School of Biological, Earth and Environmental Sciences, University College Cork, Ireland.
School of Biological, Earth and Environmental Sciences, University College Cork, Ireland.
Sci Total Environ. 2019 Aug 10;677:700-717. doi: 10.1016/j.scitotenv.2019.04.169. Epub 2019 Apr 25.
Despite introduction of legislation such as the EU Nitrates and Water Framework Directives (Directives 91/676/EEC and 2000/60/EC respectively), agricultural practices are often still regarded as a major factor in poor water quality across many EU member states. Elevated inputs of nutrients, organic matter and agro-chemicals to receiving waters from agricultural lands in particular are now widely recognised as potentially major causes of deteriorating water quality. Such inputs may emanate from diffuse sources such as agricultural fields, and small point- or intermediate-sources, including farmyards and farm trackways. However, while inputs from these latter intermediate sources may be substantial, their overall contribution to catchment-wide water quality at high temporal or spatial resolution is still largely unknown. In this study, we surveyed water chemistry throughout the multiple natural and artificial watercourses within a single drainage network at high spatial resolution in a predominantly dairy farming area in Southern Ireland. We found that most headwaters at the time of study were impacted by organic inputs via drainage ditches emanating from the vicinity of farmyards. These farmyard drains were found to have elevated concentrations of ammonium, phosphorus, potassium, suspended sediment and biochemical oxygen demand above background levels in the study catchment. Concomitant assessment of macro-invertebrate communities at study sites indicated that the ecological quality of headwaters was also impaired by these inputs. The individual and aggregate contributions of farmyard drains to water quality within a single catchment, when mapped at high spatial resolution, indicates that they constitute a major contribution to catchment scale 'diffuse' agricultural inputs. However, our data also suggest that engineering farmyard drains to maximise their retention and attenuation function may prove to be a cost-effective means of mitigating the effects of point source farmyard inputs.
尽管引入了欧盟硝酸盐和水框架指令（分别为指令 91/676/EEC 和 2000/60/EC）等法规，但农业实践在许多欧盟成员国仍然被认为是水质不佳的主要因素。特别是从农业土地输入到受纳水体的营养物质、有机物和农用化学品的增加，现在被广泛认为是水质恶化的潜在主要原因。这些投入可能来自农业用地等漫射源，以及小型点源或中间源，包括农场院和农场道路。然而，尽管这些中间源的投入可能很大，但它们对整个流域范围内水质在高时间或空间分辨率下的总体贡献仍在很大程度上未知。在这项研究中，我们在爱尔兰南部一个以奶牛养殖为主的地区，以高空间分辨率对单一排水网络内的多个自然和人工水道的水质进行了调查。我们发现，在研究时，大多数源头都受到了来自农场院附近的排水渠的有机物质输入的影响。这些农场院排水渠的铵、磷、钾、悬浮泥沙和生化需氧量浓度均高于研究流域的背景水平。同时对研究点的大型无脊椎动物群落进行评估表明，这些输入也损害了源头的生态质量。当以高空间分辨率绘制时，单个和综合的农场院排水渠对单一流域内水质的贡献表明，它们构成了对流域尺度“漫射”农业投入的主要贡献。然而，我们的数据还表明，对农场院排水渠进行工程设计以最大限度地提高其保留和衰减功能，可能是一种具有成本效益的减轻点状农场投入影响的方法。
