Anthropogenic disturbances influence mineral and elemental constituents of freshwater lake sediments.

Lake sediments can provide valuable insights into anthropogenic disturbances such as intensive aquaculture and land use changes. These disturbances often manifest as elevated levels of nutrients and elements within the sediments. This paper uses several analytical techniques, i.e., FTIR (Fourier-transform infrared spectroscopy), XRD (X-ray diffraction), EDS (energy-dispersive X-ray spectroscopy), and SEM (scanning electron microscopy), to examine the elemental constituents of lake sediments, along with their relative mineral abundances and surface morphology. The selected freshwater lakes are from the Central Gangetic Plain. The analysis provides a "fingerprint" of geogenic and biogenic mineral constituents of the sediments. Physicochemical, mineralogical, and elemental analysis shows that intensive aquaculture activities in lake alter the sediment chemistry as evidenced by the increase in pH, organic carbon, organic matter, and total phosphorus which is not observed in the lake where aquaculture is prohibited. Freshwater lake sediment is characterized by a high content of biogenic silica and carbonate minerals. The variations in sediment nutrients and mineral fluxes of the selected lakes are mainly attributed to diverse anthropogenic pressures, differences in lake productivity, and the overall ecological condition of the lakes. In the selected three lakes, major variation was reported in the autochthonous sediments in comparison to the allochthonous sediments. The study concludes that catchment and biotic deposit variations in the lakes cannot be evened out by in-lake mixing mechanisms due to variations in the terrigenous and pelagic deposits of the lake. The results highlight the importance of studying annual fluctuations and spatial variations in geogenic and biogenic mineral particle fluxes in lakes. Such investigations provide valuable insights into the annual dynamics of minerals within lakes, contributing to a more comprehensive understanding of their behavior and distribution.

Wastewater generation and treatment by various eco-friendly technologies: Possible health hazards and further reuse for environmental safety.

The discharge of untreated wastewater as a result of various developmental activities such as urbanization, industrialization and changes in lifestyle poses great threats to aquatic ecosystems as well as humans. Currently, ∼380 billion m3 (380 trillion liters) of wastewater is generated globally every year. Around 70% of freshwater withdrawals are used for agricultural production throughout the world. The wastewater generated through agricultural run-off further pollutes freshwater resources. However, only 24% of the total wastewater generated from households and industries is treated before its disposal in rivers or reused in agriculture. The most problematic contaminants associated with ecological toxicity are heavy metals such as Cd, Cr, Cu, Ni, Zn, Fe, Pb, Hg, As and Mn. One of the most important issues linked with wastewater generation is the residual presence of pathogenic microorganisms which pose potential health hazards to consumers when they enter into the food chain. It is estimated that in India almost USD 600 million (48.60 billion INR) is spent per year to tackle waterborne diseases (WBD). In light of this, immediate action is needed to effectively treat wastewater and develop safer reuse prospects. Various wastewater treatment technologies have been established and they work well to provide an alternative water source to meet the growing demand. The main concern towards treating wastewater is to eliminate inorganic and organic substances and lower the nutrient concentration, total solids, and microbial pathogens to prevent freshwater pollution and health risks.

Constructed wetlands for the removal of pharmaceuticals and personal care products (PPCPs) from wastewater: origin, impacts, treatment methods, and SWOT analysis.

The continuous exposure to pharmaceuticals and personal care products can lead to a series of individual antagonistic and synergistic effects and long-lasting toxicity to humans and aquatic lives. This may also lead to developing antibiotic resistance, teratogenic, carcinogenic, and endocrine-disrupting effects. However, several PPCPs are also considered biologically active for non-target aquatic organisms, such as mosquito fish, goldfish, and the algae Pseudokirchneriella subcapitata. Various physicochemical methods such as ozonation, photolysis, and membrane separation are recognized for the effective removal of PPCPs. However, the high operation and maintenance costs and associated ecological impacts have limited their further use. Constructed wetlands are considered eco-friendly and sustainable for the removal of pharmaceuticals and personal care products together with antibiotic resistance genes. Several mechanisms such as sorption, biodegradation, oxidation, photodegradation, volatilization, and hydrolysis are occurring during the phytoremediation of PPCPs. During these processes, more than 50% of PPCPs can be eliminated through constructed wetlands. They also offer several additional benefits as obtained macrophytic biomass may be used as raw material in pulp and paper industries and a source for second-generation biofuel production. In this study, we have discussed the origin and impacts of PPCPs together with their treatment methods. We have also investigated the strengths, weaknesses, opportunities, and threats associated with constructed wetlands during the treatment of wastewater laden with pharmaceutical and personal care products.

