Study region: The study focuses on the Indus River Basin and southern Pakistan, severely affected by flooding in 2022. Study focus: This study assessed how land surface temperature, snow cover, soil moisture, and precipitation contributed to the deluge of 2022. This study mainly investigated MODIS-AIRS land surface temperature, MODIS snow cover (NDSI), SMAP soil moisture, and GPM IMERG precipitation accumulation. Furthermore, different flood visualization and mapping techniques were applied to delineate the flood extent map using Landsat 8-9, Sentinel-2 MSI, and Sentinel-1 SAR data. New hydrological insights for the region: The region experienced some of the most anomalous climatic events in 2022, such as prolonged heatwaves as observed with higher-than-average land surface temperatures and subsequent rapid decline in snow cover extent during the spring, increased soil moisture followed by an abnormal amount of extreme monsoon precipitation in the summer. The upper subbasins experienced more than 8 degrees C in positive temperature anomaly, indicating a warmer climate in spring. Subsequently, the snow cover declined by more than 25 % in the upper subbasins. Further, higher surface soil moisture values (> 0.3 m3/m3) were observed in the basin during the spring due to the rapid snow and ice melt. Furthermore, the basin received more than 200 mm of rainfall compared to the long-term average rainfall of about 98 mm, translating to about 300 % more rainfall than usual in July and August. The analysis helps understand the spatial and temporal variability within the basin and facilitates the understanding of factors and their intricate connections contributing to flooding.
Reconstructing fluvial dynamics is a fundamental requirement for understating the interaction between past environmental changes and human adaptation. This study focuses on the central part of the floodplain of the Nan River in northern Thailand that likely played a role in the catastrophic flood of 1818 CE, which damaged the ancient of Nan city and forced its relocation. We investigated nine sediment cores from the floodplain and from the eastern tributaries of the Nan River, to identify the potential source of floods in the past. By combining the analyses of sedimentary characteristics and provenance, the study reveals that the eastern tributaries were the dominant sediment source for most areas, with the Nan River only influencing areas close to its channel. According to optically stimulated luminescence dating, the highest sediment accumulation occurred during the eleventh to thirteenth centuries CE, coinciding with agricultural expansion and deforestation, suggesting increased erosion in the catchment of the tributaries. These findings challenge the assumption that the main Nan River has been the primary contributor to flooding catastrophes in the region and highlights the potential crucial role of smaller tributaries in similar settings in other parts of the globe.
Biocomposite sheets were created by blending taro pulp with rice straw, pineapple fibre, guar gum, and corn starch. The optimal composition, comprising 90 % taro pulp and 10 % corn starch, demonstrated impressive mechanical properties, including a tensile strength of 61.42 MPa, bursting strength of 13.19 kg/cm2, a contact angle of 63.4 degrees, and water uptake of 82.33 %. To understand whether these qualities can be improved by coating with chitosan, silk fibroin, or combinations of both, coated samples were also studied. Chitosan coating displayed a tensile strength of 26.79 MPa, while fibroin coating further reduced it to 15.87 MPa. Notably, a 50:50 chitosanfibroin blend increased the contact angle to 117.8 degrees, reducing water uptake to 49.67 % and water vapor transmission rate to 4.73 %, compared to 46.15 % and 3.96 % for pure fibroin coating. Analysis revealed similar spectra among coatings, indicating analogous functional groups. XRD showed a crystalline cellulose I structure with crystallinity indices of 71.96-74.18 %. DSC displayed transitions near 190-240 degrees C, while TGA showed two- stage degradation with T5 at 130-180 degrees C, T10 at 244-264 degrees C, and T50 at 325-336 degrees C. SEM confirmed surface modifications induced by coatings. Combinations with higher fibroin content exhibited reduced water uptake and water vapor transmission rates compared to pure chitosan due to differences in chemical composition. While chitosan enhanced tensile strength, fibroin had a mitigating effect. Although not fully biodegradable, the coated sheets showed varying degrees of biodegradability under soil burial conditions for 60 days. These findings highlight the tunable properties of biocomposite sheets through composition and coatings, promising for packaging applications.
introduction: The study investigates the impact of atmospheric fluoride emitted from brick kilns on soil fertility and earthworm activity in fruit orchards in South Asia. Due to the proximity to unregulated kilns, local fruit productions like peaches and plums have seen a decline. The brick kiln emissions, primarily fluoride in the form of hydrogen fluoride (HF), have been shown to negatively affect both plant life and soil health, particularly impacting earthworms which are crucial for soil nutrient cycling. Method: The research focused on peach and plum orchards near Peshawar, within 500 meters of brick kilns. Soil and leaf samples were collected and analyzed for fluoride content. Earthworm experiments were conducted to assess the impact of fluoride on their growth and reproduction by exposing them to contaminated leaf litters. Results: The results showed elevated levels of fluoride in both soil and leaf samples from the proximity of brick kilns. Earthworms exposed to this contaminated environment exhibited reduced growth rates and cocoon production, highlighting the detrimental effects of fluoride on soil biota. This aligns with previous findings that link industrial emissions to ecological damage in agricultural settings. Conclusion and Recommendations: The study confirms that fluoride emissions from brick kilns can substantially decrease soil fertility and harm earthworm populations, which are vital for maintaining soil health. It recommends implementing strategies such as using calcium-rich amendments, enhancing organic matter in the soil, and regular monitoring of soil fluoride levels to mitigate these effects. These measures could improve soil conditions, thereby supporting healthier crop growth and restoring ecological balance in affected areas.
