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A tropical sediment toxicity test using the dipteran Chironomus crassiforceps to test metal bio availability with sediment pH change in tropical acid‐sulfate sediments
Author(s) -
Peck Mika R.,
Klessa David A.,
Baird Donald J.
Publication year - 2002
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 - 10.1002/etc.5620210406
Subject(s) - environmental chemistry , sediment , bioavailability , chemistry , toxicity , bioassay , metal toxicity , sulfate , biotic ligand model , metal , ecotoxicology , ecology , geology , biology , heavy metals , paleontology , bioinformatics , organic chemistry
The wetlands of the Magela floodplain of northern Australia, which is the major sink for dissolved metals transported in the Magela Creek system, contain acid‐sulfate sediments. The rewetting of oxidized acid‐sulfate soil each wet season produces acidic pulses that have the potential to alter the bioavailability of sediment‐associated metal contaminants. Acute toxicity tests (72‐h mean lethal concentration [LC50]) using the tropical chironomid Chironomus crassiforceps Kieffer showed that copper toxicity decreased from 0.64 mg/L at pH 6 to 2.30 mg/L at pH 4. Uranium toxicity showed a similar trend (36 mg/L at pH 6 and 58 mg/L at pH 4). Sediment toxicity tests developed using C. crassiforceps also showed that both metals were less toxic at the lower sediment pH with pore‐water copper toxicity having a lowest‐observed‐effect concentration of 4.73 mg/L at pH 4 compared to 1.72 mg/L at pH 6. However, a lower pH increased pore‐water metal concentrations and overlying water concentrations in bioassays. Hydrogen ion competition on metal receptor sites in C. crassiforceps was proposed to explain the decrease in toxicity in response to increased H + activity. This study highlights the need to consider site‐specific physicochemical conditions before applying generic risk assessment methods.