[en] This work provides new insights into the presence of ²³⁹Pu, ²⁴⁰Pu, ²⁴¹Pu, and ²³⁶U in the Southern Hemisphere through the study of peat bog cores from marshlands in Madagascar (19°S). ²¹⁰Pb, ²³⁸Pu and ^239+240Pu activities were characterized by alpha spectrometry in previous studies. Here, Pu from alpha-spectrometry discs corresponding to 10 peat-bog cores (85 samples) was reassessed for the aim of completing its isotopic composition (²³⁹Pu, ²⁴⁰Pu, and ²⁴¹Pu) by Accelerator Mass Spectrometry. In addition, ²³⁶U was studied in a single core exhibiting unusually low ²⁴⁰Pu/²³⁹Pu ratios. Integrated ²⁴⁰Pu/²³⁹Pu atom ratios in the single cores ranged above and below the (0–30°S) fallout average ratio, 0.173±0.027, from 0.126±0.003 to 0.206±0.002, without a regional pattern, thereby demonstrating the heterogeneous distribution of the ²³⁹Pu and ²⁴⁰Pu signal. However, such a variability was not observed for ²⁴¹Pu/²³⁹Pu, ranging from (6± 1) · 10⁻⁴ to (11 ± 1) · 10⁻⁴ and consistently below the (0–30°S) fallout ratio of (9.7± 0.3) · 10⁻⁴ (2012). The integrated ²³⁶U/²³⁹Pu atom ratio in the studied core, 0.147 ± 0.005, was also significantly lower than the values reported for the global fallout in the Northern Hemisphere, in the 0.20–0.23 range. Our results point out to stratospheric fallout as the main source of both ²³⁶U and ²⁴¹Pu at the studied site, whereas ²³⁹Pu and ²⁴⁰Pu signals show the influence of tropospheric.

[en] Specific activity of 137Cs, 40K, and 210Pb radionuclides in fifteen selected medicinal herbs from three locations in Central Serbia (two mountains, Kopaonik and Zlatar, and a valley, Sokobanja) was measured using two semiconductor HPGe spectrometer systems. The obtained values are in intervals (<0.3 ÷ 9.7) Bq/kg, (<0.2 ÷ 24.7) Bq/kg, and (<0.2 ÷ 5.7) Bq/kg for 137Cs; in intervals (125 ÷ 1100) Bq/kg, (104 ÷ 872) Bq/kg, and (103 ÷ 954) Bq/kg for 40K, and in intervals (3.6 ÷ 49.0) Bq/kg, (3.9 ÷ 57.9) Bq/kg, and (2.8 ÷ 103) Bq/kg for 210Pb, for herbs from Kopaonik, Sokobanja and Zlatar, respectively. The highest activity measured in individual herbs was: 24.7 Bq/kg for 137Cs (Sokobanja valley), 1100 Bq/kg for 40K (Mt. Kopaonik) and 103 Bq/kg for 210Pb (Mt. Zlatar). The corresponding individual annual effective doses due to ingestion calculated from the measured activity concentrations, of the radionuclides are: in intervals (<1.7 ÷ 82.9) nSv, (<1.4 ÷ 211) nSv, and (<1.1 ÷ 48.7) nSv for 137Cs; in intervals (0.76 ÷ 4.5) μSv, (0.64 ÷ 4.4) μSv, and (0.63 ÷ 4.9) μSv for 40K, and in intervals (1.1 ÷ 18.2) μSv, (1.3 ÷ 21.6) μSv, (0.9 ÷ 38.3) μSv for 210Pb, respectively. The specific activity concentration values of 137Cs and 40K obtained for the investigated herbs are similar to the literature data, while no information was found in literature about specific activity concentration of 210Pb. The all values obtained for individual annual effective dose due to ingestion are less than 100 μSv, which means that the daily use of 200 mL of herbal infusion during a year made from the investigated herbs does not represent a radiological risk for health. However, a high individual annual effective dose of ingestion of 210Pb obtained for some herbs indicate that their consumption in larger amounts 2–3 cups of infusion daily over a year could make the dose to exceed the recommended level, and points to necessity for extensive investigation of 210Pb activity concentration worldwide. © 2019 Elsevier B.V.

