Department of Biological Sciences, Kent State University, Kent, OH, USA.
Department of Biological Sciences, Kent State University, Kent, OH, USA.
Sci Total Environ. 2020 Apr 10;712:135597. doi: 10.1016/j.scitotenv.2019.135597. Epub 2019 Nov 18.
In urbanized landscapes, green infrastructure is proposed as a method for using relatively small plots of land to manage stormwater and protect receiving ecosystems from pollutants. Bioretention cells can infiltrate stormwater from roads and parking lots, and as stormwater passed through the soils, metals can be removed. Metal removal and storage has been demonstrated in laboratory media columns and field-scale test cells, but we have an incomplete understanding of metal removal and accumulation in aging bioretention cells in the field. We surveyed 25 bioretention cells (0-7 years of service) for soil physicochemistry to determine which characteristics related to soil metal (Cu, Pb, and Zn) concentrations. We collected soil cores and treated them with simulated stormwater to measure potential rates of metal removal under different metal and salt concentrations. Older bioretention cells had higher Cu, Pb, and Zn concentrations in soil, which indicates accumulation and storage over time. The oldest cells had metal concentrations that were not a risk to human health but which approached screening thresholds for potential impairment of plants. Soil organic matter content (OM) was positively associated with metal concentrations which highlights the importance of OM in the functioning of cells. Retrofit bioretention cells were younger with less OM and more clay than cells built concurrently with new parking lot construction (i.e., de novo), but after 2.7 years of service, soil OM was similar between retrofit and de novo builds. Soil cores from de novo bioretention cells retained more stormwater metals than soil cores from retrofit cells, and this was likely due to differences in soil OM. Elevated road salt in stormwater was associated with less effective metal removal and leaching of Zn from soils. Overall, these data suggest that management (e.g., salting) and design (e.g., construction) decisions can greatly influence metal removal function of bioretention cells.
在城市化景观中，绿色基础设施被提议作为一种利用相对较小的土地面积来管理雨水和保护受纳生态系统免受污染物影响的方法。生物滞留池可以渗透道路和停车场的雨水，而当雨水穿过土壤时，金属可以被去除。金属去除和储存已在实验室介质柱和现场规模的测试池中得到证明，但我们对现场老化生物滞留池中金属的去除和积累仍缺乏全面的了解。我们调查了 25 个生物滞留池（使用 0-7 年）的土壤物理化学性质，以确定哪些特征与土壤金属（铜、铅和锌）浓度有关。我们收集了土壤芯并对其进行了模拟雨水处理，以测量在不同金属和盐浓度下潜在的金属去除率。较老的生物滞留池的土壤中含有更高浓度的 Cu、Pb 和 Zn，这表明随着时间的推移会发生积累和储存。最老的细胞的金属浓度虽然对人类健康没有风险，但接近植物潜在损害的筛选阈值。土壤有机质含量（OM）与金属浓度呈正相关，这突出了 OM 在细胞功能中的重要性。改造后的生物滞留池比与新停车场建设同时建造的生物滞留池（即新建）更新，具有更少的 OM 和更多的粘土，但在 2.7 年的服务后，改造后的和新建的生物滞留池的土壤 OM 相似。来自新建生物滞留池的土壤芯保留了更多的雨水金属，而来自改造后的生物滞留池的土壤芯则较少，这可能是由于土壤 OM 的差异。雨水高浓度的道路盐与金属去除效率降低和 Zn 从土壤中浸出有关。总的来说，这些数据表明，管理（例如撒盐）和设计（例如施工）决策可以极大地影响生物滞留池的金属去除功能。
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