Occurrence of arsenic in two large shallow freshwater lakes in China and a comparison to other lakes around the world

Abstract

Elevated levels of arsenic (As) have been found in lakes and rivers due to intensive anthropogenic activities. However, information on the occurrence of As in large freshwater lakes has scarcely been available. This study aimed at integrated exploration of the occurrence of As in multiple media of the limnetic ecosystems, mainly waters, sediments, macrophytes, invertebrates and fish in two large freshwater lakes (Taihu and Dianchi) during 2009–2010. The dissolved As concentrations in lake water for Lake Dianchi (3.08–10.48 μg L− 1) were significantly higher than the dissolved As concentrations in Lake Taihu (1.39–5.65 μg L− 1). The As concentrations in sediments by dry weight in Lake Dianchi (12.49–169.25 mg kg− 1) were also significantly higher than the As concentrations in Lake Taihu sediments (4.66–10.85 mg kg− 1). The highest As concentration observed for invertebrates was registered in a mussel species (Novaculina chinensis) at 25.0 mg kg− 1, and the lowest As concentration was observed in shrimp (Exopalaemon modestus) at 1.2 mg kg− 1 in Lake Taihu. Although different macrophyte species were sampled in the two lakes, a common pattern was observed for the As concentrations in the plants. Submerged plants had higher levels of As than floating plants. Arsenic concentrations in Lake Taihu Ceratophyllum demersum L. could be 12.0 mg kg− 1; in contrast, in Nymphoides peltatum, the As concentration was 1.4 mg kg− 1. Six common fish species were collected in Lakes Taihu and Dianchi. No significant differences in As concentrations in fish muscles from the two lakes were found, although As bioaccumulation factors (BAFs) for fish muscles in Lake Taihu were much higher than the BAFs observed in Dianchi. This difference suggests that fish in Taihu and Dianchi have a balancing mechanism for As through metabolism, which might regulate As concentration in muscle tissues at relatively low levels. Overall, the occurrence of As in the two large shallow freshwater lakes in China is relatively lower in concentration than As levels in other lakes around the world, but human health risks from As contamination exist.