Loris Deirmendijian, COTE doctoral student in the Epoc unit
A PhD Student who has followed an unusual path, Loris carries out research for the Leyre CNP project, funded by LabEx COTE. This project brings together the Epoc and Ispa research units and aims to study carbon, nitrogen and phosphorus (CNP) behavior through one of the less well documented interfaces in water catchment areas: the soil-groundwater-river transition zone. His role in the project was primarily to establish a network of 30 sampling stations that represent the diversity of the Leyre catchment area. Samples will be collected from these stations on a monthly basis for two years; the analysis that follows will ultimately enable the project's objectives to be met.
Loris did not follow a linear career path to the Epoc research unit and the Leyre CNP project. Having a fascination for the infinitely small, in particular DNA, he began by studying structural biochemistry. Disappointed by the course's mainly industrial applications, he abandoned it after the first year of the Masters. After a year of travelling and thinking, he came to University of Bordeaux 1 for the Masters in Oceanography. "I've always had a passion for the environment and oceanography," he explains.
He was very impressed with this new integrative, very multidisciplinary way of looking at things, combining geology, chemistry and hydrology, which is both specific and general. It was therefore entirely natural for him to continue with a research M2. "It wasn't my initial goal but a very good M1 course steered me in that direction". It was during the M2 course that he really discovered the world of research, and acquired a taste for it, studying the underground estuary of the sandy beach at Truc Vert (Aquitaine, France).
"Why did I choose LabEx COTE and the Leyre CNP project?'' I was immediately interested by the project because of its transdisciplinarity, it even combines several different teams!" Loris cheerfully explains. However, the project itself was not quite so simple. "What took time was establishing the right sampling strategy based on a GIS [1], finding tolerant owners of agricultural and forestry plots who would let us install piezometers, and taking into account the accessibility of sampling stations, etc." All of which was a necessary preliminary stage in the "field" component of his thesis, a substantial undertaking, representing one week per month, with 24 "river stations" and 6 "surface groundwater stations".
His work on a day to day basis consisted of taking samples of river water and surface ground water and measuring nutrient salts [2], and the various forms of dissolved carbon and their isotopic composition [3]. He also measured the water's physico-chemical parameters [4]. And that's not all: he collected a flask per station to measure the particulate fraction, by filtering it in the laboratory. He determined the quantity of solids in suspension, the quantity of particulate organic carbon (POC) and its ?13C-COP isotopic composition, the particulate phosphorus (OPP), and chlorophyll a content. This was followed by some equally intense laboratory work, involving no less than 10 different manipulations [5]. This extensive task was nevertheless necessary and "very useful personally, to understand the complex path that leads to the data that I can then interpret", the doctoral student explains.
LabEx COTE Summer School
Loris enjoyed the course programme, based on an integrative overview of environmental sciences. "I also liked the event's international character, with a chance to meet people of so many different nationalities, and all the discussion, not only of scientific issues but also on a friendly, cultural basis".
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[1] Geographical information system
[2] Nitrates, nitrites, phosphates, silica and ammonium, iron (II)
[3] Partial CO2 pressure in water (pCO2), dissolved organic carbon (DOC) and ?13C-DOC, dissolved inorganic carbon (DIC) and ?13C-DIC, Methane (CH4), and Alkalinity (HCO3- + CO32-)
[4] Temperature, pH, saturation in dissolved oxygen and conductivity
[5] Traditional colorimetry (nutrient salts), titration (alkalinity), mass spectrometry (isotopes), gas chromatography (CH4), LiCor analysis (pCO2 and DIC), LeCo Analysis (POC), shimadzu analysis (DOC), ascorbate extraction, HCl and H2SO4 (OPP) etc.