Mahesh Mohan

Water and sediment quality of Ashtamudi estuary, a Ramsar site, southwest coast of India—a statistical appraisal

Ashtamudi estuary, situated on the southwest coast of India, is enormously affected by anthropogenic interventions. Physicochemical quality of water and sedimentological features of the estuary are evaluated during monsoon and nonmonsoon seasons to elucidate its quality variations and to link the same with existing environmental scenario. The whole data has been factorized using principal component analysis for extracting the total variability and linear relationships existing among a set of different physicochemical parameters of the backwater system. In PCA, high loadings were obtained for conductivity, salinity, fluoride, calcium, magnesium, sulfate, boron, and pH. The results were revealed that all the physicochemical processes depend upon seasonal fluctuation of freshwater input and seawater intrusion. Wide spatial concentration fluctuations of organic carbon and iron in bottom sediment have been noticed and both constituents reveal good correlation with sediment texture. The results showed high deterioration of the physicochemical quality of water during nonmonsoon season with respect to monsoon season.

Environmental impacts of perchlorate with special reference to fireworks—a review

Perchlorate is an inorganic anion that is used in solid rocket propellants, fireworks, munitions, signal flares, etc. The use of fireworks is identified as one of the main contributors in the increasing environmental perchlorate contamination. Although fireworks are displayed for entertainment, its environmental costs are dire. Perchlorates are also emerging as potent thyroid disruptors, and they have an impact on the ecology too. Many studies have shown that perchlorate contaminates the groundwater and the surface water, especially in the vicinity of fireworks manufacturing sites and fireworks display sites. The health and ecological impacts of perchlorate released in fireworks are yet to be fully assessed. This paper reviews fireworks as a source of perchlorate contamination and its expected adverse impacts.

Mercury in the sediments of Vembanad Lake, western coast of India

Mercury, a global pollutant, is popping up in places where it was never expected before and it burdens in sediments and other non-biological materials. It is estimated to have increased up to five times the pre-human level due to anthropogenic activities. Vembanad backwaters, one of the largest Ramsar site in India, which have extraordinary importance for its hydrological function, are now considered as one of the mercury hot spots in India. In this study, surface sediment samples of Vembanad Lake and nearshore areas have been seasonally analysed for total mercury and methyl mercury concentrations while the core sediment samples were analysed for total mercury. The results showed that the northern part of the lake was more contaminated with mercury than the southern part. The mercury concentration was relatively high in the subsurface sediment samples, indicating the possibility of historic industrial mercury deposition. A decreasing trend in the mercury level towards the surface in the core sediment was also observed. The geochemical parameters were also analysed to understand the sediment mercury chemistry. Anoxic conditions, pH and organic carbon, sulphur and Fe determined the presence of various species of mercury in the sediments of Vembanad Lake. The prevailing physical and geochemical conditions in Vembanad Lake have indicated the chances of chemical transformation of mercury and the potential hazard if the deposited mercury fractions are remobilised.

Review on Fate, Toxicity, and Remediation of Perchlorate

Several issues regarding the adverse impacts of the chemical—perchlorate—have been identified recently. Perchlorate is a persistent chemical, and remains in water and soil, thereby accumulating in plants and animals. Fetuses suffer the most from perchlorate contamination. There are ongoing debates about the impacts, toxicity and health effects of perchlorate. Many studies have been conducted on its ecotoxicity and its effects, but standards do not exist for perchlorate. This study aims to review the sources, impacts, fate, transport and remediation of perchlorate.

Plant Growth Enhancement, Disease Resistance, and Elemental Modulatory Effects of Plant Probiotic Endophytic Bacillus sp. Fcl1

Endophytic bacteria have already been studied for their beneficial support to plants to manage both biotic and abiotic stress through an array of well-established mechanisms. They have either direct or indirect impact on mobilizing diverse nutrients and elements from soil to plants. However, detailed insight into the fine-tuning of plant elemental composition by associated microorganism is very limited. In this study, endophytic Bacillus Fcl1 characterized from the rhizome of Curcuma longa was found to have broad range of plant growth-promoting and biocontrol mechanisms. The organism was found to have indole acetic acid and 1-aminocyclopropane-1-carboxylate deaminase production properties along with nitrogen fixation. The Bacillus Fcl1 could also inhibit diverse phytopathogens as confirmed by dual culture and well diffusion. By LC-MS/MS analysis, chemical basis of its antifungal activity has been proved to be due to the production of iturin A and a blend of surfactin compounds. Moreover, the organism was found to induce both plant growth and disease resistance in vivo in model plant system. Because of these experimentally demonstrated multiple plant probiotic features, Bacillus Fcl1 was selected as a candidate organism to study its role in modulation of plant elemental composition. ICP-MS analysis of Bacillus Fcl1-treated plants provided insight into relation of bacterial interaction with elemental composition of plants.

