| 1. |
- Duttagupta, Srimanti, et al.
(författare)
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Role of aquifer media in determining the fate of polycyclic aromatic hydrocarbons in the natural water and sediments along the lower Ganges river basin
- 2020
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Ingår i: Journal of Environmental Science and Health. Part A. - : TAYLOR & FRANCIS INC. - 1093-4529 .- 1532-4117. ; 55:4, s. 354-373
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Tidskriftsartikel (refereegranskat)abstract
- Groundwater-sourced drinking water quality in South Asia, specifically India, is extremely stressed, mostly from the presence of many pervasive and geogenic pollutants. The presence and behavior of anthropogenic pollutants like polycyclic aromatic hydrocarbons (PAHs) are poorly investigated on a regional or basin-wide scale. The present study provides one of the first documentation of the presence and behavior of PAH in the aquifer sediments in the Ganges river basin. Lower and medium molecular weight PAHs, e.g., naphthalene, phenanthrene, and fluoranthene were detected in 79, 36, and 13% of samples (n = 25). The PAH level in groundwater was approximately five times lower than river water. The sorption behavior of PAHs were studied in experiments in presence/absence of organic carbon and by simulating advective transport of low to medium molecular weight PAHs, e.g., naphthalene, phenanthrene, and fluoranthene in aquifer sediments collected from agricultural, peri-urban, and urban areas. Naphthalene and phenanthrene adsorbed on quartz and kaolinite, but not on clay minerals like kaolinite. Fluoranthene adsorbed more favorably on kaolinite. Numerical modeling of the advective transport of PAHs in aquifers suggest up to 25 times faster movement of pollutants from irrigation-induced pumping, indicating the strong control of hydraulics on the spatial distribution of PAHs in subsurface.
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| 2. |
- Mukherjee, Abhijit, et al.
(författare)
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Occurrence, predictors and hazards of elevated groundwater arsenic across India through field observations and regional-scale AI-based modeling
- 2021
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 759
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Tidskriftsartikel (refereegranskat)abstract
- Existence of wide spread elevated concentrations of groundwater arsenic (As) across South Asia, including India, has endangered a huge groundwater-based drinking water dependent population. Here, using high-spatial resolution As field-observations (similar to 3 million groundwater sources) across India, we have delineated the regional-scale occurrence of elevated groundwater As (>= 10 mu g/L), along with the possible geologic-geomorphologic-hydrologic and human-sourced predictors that influence the spatial distribution of the contaminant. Using statistical and machine learning method, we also modeled the groundwater As concentrations probability at 1 Km resolution, along with probabilistic delineation of high As-hazard zones across India. The observed occurrence of groundwater As was found to be most strongly influenced by geology-tectonics, groundwater-fed irrigated area (%) and elevation. Pervasive As contamination is observed in major parts of the Himalayan mega-river Indus-Ganges-Brahmaputra basins, however it also occurs in several more-localized pockets, mostly related to ancient tectonic zones, igneous provinces, aquifers in modern delta and chalcophile mineralized regions. The model results suggest As-hazard potential in yet-undetected areas. Our model performed well in predicting groundwater arsenic, with accuracy: 82% and 84%; area under the curve (AUC): 0.89 and 0.88 for test data and validation datasets. An estimated similar to 90 million people across India are found to be exposed to high groundwater As from field-observed data, with the five states with highest hazard are West Bengal (28 million), Bihar (21 million), Uttar Pradesh (15 million), Assam(8.6 million) and Punjab (6 million). However it can be much more if the modeled hazard is considered (>250 million). Thus, our study provides a detailed, quantitative assessment of high groundwater As across India, with delineation of possible intrinsic influences and exogenous forcings. The predictive model is helpful in predicting As-hazard zones in the areas with limited measurements.
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| 3. |
- Sharifi-Yazdi, Masoud, et al.
(författare)
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Influence of the Late Quaternary climate on sedimentology of the Jazmurian Playa, SE Iran
- 2022
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Ingår i: Journal of Paleolimnology. - : SPRINGER. - 0921-2728 .- 1573-0417. ; 68, s. 169-187
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Tidskriftsartikel (refereegranskat)abstract
- The Jazmurian Playa in southeast Iran is a sediment archive that has preserved a record of climate and environmental changes since the late Pleistocene. The late Pleistocene was dominated by sub-arid to arid climate interspersed with short periods of warm and humid conditions that impacted the vegetation cover and landscape. This study used sedimentological variations in a sediment core, supported by geochemical and mineralogical characteristics, to reconstruct climate change impacts and water-level fluctuations in the playa. These changes were inferred using grain-size data, magnetic susceptibility, total organic matter content, carbonate content, elemental concentrations, and mineralogical composition in a C-14-dated sediment core. Based on the inferred water level fluctuations in the playa, the core was divided into two major units. Unit 2 belonged to the late Pleistocene, characterized by a cold and dry climate. In contrast, Unit 1 was deposited during the Holocene, a time marked by prevailing warm and humid conditions, with short periods of intense dust storms. Since the late Holocene, the IOSM (Indian Ocean Summer Monsoon) has played a dominant role in regional climate. Water-level fluctuations related to humidity significantly influenced the sedimentological variables, including grain-size distribution, sorting, skewness, and roundness. During cold and arid conditions, the water level was low, and coarse sediments were deposited in the playa, with low organic matter content, low concentrations of Cu, Mn, P, and V, and evaporite minerals. In contrast, high organic matter content, presence of illite, and high concentrations of Cu, Mn, P, and V and low values of ICV (Index of Compositional Variability) imply a warm and humid climate during the Holocene. The paleoclimate reconstruction in the playa provides evidence about ongoing changes that are closely related to the paleohydrological conditions in this region.
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