The purpose of this paper was to assess the effect of the diversion of wastewater on the trophic status of Lake Bidighinzu, a hypertrophic man-made lake in Northern Sardinia, used as a drinking water reservoir. There have been problems with potabilization since the early years of the diversion operation, particularly in the summer-autumn period. Data available (August 1978, February 1979 and March 1985) before the reservoir (1987) were compared with those collected during a study carried out in the annual cycle immediately after (1988-1989) and after some years (1994 and 1996-1997). The study examined the dynamics of temperature, main nutrients (total phosphorus, nitrate and ammonia), chlorophyll-a and phytoplanktonic biomass. No particular variation in the water nutrient availability emerged from the comparison between these two situations - especially for total phosphorus, whose annual mean concentrations were similar in the two annual cycles (386 mg P m -3 in 1988-1989 and 305 mg P m -3 in 1996-1997). Chlorophyll-a and biomass were high during each period of study (annual mean values were 17 mg m -3 and 3.7 mg l -1 in 1988-1989 and 11 mg m -3 and 4.6 mg l -1 in 1996-1997). However, peaks were never higher than values recorded in August 1978 (112 mg m -3 and 133 mg l -1 ) due to an extraordinary bloom of Ceratium hirundinella (O.F. Muller). Species composition of phytoplankton was typical of highly trophic conditions and was frequently characterised by the presence of Cyanophyceae and Bacillariophyceae. Results demonstrated that, ten years after construction of the by-pass, the lake had shown no improvement in its trophic status. This might depend on many factors, among which the most likely might be the non-use or partial use of the diversion system, which allows the sewage to continue to flow into the lake and keep its trophic status almost unchanged.

中文翻译：

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Bidighinzu水库（撒丁岛）在污水分流前后的营养状况

本文的目的是评估废水分流对 Bidighinzu 湖营养状况的影响，Bidighinzu 湖是撒丁岛北部肥厚的人工湖，用作饮用水水库。自改水作业的早期以来，尤其是在夏秋季节，就出现了饮用问题。将水库之前（1987 年）的可用数据（1978 年 8 月、1979 年 2 月和 1985 年 3 月）与紧接在此之后（1988-1989 年）和若干年后（1994 年和 1996-1997 年）的年度周期中进行的研究中收集的数据进行了比较. 该研究检查了温度、主要营养素（总磷、硝酸盐和氨）、叶绿素-a 和浮游植物生物量的动态变化。从这两种情况的比较中，水养分的有效性没有出现特别的变化——尤其是总磷，其年平均浓度在两个年度循环中相似（1988-1989 年为 386 mg P m -3 和 305 mg P m - 1996-1997 年第 3 次）。在每个研究期间，叶绿素-a 和生物量都很高（1988-1989 年的年平均值分别为 17 mg m -3 和 3.7 mg l -1 ，1996-1997 年平均值为 11 mg m -3 和 4.6 mg l -1）。然而，峰值从未高于 1978 年 8 月记录的值（112 mg m -3 和 133 mg l -1 ），原因是 Ceratium hirundinella (OF Muller) 异常盛开。浮游植物的物种组成具有典型的高营养条件，并且经常以蓝藻科和芽孢杆菌科的存在为特征。结果表明，修建旁路十年后，该湖的营养状况并没有改善。这可能取决于许多因素，其中最有可能的可能是导流系统未使用或部分使用，这使得污水可以继续流入湖中并保持其营养状态几乎不变。