title: Soil geochemistry and digestive solubilization control mercury bioaccumulation in the earthworm Pheretima guillemi.
abstract: Mercury presents a potential risk to soil organisms, yet our understanding of mercury bioaccumulation in soil dwelling organisms is limited. The influence of soil geochemistry and digestive processes on both methylmercury (MeHg) and total mercury (THg) bioavailability to earthworms (Pheretima guillemi) was evaluated in this study. Earthworms were exposed to six mercury-contaminated soils with geochemically contrasting properties for 36 days, and digestive fluid was concurrently collected to solubilize soil-associated mercury. Bioaccumulation factors were 7.5-31.0 and 0.2-0.6 for MeHg and THg, respectively, and MeHg accounted for 17-58% of THg in earthworm. THg and MeHg measured in soils and earthworms were negatively associated with soil total organic carbon (TOC). Earthworm THg and MeHg also increased with increasing soil pH. The proportion of MeHg and THg released into the digestive fluid (digestive solubilizable mercury, DSM) was 8.3-18.1% and 0.4-1.3%, respectively. The greater solubilization of MeHg by digestive fluid than CaCl2, together with a biokinetic model-based estimate of dietary MeHg uptake, indicated the importance of soil ingestion for MeHg bioaccumulation in earthworms.
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Dang
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; College of Environmental Science and Engineering, Anhui Normal University, Wuhu 241003, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Department of Environmental Health Science, University of California, Berkeley, CA 94720, USA.
authors.forename: Ben K
authors.initials: BK
authors.lastname: Greenfield
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China.
authors.forename: Huan
authors.initials: H
authors.lastname: Zhong
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Yujun
authors.initials: Y
authors.lastname: Wang
authors.affiliation: College of Environmental Science and Engineering, Anhui Normal University, Wuhu 241003, China.
authors.forename: Zhousheng
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China. Electronic address: dmzhou@issas.as.ac.cn.
authors.forename: Dongmei
authors.initials: D
authors.lastname: Zhou
mesh_terms: D000818:Animals; D008628:Mercury / Q000378:metabolism*; D009835:Oligochaeta / Q000378:metabolism*; D012995:Solubility
chemical_list: D008628:Mercury
keywords: Digestive solubilization; Earthworm (Pheretima guillemi); Methylmercury; Total organic carbon