Nowadays, surface and groundwater quality deterioration is considered as one of the most disturbing environmental problems in the world, with major impacts on environment and human health. 

One of the most dangerous water contaminants are heavy metals. Some of them are essential elements for living organisms, but they could become an ecological hazard if exceeding certain thresholds. In this line, there is a growing concern about the human activities that have drastically altered the geochemical cycles of heavy metals, as well as their biochemical balance. The presence of heavy metals in natural environments has seen a drastic increase in recent years [Singh et al., 2011]. Factors empowering this fact in the last century include the technological and industrial development, the consumerism and the enormous production of waste. 

An early effect of the presence of heavy metals in the environment is the degradation of the soil, decreasing its productivity. The accumulation of heavy metals in plants and crops, over long periods of time, can also affect the natural fauna. Last, but not least, prolonged exposure to heavy metals that are toxic or carcinogenic (such as cadmium, lead, nickel, arsenic or mercury), can cause deleterious health effects in humans. For that reason, it is important to avoid the ingestion of food in contact with contaminated waters, since chemical substances used in the agricultural industry sometimes contain heavy metals, contaminating vegetables, fruits and meat for human consumption [Kahn et al., 2008]. 

A paradigmatic case of heavy metal is that of mercury, heavily linked to food consumption. According to the European Environment Agency (EEA), mercury is the most hazardous metal in European rivers, lakes and oceans, mostly due to their ingestion by fishes, which are further consumed by animals and humans. This drafts a clear pathway for mercury ingestion on a daily basis, considering the significant presence of this heavy metal in Europe. 

Nitrate is another problematic substance present in water resources that can cause a negative impact on environment and human health. Actually, diffuse pollution from agriculture is one of the main environmental problems in Europe, responsible for poor water quality. Nitrate levels in water resources have increased specifically in many areas of the world due to the rise of intensive farming, with excessive applications of inorganic fertilizer and animal manure in agricultural areas [Mateo-Sagasta et al., 2017]. 

The accumulation of nitrate in surface and groundwater may cause serious illness to both wildlife and humans. It favours water eutrophication, promoting structural changes to the aquatic ecosystem, with increased production of algae and aquatic plants and depletion of fish species when the oxygen is consumed. At the same time, nitrate intake from drinking water can be direct cause of several health conditions, including methemoglobinemia, specific cancers or birth defects [Ward et al., 2018].

Our region, Navarra, is not alien to this problem. Following the EU Directive 91/676/CEE, addressed to the protection of waters from cross contamination from agricultural activities, different regions were detected and put under supervision for their potential health-damaging situations. Such regions are the hydrological basins of the rivers Cidacos, Robo and Ebro-Aragon. Our local government did not only restrict to comply with EU regulations, also passing regional laws (Orden Foral, in their local naming) 247/2018. This law regulates the control of the areas, including registered supervision and, additionally, established an action plan to be executed in the period 2018-2022. Interestingly, the plan includes a specific section addressed to the scientific dissemination of the problem of water contamination, including public information and spread of good agricultural practices. This dissemination is being taken coordinately with the EU-funded LIFE Concert’eau project.

Detection and elimination of heavy metals and nitrate from our environment should be, therefore, a priority in our local socio economical context. Our team is concerned about this issue. Hence, our goal for the project is to develop genetically engineered bacterial biosensors to detect and quantify the concentration of heavy metals (cadmium, copper and mercury) and nitrate in water. The biosensors should be able to take different colour intensities depending on the concentration of the target substances. Hence, a mathematical study will be needed to correlate such colour intensities to contamination levels. In practical terms, this should empower the distribution of cheap alert kits composed of (a) simplistic bacterial recipients on which potential contaminated water is to be poured and (b) a cell phone App able to estimate the concentration of contaminants from pictures of the recipient.  Having this kit would allow environmental agents and technicians to autonomously obtain early on-site estimates of water pollution within minutes.

Our team is composed of 15 students who study different scientific degrees pioneers at the university, which are Biotechnology, Sciences, Biomedical Engineering and Data Science, all of them enrolled at the Universidad Publica de Navarra (UPNA). This is the first time the UPNA enlists a team for the iGEM competition. If you want to set out on this journey with us, you can follow us on our social media (Instagram, Twitter and Facebook). We also have a blog where we write about our daily work and some funny anecdotes. If you want to contact us directly, send us a message to our email or any other available social media.

References:

- Singh, R., Gautam, N., Mishra, A., and Gupta, R. 2011. Heavy metals and living systems: An overview. Indian Journal of Pharmacology 43(3), 246–253.

- Kahn, S., Cao, Q., Zheng, Y.M., Huang, Y.Z. and Zhu, Y.G. 2008. Health risks of heavy metals in contaminated soils and food crops irrigated with wastewater in Beijing, China. Environmental Pollution 152(3), 686-692.

- Mateo-Sagasta, J.; Zadeh, S. M.; Turral, H. and Burke, J. 2017. Water pollution from agriculture: a global review. Executive summary. Rome, Italy: FAO; Colombo, Sri Lanka: International Water Management Institute (IWMI). CGIAR Research Program on Water, Land and Ecosystems (WLE). 35p.

- Ward M.H, Jones R.R, Brender J.D, de Kok T.H, Weyer P.J, Nolan B.T, Villanueva C.M, and van Breda S.G. 2018. Drinking water nitrate and human health: An updated review. International Journal of Environmental Research and Public Health 15(7): 1557.

Edited by: Stefano Donati