Biotreatment strategies for the removal of microplastics from freshwater systems. A review

Environmental Chemistry Letters - Research on plastic pollution has recently evidenced the ubiquitous presence of tiny plastic particles called microplastics. Microplastics alter organisms because...     

The Pollution Load by Nitrogen and Phosphorus IN the Jadro River

The objective of the investigations of the Jadro River, located in Croatia, was to estimate the nitrogen and phosphorus loads in the Jadro River spring and its streamflow by calculating the load in kg/day or tons/year and to compare this with the load for the maximum allowed concentrations (MAC) for drinking water (Official Bulletin, No 46/94) expressed in kg/day or tons/year.Daily pollution loads at the Jadro River spring for total N ranged from 0 to 304 kg, for NH₃-N from 0 to 38 kg, for NO₃-N from 0–1321 kg and for PO₄-P from 0–92 kg in the period from September 1993 to September 2003. When compared with MAC loads the results prove that the Jadro River spring is not polluted by nitrogen compounds and phosphorus.The average annual load for total N ranged from 10 to 33 t, for NH₃-N from 0.25 to 5.15 t, for NO₃-N from 40 to 190 t, and for PO₄-P from 0.3 to 11.5 t. The nitrogen compounds and phosphorus loads vary from one year to another without any constant decreasing or increasing trends. The annual average loads compared with the average annual MAC loads (especially for NH₃-N and PO₄-P) show that there were no threats of constant pollution of the spring.The loads for total N and PO₄-P along the Jadro River flow from the spring to the fishpond entrance were monitored over a five year period from September 1999 to September 2004. The results show no regularities. The highest annual total nitrogen load of 45 t was recorded at the entrance to the fishpond during the 2002/2003 period. The highest annual PO₄-P load of 10 t was measured at the Vidović Bridge during the 2003/2004 period; however, the concentrations of N and P did not exceed the MAC concentrations which are prescribed for drinking water.According to the investigation results of the daily and average annual loads compared with MAC loads for drinking water, it can be concluded that the Jadro River spring and its streamflow are not polluted by nitrogen and phosphorus.     

Utilization of municipal solid waste bottom ash and recycled aggregate in concrete

In the combustion process of municipal solid waste (MSW), bottom ash (BA) represents the major portion of the solid residue. Since BA is composed of oxides, especially SiO(2) and CaO, the feasibility of its application in concrete as a substitute for cement was tested. It was found that at the age of 28 days, the flexural and compressive strengths of the binder linearly decrease at the rate of 0.03 and 0.02 MPa per wt% of BA in the binder, respectively. According to the results it may be recommended to replace up to 15 wt% of cement by BA and to use such binder where a low strength of concrete elements is required. Furthermore, the aggregate used for low strength concrete need not be of a very good quality. Therefore, gravel aggregate was partially replaced by recycled aggregate (RA). Consistency measured by slump was significantly reduced (>50%) when BA or/and RA were introduced into the mixture. However, concrete density and compressive strength were not affected and were approximately 2300 kg/m(3) and approximately 40 MPa, respectively.     

The sensitivity of soil enzymes,microorganisms and spring wheat to soil contamination with carfentrazone-ethyl

Herbicides pose a significant threat to the natural environment, in particular in soils that are most exposed to plant protection agents. Prolonged herbicide use leads to changes in soil metabolism and decreases soil productive potential. In this study, the influence of carfentrazone-ethyl (CE) on the microbiological and biochemical properties of soil and the yield of Triticum aestivum L. was evaluated. Carfentrazone-ethyl was applied to sandy loam (pH_KCl – 7.0) in doses of 0.000, 0.264, 5.280, 10.56, 21.18, 42.24, 84.48 and 168.96 µg kg^?1 DM soil. Soil samples were subjected to microbiological and biochemical analyses on experimental days 30 and 60. Carfentrazone-ethyl disrupted the biological equilibrium in soil by decreasing the abundance and biodiversity of soil-dwelling microorganisms, the activity of soil enzymes, the values of the biochemical activity indicator and spring wheat yields. Carfentrazone-ethyl had the most adverse effects when applied in doses many fold higher than those recommended by the manufacturer. The toxic effects of CE were also determined by its soil retention time. Soil treated with CE was characterized by higher counts of oligotrophic bacteria, organotrophic bacteria, bacteria of the genus Azotobacter, actinomycetes and fungi on day 60, and spore-forming oligotrophic bacteria on day 30. The activity of dehydrogenases, urease, alkaline phosphatase and β-glucosidase was higher on day 30 than on day 60.     

