Rita Maurício in Biosfera

What impact do nitrates have on aquatic ecosystems? MARE researcher Rita Maurício answers this question in the latest episode of RTP's Biosfera programme. 

Currently, less than half of the water bodies are in good condition. Part of the problem of poor water quality in our country is related to the presence of various contaminants that harm ecosystems. One of the main contaminants is nitrate, a nitrogen compound present in rivers, oceans, in our food and even in our bodies. 

Nitrogen is one of the most common elements on our planet, making up around 78 per cent of the Earth's atmosphere. The problem is that when nitrogenous compounds easily found in fertilisers, manure or animal waste are found in high concentrations in the environment, they become harmful to the ecological balance. 

It is within this premise that MARE researcher Rita Maurício explained on the RTP programme that ‘after pesticides, nitrates or nitrogen compounds, whether in the form of nitrates, nitrites or even ammoniacal nitrogen, are described as the second largest source of aquatic contamination at a global level’.  According to the researcher, the amount of nitrogen in water bodies has doubled since the 1920s, when nitrogen-based fertilisers began to be produced.

Para além dos problemas a nível ambiental, estas elevadas concentrações podem ter também um impacto bastante negativo na saúde humana. “Há efeitos bastante nocivos do consumo de nitratos e nitritos”, refere a investigadora do MARE, enumerando doenças como a cianose, a diabetes ou o cancro do colo retal.

In addition to their agricultural origins, nitrates can also reach water bodies through domestic and industrial wastewater run-off after treatment in wastewater treatment plants. 

‘Wastewater treatment plants may or may not remove nitrogen and phosphorus. The obligation to remove these two nutrients lies in where we are discharging,’ explains Rita Maurício. ‘If we are discharging into a sensitive environment, i.e. an area that could be a source of eutrophication, then there is an obligation to remove this nitrogen and phosphorus.’

Despite this, ‘there are many stations that don't remove nitrogen and phosphorus, because the receiving environment is not sensitive and therefore there is no need to protect the receiving environment’. In this context, part of the researcher's work involves the isolated reuse of the nitrogen and phosphorus that is not removed in wastewater treatment plants.

‘The main resource in wastewater is water, but not only water. I have, for example, nutrients inside waste water that are essential to life,’ concludes Rita Maurício, who explains how she tries to “recover that nitrogen and phosphorus and use it in another way”.

To access the episode click HERE