Assessment of nitrogen excess in an agricultural area using a nitrogen balance approach

A pilot study has been initiated to develop an approach for quantification of nitrogen excesses from agricultural activities that involve greenhouse farming in Kumluca Plain, Turkey. Detailed calculations utilizing the nitrogen balance method (NBM) were carried out at nine different locations within the plain over a time period of one year. The major contributing factors and governing operative mechanisms taken into consideration were nitrogen application rates both as organic and chemical fertilizers, irrigation water application practices, and nitrogen uptake by plants. The adopted approach yielded valuable information such as plant nitrogen uptake efficiencies, excess nitrogen, leaching rates and leachate nitrogen concentrations. Further, a site specific multiple linear regression model has been developed to estimate the ratio (Nleachate/Ngroundwater) as a function of independent variables: farming age, excess nitrogen application and SEEPAGE Index Number. The negative sign of the model parameters implies that the ratio (Nleachate/Ngroundwater) decreases as values of the independent variables increase. The adopted approach and the obtained results can beneficially be applied to similar sites to establish basic parameters of irrigation and fertilizer application operations.</jats:p

Assessment of groundwater contamination risk with scenario analysis of hazard quantification for a karst aquifer in Antalya, Turkey

Karst aquifers usually have high vulnerability to groundwater pollution. This study aims to assess the risk of groundwater contamination in karst aquifers by two index overlay methods of intrinsic vulnerability (COP and PI) and to discuss the importance of hazard index values on risk assessment. Altinova region of Antalya, with intensive agricultural activities, was chosen as the pilot study area (PSA) for application. Seasonal monitoring studies were conducted at 25 sampling wells for many water quality parameters in addition to soil characteristics and depth to groundwater. The areas for low, moderate and high levels of vulnerability and risk were determined, where more than 90% of the PSA was classified as having moderate to very high vulnerability levels according to COP and PI methods. For validation of risk analysis results, nitrate concentrations were correlated with risk intensity values. Both methods were successful to assess the vulnerability and risk to groundwater pollution with high correlation. In addition, the impacts of hazard index values on groundwater pollution risk were investigated for two scenario conditions which represent the increase in the relative amount of pollutants caused by the greenhouses. As a result, the karstic part of the PSA was assessed to have a high risk of groundwater contamination by the COP method, where immediate control measures are necessary. In conclusion, the selection of suitable vulnerability methods for karst aquifers and assignment of realistic hazard index values are highly effective on risk analysis results to represent the actual conditions