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Single versus multiple occupancy—effects on toxcityp parameters measured on Eisenia fetida in lead nitrate–treated soil
Author(s) -
Currie Mark,
Hodson Mark E.,
Arnold Rebecca E.,
Langdon Caroline J.
Publication year - 2005
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/03-686.1
Subject(s) - eisenia fetida , earthworm , loam , zoology , soil water , toxicology , oligochaeta (plant) , occupancy , chemistry , dry weight , confidence interval , population , environmental chemistry , environmental science , biology , mathematics , agronomy , ecology , soil science , medicine , statistics , environmental health
The mortality (7 and 14 d), weight change (7 and 14 d), and metal uptake of Eisenia fetida (Savigny, 1826) kept in Pb(NO 3 ) 2 ‐treated Kettering loam soil in single‐ and multiple‐occupancy (10 earthworms) test containers were determined. The number of earthworms to dry mass (g) ratio of soil was 1:50 in both sets of test containers. Lead concentrations were in the nominal range of 0 to 10,000 mg Pb/kg soil (mg/kg hereafter). Levels of mortality at a given concentration were statistically identical between the single‐ and multiple‐occupancy tests, except at 1,800 mg/kg, at which significantly ( p ≤ 0.05) more mortality occurred in the multiple‐occupancy tests. Death of individual earthworms in the multiple‐occupancy tests did not trigger death of the other earthworms in that soil. The LC50 values (concentration statistically likely to kill 50% of the population) were identical between the multiple‐ and single‐occupancy soils: 2,662 mg/kg (2,598–2,984, 7 d) and 2,589 mg/kg (2,251–3,013, 14 d) for the multiple‐occupancy soils and 2,827 mg/kg (2,443–3,168, both 7 and 14 d) for the single‐occupancy soils (values in brackets represent the 95% confidence intervals). Data were insufficient to calculate the concentration statistically likely to reduce individual earthworm mass by 50% (EC50), but after 14 d, the decrease in earthworm weight in the 1,800 and 3,000 mg/kg tests was significantly greater in the multiple‐ than in the single‐occupancy soils. At 1,000, 1,800, and 3,000 mg/kg tests, earthworm Pb tissue concentration was significantly ( p ≤ 0.05) greater in earthworms from the multiple‐occupancy soils. The presence of earthworms increased the NH 3 content of the soil; earthworm mortality increased NH 3 concentrations further but not to toxic levels.