Interspecific competition and their impacts on the growth of macrophytes and pollutants removal within constructed wetland microcosms treating domestic wastewater.

Eight free water surface constructed wetland microcosm (CWM) units are designed with single as well as mixed planting of Pistia stratiotes, Phragmites karka, and Typha latifolia with control to assess their competitive value (CV), relative growth rates (RGR), and pollutants removal efficiency. Further, the total dry biomass production and other growth parameters such as number of macrophytes, above-ground biomass, below-ground biomass, and root length were also measured to understand the dominant characteristics of the macrophytes. The CWM units with species mixture out-performed species monocultures. Removal of BOD, TP, SRP, NH4+-N, NO3--N, and NO2--N by mixed planting of P. stratiotes and P. karka was higher at most of the time. Typha latifolia was the superior competitor against both P. stratiotes and P. karka due to its aggressive characteristics that inhibits the growth of neighboring macrophytes. However, P. karka was the superior competitor against P. stratiotes. The RGR of T. latifolia in all experimental units was almost two times more than that of P. karka. Novelty Statement The CWM units with species mixture out-performed species monocultures. CWMs with more than one macrophytic species are less vulnerable to seasonal fluctuations and more effective in contaminants removal as compared to single macrophyte wetlands. Removal of BOD, TP, SRP, NH4+-N, NO3--N, and NO2--N by mixed planting of P. stratiotes and P. karka was higher at most of the time. The CWMs with P. stratiotes and P. karka are superior choice due to their higher wastewater nutrients removal capacity. The application of these three macrophytes in mixed cultures in free water surface constructed wetland is rare. The results are useful in designing large-scale multi-species wetlands which are less susceptible to seasonal variation and more effective in pollutants removal than single-species wetlands.

Wastewater-based epidemiology: a new frontier for tracking environmental persistence and community transmission of COVID-19.

Recent research in many parts of the world has pointed towards evidence of SARS-CoV-2 RNA in both treated and raw municipal wastewater discharged by communities. Therefore, concerns regarding it being a possible enteric virus are abundant. Past history of SARS-CoV-1 outbreaks and viral survival information helps in establishing information regarding possible viral infectivity and survival of SARS-CoV-2. The paper examines the existing strategies and techniques including the efficacy of laboratory-based RT-qPCR technique for tracking environmental persistence and community transmission of COVID-19. Analysis of studies targeting untreated and treated wastewater as source of samples is carried out. The analysis shows that untreated samples were mostly positive for SARS-CoV-2 RNA in the target studies. Infectivity estimation from viral load data was found to be about two orders of magnitude higher than actual case data in one of the studies. Additionally, relevant research on environmental survivability of SARS-CoV-2 and possible gaps are examined. Biosensors and excretion metabolite tracking in viral detection are also examined, which hold tremendous importance for future research. Wastewater-based epidemiology (WBE) shows incredible promise in the near future for tracking environmental persistence and community transmission of highly infectious diseases such as SARS-CoV-2. With limited research available on SARS-CoV-2 with regard to WBE, it is imperative that focus be established on the evidence-based targeted studies.

Recent advances in satellite mapping of global air quality: evidences during COVID-19 pandemic.

