NITRATE IN GROUNDWATER Why is it a hazard and how to control it?

2007

Groundwater nitrate contamination is a source of rising concern that has been faced through the introduction of several regulations in different countries. However the methodologies used in the definition of Nitrate Vulnerable Zones are not included in the regulations. The aim of this work was to compare different methodologies, used to asses groundwater nitrate contamination risks, based on parametric systems or simulation modelling. The work was carried out in Piedmont, Italy, in an area characterised by intensive animal husbandry, high N load, a shallow water table and a coarse type of sub-soil sediments. Only N loads from agricultural non-point sources were considered. Different methodologies with different level of information have been compared to determine the groundwater nitrate contamination risk assessment: N load, IPNOA index, the intrinsic contamination risk from nitrates, leached N and N concentration of the soil solution estimated by the simulation model. The good correlation between the IPNOA index and the intrinsic nitrate contamination risk revealed that the parameters that describe the soil in this area did not lead to a different classification of the parcels. The intrinsic nitrate contamination risk was greatly influenced by N fertilisation, however the effect of the soils increased the variability in comparison to the IPNOA index. The leached N and N concentration in the leaching were closely correlated. The dilution effect of percolated water was almost negligible. Both methodologies were slightly correlated to the N fertilisation and the two indexes. The correlations related to the intrinsic nitrate contamination risk was higher than those related to IPNOA, and this means that the effect of taking into account soil parameters increases the correlation to the prediction of the simulation model.

Water, 2020

Shallow aquifers of coastal and internal alluvial plains of developed countries are commonly characterized by the challenging management of groundwater resources due to the intense agricultural and industrial activities that determine a high risk of groundwater contamination. Among the principal origins of pollution in these areas are agricultural practices based on the amendment of soils by nitrate fertilizers, which have been recognized as one of the most severe environmental emergencies for which specific policies and regulations have been issued (e.g., EU Directive 2006/118/EC). In such a framework, the results of research aimed at assessing the specific vulnerability of shallow alluvial aquifers to nitrate fertilizer pollutants by coupled process-based and empirical approaches are here proposed. The research focused on assessing the specific vulnerability to nitrate pollution of a shallow alluvial aquifer of the Campania region (southern Italy), which was selected due to its re...

JOURNAL OF ENVIRONMENTAL ENGINEERING AND LANDSCAPE MANAGEMENT, 2005

In Lithuania almost the whole drinking water is derived from groundwater sources. The concept of ground@water vulnerability is based on an assumption that a physical environment may provide some degree of protection to groundwater against human impact.The earth materials may act as natural filters to screen out some contaminants. Groundwater vulnerability depends on the natural characteristics of a site and relates to the pathways and rate of downward movement of pollutants. Pollutant migration through the soil zone depends just on the depth of waterlogging, texture, organic matter content, quantity of precipitation.. Pollutants accumulating in shallow groundwater in the Lithuanian area are, first of all, nitrates and organic matter. Regularities of groundwater chemistry can be determined only after investigation into the processes of their formation. That is why we need to find out the main factors of nitrate concentrations in groundwater. Investigation took place in Karkiškes obje...

Scientists are deeply concerned with the state of vulnerability of groundwater reservoirs. It is a complex task because of the difficulties in determining the degree of pollution of the ground water. Many methods have been adopted like DRASTIC, GOD, SI, SINTACS, etc. The present article targets the determination of the vulnerability of groundwater reservoirs of a climatic Mediterranean region (Nil valley region, Jijel). The excessive use of fertilizers in agriculture has been the main reason behind the increase of the Nil valley groundwater pollution with nitrates (Jijel, North-East Algeria). In fact, the use of fertilizers in high quantities relatively to the needs of the plants lead to the leaching and infiltration of the excess fertilizers into groundwater which increases the nitrates percentage; as a result, the allowed norms of water consumption are exceeded. Relevant to this, the aim of this study was to assess the aquifer vulnerability caused by pollution with nitrates using DRASTIC, GOD and SI methods. The spatial distribution of the found nitrates in groundwater shows that the DRASTIC method is the most appropriate method in this case with a percentage of 71% vs. 54 and 63% for GOD and SI methods, respectively. Moreover, it was found that the studied water is characterized by a medium to high degree of vulnerability. Pertinent to this, it is highly recommended to find solutions to better protect and preserve the Nil valley groundwater.

