Sources and Pathways of Contaminants to the Leichhardt River Sources and Pathways of Contaminants to the Leichhardt River
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Lead Pathways Study – Water Sources and Pathways of Contaminants to the Leichhardt River Sources and Pathways of Contaminants to the Leichhardt River 2 Centre for Mined Land Rehabilitation – Sustainable Minerals Institute Sources and Pathways of Contaminants to the Leichhardt River Lead Pathways Study – Water Sources and Pathways of Contaminants to the Leichhardt River 11 May 2012 Report by: Barry Noller1, Trang Huynh1, Jack Ng2, Jiajia Zheng1, and Hugh Harris3 Prepared for: Mount Isa Mines Limited Private Mail Bag 6 Mount Isa 1 Centre for Mined Land Rehabilitation, The University of Queensland, Qld 4072 2 National Research Centre for Environmental Toxicology, The University of Queensland Qld 4008 3 School of Chemistry and Physics, The University of Adelaide SA 5005 Centre for Mined Land Rehabilitation – Sustainable Minerals Institute 3 Sources and Pathways of Contaminants to the Leichhardt River This report was prepared by the Centre for Mined Land Rehabilitation, Sustainable Minerals Institute, The University of Queensland, Brisbane, Queensland 4072. The report was independently reviewed by an environmental chemistry specialist, Dr Graeme Batley. Dr Graeme Batley, B.Sc. (Hons 1), M.Sc, Ph.D, D.Sc Chief Research Scientist in CSIRO Land and Water’s Environmental Biogeochemistry research program Dr Graeme Batley is the former director and co-founder of the Centre for Environmental Contaminants Research (CECR), a program that brings together CSIRO’s extensive expertise in research into the contamination of waters, sediments and soils. He is also a Fellow of the Royal Australian Chemical Institute, member Australasian Society for Ecotoxicology and Foundation President and Board Member of the Society of Environmental Toxicology and Chemistry (SETAC) Asia/Pacific. Dr Batley received his B.Sc (Hons 1) in 1962 (UNSW); M.Sc in 1964 (UNSW); and his PhD in 1967 (UNSW and his D.Sc in 1994 (UNSW). Dr Batley has achieved many awards including, most recently, the Land & Water Australia Eureka Prize for Water Research (2006); CSIRO Medal for Research Achievement (2006); and the Society of Environmental Toxicology and Chemistry Herb Ward Exceptional Service Award (2006). He is the author of over 300 research papers, book chapters and reports and is the author and editor of four books. Dr Batley’s research expertise is in the area of the analytical and environmental chemistry of trace contaminants in natural water systems, with particular emphasis on heavy metals and their chemical forms, fate, transport, bioavailability and ecotoxicology in waters and sediments. Copies of this report may be obtained by contacting Xstrata Mount Isa Mines community information line on 1800 982982. 4 Centre for Mined Land Rehabilitation – Sustainable Minerals Institute Sources and Pathways of Contaminants to the Leichhardt River Executive Summary The Lead Pathways Study — Water Sources and pathways of contaminants to the Leichhardt River investigated: • the potential sources and pathways of lead and other heavy metals and metalloids in water from the Leichhardt River catchment, particularly at, and below, Mount Isa City and the Mount Isa Mines lease area • the risk to human, agricultural pastoral, and ecological health from the contributions of lead and other heavy metals and metalloids. The study had three specific components: • water quality study • sediment quality study • aquatic toxicity assessment in water and sediment. These components of the study provided data that were then used as inputs to the development of site-specific guidelines for the Leichhardt River catchment. Nationally, a number of strategies and guidelines regulate water quality outcomes. The major strategies and guidelines, which are the basis for undertaking this study, are: • National Water Quality Management Strategy • ANZECC/ARMCANZ Water Quality Guidelines • Queensland Water Quality Guidelines. A site-specific risk assessment was also conducted to address human health and ecological concerns in areas where water and sediment contaminants were identified at concentrations above the guideline levels for metals and metalloids. The study area covered: • environmental receptors in the Leichhardt River (11 sites both upstream and downstream) • tributaries from the mine lease (Tailing Dams 5, 7, and 8 and Lena, King Gully, and George Fisher creeks) • urban discharge (Breakaway Creek). This study determined the distribution of metal and metalloid concentrations within the study area and their pathways. The study area comprised the Leichhardt River above and below Mount Isa City down to below Lake Moondarra and taking into account all tributaries from the mine lease and city. Upstream sampling