Aquatic Ecology & Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands.
Water Res. 2012 Apr 1;46(5):1447-59. doi: 10.1016/j.watres.2011.11.008. Epub 2011 Nov 13.
Sediment dredging and Phoslock(®) addition were applied individually and in combination in an enclosure experiment in a Dutch hypertrophic urban pond. These measures were applied to control eutrophication and reduce the risk of exposure to cyanobacterial toxins. Over the 58 days course of the experiment, cyanobacteria (predominantly Microcystis aeruginosa) gradually decreased until they dropped below the level of detection in the combined treated enclosures, they were reduced in dredged enclosures, but remained flourishing in controls and Phoslock(®) treated enclosures. Cyanobacteria were, however, less abundant in the enclosures (medians chlorophyll-a 30-87 μg l(-1)) than in the pond (median chlorophyll-a 162 μg l(-1)), where also a thick surface scum covered one-third of the pond for many weeks. Soluble reactive phosphorus (SRP), total phosphorus and total nitrogen concentrations were significantly lower in the combined dredged and Phoslock(®) treated enclosures than in controls. Median SRP concentrations were 24 μg P l(-1) in the combined treatment, 58 μg P l(-1) in dredged enclosures, and 90 μg P l(-1) in controls and 95 μg P l(-1) in Phoslock(®) treated enclosures. Hence, the combined treatment was most effective in decreasing SRP and TP, and in lowering cyanobacterial biomass. Microcystin (MC) concentrations were analyzed by LC-MS/MS. MC concentrations and cyanobacterial biomass were positively correlated in all treatments. Mean MC concentrations in controls (71 μg l(-1)), Phoslock(®) treated enclosures (37 μg l(-1)) and dredged enclosures (25 μg l(-1)) exceeded the provisional guideline of 20 μg l(-1), whereas mean MC concentrations were 13 μg l(-1) in the combined treated enclosures. All samples contained the MC variants dmMC-RR, MC-RR, MC-YR, dmMC-LR and MC-LR; traces of MC-LY and nodularin were detected in few samples. The different treatments did not change the relative contribution of the variants to the MC pool; MC profiles in all treatments and the pond showed dominance of MC-RR followed by MC-LR. In the surface scum of the pond, total MC concentration was extremely high (64000 μg l(-1) or 1300 μg g(-1) DW), which poses a serious health hazard to children playing on the banks of the pond. Based on our results and pond characteristics, we propose combined sediment dredging and Phoslock(®) addition, fish removal and strong reduction of duck feeding by the neighborhood as most promising measures controlling cyanobacterial hazards in this pond.
在荷兰富营养化城市池塘的围隔实验中，单独和联合应用了底泥疏浚和 Phoslock（®）添加措施，以控制富营养化并降低暴露于蓝藻毒素的风险。在实验进行的 58 天中，蓝藻（主要是铜绿微囊藻）逐渐减少，直到在联合处理的围隔中检测不到，在疏浚围隔中减少，但在对照和 Phoslock（®）处理的围隔中仍大量存在。然而，蓝藻在围隔中的丰度低于池塘（中值叶绿素-a 为 162μg l（-1）），其中厚厚的表面浮渣在数周内覆盖了池塘的三分之一。与对照相比，联合疏浚和 Phoslock（®）处理的围隔中可溶反应性磷（SRP）、总磷和总氮浓度显著降低。联合处理的 SRP 浓度中位数为 24μg P l（-1），疏浚围隔为 58μg P l（-1），对照为 90μg P l（-1），Phoslock（®）处理为 95μg P l（-1）。因此，联合处理在降低 SRP 和 TP 以及降低蓝藻生物量方面最为有效。通过 LC-MS/MS 分析微囊藻毒素（MC）浓度。所有处理中 MC 浓度与蓝藻生物量呈正相关。对照（71μg l（-1））、Phoslock（®）处理的围隔（37μg l（-1））和疏浚围隔（25μg l（-1））中的 MC 浓度均值均超过 20μg l（-1）的临时指南，而联合处理的 MC 浓度均值为 13μg l（-1）。所有样品均含有 MC 变体 dmMC-RR、MC-RR、MC-YR、dmMC-LR 和 MC-LR；少数样品中检测到 MC-LY 和节球藻毒素的痕迹。不同的处理方法并未改变变体对 MC 库的相对贡献；所有处理和池塘的 MC 图谱均以 MC-RR 为主，其次是 MC-LR。池塘表面浮渣中的总 MC 浓度极高（64000μg l（-1）或 1300μg g（-1）DW），对在池塘岸边玩耍的儿童构成严重健康危害。基于我们的结果和池塘特征，我们建议联合进行底泥疏浚和 Phoslock（®）添加、去除鱼类以及减少附近鸭子的喂养，作为控制该池塘蓝藻危害的最有前途的措施。
