This study investigated the hydrogeological characteristics and groundwater dynamics in the shallow aquifer zones of inner Guwahati city, Assam, India. Sixteen dug wells spread across the city, specifically used for domestic purposes, were selected for this study. Additionally, ten wells were selected for trend analysis. The borehole lithology reveals predominant compositions of clay, sand, and granules, with thin clay cappings indicating significant groundwater potential. Depth-to-water level analysis revealed varying water levels across the study area, with shallow levels in the northern and western regions and gradual deepening toward the eastern and southern parts. The groundwater flow directions show nonuniform patterns and reflect the influence of topography and domestic pumping in urban residential zones. The general groundwater flow direction is toward the Brahmaputra River. Trends in groundwater level, assessed using the Mann–Kendall test and Sen’s slope, suggest both falling and rising trends across different locations, indicating complex groundwater dynamics influenced by factors such as recharge, extraction, and topography. However, the long-term rainfall data indicate no significant trend over the studied period, suggesting limited natural influence on groundwater level trends. These findings may contribute to a comprehensive understanding of groundwater dynamics in the study area and are essential for sustainable water resource management and mitigation of groundwater depletion risks.

This study evaluated the influence of four thermal pretreatment techniques—autoclaving, hot-air oven treatment, hot-water immersion, and microwave irradiation—on Parthenium hysterophorus biomass to improve its biodegradability and biogas generation potential under batch anaerobic digestion. Among the investigated methods, hot-air oven pretreatment at 110 °C for 90 min exhibited the most significant enhancement in biomass solubilization, as indicated by a 51.5% rise in soluble chemical oxygen demand (sCOD) and an increase in volatile fatty acids (VFAs) compared with the untreated control. These compositional improvements facilitated faster hydrolysis and led to a 25.73% higher cumulative methane yield in biochemical methane potential (BMP) assays. Structural analysis revealed pronounced alterations in the lignocellulosic matrix, with reductions in hemicellulose and partial delignification improving substrate accessibility. Complementary characterisation using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) confirmed the disruption of crystalline cellulose regions and modification of functional groups, supporting the observed biochemical improvements. Collectively, the results demonstrate that hot-air oven pretreatment is a practical and energy-efficient approach for enhancing the digestibility of P. hysterophorus biomass, promoting its utilisation as a sustainable feedstock for renewable biogas production and environmental management of this invasive weed.

Wetlands span 1500 million hectares and contribute 43.5% of overall ecosystem service value globally. With 35% loss globally since 1970, tropical wetlands are considered the most exploited and threatened ecosystem. Therefore, it is vital for identifying and comprehending driving factors contributing to the degradation of wetlands. This review examines wetlands of international significance located in Northeast India. The existing literature on wetlands, specifically Loktak Lake in Manipur, Deepor Beel in Assam, and Rudrasagar Lake in Tripura, has been meticulously examined. The findings indicated that Ramsar sites experienced persistent degradation due to factors including land use change, policy and management issues, and climate change, alongside other anthropogenic activities encompassing the release of domestic sewage, untreated industrial effluents, and with excessive fertilizer application, all of which exacerbate the overexploitation of wetland resources. In principle, water quality is evaluated via physicochemical as well as biological parameters. Consequently, the WQI (Water Quality Index) has been a significant tool for water quality evaluation. Wetlands are lentic water bodies, leading to the deposition of various toxic pollutants over time. The present study provides an overview of different indices including HMI (Heavy Metal Index), EF (Enrichment Factor), I _geo (Geoaccumulation Index) used for determining heavy metals contamination in wetland sediments besides nutrient loading effect on water quality. This review on Ramsar sites further suggests the integration of all the aspects of limnology for better sustainable management of wetlands.

This study evaluated the influence of four thermal pretreatment techniques—autoclaving, hot air oven treatment, hot water immersion, and microwave irradiation—on Parthenium hysterophorus biomass to improve its biodegradability and biogas generation potential under batch anaerobic digestion. Among the investigated methods, hot air oven pretreatment at 110 °C for 90 minutes exhibited the most significant enhancement in biomass solubilization, as indicated by a 51.5% rise in soluble chemical oxygen demand (sCOD) and an increase in volatile fatty acids (VFAs) compared with the untreated control. These compositional improvements facilitated faster hydrolysis and led to a 25.73% higher cumulative methane yield in biochemical methane potential (BMP) assays. Structural analysis revealed pronounced alterations in the lignocellulosic matrix, with reductions in hemicellulose and partial delignification improving substrate accessibility. Complementary characterization using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) confirmed the disruption of crystalline cellulose regions and modification of functional groups, supporting the observed biochemical improvements. Collectively, the results demonstrate that hot air oven pretreatment is a practical and energy-efficient approach for enhancing the digestibility of P. hysterophorus biomass, promoting its utilization as a sustainable feedstock for renewable biogas production and environmental management of this invasive weed.