoon in sediments and re-suspension of the sediments were the main factors affecting internal nutrient loading. To validate the models, R2, RMSECV, and RPDCV were used. The PLS model was stronger than the other models. Also, classification analysis of the Gomishan Lagoon identified two hydrological zones: (i) a North Zone characterized by higher water exchange, higher dissolved oxygen and lower salinity and nutrients, and (ii) a Central and South Zone with high residence time, higher nutrient concentrations, lower dissolved oxygen, and higher salinity. A recommendation for the management of coastal lagoons, specifically the Gomishan Lagoon, to decrease or eliminate nutrient loadings is discussed and should be transferred to policy makers, the scientific community, and local inhabitants.

Spatio-temporal variations in water quality of Muttukadu Backwaters, Tamilnadu, India.

Muttukadu Backwater, located on the east coast of Tamilnadu, is one of healthiest estuarine environments in the region. A study pertaining to seasonal variations in physico-chemical properties in water was conducted at nine sites of Muttukadu Backwater for a period of one year (January to December 2009). Multivariate statistical techniques, such as cluster analysis and principal component analysis (PCA), were applied to evaluate the variation in water quality of Muttukadu Backwater and to identify pollution sources. In order to analyze water quality, a geographic information systems (GIS) software package, Arc GIS version 9.3, was used (Esri, Redlands, California). An interpolation technique, inverse distance weighting, was used to produce the spatial distribution of water quality parameters over the backwater. The purpose of the technique was to aid in protection of the environment and ecology of the estuary and aid in effective management. In the present study, observed values of salinity, nitrite, nitrate, ammonia, total nitrogen, phosphate, and silicate were significantly high in the estuarine zone. PCA resulted in three factors explaining 75.9% of the total variance. Principal component 1 exhibited a high correlation with significant physico-chemical variables representing the influence of tidal action and sandbar formation. Principal component 2 represented natural pollution as a result of surface runoff. Principal component 3 represented natural pollution as a result of nutrient pollution.

Shoreline change analysis of Vedaranyam coast, Tamil Nadu, India.

The coastal zone is one of the nation's greatest environmental and economic assets. The present research aims at studying the shoreline changes along Vedaranyam coast using conventional and modern techniques including field sampling, remote sensing, and geographical information system (GIS). The study area was divided into three zones. Dynamic Land/Sea polygon analysis was performed to obtain the shore line changes at different time periods between 1930 and 2005. From the multidate shoreline maps, the rate of shoreline change was computed using linear regression rate and end point rate. Further, the shoreline was classified into eroding, accreting, and stable regions through GIS analysis. The eroding, accreting, and stable coastal stretch along Vedaranyam is observed as 18 %, 80.5 %, and 1.5 %, respectively. Net shoreline movement is seaward, i.e., the coast is progressive with an average rate of 5 m/year. A maximum shoreline displacement of 1.3 km towards the sea is observed near Point Calimere. During the Asian Tsunami 2004, the eastern part of the study area showed high erosion. Sediment transport paths derived from the grain size analysis of beach sediments collected during different seasons help to identify the major sediment source and sinks. Point Calimere acts as the major sink for sediments whereas Agastiyampalli and Kodiakkarai are found to be the major sources for the sediment supply along the Vedaranyam coast. Shoreline change study from field and satellite data using GIS analysis confirms that Vedaranyam coast is accreting in nature.

Spatio-temporal variation in physicochemical properties of coastal waters off Kalpakkam, southeast coast of India, during summer, pre-monsoon and post-monsoon period.

Seasonal observations on water-quality parameters and chlorophyll-a in the coastal waters off Kalpakkam, southeast coast of India, was carried out covering an area of about 30 km(2) to find out the variations in physicochemical properties during a monsoonal cycle of the year. Most of the parameters exhibited a significant spatial and seasonal variation. It revealed that the coastal water was significantly influenced by freshwater input from the nearby backwaters during North-east monsoon and post-monsoon periods. A marginal increase in pH from coast towards offshore was noticed during the observation. Relatively low salinity values were observed during pre and post monsoon when compared to summer. Bottom water was found to be highly turbid during summer and pre-monsoon conditions when compared to surface. This could be attributed to the strong northerly wind and northward current prior to the onset of southwest monsoon. N, P and Si based nutrients are relatively high in their concentration in the bottom water. Nitrate was significantly high during post-monsoon and contributed greatly towards total nitrogen as evident from the statistical correlation. Ammonia concentration was relatively high in the bottom samples during all the seasons except on a few occasions during post-monsoon. In general, phosphate and total phosphorous values remained low and particularly so in the surface water. Higher silicate concentration was observed in the bottom water, and there was a reducing trend towards offshore. High chlorophyll-a values were observed during summer and surface water was found to have higher pigment concentrations as compared to the bottom. Results show that phosphate acts as the limiting factor for phytoplankton production particularly during post-monsoon period whereas; none of the nutrients were found to be limiting the phytoplankton growth during other seasons.