There was a significant decline in air pollution in different parts of the world due to enforcement of lockdown by many countries to check the spread of the coronavirus (COVID-19) pandemic. In particular, commercial and industrial activities had been limited globally with restricted air and surface traffic movements in response to social distancing and isolation. Both satellite remote sensing and ground-based monitoring were used to measure the change in the air quality. There was momentous decline in the averaged concentrations of nitrogen dioxide (NO2), carbon dioxide (CO2), sulphur dioxide (SO2), methane (CH4) and aerosols. Many cities across India, China and several major cities in Europe observed strong reductions in nitrogen dioxide levels dropping by around 40-50% owing to lockdowns. Similarly, concentrations of SO2 in polluted areas in India, especially around large coal-fired power plants and industrial areas decreased by around 40% as evidenced by the comparative satellite mapping during April 2019 and April 2020. Recent advances in sensors on board various satellites played a significant role in real-time monitoring of emission regimes over various parts of the world. The satellite data is relying upon single scene profusion for real-time air quality measurements, and also using averaged dataset over certain time-period. The daily global-scale remote sensing data of NO2, as measured through the Copernicus Sentinel-5 Precursor Tropospheric Monitoring Instrument (S5p/TROPOMI) of European Space Agency (ESA), indicated exceptional decreases in tropospheric NO2 pollution in urban areas. Similarly, Greenhouse gases Observing Satellite (GOSAT) of Japan Aerospace Exploration Agency, with a repeat cycle of three days helped in assessing the sources and sinks of CO2 and CH4 on a sub-continental scale. Supplementary Information: The online version contains supplementary material available at 10.1007/s42398-021-00166-w.

Cleaning the River Ganga: Impact of lockdown on water quality and future implications on river rejuvenation strategies.

Clean rivers and healthy aquatic life symbolize that the ecosystem is functioning well. The Ganga River has shown signs of rejuvenation and a significant improvement on many parameters, following the eight-week nationwide lockdown due to coronavirus pandemic. Since industrial units and commercial establishments were closed, water was not being lifted by them with a negligible discharge of industrial wastewater. It was observed that during the lockdown period most of the districts falling under the Ganga basin observed 60% excess rainfall than the normal, which led to increased discharge in the river, further contributing towards the dilution of pollutants. Further, data analysis of live storages in the Ganga Basin revealed that the storage during the beginning of the third phase of lockdown was almost double than the storage during the same period the previous year. Analysis of the storage data of the last ten years revealed that the storage till May 6, 2020 was 82.83% more than the average of the previous ten years, which meant that more water was available for the river during the lockdown period. The impact could be seen in terms of increased dissolved oxygen (DO) and reduced biological oxygen demand (BOD), Faecal coliform, Total coliform and nitrate (NO3-) concentration. A declining trend in nitrate concentration was observed in most of the locations due to limited industrial activities and reduction in agricultural run-off due to harvesting season. The gradual transformation in the quality of the water has given a sign of optimism from the point of restoration. Yet, it is believed that this improvement in water quality is 'short-lived' and quality would deteriorate once the normal industrial activities are resumed, indicating a strong influence of untreated commercial-industrial wastewater. The paper concludes that the river can be rejuvenated if issues of wastewater and adequate flow releases are addressed.

Biopesticides in India: technology and sustainability linkages.

Despite enhancing the crop yields, the so called green revolution (GR) has proven unsuccessful in assuring long term agricultural sustainability. The methods used for productivity enhancement during GR have not only proven to be problematic but have also resulted in deterioration of soil quality and several other issues related to ecosystems and health issues. The damage was mainly caused by the indiscriminate use of chemical fertilizers and insecticides. Various types of pesticides, are now known to be causing huge problems in the agro-ecosystems. In such a situation, where chemicals have caused or are causing irreversible impacts on agroecosystems, the use of biopesticides has emerged as a sustainable alternative leading to safe organic farming. At the global level, environmentally benign nature and target-specificity of biopesticides are gaining wide popularity. However, in developing countries like India usage of biopesticides is still minuscule in comparison to conventional chemical pesticides. Although the Indian government has encouraged the use of biopesticides by placing them into many of the agricultural schemes, at the grassroots level, biopesticides are facing many challenges. The lower adaptability and declining interest of farmers towards biopesticides have become a matter of concern. However, technological challenges related to production, manufacture and application in agroecosystems have also raised a question on their long-term sustainability. The main objective of this review is to highlight the developing trend in the field of biocontrol products in India. Apart from this, the review also focuses on the technological perspectives that are required for the long-term sustainability of biological control products in Indian agriculture and market.

Variation in extracellular enzyme activities and their influence on the performance of surface-flow constructed wetland microcosms (CWMs).

