Boston University , Department of Biology, 5 Cummington Mall, Boston, Massachusetts 02215, United States.
Boston University , Department of Earth and Environment, 685 Commonwealth Avenue, Boston, Massachusetts 02215, United States.
Environ Sci Technol. 2017 Jul 5;51(13):7403-7411. doi: 10.1021/acs.est.7b01276. Epub 2017 Jun 13.
In large rivers, the ratios of silicon (Si)/nitrogen (N)/phosphorus (P) have changed dramatically as anthropogenic additions of N or P are not matched by Si. Wastewater effluent is a recognized source of N and P to coastal environments. Few previous studies, however, have examined the Si load of a large wastewater plant's effluent or the molar ratios of Si/N and Si/P in effluent. We examine the annual flux of dissolved silicon (DSi) carried by effluent from the second largest treatment plant by flow in the United States (Deer Island Treatment Plant, DITP, Boston, MA). We compare treatment plant nutrient fluxes to local urban river nutrient fluxes and trace the impact of the DITP DSi loading on receiving waters. Estimates (±95% confidence interval) of treated effluent (67 800 ± 1500 kmol DSi year) compared to untreated (69 500 kmol DSi year) indicate that the process of sewage treatment at DITP likely does not remove DSi. DITP effluent was Si-limited and this Si-limitation is reflected in the receiving waters (Massachusetts Bay). However, Si-limitation appears only in the area immediately surrounding the effluent discharge. We use these results to explain phytoplankton patterns in Massachusetts Bay and to provide the first estimate of DSi loading (3.6 Gmol SiO year) from wastewater effluent across the US.
在大型河流中，硅 (Si)/氮 (N)/磷 (P) 的比例发生了巨大变化，因为人为添加的 N 或 P 与 Si 不匹配。废水是沿海环境中 N 和 P 的公认来源。然而，很少有先前的研究检查过大的废水厂的废水 Si 负荷或废水中 Si/N 和 Si/P 的摩尔比。我们检查了美国第二大处理厂（波士顿的 Deer Island 处理厂，DITP）的流量中每年通过废水排放的溶解硅 (DSi) 的通量。我们将处理厂的营养物通量与当地城市河流的营养物通量进行比较，并追踪 DITP DSi 负荷对接收水的影响。处理后的废水（67800±1500 kmol DSi 年）与未处理的废水（69500 kmol DSi 年）的估计值（±95%置信区间）表明，DITP 的污水处理过程可能不会去除 DSi。DITP 废水受到 Si 的限制，这种 Si 限制反映在接收水中（马萨诸塞湾）。然而，Si 限制仅出现在废水排放口周围的区域。我们使用这些结果来解释马萨诸塞湾的浮游植物模式，并提供了美国废水排放的 DSi 负荷（3.6 Gmol SiO 年）的首次估计。
