# Nitrate-Polluted Waterbodies Remediation: Global Insights into Treatments for Compliance
## 3 Processes Responsible for Nitrate Pollution in Water  
Nitrogen is an essential macronutrient that enables plants and crops to grow, but excessive concentrations in water are detrimental to people and nature. The nitrate ion (NO3-) is the most thermodynamically stable nitrogenous compound present in aqueous and oxygenated earth systems, so there is a tendency for all nitrogenous materials to be readily converted to nitrate in these environments. The release of massive levels of nitrate ions into waterbodies causes cumulative impacts on living organisms and ecosystems. Nitrate pollution is widespread throughout the world in recent decades because of anthropogenic actions and natural processes, and a number of studies have been recently published warning of its consequences [31; 32; 33]. The processes responsible for the accumulation of nitrates in different ecosystems are many and varied, and it is recognized that they can be divided broadly according to their origin as geogenic or anthropogenic processes, depending on whether the source is natural or directly related to human action [34; 35]. Geogenic sources of nitrogen compounds in the environment include weathering and erosion of igneous rocks and minerals [36], lightning storms through different precipitation and rainfall modes [37], and atmospheric deposition of nitrogen oxides and symbiotic fixation by selected plants and cyanobacteria [38]. All these processes are responsible for the input of nitrogenous forms into the soil, which enter the biogeochemical cycle, and under normally oxidizing conditions lead to their accumulation in the form of NO3-, which are easily leached to deep layers and reach groundwater bodies. Runoff processes that displace large quantities of soil, due to torrential rainfall, are increasingly frequent in certain areas of the planet and also entail the entrainment and incorporation of significant levels of NO3- and other nutrients into waterbodies. The main environmental contamination with NO3- has typically been attributed to anthropogenic activities. Due to anthropogenic actions, the natural nitrogen (N) cycle has been significantly altered by a 100% increase in the rate of N influx into the global N cycle. The abuse of organic and inorganic N-based fertilizers in agriculture is a major source of diffuse pollution, contributing to the increase of NO3- contamination in waterbodiesand to the increase of nitrous oxide in the atmosphere [39; 40]. Nitrogen is one of the three macronutrients for plants (N-P-K), and its application has a direct influence on the development of plants, which is why it tends to be abused to ensure maximum agricultural yields. Intensive agricultural practices also lead to a high demand for nitrogen fertilizers. Inorganic nitrogen is normally added to the soil as NH\({}_{4}\)\({}^{+}\) and NO\({}_{3}\)\({}^{-}\) in quantities above the nutritional needs of plants, and is therefore not partially assimilated by crops and beaches from agricultural irrigation and rainfall to be discharged into surrounding waterbodies [41]. Although there is a direct correlation between the higher consumption of nitrogen fertilizers and the increase in crop production to supply the world's growing population, concerns have been expressed about the environmental sustainability of these activities in terms of the impairment they cause to water resources [40]. Intensive livestock production, and the proliferation of large-scale farms, is also a potential source of NO\({}_{3}\)\({}^{-}\) pollution. Livestock waste contains nitrogen in the form of both organic and inorganic compounds. Microbial action breaks down waste containing organic nitrogen into NH\({}_{4}\)\({}^{+}\), which is then transformed into NO\({}_{2}\)\({}^{-}\) and NO\({}_{3}\)\({}^{-}\)[42]. NO\({}_{2}\)\({}^{-}\) is further readily converted to NO\({}_{3}\)\({}^{-}\). Thus, organic waste generated from livestock farming is a potent source of NO\({}_{3}\)\({}^{-}\) inputs that pollute surrounding waterbodies.