Spatio-temporal analysis of land use/land cover change and its effects on soil erosion (Case study in the Oplenac wine-producing area,Serbia)

In this paper, various spatial modelling techniques were applied to analyse changes in soil cover and their impact on soil erosion in the Oplenac wine-producing area in Serbia in the past (1985 and 2013) and in the future (with predictions for 2041). The Integrated Valuation of Ecosystem Services and Trade-offs Sediment Delivery Ratio (InVEST SDR) model and the Modules for Land Use Change Evaluation (MOLUSCE) model, integrated with methods of remote sensing, were successfully applied and were shown to be valid tools for predicting the impact of Land Use Land Cover (LULC) changes when estimating soil loss. The results revealed that the greatest impact of land use changes between 1985 and 2013 was on a reduction in areas under vineyards and an extension of meadow and pasturelands as an individual and social response to economic conditions during the research period. The forecast for 2041 reflected the trends observed in the previous period, with the greatest changes witnessing an increase in urban areas and a decrease in areas of arable land. It was also found that the effect of LULC changes on spatio-temporal patterns in the Oplenac wine-producing area did not have a major impact on soil loss, meaning this area, with its good agro-climatic characteristics, is suitable for the intensification of agricultural production.     

Size-segregated trace elements in continental suburban aerosols: seasonal variation and estimation of local,regional, and remote emission sources

We have measured trace element contents in suburban aerosols from six size fractions in the range of PM_0.27–16 from a background station in Belgrade (Serbia). The distribution and concentration of elements were determined within each of the investigated Dp fractions with emphasis on the fine and coarse modes. Fine/coarse mode ratios of element can provide information regarding their anthropogenic or natural origin. Analysis of seasonal variations of element contents in fine and coarse mode show that Cd, Co, K, and V have higher concentrations in the fine mode during heating season, while Fe contents are lower. In the coarse mode, Cu and V have higher concentrations during the heating season, while Al, Fe, Mg, Mn, and Sb contents are lower. We also apply a distribution probability model (normal, log-normal, and three-parameter Weibull) as new approach to estimate the distances of emission sources that can contribute to pollutant contents in particulate matter of the investigated location.     

Characteristics and origin of the hydrogen sulphide spring water from the Split spa (Southern Croatia)

The objective of this paper is to study the hydrological characteristics and origin of the hydrogen sulphide spring water from the Split spa in Southern Croatia in 1987, 1988 and 2003. This paper presents the results of monitoring the content of chlorides and hydrogen sulphide as well as the temperature of the hydrogen sulphide spring water. Since the hydrogen sulphide content during the dry periods significantly differs from the hydrogen sulphide content during rainy periods, this paper also compares the results obtained for those two periods. Under the influence of great quantities of rainfall during cold periods (winter and the beginning of spring) the ratio between seawater and surface water changes and thus the reduction of chlorides and other minerals occurs. The lowered temperature also reduces hydrogen sulphide which can disappear completely. The concentration of 12‰ chlorides (76–94.4% days/year) and 12 mg/L hydrogen sulphide (66.7–88.9% days/year) has been taken as a limit value between water with a normal typical content and water in cold rainy periods. According to the monitoring results it can be concluded that hydrogen sulphide spring water consists of seawater and hydrogencarbonate surface water with a fairly constant content during dry periods while the hydrogencarbonate content increases during rainy periods.     

