Chemical Loading into Surface Water along a Hydrological, Biogeochemical, and Land Use Gradient:  A Holistic Watershed Approach

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.

Distribution of nonprescription pharmaceuticals in central Indiana streams and effects on sediment microbial activity

“…Barber et al (2006) found lithium to be a good indicator of anthropogenic waste inputs into streams, consistent with this study. Lithium is a drug used for the treatment of mood disorders (Price and Heninger 1994).…”

Quantifying the effects of stream channels on storm water quality in a semi-arid urban environment

“…Urbanization in arid and semi-arid regions can negatively impact stream and drinking water quality by increasing loads of nutrients, metals and organic pollutants to surface and ground water (Asaf et al, 2004;Barber et al, 2006;Carlson, 2004;Gallo et al, 2012;e.g. Hamilton et al, 2004;Lewis and Grimm, 2007), yet little is known regarding how the characteristics of the stormwater drainage system, and specifically the characteristics of the stream channel substrate, alter urban runoff hydrochemistry.…”

Medical image of the week: acute pneumonitis secondary to boric acid exposure

“…The boron concentrations of surrounding irrigated soils before the waste water discharges began were 0.15 ppm (0-20 cm depth) and 0.19 ppm (80-100 cm depth), while after the discharges, the boron concentrations were 13.90 ppm (0-20 cm depth) and 3.66 ppm (80-100 cm depth) (Akar 2007). Barber et al (2006) reported that daily loads of boron in the Boulder Creek, Colorado of 0-55 kg/day are mostly due to the effluent of the Boulder waste water treatment plant. Mumma et al (1984) reported that the boron concentration in sewage sludges from 23 U.S. cities ranged from 7.1 to 53.3 mg/kg.…”