Jessica Salcedo Borda earns PhD for research on alteration of nutrient concentration along the Danube

Human activities, such as agriculture, the construction of reservoirs, and wastewater treatment plants have changed the amount of silica (Si) – an element required by phytoplankton (e.g. diatoms) and by plants – that flows from the Danube River to the Black Sea. This alteration can affect the composition of phytoplankton, with impacts through the whole aquatic food web. If there’s less Si, the phytoplankton communities will change: there will be less diatoms and more cyanobacteria, which leads to the degradation of the water quality. Although flows of nitrogen (N) and phosphorous (P) and the impacts of human activity on these are relatively well understood, the combined effects of the ratios of Si, N, and P have rarely been evaluated simultaneously in one basin. That’s what I did: My research assesses the effects of natural and human activities such as agriculture and wastewater treatment plants on the amount of Si, N, P nutrients and their proportion fin the Danube River and its tributaries.

I found that the most important factor affecting the level of river nutrients - Si, N and P - is land use and land cover. These factors have a bigger influence than reservoirs, the characteristics of rocks in or near the river and wastewater treatment plants. I analysed data from at the Reni monitoring station just upstream from the Danube Delta and found that the levels of dissolved Silica (DSi) have decreased since 2000. This poses a severe risk to the Black Sea water quality.

To reach and maintain a good ecological status as established by the European Commission’s Water Framework Directive,  future policies for the Danube River basin should reduce the effect of land use changes and land management on river water quality. My research aims to contribute to sound river basin management.  Studies project that the Danube River Basin will see a 10.5% increase in urban areas by 2050, at the expense of farm land. This development could damage the river water quality , and action is needed soon to avoid further damage.

The most challenging part of my PhD Challenges during my PhD studiesstudies was getting the yearly financial support. My PhD was funded by  Faculty for the Future which is a scholarship that provides funding on a year-to-year basis. I had both to renew my application to this scholarship while also looking for other options to cover my fieldwork and some materials. Luckily, in the second year of PhD I got another scholarship from the Peruvian Government. Thanks to this funding I was able to complete my PhD.