2012

In many rapidly urbanizing cities, groundwaters are constantly affected by anthropogenic factors such as landscaping, additional abstractions, reduction in catchment perviousness, etc. Population growth has been uninterrupted and accelerating phenomena in parts of Moulares-Redayef basin, where urbanization is increasing at an unprecedented rate. Urban agglomeration is causing radical changes in groundwater recharge and modifying the existing mechanisms. The Moulares city and majority of the phosphate laundries are sited on unconfined or semi confined aquifers depend upon wadis water for most of their water supply and disposal of most of their liquid effluents and solid residues. There has also been an inevitable rise in waste production. Drainage of surface water has been disrupted as the small natural channels and low lying areas have been in filled, often with municipal waste. In agricultural areas, fertilizer application is the main source of nitrate contamination of groundwater....

Journal of …, 2009

Boletín de la Sociedad Geológica Mexicana, 2013

Nitrate pollution is a worldwide problem in groundwater, as it may limit water supply and increase health risk when high concentrations are present. The North Maresme coastal alluvial groundwater-dependent agrosystem, one of the most heavily nitrate polluted aquifers in Spain, is located 70 km northeast from Barcelona. Field monitoring campaigns performed in this aquifer yielded nitrate concentrations up to ten times the permitted limit for drinking water suggested by the World Health Organization (50 mg/l), with a maximum concentration of 567 mg/l and a mean of 137.5 mg/l. Nitrate contamination was quantified by means of a mass balance, taking into account the main hydrogeological and anthropogenic processes that control the behavior of this ion in the aquifer, such as recharge, groundwater extraction, irrigation and fertilizer application to crops. Nitrate balance is an integrative approach for assessing nitrate loading based on linking different sources of nitrates to a groundwater balance. This methodology considers nitrate as a conservative ion because the geological-geochemical medium behaves under oxidant conditions. Results show that the studied aquifer system receives, yields and retains approximately 935, 844 and 91 tons of NO 3-/year, respectively. This methodology can be applied to other nitrate-contaminated aquifers with similar conditions to improve management of fertilizers practices in areas of intensive agriculture.

Current Science

Nitrate is an important and widespread contaminant of groundwater and surface water resources. Nitrate formed either by the natural processes (atmospheric fixation, lightning storms) or added through anthropogenic activities (fertilizer applications, septic tanks) enters the hydrosphere with virtual ease. In this article we review various concepts discussing the different sources behind elevated nitrate levels. Moreover, an attempt is also made towards preparing a comprehensive framework to understand the leaching of nitrate in groundwater. This framework would effectively help in understanding the origin and dynamics controlling the fate of nitrate in groundwater, which is vital for managing the associated risks and safeguarding the water supplies.

Agricultural Water Management, 2008

Agricultural Systems, 2011

Fertilizers that are spread on agricultural fields can leach into aquifers and contaminate groundwater sources for drinking water particularly with nitrate. Modeling this phenomenon can help in evaluating the impact of current or future agricultural practices on nitrate content within an aquifer. The threedimensional Water flow and Nitrate transport Global Model (WNGM), that was previously developed and applied to a well-capture zone, is actually used to simulate future land management scenarios over the same zone. The studied area is located in a region with intensive agricultural practice in Southern Québec (Canada). The sandy unconfined aquifer underlying the agricultural fields is highly vulnerable to nitrate contamination from ground surface and nitrate concentrations around critical threshold of 45 mgNO À 3 /L were observed in the municipal well. Using the calibrated WNGM, a number of land management scenarios were simulated in order to predict future trends of nitrate concentrations in the pumping well from 2008 through 2040 that could be induced by changes in land management practices over this well-capture zone. More specifically, these scenarios simulate implementation of improved or ideal agricultural practices within the agricultural portion of the well-capture zone, and modification of the pumping rate at the municipal well. The results show how a decrease and stabilization of nitrate concentration should occur at the municipal well after a period varying from 5 to 30 years depending on the implemented agricultural modifications. It is also shown that, in this particular case, an increase of the pumping rate at the municipal well from 700 to 2800 m 3 /d would lead to an increase of the well-capture zone from 0.8 to 2.5 km 2 and to a decrease of nitrate concentrations at the municipal well from 43 to 34 mgNO À 3 /L. Furthermore, it is predicted that application of improved agricultural practices in the vicinity of this municipal well could lead to a reduction of nitrate concentrations at the well of about 8 mgNO À 3 /L.