National Research Council Postdoctoral Research Associate, Washington, DC, United States of America; Department of Geology, University of Maryland, College Park, MD, United States of America.
USEPA, National Health and Environmental Effects Research Laboratory, Corvallis, OR, United States of America.
Sci Total Environ. 2019 Feb 20;652:134-146. doi: 10.1016/j.scitotenv.2018.10.197. Epub 2018 Oct 16.
Regenerative stormwater conveyance (RSC), a relatively new stormwater management approach, is extensively implemented throughout the mid-Atlantic for nutrient control, but little is known of its pollutant reduction capabilities and controlling factors. This study examined effects of organic carbon (C) quantity and quality on stream water quality and nutrient retention at two RSCs near Annapolis, Maryland, USA by comparing longitudinal changes in water quality at paired restored and unrestored stream reaches, and conducting lab experiments simulating RSC processes. Results showed that RSCs consistently had lower dissolved oxygen saturation (DO%) and pH relative to nearby unrestored streams, probably due to release of labile dissolved organic carbon (DOC). At one RSC, with high nitrate (NO) inputs, retention of N (16-37%) and release of DOC (18-54%) were observed with the highest retention of N during summer, and the rates of N retention and DOC release were larger than that of the adjacent unrestored tributary (N: 5-8%, DOC: <18%). At another RSC site with lower NO concentrations, N retention and DOC release were not apparent. Mesocosm experiments showed that NO retention varies with organic C quantity and quality depending on incubating temperature; retention of total N did not increase with organic C due to release of other N species (e.g., organic N). Lab mesocosms showed an increase in the release of soluble reactive phosphorus (SRP) with increasing organic C quantity and quality. However, field measurements did not show any evidence of SRP release at RSCs. The changes in SRP concentrations in streams seemed to be a function of iron levels and leaf litter inputs, but control factors for SRP warrant further investigation. This study suggests that RSC as a restoration approach may be effective for reducing N depending upon C quantity and quality as well as water temperature and N levels.
再生雨水输送 (RSC) 是一种相对较新的雨水管理方法，在美国马里兰州的安纳波利斯附近广泛应用于营养物控制，但对于其污染物去除能力及其控制因素知之甚少。本研究通过比较两个 RSC 恢复和未恢复的溪流的水质沿程变化，以及进行模拟 RSC 过程的实验室实验，研究了有机碳 (C) 的数量和质量对溪流水质和养分截留的影响。结果表明，RSC 的溶解氧饱和度 (DO%) 和 pH 值相对于附近的未恢复溪流始终较低，这可能是由于易降解溶解有机碳 (DOC) 的释放所致。在一个 RSC 中，由于硝酸盐 (NO) 输入较高，观察到 N (16-37%) 的截留和 DOC (18-54%) 的释放，且夏季的 N 截留率最高，N 截留率和 DOC 释放率均大于相邻的未恢复支流（N：5-8%，DOC：<18%）。在另一个 NO 浓度较低的 RSC 站点，没有明显的 N 截留和 DOC 释放。中间尺度实验表明，NO 的截留取决于有机 C 的数量和质量，取决于孵育温度；由于其他 N 物种（例如有机 N）的释放，总 N 的截留不会随有机 C 的增加而增加。实验室中间尺度实验表明，随着有机 C 数量和质量的增加，可溶性反应磷 (SRP) 的释放量增加。然而，在 RSC 中没有观察到 SRP 释放的任何证据。溪流中 SRP 浓度的变化似乎是铁水平和叶凋落物输入的函数，但 SRP 的控制因素仍需进一步研究。本研究表明，RSC 作为一种恢复方法，可能会有效减少 N 的排放，这取决于 C 的数量和质量以及水温、N 水平等因素。
