Pesticide contamination and phytotoxicity of sediment interstitial water to tropical benthic microalgae

Magnusson, Marie, Heimann, Kirsten, Ridd, Michael, and Negri, Andrew P. (2013) Pesticide contamination and phytotoxicity of sediment interstitial water to tropical benthic microalgae. Water Research, 47 (14). pp. 5211-5221.

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Abstract

Many organic compounds including some herbicides concentrate in sediment, thus it may be expected that interstitial waters contain higher concentrations of these contaminants than the water column. To estimate benthic microalgal exposure to pesticides, sediment and interstitial water sampled in the dry season from four major rivers in north Queensland, Australia, were analysed for these contaminants. Interstitial water extracts from the sediments were tested for acute phytotoxicity to benthic microalgae using PAM fluorometry and the results were compared with chemical analyses of the same water samples. A range of pesticides were detected in both sediment and interstitial waters from all sites, notably the herbicide diuron at concentrations ranging from 0.3 to 11 μg kg⁻¹ dry weight sediment, and up to 68 ng L⁻¹ in interstitial waters. Herbicide concentrations estimated from partition coefficients and the sediment concentrations typically overestimated analytically determined concentrations present in interstitial water by an order of magnitude. The analytically determined herbicide concentrations in the interstitial water explained most of the phytotoxicity measured with the bioassay; however, photoinhibition was slightly higher than expected based on analytical results, indicating the presence of unidentified phytotoxins. These results demonstrate the presence of pesticides in interstitial waters in the Tropical dry season, sometimes at concentrations that may affect sensitive benthic organisms, and supports the use of the I-PAM bioassay as a valuable tool in exposure- and environmental risk- and impact-assessments.

Item ID: 28183
Item Type: Article (Refereed Research - C1)
Keywords: sediment, pore water, microalga, diuron, herbicide, pesticide
ISSN: 1879-2448
Funders: AIMS@JCU, Australian Research Council (ARC), Endeavour IPRS
Projects and Grants: LE0347105
Date Deposited: 23 Jul 2013 23:20
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050204 Environmental Impact Assessment @ 40%
06 BIOLOGICAL SCIENCES > 0607 Plant Biology > 060701 Phycology (incl Marine Grasses) @ 30%
03 CHEMICAL SCIENCES > 0399 Other Chemical Sciences > 039901 Environmental Chemistry (incl Atmospheric Chemistry) @ 30%
SEO Codes: 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960503 Ecosystem Assessment and Management of Coastal and Estuarine Environments @ 50%
96 ENVIRONMENT > 9611 Physical and Chemical Conditions of Water > 961102 Physical and Chemical Conditions of Water in Coastal and Estuarine Environments @ 50%
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