Escuela de Ciencias del Mar, Pontificia Universidad Católica de Valparaíso, Valparaiso, Chile.
Grupo Ecotox, Área de Ecología, Departamento de Biología Funcional, Escuela Politécnica Superior de Ingeniería, Universidad de Santiago de Compostela, Lugo, Spain.
Water Res. 2020 Feb 1;169:115247. doi: 10.1016/j.watres.2019.115247. Epub 2019 Oct 31.
Environmental impact studies of rivers affected by wastewater treatment plant (WWTP) effluents have been greatly restricted by the difficulties associated with carrying out bioassays in the field and also by the complex interactions between the pollutants contained in the discharges. The cotton-strip assay (CSA) enables study of the organic matter decomposition potential, an important ecosystem process in rivers, by taking all of the factors affecting this process into account. However, the CSA has never been used for assessment of WWTP effluents. In the present study, we selected six fluvial zones affected by discharges from small WWTPs and placed cotton strips at increasing distances from the discharge points in each zone. After 17 days, we evaluated decay of the strips by measuring cotton tensile strength loss (CTSL) and cotton mass loss (CML). We then determined the relationships between these parameters and various physico-chemical and biological properties in the water, as well as the δN isotopic signal and metal contents of aquatic mosses transplanted in the same sampling sites and used as biomonitors. Although the WWTPs were similar, some of the discharges stimulated and others inhibited decomposition of the cotton strips. This was probably due to differences in the proportions of various types of pollutants (with trophic or toxic effects) in the discharges. The CSA proved to be a simple, practical and economic bioassay and suitable for evaluating the ecological integrity of fluvial ecosystems.
受污水处理厂（WWTP）废水影响的河流的环境影响研究受到了极大的限制，这是因为在野外进行生物测定存在困难，而且排放物中的污染物之间存在复杂的相互作用。棉条测定法（CSA）通过考虑影响这一过程的所有因素，能够研究有机物分解潜力，这是河流生态系统中的一个重要过程。然而，CSA 从未用于评估 WWTP 废水。在本研究中，我们选择了受小型 WWTP 排放物影响的六个河流区域，并在每个区域的排放点的不同距离处放置棉条。17 天后，我们通过测量棉条拉伸强度损失（CTSL）和棉条质量损失（CML）来评估条带的降解情况。然后，我们确定了这些参数与水中各种理化和生物学特性之间的关系，以及在相同采样点中移植的水生苔藓的 δN 同位素信号和金属含量，这些苔藓被用作生物监测器。尽管 WWTP 相似，但有些排放物刺激了棉条的分解，而有些则抑制了棉条的分解。这可能是由于排放物中各种类型污染物（具有营养或毒性作用）的比例不同所致。CSA 被证明是一种简单、实用且经济的生物测定法，适用于评估河流生态系统的生态完整性。
