Abstract

A short lacustrine sediment core (41 cm) from Lake Bosten in arid central Asia was used to investigate the environmental changes that occurred in the past ≈150 years based on the superposition of climate and anthropogenic factors. Geochemical elements, total organic carbon (TOC) and nitrogen (TN), and stable isotope data (δ13Corg and δ15N) were used to identify abnormal environmental changes. The average C/N ratio in the sediments of Lake Bosten suggested that the organic matter in lake sediments was mainly from aquatic plants. The δ13Corg and δ15N in the lake sediments mainly reflect changes in the structure of the lake’s ecosystem. Before the 1960s, the primary productivity of the lake was relatively low with a relatively stable lake water environment. From the 1960s to the mid-1980s, the lake’s ecosystem was closely related to a significant decline in water levels caused by human activities and an increase in salinity. From the late 1980s to ≈2000, the aquatic plant structure of Lake Bosten did not change significantly. After 2000, the upper part of the sedimentary record suggested enhanced productivity due to urban and industrial development in the catchment area. However, sedimentary perspectives of the responses of different environmental proxies in sediments to human activities were anisochronous, and the increasing heavy metal (Pb and Cu) and P accumulations appeared in 1970, reflecting heightened human impacts. Through the comparison between the Aral Sea and Lake Bosten, it was inferred that, under the intervention of human activities, the lake experienced a completely different evolution trend. Humans, as geological agents, should protect our living environment while satisfying social development. The results will provide an important supplement to a large spatial scale study of the influences of human activities on the environment in Central Asia, which also has some significant implications for the protection of the ecological environment and the realization of sustainable development in arid regions.

Highlights

  • As one of the most vulnerable terrestrial ecosystems, the arid regions of Central Asia are intertwined by the westerly circulation, the Arctic Ocean airflow, and the Indian Monsoon Current, making them sensitive to global change [1,2]

  • The specific activity of the excess 210 Pb was obtained by measuring the amount of 210Pb and 226Ra within a layer [57]. 210Pb and 226Ra were in equilibrium at 39 cm, and the chronology of the Lake Bosten sediment was established using the constant rate of supply (CRS) model [58] supported by 210Pbex data (210Pbex = 210Pb − 226Ra)

  • Human activities have had an important influence on the source of terrigenous clastic materials in the lacustrine sediments of Lake Bosten

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Summary

Introduction

As one of the most vulnerable terrestrial ecosystems, the arid regions of Central Asia are intertwined by the westerly circulation, the Arctic Ocean airflow, and the Indian Monsoon Current, making them sensitive to global change [1,2]. Due to the combined effects of climate change and human activities, the regional land surface processes are undergoing extensive changes [5], which are illustrated by changes in the hydrological processes and the resulting ecological and environmental effects [6,7]. Lakes in Central Asia are an important part of the regional water resource system [8]. They play an important supporting role in maintaining the balance between regional ecosystems. Lakes and terrestrial ecosystems are undergoing extensive material and energy exchanges, and we can use changes in the lake environments of Central Asia and the factors influencing them to investigate regional environmental changes and improve regional ecological environmental protection plans. The study in this paper will provide an opportunity to investigate the interaction between human activities and climate change in basins

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