ABSTRACT
Biomass burning play a key role in the global carbon cycle by altering the atmospheric composition, and affect regional and global climate. Despite its importance, a very few high-resolution records are available worldwide, especially for recent climate change. This study analyzes levoglucosan, a specific tracer of biomass burning emissions, in a 38-year ice core retrieved from the Shulehe Glacier No. 4, northeastern Tibetan Plateau. The levoglucosan concentration in the Shulehe Glacier No. 4 ice core ranged from 0.1 to 55 ng mL-1, with an average concentration of 8 ± 8 ng mL-1. The concentrations showed a decreasing trend from 2002 to 2018. Meanwhile, regional wildfire activities in Central Asian also exhibited a declining trend during the same period, suggesting the potential correspondence between levoglucosan concentration of the Shulehe Glacier No. 4 ice core and the fire activity of Central Asia. Furthermore, a positive correlation also exists between the levoglucosan concentration of the Shulehe Glacier No. 4 ice core and the wildfire counts in Central Asia from 2002 to 2018. While backward air mass trajectory analysis and fire spots data showed a higher distribution of fire counts in South Asia compared to Central Asia, but the dominance of westerly circulation in the northern TP throughout the year. Therefore, the levoglucosan in the Shulehe Glacier No. 4 provides clear evidence of Central Asian wildfire influence on Tibetan Plateau glaciers through westerlies. This highlights a great importance of ice core data for wildfire history reconstruction in the Tibetan Plateau Glacier regions.
ABSTRACT
The world's large rivers have been intensely studied to better understand the impact of climate change and direct human interventions on river water quality and quantity. Of particular importance is the extent to which industrial, domestic, and agricultural discharges are modifying the dissolved inorganic constituents (major elements, trace elements, nutrients, and heavy metals) of large river systems vis-à-vis water quality. The COVID-19 pandemic lockdown provides a rare opportunity to quantify the impact of restricted anthropogenic activities on the water chemistry resilience of large rivers. By analyzing the daily geochemical record of the Ganga River, we demonstrate that reduced industrial discharge during 51 days of mandated nationwide lockdown decreased the dissolved heavy metal concentrations by a minimum of 50%. In contrast, nitrate and phosphate inputs predominantly derived from agricultural runoff and domestic sewage maintained a chemical status quo as these sources were not impacted by the nationwide confinement or their residence time was longer than the characteristic time of the perturbation. We demonstrate the high resilience of dissolved heavy metals and conclude that industrial wastewater minimization programs will substantially improve heavy metal pollution of the Ganga River in a short time span of a few months.
ABSTRACT
Atmospheric pollutant transport and deposition at the Himalaya affects the climate, cryosphere, and monsoon patterns and impose an adverse impact over the Himalayan ecosystem. At present, the data on trace elements (TEs) concentrations and dynamics over the high-altitude Himalayan region are scarce and has received less attention. Therefore, in the present study, we investigated the TEs concentration and depositional pattern at Dokriani Glacier, central Himalaya to understand their levels, dynamics, and potential effects. A total of 39 samples were collected from two snowpit stratigraphies, deposited during non-monsoon period and monsoonal precipitation between 4530 to 4630 m a.s.l. altitude in the year 2017. The results of analyzed trace metals (Al, Cr, Mn, Fe, Sr, Co, Ni, Cu, Zn, Cd, As, and Pb) showed high enrichment values for Zn, Cr, Co, Ni and Mn compared to other parts of the Himalayan region, suggesting the influence of anthropogenic emissions (e.g., fossil fuel, metal production, and industrial processes) from urbanized areas of South Asia. Our results also revealed the possible health effects related to the enrichment of Zn and Cd, which may be responsible for skin-related diseases in Uttarakhand region. We attribute increasing anthropogenic activities in the environment to have a significant impact on the ecosystem health of the central Himalayan region. This study provides the baseline information on TEs concentration and sources in the Himalayas, which needs wide dissemination to scientific community as well as policymakers. Therefore, systematic observations, management, and preparing action plan to overcome the health effects from TEs pollution are urgently needed over the remote, pristine Himalayan region.