Big Data Analytics and Social Media in Disaster Management

Abstract This chapter presents the use of Big Data analytics and data mining of social media (SM) for effective emergency management and its uses during different phases of disaster management processes. It draws attention to the basic concepts of SM (characters, type), Big Data (data mining and analytics), interlinks in SM, and disaster management. Some case studies are also narrated to show how Big Data and SM usages are helpful in preparedness, response, recovery, and mitigation phases to reduce the hazard, risk, and vulnerability of the affected communities. The uses of SM are now emergent and are used in all sectors right from individual citizens to non-government organizations, private sector, government stakeholders, and volunteering organizations for aiding in information communication or knowledge transfer during disaster situations. The power of SM has spanned new fields of research, which harness the power to arrive at instantaneous decisions which are needed in disaster situations. Big Data analytics thus provides a new tool that matches the speed with which disasters occur and thus aids in very quick decision-making. These technologies are beneficial for adaptation and can help communities to become more resilient.

Rate of sediment accumulation and historic metal contamination in a tidewater glacier fjord, Svalbard

The sedimentation rates in Arctic fjords are influenced by the changes in the glacial inputs. The recent studies have indicated the retreat of glaciers due to climate change and subsequent increase in melt water outflow with high content of debris. The debris may contain natural and anthropogenically originated contaminants. The present study analysed the sedimentation rate in inner Kongsfjorden, Ny-Ålesund, Svalbard using 210Pb/210Po dating technique. The sedimentation rate ranged between 0.22 and 0.37 cm/year during the last 112 years. The average sedimentation rate obtained was 0.28 cm/y. The rate has been increased during the last 20 years and it might be due to the increased influx of glacial melt water containing debris. Metals and other elements showed an increasing trend towards the surface and observed high deposition rate since 1970s, indicating influence of industrial emissions and it can be a potential threat to Arctic biota.

Distribution of priority pollutants in the sediment of Vembanad Estuary, Peninsular India

The existence of Organochlorine pesticides (OCPs) and trace metals in tropical aquatic environments may cause a severe threat on account of their ubiquitous nature and long persistence. Monitoring of such contaminants has assumed immense significance in recent times. The present study assessed the OCPs and trace metal contamination in the surface sediments of the Vembanad wetland system in India. Various pollution indices were calculated to determine the sediment quality of the system and were also compared with uncontaminated sediments. Geo-accumulation index for Mercury varied from moderately to extremely polluted. The mean concentration of pesticide residues and trace metals in the sediments of Vembanad is found to be higher than in other aquatic systems in India. The situation demands further studies which focus on the potential bioaccumulation of OCPs and metals in the benthic food chain, succeeding biota and their impact on human consumption as the system supports a huge population for their livelihood. The Present study provides a baseline information on the spatial distribution of priority pollutants along with ecological risk status of Vembanad estuarine system (VES).

Mercury tolerance and biosorption in bacteria isolated from Ny-Ålesund, Svalbard, Arctic

Mercury tolerant bacteria Pseudarthrobacter oxydans strain MM20 and Pseudomonas frederiksbergensis strain SS18 were isolated from the tundra ecosystem of Ny‐Ålesund, Svalbard, where commercial exploitation of the coal existed till 1960s. Minimum inhibitory concentration (MIC), mercury removal, mercury biosorption, and antibiotic resistance of these strains were analyzed. P. frederiksbergensis strain SS18 showed high tolerance (2.0 ppm) to mercury than P. oxydans strain MM20 (1.5 ppm). Mercury removal and biosorption studies were carried out in liquid media containing 1.0 ppm mercury. More than 90% of mercury was removed from the culture media by the selected strains. The mercury biosorption assay revealed that a part of mercury was accumulated in cell pellets and was 22 and 25% respectively for P. oxydans strain MM20 and P. frederiksbergensis strain SS18. Fourier transform infrared study revealed that alkyl halide, alkynes, alcoholic, aliphatic and aromatic amines, alkanes, nitro compound, primary amines, carboxylic acid, alkenes, and amide groups play a major role in the development of tolerance towards mercury. Out of eleven antibiotics tested, P. oxydans strain MM20 was found to be resistant to lincomycin and novobiocin while P. frederiksbergensis strain SS18 was found to be resistant to seven antibiotics. Our study demonstrates that under experimental conditions, bacterial isolates undergo detailed structural and functional changes to tolerate as well as immobilize toxic elements like mercury.