Trends and environmental factors of arsenic in sediments from the five lake ecoregions, China.

Abstract

The behavior and risk of arsenic (As) closely relate to its geochemical fractionation and environmental factors in sediments. The soluble (F1), reducible (F2), oxidizable (F3), and residual fraction (F4) of As were extracted in the sediments from Lake Hulun, Wuliangsuhai, and Dalinor of Inner Mongolia Plateau. Coupled with lakes from Eastern and Northeast Plain, Yunnan-Guizhou and Qinghai-Tibetan Plateau, the responses of As fractions to environmental conditions were investigated according to the spatial distribution of As fractionations in five lake ecoregions at a national scale of China. Generally, F1 was more sensitive to environmental changes, and the pH presented significantly negative effects on the amount of soluble As, while water depth played an important role in regulating the distribution of the fraction F2 and F4. The As pools in surface lake sediments presented a latitudinal zonation due to the gradient effects of climate and anthropogenic activities on nutrient decomposition, and their influence on the capacity of sediments holding As. This work indicated that nutrients played a coordinating role in regulating the impacts of climate and environmental factors on As fractionation in aquatic environments.