Spatial distribution of microplastic concentration around landfill sites and its potential risk on groundwater.

Plastic plays a major role in today's human life; moreover, it becomes a part of our life, yet it is a most challenging threat for the freshwater ecosystems in the future. The present study identifies, characterizes, and quantifies the microplastics in groundwater samples around Perungudi and Kodungaiyur municipal solid waste dumpsites in South India. To evaluate and assess the microplastic abundance, characteristics (composite, size, colour, shape, and surface morphology), detection methods of plastic particles, and potential risk factors from the absorption of microplastic in groundwater. Further, the microplastic particle classification was performed using LB-340 Zoom Stereo Microscope with LED Illumination, ATR-FTIR fitted with SEM with EDX analyzer. The groundwater samples (n = 20) were found contaminated with microplastic particles in the range of 2-80 items/L with coloured particles, white (38%), black (27%), green (8%), red (18%), blue (6%), and yellow (2%). The polymer type was found to occur in the following order: nylon (70%), pellets (18%), foam (6%), fragments (3%), fibers/PVC (2%), and polythene (1%). In both sampling sites, 90% of microplastics are derived from the buried plastics and waste fragmentation which are predominantly of polypropylene (PP), polystyrene (PS). Micro and nano plastics abundance in groundwater is of paramount importance as it has a major impact on human health. This study throws light on the characteristics and quantification of the microplastics in groundwater that initiates further research by which microplastics enter into the environment.

Microplastics as an emerging threat to the freshwater ecosystems of Veeranam lake in south India: A multidimensional approach.

In the current scenario, microplastic, as a contaminant, is becoming an ecological threat to the freshwater ecosystem. The present study attempted to determine the quality and quantity of microplastic contaminants in water and soil samples at Veeranam lake in Tamil Nadu, India. It is very important to mention that the Veeranam lake in Tamil Nadu, is a major urban water source of the capital district of Tamil Nadu. Using Van Veen grab-sampling equipment and trawl methods, the study detected the presence of microplastics in 28 sediment samples and 31 water samples from the collected samples. In addition to this, the density separation was performed with zinc chloride solution using the Sediment-Microplastic Isolation (SMI) unit. The quantum of total plastic particle present in surface water were in the range of 13-54 items/km2 with a mean value of 28 items/km2. In the case of sediment samples, the amount of total plastic particle was found in the range of 92-604 items/kg with a mean value of 309 items/kg. The abundance of microplastic particles in water and sediments in various shape, colour, and composition as in the order of nylons > polythene > fibres/PVC > fragments > foam > pellets; dominant colours as white > red > black > green > blue and yellow at the sampling sites. In term of percentage of contaminant distribution, the study found that the collected water and sediment samples deposited with polymer type of plastic particles were nylon (39%), polyethylene (23%), polystyrene (19%), polypropylene (15%), and polyvinyl chloride (4%). The research work is a baseline study for the proposed site of Veeranam lake for microplastics contamination.

Variations of physicochemical properties in Kalpakkam coastal waters, east coast of India, during southwest to northeast monsoon transition period.

A significant variation in physicochemical properties of the Kalpakkam coastal waters, eastern part of India, was observed during the event of southwest to northeast monsoon transition. Increase in nitrate, total nitrogen, and silicate concentrations were noticed during post-transition period. Ammonia concentration was at peak during transition period as compared to pre- and post-transition periods. Hypo-saline condition (~23 psu) was observed during post-transition as the surface water salinity decreased by ~10 psu from the pre-transitional values. Turbidity, suspended particulate matter, phosphate and total phosphorous values decreased marginally, coinciding with northward to southward current reversal. A drastic decrease (eightfold) in chlorophyll-a concentration was observed in the coastal water during post-transition period.

Air pollution improvement and mortality rate during COVID-19 pandemic in India: global intersectional study.

