CITAB - Centre for the Research and Technology of Agro-Environment and Biological Sciences, Universidade de Trás-os-Montes e Alto Douro, Ap 1013, 5001-801 Vila Real, Portugal.
CQVR - Vila Real Chemistry Research Centre, Universidade de Trás-os-Montes e Alto Douro, Ap 1013, 5001-801 Vila Real, Portugal.
Sci Total Environ. 2017 Apr 1;583:466-477. doi: 10.1016/j.scitotenv.2017.01.106. Epub 2017 Jan 21.
The results of three Partial Least Squares (PLS) regression models were used to gain a holistic view on the consequences of natural processes and anthropogenic pressures for water quality degradation and biodiversity decline in a multi-use watershed. The processes were soil erosion and wildfire risk; the pressures comprised land use conflicts, leachates from domestic and industrial waste, arable farming intensity and livestock density. Water quality was characterized for concentrations of nutrients (nitrate, phosphate), oxygen demands (Biochemical Oxygen Demand - BOD, Chemical Oxygen Demand - COD) and various metals (e.g., As, Cr). Ecological integrity was assessed by the recently developed MELI (Multiple Ecological Level Index). In total, 18 variables were processed in the regression models. Two models were called "nested models" because they dealt with initial (pressures), intermediate (water quality) and final (MELI) environmental descriptors, used as dependent (MELI, quality) or independent (quality, pressures) variables. The third was called "bypass model" because it dealt solely with initial and final descriptors. Overall, the results of PLS regression linked the ineffective treatment of domestic sewage to water quality and ecological integrity declines in the studied watershed. Put another way, all models recurrently affirmed the major role of local factors, meaning of point source pollution, in determining the quality of stream water and the integrity of freshwater ecosystems. Sources of diffuse pollution were accounted for as contributing factors in the PLS regressions, but their influence was scarcely perceptible in the results. The poor treatment of domestic effluents is a public concern. In their strategic plans for mitigating this problem in the forthcoming years, administrative authorities are concentrated on management initiatives to improve the quality of provided services, instead of considering the construction of new wastewater treatment plants.
使用三个偏最小二乘 (PLS) 回归模型的结果，从整体上了解自然过程和人为压力对多用途流域水质恶化和生物多样性下降的影响。这些过程包括土壤侵蚀和野火风险；压力包括土地利用冲突、家庭和工业废物浸出物、耕地强度和牲畜密度。水质特征包括营养物（硝酸盐、磷酸盐）、需氧量（生化需氧量 - BOD、化学需氧量 - COD）和各种金属（如砷、铬）的浓度。生态完整性采用最近开发的 MELI（多生态水平指数）进行评估。总共有 18 个变量在回归模型中进行了处理。两个模型被称为“嵌套模型”，因为它们处理了初始（压力）、中间（水质）和最终（MELI）环境描述符，用作依赖（MELI、质量）或独立（质量、压力）变量。第三个模型被称为“旁路模型”，因为它仅处理初始和最终描述符。总的来说，PLS 回归的结果将生活污水的无效处理与研究流域的水质和生态完整性下降联系起来。换句话说，所有模型都反复肯定了当地因素的主要作用，即点源污染的意义，在决定溪流水质和淡水生态系统完整性方面的作用。漫射污染的来源被视为 PLS 回归中的影响因素，但它们的影响在结果中几乎无法察觉。生活污水的处理不当是一个公众关注的问题。在未来几年缓解这一问题的战略计划中，行政当局集中精力采取管理举措来提高所提供服务的质量，而不是考虑建造新的污水处理厂。
