Chow Alex T, Dahlgren Randy A, Harrison John A
College of Environmental Science and Engineering, South China University of Technology, Guangzhou, People's Republic of China 51064.
Environ Sci Technol. 2007 Nov 15;41(22):7645-52. doi: 10.1021/es070621t.
High levels of dissolved organic carbon (DOC) and bromide (Br) in the Sacramento and San Joaquin River waterways are of concern because DOC and Br are organic and inorganic precursors, respectively, of carcinogenic and mutagenic disinfection byproducts (DBPs). The Sacramento and San Joaquin Rivers are the two major rivers supplying water to the San Francisco Bay Delta, but sources and loads of DBP precursors into the Delta are still uncertain. The major objectives of this study were to evaluate both the quantity (DOC and Br fluxes) and the quality (reactivity in forming DBPs) of DBP precursors from the Sacramento and San Joaquin watersheds. Water samples were collected every 2 weeks at up to 35 locations along the Sacramento and San Joaquin Rivers and selected tributaries and analyzed for DOC (4 years), Br (1 year), and ultraviolet absorbance at 254 nm (1 year). Selected water samples were also tested for THM formation potential. Estimated fluxes for the Sacramento River were 39 000 +/- 12 000 Mg DOC year(-1) and 59 Mg of Br year(-1) as compared to 9000 +/- 5000 Mg of DOC year(-1) and 1302 Mg of Br year(-1) for the San Joaquin River. The THM formation potential was higher in the San Joaquin River (441 +/- 49 microg L(-1)) than the Sacramento River (176 +/- 20 microg L(-1)) because of higher concentrations of both organic (DOC = 3.62 +/- 0.14 vs 1.92 +/- 0.09 mg L(-1)) and inorganic DBP (Br = 0.80 +/- 0.07 vs < 0.03 +/- 0.01 mg L(-1)) precursors. The Sacramento River's greater DOC load despite lower DOC concentrations is due to its discharge being about 5 times greater than the San Joaquin River (50 x 10(9) vs 10 x 10(9) L day(-1)). The DOC concentration was significantly correlated with several land-cover types, including agriculture; however, no relationship was found between DOC quality and land-cover at the watershed scale.
萨克拉门托河和圣华金河水道中高水平的溶解有机碳（DOC）和溴化物（Br）令人担忧，因为DOC和Br分别是致癌和致突变消毒副产物（DBP）的有机和无机前体。萨克拉门托河和圣华金河是为旧金山湾三角洲供水的两条主要河流，但进入三角洲的DBP前体的来源和负荷仍不确定。本研究的主要目标是评估来自萨克拉门托和圣华金流域的DBP前体的数量（DOC和Br通量）和质量（形成DBP的反应性）。沿着萨克拉门托河和圣华金河以及选定的支流，每2周在多达35个地点采集水样，并分析DOC（4年）、Br（1年）和254nm处的紫外线吸光度（1年）。还对选定的水样进行了三卤甲烷生成潜力测试。萨克拉门托河的估计通量为39000±12000 Mg DOC年-1和59 Mg Br年-1，而圣华金河的通量为9000±5000 Mg DOC年-1和1302 Mg Br年-1。由于有机（DOC = 3.62±0.14对1.92±0.09 mg L-1）和无机DBP（Br = 0.80±0.07对<0.03±0.01 mg L-1）前体的浓度较高，圣华金河的三卤甲烷生成潜力（441±49 μg L-1）高于萨克拉门托河（176±20 μg L-1）。尽管DOC浓度较低，但萨克拉门托河的DOC负荷更大，这是因为其流量比萨克拉门托河大5倍左右（50×109对10×109 L天-1）。DOC浓度与包括农业在内的几种土地覆盖类型显著相关；然而，在流域尺度上未发现DOC质量与土地覆盖之间的关系。
