Editorial

During the last decades, major environmental and public health problems associated to nitrogen contamination have emerged due to intensive anthropogenic activities. Nitrogen production is dominated by agricultural activities, but fossil fuel energy generation plays a major role as well. Besides the nitrogen pollution linked to intensive agriculture and combustion of fossil fuels, an important source of this contamination comes from industries demanding different nitrogenous compounds. For instance, ammonium is used as a raw material to create multiple products, such as nylon, plastics, resins, glues, animal/fish/shrimp feed supplements, and explosives.

The acceleration of the nitrogen cycle caused by anthropogenic activities has certainly fulfilled essential requirements to sustain an increasing global population, such as providing enough food and fuel. Nevertheless, the nitrogen cycle has shifted from how to promote food and fuel production to the realisation that over intensification of nitrogen cycling damages environmental systems. Furthermore, the global nitrogen demand for nutritional purposes does not match the nitrogen production in many regions. Indeed, in some parts of the world, particularly in industrialized countries, nitrogen has been used to create an excess of food, while also contributing to a host of environmental problems. Nitrogen production increased worldwide from ~15 Tg N year⁻¹ in 1860 to 156 Tg N year⁻¹ in 1995. The change was enormous, and it increased further to 187 Tg N year⁻¹ in 2005, in large part because cereal production increased from 1,897 to 2,270 million tons (20%), and meat production increased from 207 to 260 million tons (26%). These rising agricultural demands were sustained by a rise in nitrogen production from 100 to 121 Tg N year⁻¹ (20%). In contrast, other world regions, such as Africa and Central America, lack sufficient nitrogen to meet even the most basic caloric demands of hundreds of millions of people.

Therefore, two paradigms are currently considered when addressing nitrogen management. Firstly, efficient nitrogen removing technologies should be implemented in those sectors generating high concentrations of nitrogenous compounds, such as factories of fertilizers and seafood, as well as piggery farms. Where possible, pollution prevention approaches should be executed. Contamination linked to recalcitrant nitrogenous compounds, such as azo dyes, nitroaromatics and aromatic amines, requires special attention given the outsized impacts of these contaminants on public health and on the environment. Secondly, as an essential nutrient, nitrogen should be recovered from concentrated streams generated in several industrial sectors and connected to those activities demanding large amounts of this element like intensive agriculture.

A number of research lines have been started by several research groups around the world to achieve a sustainable management of nitrogen pollution in different industrial sectors. For instance, studies documenting the ecological, toxicological and economical effects of nitrogen pollution have been developed. Moreover, new treatment processes, such as bio-electricity generation coupled to ammonium oxidation in microbial fuel cells, have recently become known. On the other hand, further studies are demanded to verify the convenience of applying nitrogenous compounds recovered from wastewaters (e.g. via struvite precipitation) in agricultural activities since several micro-pollutants may be channelled throughout these recovery strategies and accumulate in the food chain.

RESB constitutes a suitable niche to disseminate the state of the art of these research topics, which are required for better achieving sustainable management of nitrogen pollution. RESB publishes mini-reviews and full-length reviews. Additionally, contributors are encouraged to submit articles for the newly added sections, such as Project Update, Science Career, Web Alert and Horizon Paper, to promote the latest developments on nitrogen pollution management strategies.