Details:

Creators:
Flury, Markus ; Mullane, Jessica M. ; Chahal, Maninder K. ; Cogger, Craig G.
Flury, Markus ; Mullane, Jessica M. ; Chahal, Maninder K. ; Cogger, Craig G. Less -
Corporate Creators:
Washington State University. Dept. of Crop and Soil Sciences
Corporate Contributors:
United States. Federal Highway Administration
Subject/TRT Terms:
[+]
Compost Copper Evaluation Leachate Nitrates Particulates Phosphorus Runoff
Publication/ Report Number:
WA-RD 848.1
Resource Type:
Tech Report
Geographical Coverage:
Washington
Corporate Publisher:
Washington (State). Dept. of Transportation. Office of Research and Library Services
Abstract:
Compost is often used in raingardens, roadsides, and bioretention systems, not only because of

its beneficial properties on soil quality, but also because compost improves water infiltration and

retains stormwater contaminants. However, when compost is freshly applied, materials from

compost can leach out when rain or stormwater seep through compost or compost-amended

bioretention media. The goal of this research project was to experimentally evaluate and

characterize leachates from compost. We quantified and characterized the leachate composition

of compost following intermittent, simulated storm events. We used municipal compost of

different ages and different source materials. Compost was filled into columns and then irrigated

with deionized water and stormwater. Stormwater was spiked with copper to increase copper

concentrations. Six-month, 24-hour rain storms were applied every two weeks for a total of up to

18 rain storms. Outflow was analyzed for pH, electrical conductivity (EC), particulate

concentration, surface tension, dissolved organic carbon (DOC), nitrogen, phosphorus, and

copper. Particulate and dissolved organic matter was further characterized for molecular structure

by Nuclear Magnetic Resonance (NMR) and Fourier-Transformed Infrared (FTIR) Spectroscopy.

Our results showed that concentrations of dissolved and particulate organic carbon and electrical

conductivity in the leachate where high at the onset of each storm, but decreased as the storm

progressed. However, each new storm released another peak of constituents. Leaching from

mature compost was less a function of age and type, but more a function of number and

frequency of storms and leaching history. Concentrations of nitrogen, phosphorus, and copper were high in the initial few storms, and then decreased. Only a small fraction (3%) of the copper

present in the compost leached out, but nonetheless, the copper concentrations in the leachate

remained above the regulatory waste discharge standards. NMR and FTIR analyses revealed that

dissolved organic carbon consisted mainly of aliphatic and aromatic components typical of fulvic

and humic acids. Our results show that municipal compost can serve as a sustained source of

leaching of nutrients and metals, regardless of compost age and source. However, the copper

concentrations observed in our experiment are likely not toxic due to the presence of elevated

DOC, as DOC readily forms complexes with dissolved copper thereby reducing its toxicity to

aquatic organisms. The DOC plays a dual role in terms of copper fate and transport: DOC can

enhance leaching of copper by forming aqueous complexes, but at the same time, reduces toxicity

of copper because copper-DOC complexes are less bioavailable.


Format:
PDF
Funding:
T1462-03
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:dce3b6ef295f1f271f69396a09965df02d044ae29a8f9db0983e0d3944579952
Download URL:
https://rosap.ntl.bts.gov/view/dot/29510/dot_29510_DS1.pdf
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