Historical Black Carbon Reconstruction from the Lake Sediments of the Himalayan–Tibetan Plateau

Abstract

Black carbon (BC) is one of the major drivers of climate change, and its measurement in different environment is crucial for the better understanding of long-term trends in the Himalayan−Tibetan Plateau (HTP) as climate warming has intensified in the region. We present the measurement of BC concentration from six lake sediments in the HTP to reconstruct historical BC deposition since the pre-industrial era. Our results show an increasing trend of BC concurrent with increased anthropogenic emission patterns after the commencement of the industrialization era during the 1950s. Also, sedimentation rates and glacier melt strengthening influenced the total input of BC into the lake. Source identification, based on the char and soot composition of BC, suggests biomass-burning emissions as a major contributor to BC, which is further corroborated by open-fire occurrence events in the region. The increasing BC trend continues to recent years, indicating increasing BC emissions, mainly from South Asia.

APCC Data Report I: Black carbon and organic carbon dataset from atmosphere, glaciers, snow cover, precipitation, and lake sediment cores over the Third Pole

“…Sediment cores were studied from 7 lakes distributed across the Himalayas and TP (Cong et al, 2013;Neupane et al, 2019) (Table 3, Fig. 1).…”

“…Lake sediment cores were drilled from the deep basin of the studied lakes during 2008−2017 using a gravity coring system with a 6 cm inner diameter polycarbonate tube (Cong et al, 2013;Neupane et al, 2019). The core sediments were sliced in the field at intervals of 0.5 cm, except for Lingge Co and Ranwu Lake, which were sliced at 1 cm intervals, stored in plastic bags, and kept frozen until analysis.…”

“…14). The relatively constant trend of BC before the 1950s could be attributed to the background level with minimal inputs from anthropogenic activities (Cong et al, 2013;Neupane et al, 2019). Previous studies pointed out that the deposition of BC in lake sediment cores was mainly related to river transport from the lake basin as a result of climate change (e.g., increases in temperature and precipitation) (Li et al, 2017).…”

“…As BC is chemically inert in the lake sediment cores, it can serve as an archive and reliable indicator to investigate the source and transport of BC in the past (Han et al, 2012). The BC investigation from lake sediment cores over the plateau revealed an increasing trend of BC concurrent with increased anthropogenic emissions since the 1950s (Cong et al, 2013;Han et al, 2015;Neupane et al, 2019;Zhu et al, 2020), and suggested that BC deposition in recent decades have increased about 2−3 fold compared to the background level.…”

Geochemical and multivariate assessment of water quality in the Rajarani Lake, Dhankuta, Nepal

“…This sediment loads strongly influences multi-usage components of lake water (Filik et al, 2008;Zhong et al, 2018). Moreover, high level of aerosol optical depth and clear indication of biomass burning on Himalayan atmospheric environment is reported by tracers (Bhattarai et al, 2019a;Bhattarai et al, 2019b;Wan et al, 2019), and these aerosols constitute a wide range of carbonaceous substances, such as black carbon (Neupane et al, 2019) and mercury (Sun et al, 2020). These pollutants, once deposited to aquatic ecosystems, could adversely affect water quality resulting bioaccumulation and biomagnifications (Pant , 2013;.…”