Pesticide residues in waterways of the lower Burdekin region: challenges in ecotoxicological interpretation of monitoring data
Journal Publication ResearchOnline@JCUAbstract
Pesticide monitoring was conducted through the 2004/05 to 2007/08 water years to determine the wet and dry season dynamics of pesticide movement within the agriculturally developed floodplain of the lower Burdekin River and downstream marine environments. The Burdekin River is one of Queensland’s largest rivers draining into the waters of the Great Barrier Reef, and also forms one of the most expansive and high conservation value deltaic wetland complexes on the east coast of Australia. Our monitoring program detected fifteen herbicides and one insecticide in local waterways draining into these downstream wetlands. Most of the pesticides detected were predominantly associated with the sugarcane industry. Ametryn, atrazine (including its breakdown products desethylatrazine and desisopropylatrazine), diuron, hexazinone and 2,4-D were the chemicals commonly found at the highest concentrations during low flow conditions. Several waterways exhibited frequent low concentrations of pesticides throughout much of the year under dry season conditions. In contrast, the Barratta Creek complex, the main drainage system for the recently developed Burdekin floodplain, exhibited relatively elevated pesticide concentrations throughout the dry season. Herbicides such as atrazine and diuron were regularly above available Australian and New Zealand ecosystem protection guidelines in Barratta Creek during the dry season, suggesting prolonged exposure of aquatic ecosystems to potentially deleterious herbicide concentrations. Ametryn, atrazine (including breakdown products), diuron, and metolachlor were the chemicals most frequently found at the highest concentrations across the majority of sites monitored during flood events. Sampling of wet season flood plumes from local catchments in 2007 detected concentrations of two herbicides – atrazine and diuron – being transported to offshore marine environments. However, concentrations were below the lowest observable effect concentrations for coral and seagrass species. Assessment of monitoring results within the context of current ecosystem protection guidelines highlights an array of shortcomings that limit the capacity to make meaningful risk assessments associated with pesticide presence in natural environments. Issues such as the lack of basic guideline levels for several commonly detected pesticides, complex and potentially interacting mixtures of contaminants in receiving environments, and minimal knowledge as to the effects of chronic, long-term exposure of relevant biota to low pollutant concentrations makes informed and meaningful data interpretation difficult, if not impossible.
Journal
N/A
Publication Name
N/A
Volume
14
ISBN/ISSN
1323-3475
Edition
N/A
Issue
N/A
Pages Count
N/A
Location
N/A
Publisher
Australasian Society for Ecotoxicology
Publisher Url
N/A
Publisher Location
N/A
Publish Date
N/A
Url
N/A
Date
N/A
EISSN
N/A
DOI
N/A