Relating nutrient and herbicide fate with landscape features and characteristics of 15 subwatersheds in the Choptank River watershed

Metolachlor metabolite (MESA) reveals agricultural nitrate-N fate and transport in Choptank River watershed

“…Previously, we reported results in studies tracking nitrate-N and MESA concentrations over several years at seven stations in the Choptank River estuary (Whitall et al, 2010) and at the stream outlets of 15 headwater subwatersheds ( Fig. 1) (Hively et al, 2011). The hydrogeomorphology, land use (e.g., croplands, forest, developed, wetlands), and soil properties of the subwatersheds have been characterized and previously reported (Hively et al, 2011); some of these data are shown in Table 2 and Fig.…”

“…1) (Hively et al, 2011). The hydrogeomorphology, land use (e.g., croplands, forest, developed, wetlands), and soil properties of the subwatersheds have been characterized and previously reported (Hively et al, 2011); some of these data are shown in Table 2 and Fig. 1.…”

“…Subwatershed samples were collected at the outlets of 15 non-tidal upland subwatersheds of the Choptank River that were drained by third and fourth order streams ( Fig. 1) (Hively et al, 2011). Nine watersheds fell mostly within the well drained hydrogeomorphic region, five within the poorly drained region, and one included mixed portions of both well and poorly drained regions (Table 2).…”

“…Identified land use categories included: cropland (i.e., grain, forage, vegetable, and nursery crops); forest (deciduous and evergreen); developed areas (i.e., residential development, urban areas, industrial operations); and water (i.e., ponds, streams, drainage ditches). Land cover was prepared as total area and percent of subwatershed area (Table 2) (Hively et al, 2011). Additional geospatial data layers were developed for landscape analysis (Table 2) including hydric soils (soil classes C and D) from the Soil Survey Geographic (SSURGO) soils coverage (NRCS, 2008); and cropland on hydric soils through comparison of the previously mentioned land cover and hydric soils maps.…”

Impacts of Land Use on Surface Water Quality in a Subtropical River Basin: A Case Study of the Dongjiang River Basin, Southeastern China

“…We evaluated the data normality by means of the Kolmogorov-Smirnov test and the homogeneity of variance by means of Levene's test [47]. Because not all of the water quality parameter data met the parametric assumptions, the Kruskal-Wallis test (a nonparametric analysis of variance by rank that does not assume a Gaussian distribution) was used to determine whether the values of the water quality parameters differed significantly between the dry and the rainy seasons [41,48]. In order to determine if significant variations in water quality existed among site groups, multiple comparisons were performed using the Kruskal-Wallis test followed by Dunn's post hoc test at a significance level of p < 0.05.…”