15. An Overview of Natural Water Contamination and Sustainable Attenuation Techniques: Challenges and Opportunities

The concept of natural attenuation of environmental contaminants has been evolved through the harnessing of natural clean up processes (volatilization, biodegradation, sorption, bioaccumulation, dilution, precipitation, dispersion, etc.) for the aquatic and terrestrial ecosystems. Although several researches have been conducted in the last few decades on several aspects (geochemical parameters, performance evaluation, isotope labelling approaches, environmental biotechnology, etc.) of the natural decontamination technologies, a focused overview on its significance for performance-based monitoring and risk assessment of sustainable remediation measures are rare in the literature. In this chapter, the basic science of the water quality treatment, occurrence/fate, and contaminant biodegradation has been discussed along with the mobility and biological detoxification of pollutants. The microbial diversity surrounding the contaminant plume and mechanism of contaminant removal have been elucidated along with special emphasis on the response of the microbial communities toward various kinds of pollutant dynamics. Microbial community shifts in response/vicinity of the contaminated area within a natural wetland ecosystem have also been documented to explore the metabolic network of ecological interactions based on microbial population dynamics. Moreover, a critical assessment on the state-of-the art removal techniques and rate of dissipation of natural contaminants has been presented. Furthermore, the present chapter highlights the major pollutant detoxification pathways and their impact on groundwater flow regime.