extended to Rifle Creek Dam in the upper catchment of the Leichhardt River. The potential risk of these concentrations were assessed for: • people occasionally drinking the river water • people using the river water for recreational activities • using the river water for irrigation and livestock watering • the ecological health of the river water. The human health risk assessment was undertaken according to guidelines set by the National Health and Medical Research Council, the Australian Drinking Water Guidelines, and the National Environmental Protection Council. No site exceeded the ANZECC/ARMCANZ livestock watering guidelines for the metals and metalloids that were measured. The generic ANZECC/ARMCANZ decision-tree process was used for assessing metal and metalloid toxicants in the water. Water samples were collected from eleven sites on Leichhardt River, five tributaries from the mine lease, three tailings seepage ponds, and two urban tributaries over five sampling periods from November 2002 until June 2010. The samples were analysed for metal and metalloid concentrations in different fractions (total and 0.45 µm filtration fractions) to compare dissolved metal or metalloid concentrations as per the decision tree. The in situ measurement by Diffusive Gradients in Thin Films technique (DGT) was used to determine labile metal concentrations in the water to give the bioavailable metal concentration and alternatively speciation modelling was applied for arsenic because it was not measured by the DGT technique. Centre for Mined Land Rehabilitation – Sustainable Minerals Institute 5 Sources and Pathways of Contaminants to the Leichhardt River Six sets of sediment samples were taken from the Leichhardt River upstream down to the Lake Moondarra. The sampling program included: • sediment collected in 2007 • sediment collected concurrently with toxicity testing in October 2009 • Leichhardt River Verification Samples (13–14 November 2009) comprising seventy-nine sediment samples collected from the section of the Leichhardt River comprising Alma Crossing to Moondarra Junction, which were collected by Xstrata to confirm current sediment concentrations • regional/background stream sediment sampling program to give a background data set comprising twenty- nine sediment samples collected by Xstrata from the upstream section of the Leichhardt River (from Mica Creek up to Rifle Creek) with additional three sediment samples from Spring Creek (SPC) Bridge, and First and Second SPC Gullies lying in the upper catchment of George Fisher Creek that flows to Lake Moondarra • the Annual Stream Sediment Samples (11 November 2009) conducted as part of Xstrata’s Mine Plan Commitment. Sediment samples were analysed for total and 1M hydrochloric acid (HCl) extraction of metals and metalloids. The results were compared against ANZECC/ARMCANZ Interim Sediment Quality Guidelines-Low (ISQG-Low) for sediments. Sediment samples were also prepared as the <2 mm or <250 µm fraction and analysed for both total concentrations of metals and metalloids and bioaccessibility (%BAc). Human health risk was assessed by comparing these levels with the NEPM HIL — Level E for recreational use of dried river sediment. Aquatic toxicity assessment was undertaken as part of the ANZECC/ARMCANZ decision-tree process for both water and sediment. Three water-sampling programs collected water for aquatic toxicity testing. Three sets of sediment samples were also collected for toxicity assessment. The overall results of the water quality assessments show that the Leichhardt River water, at the time of testing, was alkaline and the water pH varied from 7.0 to 8.5 over five sampling periods. The electrical conductivity (EC) of samples at upstream sites (Leichhardt River upstream and Mica Creek upstream) and downstream sites (Moondarra Junction, Lake Moondarra and Clear Water Lagoon were within the limits for safe drinking water (<1000 µS/cm), which applies to palatability associated with total dissolved salts. However, the EC of water sampled at the Leichhardt River sites within Mount Isa City were >1000 µS/cm. The EC values of water collected at all sites in the wet season were significantly lower than pre-wet and post-wet season samples indicating a reduction in total dissolved salts with renewed river flow. Total concentrations of metals and metalloids in water were compared with Australian Drinking Water Guidelines. The results show that six sites from the Leichhardt River (19th Avenue, 23rd Avenue, Davis Crossing, Moondarra Crossing, Moondarra Junction) and four sites at tributaries from the mine lease (King Gully Creek, Lena Creek, Downstream North Tailing Dams 3 and 5) exceeded the guideline values. Two seepage ponds (Tailing Dam 5 and 8) exceeded the Australian Drinking Water Guidelines for arsenic, cadmium, and lead; however, these ponds are