This research was carried out using the open-source database system along with the continuous air quality monitoring station results from global data sets during the COVID-19 pandemic lockdown in India and the global. Our purpose of this research is to study the improvement of air quality and human mortality rates in countries worldwide during the COVID-19 pandemic lockdown. Worldwide air quality data were collected from > 12,000 continuous air quality monitoring stations on six continents covering 1000 major cities from over 100 countries. Here, we discussed the implementation of the open-source data set of basic air pollutants such as PM 2.5, NO2, temperature, relative humidity, and Air Quality Index variation during the pre-lockdown and lockdown pandemic COVID-19 in India and described the global aspect. An average concentration of PM 2.5 (145.51 µg/m3), NO2 (21.64 µg/m3), and AQI index (55.58) continuously decreased. The variation of PM 2.5, NO2, normally shows more than 25 µg/m3 every year, but during the COVID-19 lockdown period (April 2020) continuously decreased below 20 µg/m3. Similarly, the AQI index and meteorological factors such as temperature, relative humidity, and wind speed variation decreased significantly in the many countries in the world. In Asian countries, air quality improved during the national lockdown especially in the most polluted cities globally such as Beijing, Delhi, and Nanjing and also in developed cities like Madrid, New York, Paris, Seoul, Sydney, Tokyo. Furthermore, the reduction of particulate matter was in about 46%, and other gaseous pollutants during the lockdown period were observed in a 54% reduction. We are witnessing pollution reductions which add significantly to improvements in air quality. This is due to the massive decrease in the use of fossil fuel, which in turn reduces production and traffic in general. People nowadays are now willing to see a comparatively healthier world with bleached skies and natural ecosystems. This research finding demonstrates potential safety benefits associated with improving air quality and mortality rates during the COVID-19 pandemic, resulting in decreases in mortality rates in India and around the world.

GIS-based approach for optimized siting of municipal solid waste landfill.

The exponential rise in the urban population of the developing countries in the past few decades and the resulting accelerated urbanization phenomenon has brought to the fore the necessity to develop environmentally sustainable and efficient waste management systems. Sanitary landfill constitutes one of the primary methods of municipal solid waste disposal. Optimized siting decisions have gained considerable importance in order to ensure minimum damage to the various environmental sub-components as well as reduce the stigma associated with the residents living in its vicinity, thereby enhancing the overall sustainability associated with the life cycle of a landfill. This paper addresses the siting of a new landfill using a multi-criteria decision analysis (MCDA) and overlay analysis using a geographic information system (GIS). The proposed system can accommodate new information on the landfill site selection by updating its knowledge base. Several factors are considered in the siting process including geology, water supply resources, land use, sensitive sites, air quality and groundwater quality. Weightings were assigned to each criterion depending upon their relative importance and ratings in accordance with the relative magnitude of impact. The results from testing the system using different sites show the effectiveness of the system in the selection process.

Removal of trihalomethane from chlorinated seawater using gamma radiation.

Chlorine addition as a biocide in seawater results in the formation of chlorination by-products such as trihalomethanes (THMs). Removal of THMs is of importance as they are potential mutagenic and carcinogenic agents. In this context, a study was conducted that used ionizing radiation to remove THMs from chlorinated (1, 3, and 5 mg/L) seawater by applying various dosages (0.4-5.0 kGy) of gamma radiation. Bromoform (BF) showed a faster rate of degradation as compared to other halocarbons such as bromodichloromethane (BDCM) and dibromochloromethane (DBCM). In chlorine-dosed seawater, total irradiation dose of 0.4 to 5 kGy caused percentage reduction in the range of 6.9 to 76.7%, 2.3 to 99.6%, and 45.7 to 98.3% for BDCM, DBCM, and BF, respectively. During the irradiation process, pH of the chlorinated seawater decreased with increase in the absorbed dose; however, no change in total organic carbon (TOC) was observed. The results show that gamma dose of 2.5 kGy was adequate for maximum degradation of THM; but for complete mineralization, higher dose would be required.

A novel technique to monitor thermal discharges using thermal infrared imaging.

Coastal temperature is an important indicator of water quality, particularly in regions where delicate ecosystems sensitive to water temperature are present. Remote sensing methods are highly reliable for assessing the thermal dispersion. The plume dispersion from the thermal outfall of the nuclear power plant at Kalpakkam, on the southeast coast of India, was investigated from March to December 2011 using thermal infrared images along with field measurements. The absolute temperature as provided by the thermal infrared (TIR) images is used in the Arc GIS environment for generating a spatial pattern of the plume movement. Good correlation of the temperature measured by the TIR camera with the field data (r(2) = 0.89) make it a reliable method for the thermal monitoring of the power plant effluents. The study portrays that the remote sensing technique provides an effective means of monitoring the thermal distribution pattern in coastal waters.

Seasonal variability of coastal water quality in bay of Bengal and Palk Strait, Tamilnadu, Southeast Coast of India

The aim of this work was to study the physicochemical parameters of water quality collected from 12 sampling stations from Topputhurai to Muthupet in Vedaranyam located on the southeast coast of India from January to December 2008. Results showed that the DO and nutrients were the maximum in the Bay of Bengal during the monsoon period. High concentration of the nutrients in summer season was obtained near the Muthupet mangroves compared to the Palk Strait, which showed that this acted as a source of nutrients to the adjacent coastal waters. Low concentrations of the nutrients observed in the monsoon could be attributed to the terrestrial runoff from Muthupet lagoon. The physicochemical characteristics of coastal waters between the Point Calimere and Muthupet could be used as a baseline data for the monitoring, conservation and management of Point Calimere Wildlife and Bird sanctuary, Great Vedaranyam swamp and Muthupet mangrove ecosystem.