Eight constructed wetland microcosm (CWM) units have been designed using three macrophytes for domestic wastewater treatment. The main aim of this study is to evaluate enzyme activities with respect to time and soil depth and their correlation with removal efficiency of pollutants within different CWM units. The findings of this study show that the activity of enzymes and pollutants removal efficiency vary to a great extent on the soil depth, time of the sampling and type of pollutants. The correlation between removal of soluble reactive phosphorus and total phosphorus was significant with phosphatase activity in most of the CWM units. Activity of urease and NH4+-N removal was positively correlated with significant positive correlation in CWM units planted with Phragmites karka, and Pistia stratiotes (Ph + Pi) and Typha latifolia, Phragmites karka and Pistia stratiotes (T + Ph + Pi). Urease activity was found to be both positively and negatively correlated with respect to removal of NO3--N and NO2--N in different CWM units. Dehydrogenase activity showed negative correlation with respect to biological oxygen demand (BOD) removal except in CWM units with Ph + Pi and T + Ph + Pi. Similarly, a moderate positive and negative correlation exists between fluorescein diacetate hydrolysis and BOD removal. Removal of BOD and microbial biomass carbon (MBC) was negatively correlated with each other in most of the CWM units. With respect to vertical variation, the top layer of CWM units expressed significantly higher activity of extracellular enzymes and were significantly different from the deeper layer. CWM units exhibited significant variations in enzyme activity with respect to time.

Constructed wetland microcosms as sustainable technology for domestic wastewater treatment: an overview.

Constructed wetland microcosms (CWMs) are artificially designed ecosystem which utilizes both complex and ordinary interactions between supporting media, macrophytes, and microorganisms to treat almost all types of wastewater. CWMs are considered as green and sustainable techniques which require lower energy input, less operational and maintenance cost and provide critical ecological benefits such as wildlife habitat, aquaculture, groundwater recharge, flood control, recreational uses, and add aesthetic value. They are good alternatives to conventional treatment systems particularly for smaller communities as well as distant and decentralized locations. The pH, dissolved oxygen (DO), and temperature are the key controlling factors while several other parameters such as hydraulic loading rates (HLR), hydraulic retention time (HRT), diversity of macrophytes, supporting media, and water depth are critical to achieving better performance. From the literature survey, it is evaluated that the removal performance of CWMs can be improved significantly through recirculation of effluent and artificial aeration (intermittent). This review paper presents an assessment of CWMs as a sustainable option for treatment of wastewater nutrients, organics, and heavy metals from domestic wastewater. Initially, a concise note on the CWMs and their components are presented, followed by a description of treatment mechanisms, major constituents involved in the treatment process, and overall efficiency. Finally, the effects of ecological factors and challenges for their long-term operations are highlighted.

GABA mediated reduction of arsenite toxicity in rice seedling through modulation of fatty acids, stress responsive amino acids and polyamines biosynthesis.

γ-aminobutyric acid (GABA) is a free amino acid, which helps to counteract biotic and abiotic stresses in plants. In the present study, two concentrations of GABA, i.e., 0.5 mM and 1 mM were applied to examine the tolerance of rice seedlings against As(III) (25 µM) toxicity, through the modulations of fatty acids (FAs), stress responsive amino acids (AAs) and polyamines (PAs) biosynthesis. Exogenous GABA (0.5 mM) application significantly reduced the H2O2 and TBARS levels and recovered the growth parameters against As(III) stressed rice seedlings. Simultaneously, co-application of GABA (0.5 and 1 mM) and As(III), consistently enhanced the level of unsaturated fatty acids (USFA) (cis-10-pentadecanoic acid, oleic acid, α-linolenic acid and γ-linolenic acid), which was higher than saturated fatty acid (SFA). Among the USFAs, level of linolenic acid was found to be always higher with GABA application. Similarly, elevated level of AAs (proline, methionine, glutamic acid and cysteine) was also observed with the application of GABA (0.5 and 1 mM) in As(III) stressed seedlings. GABA also enhanced the expression of genes involved in the polyamine synthesis pathway namely arginine decarboxylase (AD), spermine (SPM) and spermidine (SPD) synthase against As(III) treatments, which was higher in roots than in shoots, resulting in enhanced root PAs level. Contrarily, the expression of S-adenosylmethionine decarboxylase (S-AMD) was significantly higher in shoots. Among all the PAs, level of putrescine (PUT) was found to be highest with GABA application. Overall, the study demonstrates that GABA (0.5 mM) at lower concentration plays a vital role in As(III) tolerance by enhancing the biosynthesis of USFA, AA and PA, reducing the level of TBARS and H2O2 in rice seedlings.