The Danube River is the second longest in Europe and its water quality is important for the communities relying on it, but also for supporting biodiversity in the Danube Delta Biosphere Reserve, a site with high ecological value. This paper presents a methodology for assessing water quality and long-term trends based on water quality indices (WQI), calculated using the weighted arithmetic method, for 15 monitoring stations in the Lower Danube and Danube tributaries in Romania, based on annual means of 10 parameters for the period 1996–2017. A trend analysis is carried out to see how WQIs evolved during the studied period at each station. Principal component analysis (PCA) is applied on sub-indices to highlight which parameters have the highest contributions to WQI values, and to identify correlations between parameters. Factor analysis is used to highlight differences between locations. The results show that water quality has improved significantly at most stations during the studied period, but pollution is higher in some Romanian tributaries than in the Danube. The parameters with the highest contribution to WQI are ammonium and total phosphorus, suggesting the need to continue improving wastewater treatment in the studied area. The methodology and the results of the study may be very useful instruments for specialists and decision makers in updating river basin management plans and prioritising intervention measures.
Rapeseed meal (RSM), a by-product of oilseed extraction connected to the agri-food and biofuel sectors, is currently used as animal feed and for other low-value purposes. With a biorefinery approach, RSM could be valorized as a source of bio-based molecules for high-value applications. This study provides a chemical characterization of RSM in the perspective of its valorization. A qualitative study of main functional groups by fourier transform infrared (FTIR) spectroscopy was integrated with a chemical characterization of macronutrients, minerals by inductively coupled plasma optical emission spectrometry (ICP-OES), phenolic acids and lipid components by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), HPLC-diode-array detector (HPLC-DAD) and gas chromatography-mass spectrometry/flame ionization detector (GC-MS/FID). The study, conducted on different lots of RSM collected over a one-year period from an oil pressing factory serving a biofuel biorefinery, highlighted a constant quality over time of RSM, characterized by high protein (31–34%), fiber (33–40%) and mineral (5.5–6.8%) contents. Polyphenol extracts showed a significant antioxidant activity and a prevalence of sinapic acid, accounting for more than 85% of total phenolic acids (395–437 mg kg−1 RSM). Results highlight the potentialities of RSM for further valorization strategies that may lead to the creation of new cross-sector interconnections and bio-based value chains with improvement of the economics and sustainability of the bioeconomy sectors involved.
Bucharest, the capital of Romania, is located on the banks of Dambovita River, tributary of Arges River, which, in its turn, flows into the Danube, the second longest river in Europe. Until 2011, Bucharest wastewater treatment plant (WWTP) had no advanced treatment, and since the end of 2011 the plant is able to treat half of the incoming flow. The second upgrading phase is under construction. This paper presents monitoring data of Dambovita River, upstream and downstream from Bucharest WWTP, during the period 2010-2015. Annual means of main nutrients concentrations show that water quality was mostly in the first class before the WWTP, according to Romanian norms, and in the worst class downstream from the WWTP, particularly for ammonium and total phosphorus, which are indicators of sewerage pollution. Pollution is attenuated by dilution after confluence with the Arges River. Principal Component Analysis and factor analysis of monitoring data show the differences between sampling locations and strong positive correlations between ammonium, orthophosphates and total phosphorus. Nutrient pollution downstream from Bucharest has decreased after 2010, but more efforts to improve wastewater treatment are needed in order to comply with national and international regulations.
The Danube River receives tributaries with different pollution loads, according to the social-economic characteristics of the adjacent regions. Water quality monitoring data from Chiciu, Calarasi county, Romania, for the three-year period (2010-2012), were analysed using statistical methods in order to identify correlations between parameters, as well as their evolution during the study period. The analysis has confirmedpositive correlations between nitrates and total nitrogen and between ortho-phosphates and total phosphorus. Negative correlations were found between water temperatures on one side and dissolved oxygen and nitrates on the other side. These parameters have a seasonal evolution, with high temperatures and low dissolved oxygen and nitrates levels during summer periods. Linear regression highlights decreasing nutrients pollution during the study period, which may be due to improved wastewater treatment along Danube tributaries.
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