Phytoplankton abundance and pigment biomarkers in the oligotrophic, eastern Adriatic estuary

Phytoplankton distribution and environmental characteristics were determined in a shallow, highly stratified and oligotrophic estuary (Zrmanja, eastern Adriatic). Samples were collected in two contrasting seasons; winter (February 2000), when river discharge was high, and in summer (July 2003), a period of drought. Phytoplankton distribution was closely related to salinity gradients, nutrient levels, and water residence time. Microscopic analysis revealed that phytoplankton was composed mainly of marine diatoms, dinoflagellates, cryptophytes, green flagellates, and coccolithophorids. The dominant biomarker pigments were fucoxanthin, alloxanthin and 19'-hexanoyloxyfucoxanthin, while lower, but indicative contributions of peridinin and chlorophyll b were also noted. Maximum abundance and biomass were found in the middle estuary in winter and in the upper estuary in summer. The estuary is mostly P-limited. Development of chain-forming marine diatoms was evident in winter. Due to the reduced nutrient input in summer, the biomass accumulated in the upper estuary (1,000 ng chlorophyll a l(-1)) was composed mostly of nanoplanktonic unicellular diatoms, nanoplanktonic marine dinoflagellates, cryptophytes, and chlorophytes. The concentrations of about 200 ng l(-1) hex-fuco, suggested that the contribution of prymnesiophytes to total biomass was comparable to that of diatoms and dinoflagellates. In the middle estuary and coastal sea, PO(4) and TIN were 3.5 times lower, resulting in a fivefold decrease in biomass (<100 ng chlorophyll a l(-1)). The oligotrophic Zrmanja and other karstic rivers discharging in the eastern Adriatic Sea, provide insufficient source of nutrients and low productivity of the eastern Adriatic Sea.     

Analysis of mosses and topsoils for detecting sources of heavy metal pollution: multivariate and enrichment factor analysis

In order to assess the contribution of emission sources to the pollution of areas remote from industrial facilities, a combined approach of enrichment factor analysis and multivariate statistics was used for detecting the origin of heavy metal pollution in the Zlatibor ecosystem, in Serbia. Samples of moss (Pleurozium schreberi, Hylocomium splendens, Scleropodium purum, Hypnum cupressiforme and Thuidum delicatulum) and of topsoil (0-5 cm) were collected in 2005. The concentrations of seven heavy metals (Cd, Cr, Cu, Mn, Ni, Pb and Zn) were determined in moss and soil samples by atomic absorption spectrometry. The results obtained by enrichment factor analysis and two multivariate statistical methods, principal component analysis and cluster analysis, enabled discrimination of the lithologic and anthropogenic sources of heavy metals in the mosses. Enrichment factors, calculated to evaluate the contribution to the metal content in moss from anthropogenic sources, revealed pollution of the investigated area by Cd and Pb, originating from long-range transport and fossil fuel burning.     

Fractionation and potential mobility of trace metals in Danube alluvial aquifer within an industrialized zone

Thirty-five alluvial sediments of the River Danube and 12 groundwater samples were taken within the Pan?evo Oil Refinery (Serbia). The results for groundwater samples exceed European primary drinking water standards for Fe (obtained results, >200 μg/l) and Mn (obtained results, >50 μg/l), while the levels of the trace metals are below the thresholds for drinking water quality. Sediments were treated by sequential extraction procedure with five different solutions, each having a higher extraction capacity than the previous one. We also wanted to determine the possible relationships among trace metals and between sediment properties and elemental concentrations. These solutions partitioned metals into CH₃COONH₄ extractable (F1); HCl carbonate extractable and NH₂OH·HCl easily reducible (F2); (NH₄)₂C₂O₄/H₂C₂O₄ moderately reducible (F3); H₂O₂–HNO₃ organic/sulfide extractable fractions (F4); and HCl acid-soluble residue (F5). The sum of trace metals Ni, Pb, Cu, and Zn associated with the first two fractions (exchangeable, carbonate, and easily reducible) is significant and extremely important because it represents the proportion of heavy metals that can be easily remobilized by changes in environmental conditions such as pH, redox potential, salinity, etc. Sediments located nearer the groundwater flow are exposed to stronger groundwater fluctuation and had a higher quantity of amorphous and less stable substrates of trace metals. Principal component analysis was used to understand and visualize the associations between the trace metals and certain geological forms within analyzed sediments. The observed association between Cr with total sulfur and Mn from the acid-soluble residue could indicate that Cr is in the form of reduced, less toxic Cr(III), which is from the ecochemical point of view very important.