Indian monsoon circulation is the primary driver of the long-range transboundary mercury (Hg) pollution from South Asia to the Himalayas and Tibet Plateau region, yet the northward extent of this transport remains unknown. In this study, a strong delta Hg-202 signature overlapping was found between Lake Gokyo and Indian anthropogenic sources, which is an indicative of the Hg source regions from South Asia. Most of the sediment samples were characterized with relatively large positive Delta Hg-199 values (mean = 0.07 parts per thousand-0.44 parts per thousand) and small positive Delta Hg-200 values (mean = 0.03 parts per thousand-0.08 parts per thousand). Notably, the Delta Hg-199 values in the lake sediments progressively increased from southwest to northeast. Moreover, the Delta Hg-199 values peaked at Lake Tanglha (mean = 0.44 parts per thousand +/- 0.04 parts per thousand) before decreased at Lake Qinghai that is under the influence of the westerlies. Our results suggest that transboundary atmospheric transport could transport Hg from South Asia northwards to at least the Tanglha Mountains in the northern Himalaya-Tibet.
Black carbon (BC) is one of the major aerosol components with relatively high implications on climatic patterns through its radiative forcing (RF). South Asia has recently experienced an increased concentration of pollution; however, relatively fewer studies have been carried out on long-term assessment of BC and its implications. The present study analyzed the long-term concentration of BC in selected urban locations over South Asia using the Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2). The study employed statistical analysis, including linear regression techniques, to assess the long-term concentration of BC. The results show that a rapid increase of BC is observed over most urban locations of South Asia with the predominance in winter and hence requires strict regional control measures to reduce the excess concentration of BC in the atmosphere. High concentration of BC in winter is attributed to anthropogenic activities and changes in meteorological conditions that enhance the accumulation of pollutants in the atmosphere. The relationship of BC with cloud top temperature and cloud effective radius demonstrates the direct and indirect effect of BC on cloud properties in this region. The RF results reveal that aerosol optical depth has positive aerosol RF in the atmosphere and negative RF at the top of the atmosphere (TOA) as well as at the bottom of the atmosphere (BOA). Negative RF at the TOA indicates less forcing efficiency due to fewer BC aerosols. On the other hand, averaging aerosol RF within the atmosphere reveals positive forcing, which suggests the efficiency force exerted by BC aerosols after absorbing solar radiation.
Featured Application The Middle European ecotype of Cd hyperaccumulator Solanum nigrum L. ssp. nigrum was found to show extraordinarily strong tolerance to high contents of Cd in soil (over 50 mg kg-1 Cd) and high Cd accumulation capacity at this concentration range. Its adapted A50 variety obtained from the seeds of first-generation plants grown in soil with 50 mg kg-1 Cd appeared to display further considerable enhancement of resistance to Cd stress, accumulation capacity, and healthy state. This makes the Middle European ecotype and its adapted variety A50 particularly useful to sustainable decontamination of heavily polluted hot spots in degraded post-industrial areas.Abstract The Cd hyperaccumulator Solanum nigrum L. exhibits a cosmopolitan character and proven high and differentiated efficiency. This suggests the possibility of optimizing its Cd phytoremediation capacity and applicability through searching among remote ecotypes/genotypes. However, the extensive studies on this hyperaccumulator have been limited to Far East (Asian) regions. Pioneer pot experiments on the Middle European ecotype of S. nigrum within a concentration range of 0-50 mg kg-1 Cd in soil revealed its Cd phytoremediation capacity to be comparable to Asian ecotypes but with a fundamentally different Cd tolerance threshold. While biomass of the Asian ecotypes declined sharply at Csoil approximate to 10 mg kg-1 Cd, in the Middle European ecotype, a gradual mild biomass decrease occurred within the whole Csoil approximate to 0-50 mg kg-1 Cd range with no toxic symptoms. Its adapted A50 variety was obtained from the seeds of first-generation plants grown in soil with Csoil approximate to 50 mg kg-1 Cd. In this variety, Cd tolerance, accumulation performance, and all physiological parameters (chlorophyll, carotenoids, RuBisCO, and first- and second-line defense anti-oxidant activity) were significantly enhanced, while cell damage by ROS was considerably lesser. This makes the Middle European ecotype and its adapted variety A50 particularly useful to sustainable decontamination of heavily polluted hot spots in degraded post-industrial areas.
