Troubling report sheds light on the real causes of pollution in the Mar Menor
The environmental imbalance of the Mar Menor is caused by several different factors
Europe’s largest lagoon has been balancing on a knife-edge for years and frequently swings between critically endangered and marginally more healthy. The situation is incredibly complex and just when scientists get a handle on one problem, such as the proliferation of invasive zebra mussels that appeared in the Mar Menor last year, another crisis like algae bloom rears its head.
One of the key reasons behind the never-ending environmental imbalance is the sheer volume of harmful chemicals that sweep into the lagoon’s water course each and every year.
According to a report carried out by the Technical Office of the Mar Menor, in 2022, some 456 tonnes of nitrates entered the lagoon from the Quaternary aquifer and through dams. This was on top of the 18.5 tonnes of phosphates that washed in from nearby farmland, slurry pits and the boulevards of the Sierra Minera.
Commissioned by the Ministry for the Ecological Transition and the Demographic Challenge, the study provides an exhaustive analysis of the various polluting sources harming the Mar Menor. These are the main contributors:
Irrigation
The Ministry points to the intensive irrigation of crops as one of the sources of pollution, with excess water washing nitrates and phosphorous into the Mar Menor. The rise in the water level of the Quaternary aquifer, which passes under the Campo de Cartagena, also means the streams joining the lagoon are in a constant state of overflow.
Excessive rainfall
It may have been the second-hottest summer of all time in the Region of Murcia but it was also one of the wettest. This heavy rainfall, which was mirrored throughout 2022, saturates the soil, increases the water levels of contaminated aquifers and raises piezometric levels (the depth between the upper layers of the aquifer and the lower).
According to the research, 48 cubic hectometres of water spill into the Mar Menor from the skies and an additional 18.2 come from soil run-off.
Drilling for groundwater
The extraction of groundwater through deep drilling to capture lower aquifers has also led to the contamination of the Quaternary, the only one suitable for irrigating crops.
Images: Oficina Técnica del Mar Menor
