Baseline survey on water and sediments: Agrochemicals, Hydrocarbons and Heavy Metals in an emergent mixed production area

LILIANA B. MONZA; CECILIA DUFILHO; PABLO A. MACCHI; LORENA A. LATINI; MERCEDES INDACO; ANA PECHEN D´ANGELO; LONDONIO; SMICHOWSKI; MIRIAM LOEWY

San José

Workshop; Latin American Plaguicide Residue Workshoop; 2017

Centro de Investigación en Contaminación Ambiental

The aim of the present study is to assess the ecological condition of the middle andlower basin of the Neuquen river, addressing three main aspects: hydromorphology, biologyand chemical status. This hydrographic basin is extremely important as it comprises themajor water resource for agriculture, agroindustrial, mining and drinking water (app. 400.000inhabitants). There is a great public concern about the enlargement of the agricultural borderwith a wide crop diversification and, also, about the exploitation of new tight gas, shale gasand shale oil fields. It is necessary to run independent studies providing baseline information,before the expected productive development occurs.The studied area embraces an extension of 120 km including two dams, a regulatedsection and the river after the water restitution. 28 sampling sites were selected in the river, inthe dams, and in farm drainages. Water and sediments samples were taken along 4 samplingcampaigns. Organochlorine pesticides and pyrethroids (GC-µECD); organophosphatepesticides and carbamates (GC-NPD, GC-MS), heavy metals (ICP-OES, ICP-MS), AHs and PAHs(GC-FID, GC-MS) were analyzed. At the same time, benthic macroinvertebrates were sampledusing the multi habitat method. Basic physicochemical, hydrological and habitat data weremeasured in situ.The results show that traces of organophosphate pesticides were detected in drainagesnearby the agricultural area. In a drainage sediment a high chlorpyrifos level was measured(23 µg/kg), besides detections in some river sites of pp´DDE (from 13 µg/kg to 54 µg/kg)exceeding the guidelines for aquatic life protection (CCME, 2015) probably due to historicalapplications. PAHs were not detected and the AHs distribution patterns denote a biogenicsource. No differences were observed in the structure and composition of macroinvertebratesassemblies. With reference to heavy metals, the obtained values are below the TEL or betweenthe TEL and PEL.From the hydromorphology point of view, there is an alteration of the natural river course,especially in the regulated section (app 12 m3/s). As a preliminary conclusion the ecologicalstatus of the water body can be classified as good (DIRECTIVE 2000/60/CE) with very minoranthropogenic alterations from those normally associated with undisturbed conditions. Thisis an initial recognition programme from which an ordinary monitoring program is stronglyrecommended.