wAbstract
@Dissolved organic carbon (DOC) and nitrogen (DON) concentrations
were quantified in urban and rural watersheds located in central
Texas, USA between 2007 and 2008. The proportion of urban land
use ranged from 6 to 100 in our 12 study watersheds which included
nine watersheds without waste water treatment plants (WWTP) and
three watersheds sampled downstream of a WWTP. Annual mean DOC
concentrations ranged 20.4-52.5 mg L-1. Annual mean
DON concentrations ranged 0.6-1.9 mg L-1. Only the
rural watersheds without a WWTP had significantly lower DOC concentrations
compared to those watersheds with a WWTP but all the streams except
two had significantly reduced DON compared to those with a WWTP.
Analysis of the nine watersheds without a WWTP indicated that
68 of the variability in mean annual DOC concentration was explained
by urban open areas such as golf courses, sport fields and neighborhood
parks under turf grass. There was no relationship between annual
mean DON concentration and any land use. Urban open area also
explained a significant amount of the variance in stream sodium
and stream sodium adsorption ratio (SAR). Ninety-four percent
of the variance in annual mean DOC concentration was explained
by SAR. Irrigation of urban turf grass with domestic tap water
high in sodium (181 mg Na+ L-1) may be
inducing sodic soil conditions in watershed soils in this region
resulting in elevated mean annual DOC concentrations in our streams.
Keywords: DOC; DON; Land-use; Sodium; Streams; Urbanx
Introduction
Site description
Materials and methods
@Field sampling
@Chemical analysis
@Spatial analysis
@Statistical analysis
Results
@Stream chemistry in urban, suburban and rural surface waters
with and without a WTTP
@Relationships between mean annual stream DOC, DON and land use
@Effect of irrigation water and waste water effluent on stream
DOC, DON and proteins
Discussion
@Land use effect on DOC and DON concentrations
@Effect of urban land management on dissolved organic carbon
Conclusions
Acknowledgments
References