Heavy metal effects on earthworms in different ecosystems

ABSTRACT

Elevated heavy metals in soil are a serious environmental problem that threatens human health and other organisms. Earthworms are widely used as pollution bioindicators of soil ecosystems. The influence of heavy metal content on species composition and population density of earthworms in soils of urban and natural ecosystems has been previously studied. The accumulation of heavy metals in earthworm samples was measured using atomic absorption spectrometry. This study found representatives of 11 species of earthworms in biogeocenoses of the Zailiisky Alatau foothills. The low occurrence of earthworms in ecosystems with a maximum content of cadmium (0.25±0.0024 mg/kg), lead (16±0.70 mg/kg) and arsenic (2.84±0.05 mg/kg) was marked. The number and variety of species of lumbricidofauna differed in urban and natural habitats, indicating that increased heavy metal content substantially impacts earthworms. Earthworms can absorb heavy metals from contaminated soils, which simulates the actions of key elements in the body and causes diseases. Thus, one of the primary determining factors of a positive physical and chemical state of the soil is the number and species composition of earthworms. These data can be used to monitor soil contamination near industrial facilities.