Surface albedo (SA) is crucial for understanding land surface processes and climate simulation. This study analyzed SA changes and its influencing factors in Central Asia from 2001 to 2020, with projections 2025 to 2100. Factors analyzed included snow cover fraction, fractional vegetation cover, soil moisture, average state climate indices (temperature and precipitation), and extreme climate indices (heatwave indices and extreme precipitation indices). Pearson correlation coefficient, geographical convergent cross mapping, and geographical detector were used to quantify the correlation, causal relationship strength, and impact degree between SA and the influencing factors. To address multicollinearity, ridge regression (RR), geographically weighted ridge regression (GWRR), and piecewise structural equation modeling (pSEM) were combined to construct RR-pSEM and GWRR-pSEM models. Results indicated that SA in Central Asia increased from 2001 to 2010 and decreased from 2011 to 2020, with a projected future decline. There is a strong correlation and significant causality between SA and each factor. Snow cover fraction was identified as the most critical factor influencing SA. Average temperature and precipitation had a greater impact on SA than extreme climate indices, with a 1 degrees C temperature increase corresponding to a 0.004 decrease in SA. This study enhances understanding of SA changes under climate change, and provides a methodological framework for analyzing complex systems with multicollinearity. The proposed models offer valuable tools for studying interrelated factors in Earth system science.
Winter baseflow (WB) can stabilize freshwater inputs and has important impacts on nutrient migration and the water cycle of a specific region and the oceans. This study systematically analyzed the WB variations in fourteen major Eurasian rivers and found they all had commonly increasing trends (except the Yellow River), with the mean increase ratio of 53.0% (+/- 34.8%, confidence interval 95%) over the past 100 years (the longest time series is 1879-2015). Relative to Northern Eurasia (60 degrees N-70 degrees N) and Southern Eurasia (30 degrees N-40 degrees N), the river WB in middle Eurasia (40 degrees N-60 degrees N) had the largest increase rate (0.60%/year). The increases of the WB in Northern Eurasia and Southern Eurasia have speeded up since the 1990s; on the contrary, they have slowed down or even turned to a decreasing trend after the 1990s in the middle Eurasian rivers. Using multiple linear regression analysis, the quantitative relationship between WB and winter surface air temperature (max, mean and min), snowfall, soil temperature, antecedent precipitation, as well as the river-ice dynamic were determined. We found that the winter air temperature, especially the minimum air temperature was one major factor accounting for WB variation in Eurasia over the past century. When the winter air temperature rises, this leads a reduction in the thickness and volume of river ice, and thus decreases water storage in river ice and leads to an increase in the WB. About 19.6% (6.7%-41.5%) of the winter WB increase in rivers of Siberia was caused by the decreased river ice during the past 100 years. Although groundwater recharge was the dominant reason for WB change, the role of river ice should not be ignored in hydrological study of cold regions.
Light-absorbing carbonaceous aerosols that dominate atmospheric aerosol warming over India remain poorly characterized. Here, we delve into UV-visible-IR spectral aerosol absorption properties at nine PAN-India COALESCE network sites (Venkataraman et al., 2020, ). Absorption properties were estimated from aerosol-laden polytetrafluoroethylene filters using a well-constrained technique incorporating filter-to-particle correction factors. The measurements revealed spatiotemporal heterogeneity in spectral intrinsic and extrinsic absorption properties. Absorption analysis at near-UV wavelengths from carbonaceous aerosols at these regional sites revealed large near-ultraviolet brown carbon absorption contributions from 21% to 68%-emphasizing the need to include these particles in climate models. Further, satellite-retrieved column-integrated absorption was dominated by surface absorption, which opens possibilities of using satellite measurements to model surface-layer optical properties (limited to specific sites) at a higher spatial resolution. Both the satellite-modeled and direct in-situ absorption measurements can aid in validating and constraining climate modeling efforts that suffer from absorption underestimations and high uncertainties in radiative forcing estimates. Particulate pollution in the atmosphere scatter and absorb incoming solar energy, thus cooling or warming Earth's atmosphere. In developing countries and especially in India, one of the most polluted regions of the world, the extent to which particles can absorb solar energy and warm the atmosphere is not well understood. Here, for the first time, we measure particle absorption simultaneously at nine ground sites across India, in diverse geographical regions with different levels and types of particulate pollution. We find that organic carbon particles exert large absorption at near-ultraviolet wavelengths, which contain significant solar energy. These light absorbing organic carbon particles, called brown carbon, are emitted in large quantities from biomass burning (e.g., burning crop residue and cooking on wood-fired stoves). Comparing ground measurements of absorption with satellite-retrieved measurements that are representative of the entire atmospheric column, we find that near-surface atmospheric particles can exert significant warming. This study highlights the need to improve climate model simulations of particulate pollution's impact on the climate by incorporating spatiotemporal surface-level absorption measurements, including absorption by brown carbon particles. Measurements at nine regional PAN-India sites reveal several regions with large aerosol absorption strength Brown carbon contributes significantly (21%-68%) to near-ultraviolet absorption, indicating its importance in shortwave light absorption Strong correlations observed between satellite data and surface absorption indicate future potential in modeling surface absorption