Characteristics of water pollution and ecological risk assessment of scenic rivers: a case study of Beichaogang in Shanghai
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摘要: 为推进城市景观河道水质高标准改善,以上海市北潮港为典型代表,对河道上覆水和表层沉积物开展为期一年的监测,识别污染特征并评估生态风险。结果表明:北潮港上覆水水质和沉积物污染程度在节制闸两侧呈现明显差异;上覆水稳定处于水质指数良好等级,沉积物存在较严重的有机质和营养盐累积,重金属潜在生态风险处于中风险等级。生态修复工程的实施对上覆水水质有显著提升,但未能削减沉积物中污染物含量。雨污混接造成的溢流污染和沉积物内源污染释放可能是北潮港主要污染因子BOD5、总磷和总氮的来源。Abstract: To promote high-standard improvement of water quality in urban scenic rivers, taking Beichaogang in Shanghai as a typical representative, a one-year monitoring of overlying water and surface sediments was conducted to identify pollution characteristics and evaluate ecological risks. The results show that water quality and sediment pollution degree in Beichaogang exhibited significant differences on both sides of the sluice gate. The overlying water remains stable within the good grade of water quality index, while serious accumulations of organic matter and nutrients are found in sediments, and the potential ecological risk of heavy metals is at the medium risk level. The implementation of the ecological restoration project significantly improved the water quality of the overlying water, but failed to reduce the content of pollutants in the sediments. Overflow pollution caused by the mixing of rainwater and sewage, and the release of endogenous pollutants from the sediments are likely the main sources of factors BOD5, total phosphorus, and total nitrogen in Beichaogang.
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Key words:
- scenic rivers /
- water quality assessment /
- nutrients /
- organic matter /
- heavy metals
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表 1 现场监测结果(均值 ± 标准差)
Table 1. On-site monitoring results (mean ± standard deviation)
采样点 pH值 DO/(mg·L−1) WT/℃ Turbidity/NTU SD/cm BCG-1 7.82 ± 0.29 7.57 ± 2.49 18.86 ± 8.52 8.97 ± 2.66 118.00 ± 23.48 BCG-2 8.42 ± 0.34 10.92 ± 2.40 18.96 ± 8.82 6.39 ± 3.79 116.43 ± 29.94 BCG-3 8.15 ± 0.26 9.99 ± 3.06 19.47 ± 8.70 16.16 ± 15.49 66.86 ± 17.19 BCG-4 7.68 ± 0.18 5.27 ± 2.98 19.99 ± 7.75 331.03 ± 214.57 6.33 ± 4.20 BGG-5 7.65 ± 0.13 5.73 ± 2.94 19.33 ± 7.96 239.73 ± 318.47 8.83 ± 3.45 表 2 雨水井污染物监测结果(均值 ± 标准差)
Table 2. Monitoring results of pollutants in stormwater manholes (mean ± standard deviation)
单位:mg/L 采样点 ρ(TN) ρ($\mathrm{NH}^{+}_4 $-N) ρ($\mathrm{NO}^{-}_3 $-N) ρ($\mathrm{NO}^{-}_2 $-N) ρ(TP) ρ(DP) ρ(CODCr) ρ(BOD5) YSJ-1 10.28 ± 4.43 5.60 ± 2.45 1.56 ± 2.18 0.66 ± 0.59 0.54 ± 0.35 0.20 ± 0.32 66.95 ± 37.70 16.93 ± 15.93 YSJ-2 10.37 ± 5.82 6.81 ± 6.21 0.63 ± 0.38 0.01 ± 0.01 1.59 ± 1.72 0.74 ± 0.75 192.83 ± 124.73 106.71 ± 71.97 YSJ-3 22.66 ± 25.62 21.20 ± 31.43 1.16 ± 1.00 0.19 ± 0.31 2.95 ± 2.85 1.80 ± 1.78 145.04 ± 89.71 110.98 ± 88.92 YSJ-4 51.45 ± 33.85 38.90 ± 24.09 4.05 ± 3.32 0.27 ± 0.42 6.73 ± 4.85 5.82 ± 5.20 346.76 ± 116.26 285.96 ± 200.77 表 3 沉积物中重金属含量
Table 3. Heavy metal contents in sediments
指标 wCu wPb wCr wCd wHg wAs 取值范围/
(mg·kg−1)47.84 ~ 91.95 31.12 ~ 61.40 85.25 ~ 103.62 0.20 ~ 0.47 0.07 ~ 0.22 5.91 ~ 8.16 均值/
(mg·kg−1)69.05 52.10 95.48 0.37 0.16 7.03 标准差/
(mg·kg−1)29.86 14.14 11.18 0.11 0.07 2.89 变异系数/% 43.24 27.14 11.71 29.65 45.08 41.03 背景值/
(mg·kg−1) [19]27.26 25.48 70.20 0.14 0.10 9.11 表 4 沉积物重金属潜在生态风险评价
Table 4. Potential ecological risk assessment of heavy metals in sediments
采样点 潜在生态风险指数(RI) 评价等级 BCG-1 226.76 中风险 BCG-2 226.14 中风险 BCG-3 170.32 中风险 BCG-4 101.06 低风险 均值 181.07 中风险 表 5 北潮港水质主成分分析结果
Table 5. Principal component analysis results of water quality of Beichaogang
指标 主成分因子载荷矩阵 PC1 PC2 TN 0.006 0.826 NH+4-N 0.516 0.489 BOD5 0.830 0.124 TP 0.820 0.228 CODMn 0.698 -0.363 特征值 2.115 1.121 方差贡献率/% 42.31 22.42 累积贡献率/% 42.31 64.73 -
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