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Assessment of soil organic carbon (SOC) stock and identification of the factors influencing its spatial variation are crucial for adopting appropriate mitigation and adaptation strategies under changing climatic conditions. The present study aims to measure SOC content and stock and identify the factors contributing to SOC variation in India's sub-tropical, dry sub-humid Eastern Plateau Region (EPR). It also aims to recognize the potential land uses for enhancing the C stock in the region. Soil samples were collected from two soil depth layers—0 to 10 cm and 10 to 20 cm, from locations under different soil type, land use, and topographic conditions. The Walkley-Black method was used to determine the SOC content of the samples. Ordinary kriging based on an exponential semi-variogram model was employed to analyze the spatial variability of SOC concentration and its relationship with the sampling strata. The study shows that the topsoil variation in SOC depended mainly on the land use type and the corresponding soil properties viz. pH and texture. Cultivated areas, especially those of the lowland, recorded higher SOC than other land use classes. The findings of the present study are useful for defining agricultural management practices and carbon sequestration strategies for the region in the context of climate change. [ABSTRACT FROM AUTHOR]

This study evaluates spatial trend and distribution history of selected metals in the complex coastal environment of Odisha, India. The main objective is to analyse metal enrichment and level of contamination in sediment deposits. It is also attempted to evaluate the past depositional environment and prevailing process leading to metal enrichment and contamination. Three sediment cores up to a depth of 10 m were collected from older beach deposit of Chandbali (CB) and paleochannels of Agiviligan (AG) and Kasturikaran (KK) villages located along River Baitarani, coastal Odisha. The study area, to a large extent, is a transition zone of terrestrial and marine sediments. The assessment of metal contamination is based on spatial and down-core variability of selected metals- Al2O3, MnO, Cr, Co, Cu, Zn, and Pb against their background values. Contamination is examined using enrichment factor (EF), contamination factor (CF) and geo-accumulation index (Igeo). The study exhibits a complex pattern of metal distribution over space and time. The sediments are enriched and contaminated with MnO, Cr, and Pb not only in the surface layers but also in the deeper layers such as CBL4 (–7.3 m), CBL5 (–7.9 m), CBL6 (–10 m), AGL3 (–6 m), AGL5 (–10 m) and KKL3 (–8 m). Metal enrichment in deeper layers can be associated with the past depositional environment, prevailing processes, geology and geomorphology of the region. In the surface layers, metal contamination can result from recent anthropogenic activities like untreated industrial waste from Ferro-alloys Corporation Ltd. (FACCOR) and domestic waste. There is a decline in contamination levels as we move from inland (CB) to coast (KK). The samples are also analysed for grain size and geochemistry to differentiate between sedimentary layers deposited under distinct depositional environments in the past. The results reveal the existence of humid and dry climatic phases along with oscillating sea levels in the past, influencing metal enrichment and contamination. [ABSTRACT FROM AUTHOR]

The intensity and frequency of extreme hydrological events are on the rise due to changing climate, and it is pertinent to identify the areas which are likely to suffer from such calamities. This study examines flood and drought susceptibilities in the district with a specific focus on two urban areas—Tuting and Yingkiong. To understand susceptibility enabling conditions, the study attempts an analysis of the recent climatic trends (1991–2021) in Upper Siang district employing regression analysis, Kendall tau, and Box and Whisker plots. Results reveal a general rise in the precipitation (26.42 mm/year) as well as in the temperature (0.032 °C/year) of the study area. Susceptibility is assessed based on analytic hierarchy process and using nine physical parameters viz., absolute relief, slope, drainage density, distance from streams, soil type, topographic wetness index, normalised difference vegetation index, and land use land cover. These layers are integrated to create flood and drought susceptibility maps. About 1.82% area of the Upper Siang district is highly susceptible to floods, whereas over 27% area falls under the high risk of droughts. Even though both the towns lie on the riverbank, Tuting is more prone to floods primarily due to its location on the inner concave side of a meander bend and relatively flat terrain, whereas Yingkiong is relatively safe because it lies on an elevated river terrace. Conversely, areas of the district above 2500 m a.s.l. are highly prone to droughts because of poor accessibility to water resources. It is found that the constrained and meandering valleys are more prone to floods, while steep slopes and ridgeline areas are more prone to droughts. Appropriate region-specific management options can reduce the susceptibility to extreme events in mountainous terrains. Therefore, owing to diverse topography, a region-specific physiographic approach is required in hilly environments for efficient mitigation of the impacts of extreme events. [ABSTRACT FROM AUTHOR]

The study estimates the soil organic carbon stock under various cropping systems to assess their sequestration potential in a tropical monsoon region, namely the Chulliyar-Ikshumathi sub-watershed of Bharathapuzha in Kerala, India. The cropping systems selected are the paddy, vegetables, coconut-arecanut groves, homestead farms, and mango plantations. The standard soil analyzing procedures to collect and analyze 129 soil samples from 43 locations were followed. The carbon stock (CS) of 0–10, 10–20, and 20–30 cm depth layers at each sampling location was estimated following the Walkley-Black method. The sequestration potential of soil under each cropping system is estimated to suggest an optimal cropping system for the region. The CS decreased with depth, irrespective of cropping systems. Among the cropping systems, the mango plantations, which practiced zero/no-tillage, have stability in the distribution of CS, while paddy fields showed higher variability in the CS. Even though mango plantations have more carbon sequestration potential (CSP), the coconut-arecanut grove is a better candidate for carbon sequestration (CSeq) in this region owing to its wider areal extent and acceptability. This analysis reveals the importance of assessing CS at the watershed level for sustainable land use planning to achieve better sequestration of atmospheric carbon. [ABSTRACT FROM AUTHOR]