title: Uptake dynamics of inorganic mercury and methylmercury by the earthworm Pheretima guillemi.
abstract: Mercury uptake dynamics in the earthworm Pheretima guillemi, including the dissolved uptake rate constant (ku) from pore-water and assimilation efficiencies (AEs) from mercury-contaminated soil, was quantified in this study. Dissolved uptake rate constants were 0.087 and 0.553 L g(-1) d(-1) for inorganic mercury (IHg) and methylmercury (MeHg), respectively. Assimilation efficiency of IHg in field-contaminated soil was 7.2%, lower than 15.4% of spiked soil. In contrast, MeHg exhibited comparable AEs for both field-contaminated and spiked soil (82.4-87.2%). Within the framework of biodynamic model, we further modelled the exposure pathways (dissolved exposure vs soil ingestion) to source the accumulated mercury in Pheretima guillemi. The model showed that the relative importance of soil ingestion to mercury bioaccumulation depended largely on mercury partitioning coefficients (K(d)), and was also influenced by soil ingestion rate of earthworms. In the examined field-contaminated soil, almost (>99%) accumulated IHg and MeHg was predicted to derive from soil ingestion. Therefore, soil ingestion should be carefully considered when assessing mercury exposure risk to 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: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China. Electronic address: dmzhou@issas.ac.cn.
authors.forename: Dongmei
authors.initials: D
authors.lastname: Zhou
mesh_terms: D000818:Animals; D007700:Kinetics; D008628:Mercury / Q000378:metabolism*; D008767:Methylmercury Compounds / Q000378:metabolism*; D008954:Models, Biological; D008962:Models, Theoretical; D009835:Oligochaeta / Q000378:metabolism*; D018570:Risk Assessment; D012989:Soil Pollutants / Q000378:metabolism*
chemical_list: D008767:Methylmercury Compounds; D012989:Soil Pollutants; D008628:Mercury
keywords: Dynamics; Mercury; Organisms; Soil ingestion; Uptake pathways