Prov. Department of Venice, ARPAV (Veneto Regional Prevention and Protection Agency), Via Lissa 6, 30171, Mestre-Venice, Italy.
National Research Council (CNR), Institute of Marine Sciences, Arsenale Tesa 104 Castello 2337/F30122, 30122, Venice, Italy.
Environ Sci Pollut Res Int. 2018 Dec;25(34):34306-34318. doi: 10.1007/s11356-018-3316-0. Epub 2018 Oct 6.
Microbiological impact is critical in coastal areas where tourism is particularly important for both the local and regional economy. Submarine outfalls are commonly used to enhance the dispersion of treated sewage thus avoiding pollution along the coast. The Venice lagoon (North Italy) has a very sensitive ecosystem, due to the morphological and natural characteristics of the basin and the co-existence of human activities. To preserve the lagoon, the discharge from the treatment plant for urban wastewater collected from the Venezia-Mestre agglomeration, neighbouring areas and local industries (total of 400,000 population equivalent-PE) has been moved from the lagoon to the open Adriatic Sea since November 2013 by means of an approximately 20-km pipeline. Microbiological pollution inside the lagoon can affect shellfish breeding areas instead, along the coast it affects the quality of bathing waters. In this study, and for the first time, a 3D hydrodynamic SHYFEM model (shallow water finite element model) with high spatial resolution coupled with a microbiological module has been applied to the lagoon and to the Adriatic Sea, to evaluate the effectiveness of the location of the submarine outfall. Microbiological data have been produced by the control Authority according to official analytic methods and by the plant operator. The module of survival of free Escherichia coli follows a variable rate in dependence of UV radiation, temperature and salinity in the water. Two scenarios were modelled: final discharge into the lagoon before November 2013 and after into the open sea. In the latter case, two situations have been considered, one with "Bora" and the other with "Scirocco" winds. Our results indicate that the model correctly simulates microbiological decay and dispersion. The transferral of the final discharge point far from the shoreline improves pollution dispersion, thus preserving the lagoon without evidence of impacts on the bathing waters in all meteorological conditions.
微生物学影响在旅游业特别重要的沿海地区至关重要，因为旅游业对当地和地区经济都有重要影响。海底排水口通常用于增强处理污水的扩散，从而避免沿海水域的污染。威尼斯泻湖（意大利北部）由于盆地的形态和自然特征以及人类活动的共存，拥有非常敏感的生态系统。为了保护泻湖，自 2013 年 11 月以来，从威尼斯-梅斯特城市群、邻近地区和当地工业（总计 400,000 人口当量-PE）收集的城市废水处理厂的排放物已通过一条长约 20 公里的管道从泻湖转移到开阔的亚得里亚海。泻湖内部的微生物污染会影响贝类养殖区，而沿海水域的污染则会影响浴场水质。在这项研究中，首次将具有高空间分辨率的三维水动力 SHYFEM 模型（浅水有限元模型）与微生物模块一起应用于泻湖和亚得里亚海，以评估海底排水口位置的有效性。微生物数据是由控制机构根据官方分析方法和工厂运营商提供的。自由大肠杆菌存活模块遵循随水中紫外线辐射、温度和盐度变化的变量率。模拟了两种情况：2013 年 11 月之前泻湖的最终排放和之后排入大海。在后一种情况下，考虑了两种情况，一种是“博拉”风，另一种是“西罗科”风。我们的研究结果表明，该模型正确地模拟了微生物衰减和扩散。将最终排放点转移到远离海岸线的地方可以改善污染扩散，从而在所有气象条件下保护泻湖，而不会对浴场水质造成影响。
