Latvia University of Agriculture - Latvijas Lauksaimniecības ...

V. Jansons, R. Sudārs Dimensions of Agri-Environmental Research in the Department ofEnvironmental Engineering and Water Managementenvironmental risk of agriculture. Due to the lack of monitoring data the first designationof vulnerable zones in Latvia was performed using GIS Multi-Criteria decision-makinganalysis (Kirsteina, Dzalbe, 2000). There are two main groups of factors: natural impactand the impact of human activities. The nitrate pollution risk assessment was basedon the data of soil and groundwater media, run-off, potential erosion risk, agriculturalactivities, such as agricultural land and arable land use, animal density, soil drainage,and application of fertilisers (Jansons et al., 2005). These factors have been used forthe GIS Multi-Criteria decision-making analysis. Statistical data traditionally availableon administrative level were merged with georeferenced land cover data, and maps arepresented pointing out the impact of different factors. Factor weights have been computedaccording to the results of the expert evaluation. The resulting impact data layer yieldsa map for potential agricultural risk areas in Latvia. The result of this scientific approachwas used for designation of vulnerable zones in respect of the EU and national legislation(the Nitrate Directive). Finally, part of the territory located in the central part of thecountry, in the Lielupe river basin or Dobele, Jelgava, Bauska, and Riga administrativedistricts having the most intensive agricultural production and highest pollution risk,was designated as nitrate vulnerable zone (NVZ). The designation of NVZs should berevised every four years; unless not the whole territory of the country is designated asNVZ. The procedure demonstrated in this study seems to provide an effective methodfor assessing environmental impact from the regional perspective. It may also be usedto provide a first assessment on the regional level before zooming in to focus on specificconditions such as nitrates and eutrophication, for detailed analyses.The proper farming profile, methods, and several restrictions for the territory ofNVZs should be used according to the crop, weather and soil conditions (Jansons,1999). Therefore, the first version of the Code of Good Agricultural Practice (Busmaniset al., 1999) was prepared by the scientists of LLU under a joint Danish–Latvian Projectcoordinated by P. Bušmanis.Pollution risk is an unavoidable element of our everyday activities, and it is alsounavoidable in agricultural sector (Dzalbe et al., 2005; Jansons et al., 2007; Berzinaet al., 2008). There is always a degree of uncertainty about the type, e.g., soil loss,nitrogen and phosphorus concentrations (Berzina et al., 2007), and the extent ofadverse impacts which could arise. The probability analysis that is a common method inhydrologic studies could be used to describe the water quality, e.g., the likelihood of anevent where an event is defined as occurrence of a specified value of the random variable(Jansons et al., 2009). The assessment of long time data series (1994-2007), obtainedfrom the non-point source agricultural run-off monitoring programme, has shown thatnitrate nitrogen concentrations depend on the scale of monitoring system (drainage plot,drainage field, small catchment) and intensity of agricultural production system. Theavailable long-term data series and use of the probability curves allow the assessmentof the variations of nitrate concentration on the scale of the plot, drainage field, andsmall catchments. Jansons et al. (2009) presented the estimation of risk exceeding thethreshold limits (11.3 mg L -1 NO 3-N) of the nitrates concentrations. High risk to reachnitrates concentrations over the limits has been found (about 30% of samples) in fielddrainage of the Bērze monitoring site (Fig. 6). With regard to the small catchments’ scalenitrates concentrations over limits could be expected (15% of samples) in the Bērzecatchment with high intensity of agriculture.The highest risk to reach nitrates concentrations over the limits was reported bySudārs et al. (2005) in Bauska pig farm point source monitoring point. About 77% ofwater samples in the drainage channel from 50 ha slurry utilisation field have nitratesconcentrations over limits during the period of 1995-2003.To some degree the presented study and interpretation of nitrate data may be usedfor designation of water quality standards and designation of nitrate vulnerable zones.Water Quality Standards for the Agricultural Run-offFor the 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 allwater bodies by 2015. Lagzdiņš et al. (2007a, 2007b, 2008) summarised the dataof water quality that was collected monthly over twelve years (1994-2006) in Latviaagricultural monitoring sites. All available total nitrogen (N tot) and total phosphorous(P tot) concentration data were analysed using normal distribution curves. Percentileselections of data plotted as frequency distribution were used to establish boundaries ofLatvia University of Agriculture – 70, 2009 53