Nitrate pollution of groundwater; all right…, but nothing else?

Abstract

Contamination from agricultural sources and, in particular, nitrate pollution, is one of the main concerns in groundwater management. However, this type of pollution entails the entrance of other substances into the aquifer, as well as it may promote other processes. In this study, we deal with hydrochemical and isotopic analysis of groundwater samples from four distinct zones in Catalonia (NE Spain), which include 5 different aquifer types, to investigate the influence of fertilization on the overall hydrochemical composition of groundwater. Results indicate that intense fertilizer application, causing high nitrate pollution in aquifers, also homogenize the contents of the major dissolved ions (i.e.; Cl(-), SO4(2-), Ca(2+), Na(+), K(+), and Mg(2+)). Thus, when groundwater in igneous and sedimentary aquifers is compared, significant differences are observed under natural conditions for Cl(-), Na(+) and Ca(2+) (with p-values ranging from <0.001 to 0.038), and when high nitrate concentrations occur, these differences are reduced (most p-values ranged between 0.054 and 0.978). Moreover, positive linear relationships between nitrate and some ions are found indicating the magnitude of the fertilization impact on groundwater hydrochemistry (with R(2) values of 0.490, 0.609 and 0.470, for SO4(2-), Ca(2+) and Cl(-), respectively). Nevertheless, the increasing concentration of specific ions is not only attributed to agricultural pollution, but to their enhancing effect upon the biogeochemical processes that control water-rock interactions. Such results raise awareness that these processes should be evaluated in advance in order to assess an adequate groundwater resources management.Peer ReviewedPostprint (author's final draft

Microalgae wastewater treatment: Biological and technological approaches

“…However, in addition to an inadequate clean water supply in many developing countries, water quality in industrialized nations has reached a worrying state . The pollution of municipal, agricultural, and industrial wastewater with a huge number of organic and inorganic contaminants, such as microplastics , xenobiotics , heavy metals , and high concentrations of nitrates , phosphates , and carbon (C) compounds , puts a strain on the food chain and thus the basis of human life. Wastewater treatment (WWT) is a global issue that cannot be managed by a single technology because of the extremely variable scales, types of contaminants, and regional conditions involved (Figure ).…”

Survey and zoning of nitrate-contaminated groundwater in Iran

“…Natural sources of pollution include nitrogen fixation in the soil (as a result of transformation of land) and influence the level of nitrates in the groundwater. Human sources include urban waste disposal, human waste through absorption wells, seepage from landfills, municipal wastewater, output of septic tanks and drain output caused by agricultural activity [9]. Natural transformation processes such as denitrification or nitrification also affect the nitrate concentration in groundwater.…”

Regional Variability of Agriculturally-Derived Nitrate-Nitrogen in Shallow Groundwater in China, 2004–2014

“…Generally, in agricultural ecosystems, agricultural activity is the most significant human factor influencing nitrogen sources and generating nitrate pollution in groundwater. High application rates of N fertilizer have a significant potential for nitrate leaching [3,23]. Research suggests that 8-12% of the applied fertilizer, applied at 120 kg N·ha −1 ·y −1 , leaked toward the hydrosphere [24].…”

“…Increasing diffuse nitrate (NO 3 − ) loading of groundwater has emerged as a serious environmental issue, due to its adverse effects on human populations and natural ecosystems [2,3]. The ingestion of nitrate by humans in drinking water was linked to methemoglobinemia in infants, and to stomach cancers in adults [4,5].…”

“…Empirical correlations relating increased use of inorganic fertilizers, their application rates, and nitrate leaching suggest that inorganic fertilizers contribute nitrate to the soil directly. Moreover, field studies also have confirmed that high N fertilizer rates increased the risks of nitrate (NO 3 − ) accumulation in the soil profile and of groundwater nitrate pollution [15,16]. Unfortunately, rates of N inputs have now reached the levels of diminishing returns for crop yield in China, and China has one of the lowest nationally-averaged NUE (nitrogen use efficiency) values in the world [17].…”