Chemical loading into surface water along a hydrological, biogeochemical, and land use gradient: A holistic watershed approach

Environmental Science & Technology
By: , and 

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Abstract

Identifying the sources and impacts of organic and inorganic contaminants at the watershed scale is a complex challenge because of the multitude of processes occurring in time and space. Investigation of geochemical transformations requires a systematic evaluation of hydrologic, landscape, and anthropogenic factors. The 1160 km2 Boulder Creek Watershed in the Colorado Front Range encompasses a gradient of geology, ecotypes, climate, and urbanization. Streamflow originates primarily as snowmelt and shows substantial annual variation. Water samples were collected along a 70-km transect during spring-runoff and base-flow conditions, and analyzed for major elements, trace elements, bulk organics, organic wastewater contaminants (OWCs), and pesticides. Major-element and trace-element concentrations were low in the headwaters, increased through the urban corridor, and had a step increase downstream from the first major wastewater treatment plant (WWTP). Boron, gadolinium, and lithium were useful inorganic tracers of anthropogenic inputs. Effluent from the WWTP accounted for as much as 75% of the flow in Boulder Creek and was the largest chemical input. Under both hydrological conditions, OWCs and pesticides were detected in Boulder Creek downstream from the WWTP outfall as well as in the headwater region, and loads of anthropogenic-derived contaminants increased as basin population density increased. This report documents a suite of potential endocrine-disrupting chemicals in a reach of stream with native fish populations showing indication of endocrine disruption.


Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Chemical loading into surface water along a hydrological, biogeochemical, and land use gradient: A holistic watershed approach
Series title Environmental Science & Technology
DOI 10.1021/es051270q
Volume 40
Issue 2
Year Published 2006
Language English
Publisher ACS
Contributing office(s) Toxic Substances Hydrology Program
Description 12 p.
First page 475
Last page 486