这是一篇关于废水影响城市供水抗旱的文章
Two data sets showing the summed concentrations of atrazine; carbamazepine; n,n-diety1-meta-toluamide (DEET), diazepam; diclofenac; dilantin; estradiol; estrone; ethynylestradiol; fluoxetine; gemfibrozil; meprobamate; naproxen; sulfamethoxazole; testosterone; and trimethoprim measured in the Las Vegas Wash and source drinking water are shown in Fig. 3A. Compounds which were not detected (reported as < X in the Supporting Information, where X equals the method reporting limit) were assigned a value of 0 to create Fig. 3A. It is important to note that diazepam, estradiol, and ethynylestradiol were never detected in source drinking water (see Supplemental Information). The circles and squares represent measurements made from the Method 1 and 2 analyses, respectively. As previously mentioned, these datasets are treated as separate, and are not combined due to differences in the analytical methodologies. The concentration of nitrate in the Las Vegas Wash, the Colorado River, and source drinking water are shown in Fig. 3B. Values for conductivity in the Las Vegas Wash, Colorado River, and source drinking water are shown in Fig. 3C.
A statistical analysis of both pharmaceutical and EDC dataset for significance of slope indicate that summed source water concentration increased at a rate significantly different from zero slope with > 99% confidence (Fig. 3A). The rate of concentration increase was 0.02 ng L-1D-1 (p<0.0001) for Method 1 and 0.008 ng L-1d-1 (p=0.004) for Method 2. The rate at which pharmaceutical and EDC concentrations increase or decreased in the Las Vegas Wash was not statistically different from zero for Method 1 data. Summed concentrations of pharmaceuticals and EDCs measured by Method 2 decreased at a rata of 1.0 ng L-1d-1 (p<0.0001), though this rata is heavily influenced by anomalously low November 2007 data point. Regardless, neither dataset shows an increase an concentrations of these compounds in the Las Vegas Wash. Though the flow of the Las Vegas Wash did increase at a rata that was statistically different from zero (slope=0.0000006 mL s-1d-1, p<0.0001; Fig. 2), the amount of increase was < 10% over this time period. Thus, the combination of Las Vegas Wash flow and pharmaceutical and concentrations yields a mass loading which increased by 10% far below the doubling (100% increase) of concentration observed in source drinking water over the same period of time. There are no data for the presence of these compounds in the Colorado River site, though concentrations should be negligible as there are no large inputs of wastewater upriver from Lake Mead.