Sediment-water exchange and risk assessment of pesticidal persistent organic pollutants in Bharathappuzha and Periyar Riverine region along the Arabian Sea.

Considering the extensive agricultural practices along the perennial rivers, viz. Periyar and Bharathappuzha of Kerala in the southwest coast of India, the first comprehensive surveillance of new and legacy organochlorine pesticides (OCPs) in surface sediment was conducted. Further, the sediment-water exchange fluxes have been elucidated. Mean concentrations of total HCH, DDT and endosulfan were 0.84 ng/g, 0.42 ng/g and 0.30 ng/g for Bharathappuzha Riverine sediment (BRS) and 1.08 ng/g, 0.39 ng/g and 0.35 ng/g for Periyar Riverine sediment (PRS). The dominance α-HCH and ß-HCH isomers in PRS and BRS reflect the ongoing use of technical HCH in Kerala. The calculated KSW in both rivers was very low in comparison with other Indian rivers. The average log K'OC for all the detected OCPs in both the rivers was lower than the predicted log KOC in equilibrium indicating the higher adherence of OCPs to sediment. Furthermore, fugacity fraction (fs/fw) was < 1.0 for all OCPs confirming the net deposition of OCPs into the sediment. Sediment concentrations for each of the OCPs in PRS and BRS did not surpass the threshold effect level and probable effect level as stipulated by the Canadian Council of Ministry of the Environment Guidelines. In addition, all the sites of both rivers had sediment quality guideline quotient (SQGQ) values below 0.1 indicating the absence of significant biological and ecological risks.

Water-sanitation-health nexus in the Indus-Ganga-Brahmaputra River Basin: need for wastewater surveillance of SARS-CoV-2 for preparedness during the future waves of pandemic.

The Indus-Ganga-Brahmaputra River Basin (IGBRB) is a trans-boundary river basin flowing through four major countries in South Asia viz., India, Pakistan, Bangladesh, and Nepal. Contamination of surface water by untreated or inadequately treated wastewater has been a huge problem for pathogenic microorganisms in economies in transition. Recent studies have reported that sewage surveillance can provide prior information of the outbreak data, because faeces can contain the novel coronavirus (SARS-CoV-2) shed by infected humans. Hence, in this study we geo-spatially mapped the COVID-19 hotspots during the peak time in the first and second wave of pandemic to demonstrate the need and usefulness of wastewater surveillance strategy in IGBRB during ongoing pandemic. Further we discussed the status of sanitation, health and hand-hygiene in the IGBRB along with characterization of the challenges posed by the pandemic in achieving the United Nations Sustainable Development Goals (UN-SDGs). Monthly Geographical Information System (GIS) mapping of COVID-19 hotspots in the IGBRB showed an increase in the spread along the direct sewage discharge points. The social inequalities expose the vulnerabilities of the urban poor in terms of the burden, risks and access to Water, Sanitation, and Hygiene (WASH) needs. Such an evidence-based image of the actual SARS-CoV-2 viral load in the community along the IGBRB can provide valuable insights and recommendations to deal with the future waves of COVID-19 pandemic in this region that can go a long way in achieving the UN-SDGs.

Spatial distribution and compositional profiles of organochlorine pesticides in the surface soil from the agricultural, coastal and backwater transects along the south-west coast of India.

South-west coast of India has a history of using pesticidal persistent organic pollutants (POPs) particularly endosulfan until aerial spraying was banned during early 2000. Since soil acts as a repository for such pesticidal persistent organic contaminants, we have monitored residues of seventeen organochlorine pesticides (OCPs) in the surface soil samples from the agricultural, coastal, and backwater transects along the south-west coast of India. OCPs concentration in soil were in the order agricultural > coastal > backwaters transects. Endrins, hexachlorocyclohexane (HCH) and heptachlors were among the dominant OCPs quantified in this study. Dominance of metabolites such as dichlorodiphenyldichloroethylene (DDE), dichlorodiphenyldichloroethane (DDD) and endosulfan sulfate indicates past usage. All the OCPs were dominant in the agricultural transect where plantations/agricultural activities are prevalent. In some specific sites, traces of HCH isomers showed ongoing usage of technical HCH in those sites contradicting the ban in agricultural sector. Backwater sites which are background locations showed positive correlation between soil organic carbon and soil borne OCPs thereby indicating an aged source possibly due to the short/long atmospheric transport from the site of application. Based on the policies regarding control, prevention and other measures for the management of pesticides in Kerala, it was concluded that the implementation on the ground level and the legal framework should be strengthened to prevent further illegal use of the banned pesticides.