Assessing the chemical contamination dynamics in a mixed land use stream system

WATER RESEARCH

卷:125

Article

Sonne, Anne Th.¹  McKnight, Ursula S.¹  Ronde, Vinni¹  Bjerg, Poul L.¹ 

[1] Tech Univ Denmark, Dept Environm Engn, Bygningstorvet 115, DK-2800 Lyngby, Denmark

关键词: Risk assessment;    Multiple chemical stressors;    Mixed land use stream systems;    Contaminated sites;    Contaminant mass discharge;    In-stream fate;    Toxic units;   

DOI  :  10.1016/j.watres.2017.08.031

来源: Elsevier

【 摘 要 】

Traditionally, the monitoring of streams for chemical and ecological status has been limited to surface water concentrations, where the dominant focus has been on general water quality and the risk for eutrophication. Mixed land use stream systems, comprising urban areas and agricultural production, are challenging to assess with multiple chemical stressors impacting stream corridors. New approaches are urgently needed for identifying relevant sources, pathways and potential impacts for implementation of suitable source management and remedial measures. We developed a method for risk assessing chemical stressors in these systems and applied the approach to a 16-km groundwater-fed stream corridor (Grindsted, Denmark). Three methods were combined: (i) in-stream contaminant mass discharge for source quantification, (ii) Toxic Units and (iii) environmental standards. An evaluation of the chemical quality of all three stream compartments stream water, hyporheic zone, streambed sediment made it possible to link chemical stressors to their respective sources and obtain new knowledge about source composition and origin. Moreover, toxic unit estimation and comparison to environmental standards revealed the stream water quality was substantially impaired by both geogenic and diffuse anthropogenic sources of metals along the entire corridor, while the streambed was less impacted. Quantification of the contaminant mass discharge originating from a former pharmaceutical factory revealed that several 100 legs of chlorinated ethenes and pharmaceutical compounds discharge into the stream every year. The strongly reduced redox conditions in the plume result in high concentrations of dissolved iron and additionally release arsenic, generating the complex contaminant mixture found in the narrow discharge zone. The fingerprint of the plume was observed in the stream several km downgradient, while nutrients, inorganics and pesticides played a minor role for the stream health. The results emphasize that future investigations should include multiple compounds and stream compartments, and highlight the need for holistic approaches when risk assessing these dynamic systems. (C) 2017 Elsevier Ltd. All rights reserved.

【 授权许可】

Free