Setting of the water quality standards for nutrients in runoff from agricultural land | Ūdeņu kvalitātes standarta noteikšana pēc biogēno elementu koncentrācijas notecē no lauksaimniecībā izmantotajām platībām
2008
Lagzdins, A., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Rural Engineering. Dept. of Environmental Engineering and Water Management | Jansons, V., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Rural Engineering. Dept. of Environmental Engineering and Water Management | Abramenko, K., Latvia Univ. of Agriculture, Jelgava (Latvia). Faculty of Rural Engineering. Dept. of Environmental Engineering and Water Management
The paper deals with surface water quality assessment and recommendations for the classification system based on nutrients concentrations. For EU Member States, the overall aim of the Water Framework Directive (WFD) is to achieve 'good ecological status' and 'good surface water chemical status' in all water bodies by 2015. Human activities, including the use of fertilizer and manure in agriculture, have caused widespread increase in the content of nitrogen and phosphorus in the streams. Therefore agricultural runoff is the main subject of research. To determine nutrient concentrations in drainage outlets and small catchments, water quality data was collected monthly over twelve years (1994–2006) in two agricultural monitoring sites 'Berze' and 'Mellupite' with the measurement structures and water sampling equipment. All available total nitrogen (Ntot) and total phosphorous (Ptot) concentration data were analyzed using normal distribution curves. According to Stergess formula, class intervals (c) depending on the number of observations (n) were calculated. Percentile selections of data plotted as frequency distribution were used to establish boundaries of water quality standards. The research showed that in small agricultural streams good chemical status represents concentrations of is less than 2.5 mg Ntot LE-1 and is less than 0.05 mg Ptot LE-1, but in drainage system water – is less than 5.5 mg Ntot LE-1 and is less than 0.02 mg Ptot LE-1. The most important finding of the research is that water quality standards for drainage water as well as for small catchments with intensive agriculture should be less stringent than for rivers, otherwise it will not be possible to fulfil the objectives set by the WFD.
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