[en] Transfer coefficients for radiocaesium transport from a sheep's diet to blood, muscle, lung, liver, kidney, spleen heart, brain, rumen, intestines and fat were measured in a controlled experiment involving 50 adult ewes. The animals were fed dry grass and wheat, both contaminated with Chernobyl fallout debris, for a period of 60 days. During this period half of the animals were killed at regular intervals and samples of their blood and tissues were measured for radiocaesium concentration. The rest of the animals were returned to uncontaminated food and were monitored for radiocaesium concentration through periodic slaughtering for an additional 60 days. Transfer coefficients were extracted from the plateau reached at the end of the contamination phase. The data were also analyzed by means of a recently proposed linear multiple compartment model and transport rate parameters for each compartment were extracted. Transfer coefficients computed through the model's transport rate parameters show remarkable agreement with the experimentally obtained values. (author)

[en] In 1986 a large number of farms in the Chernobyl-affected area in the county of Västernorrland in northern Sweden were investigated for radiocaesium transfer to grass and cereal grain. The soil surface layer (0-5 cm) in 1986 and the crop products in 1986-1996 were analysed. The aim was to study the impact of soil and crop rotation on sensitivity of ¹³⁷Cs transfer in a short and long term perspective. In the fallout year 1986 the transfer to grass was usually much higher than to cereal grain. In this year the transfer to grass was usually much higher in the first cut rather than the second cut. The reduction in transfer with year was large but variable with site and with crop sequence. Ploughing was effective in decreasing the transfer of ¹³⁷Cs to crops. On arable sites in 1986 the transfer to cereal straw was larger at late stem elongation (LSE) than at the maturing stage. Unexpectedly, there was no clear relationship between transfer of ¹³⁷Cs to the crops and any of the soil characteristics. In 1986 the transfer of ¹³¹I to grass and cereals was also investigated on some of the farms. The results are compared with the transfer of ¹³⁷Cs, 2 months after the Chernobyl fallout

[en] Highlights: • CAP degradation MEC was successfully driven by Ag(I) reduced MFC. • System performance was optimized using response surface methodology. • Pure silver was recovered in MFC. • CAP was completely degraded in MEC. -- Abstract: Conventional chemical and physical methods to remove antibiotics from wastewater consume large amount of energy and chemicals, and the efficiency of biological process in converting antibiotics is relatively low. Microbial electrolysis cell (MEC) has been employed to degrade recalcitrant organic compounds recently. Given it is an energy consuming device, it would be more sustainable if driven by renewable energy, e.g. power from microbial fuel cell (MFC). Here, chloramphenicol (CAP) was chosen as a representative antibiotic that is abundant in the environment, and Ag ion contained wastewater as electron acceptor in MFC, to demonstrate the feasibility of a self-driven system for recalcitrant removal and resource recovery. It was found that CAP removal in MEC can be successfully driven by Ag(I) reduced MFC without external energy consumption. Method of one-factor-at-a-time (OFAT) and response surface methodology (RSM) with central composite design were used to evaluate the system performance. Under the optimum condition, 99.8% of Ag(I) in MFC and 98.8% of CAP in MEC can be converted. EDX and XPS revealed that pure silver was obtained on the surface of electrode in MFC, reflecting Ag(I) was reduced to valuable product. The concept and methods developed in this study can be also applied to design other types of self-driven BES systems for simultaneous pollutants removal and resources recovery.

[en] Highlights: • Highest nitrate removal flux was 477 mg N/m²-d for dilute wastewater. • Effluent methane concentration was 3.3–6.8 mg/L in the MBfR. • Neither oxygenic denitrifying methanotrophs nor ANME archaea detected. • Methylococcus identified as aerobic methane oxidizer in the membrane biofilm. • Nitrate reduction to nitrite may limit MBfR denitrification. -- Abstract: A methane-based membrane biofilm reactor (MBfR) was assessed for a tertiary nitrogen removal process in domestic wastewater treatment. To mitigate effluent dissolved methane concentrations, the MBfR was operated with a 20% methane mixing ratio and a low pressure of 0.003 atm. The nitrate concentration was reduced from 20 to 4 mg/L with a low methane concentration of 3.3 mg/L in the effluent at 4 h hydraulic retention time (HRT). An in situ dissolved oxygen sensor showed a concentration of 0.045 mg/L in the MBfR, demonstrating methane oxidation under hypoxic conditions. Both 16S rRNA gene sequencing and metagenomic analysis identified bacteria capable of oxidation of methane coupled to denitrification (Methylocystis), whereas other bacteria were implicated in either methane oxidation (Methylococcus) or nitrate reduction (Escherichia). Reduced genetic potential for nitrate reduction to nitrite at a shorter HRT coincided with a decreased efficiency of denitrification, suggesting rate limitation by this initial step of denitrification. Genes encoding nitrite reduction to dinitrogen were at similar relative abundance under both HRT conditions. Our results provide mechanistic evidence for microbial syntrophy between aerobic methanotrophs and denitrifiers in methane-fed MBfRs operated under varying HRTs, with important implications for novel biological nitrogen removal to dilute wastewater.

[en] Highlights: • Magnetic montmorillonite biochar material is first prepared by one step pyrolysis. • The composite performs excellent adsorption capacity for oxytetracycline. • Adsorption is mainly controlled by hydrogen bond, π-π and ion exchange reactions. • Fe₃O₄ nanoparticles on composite provide extra adsorption sites. • The spent composite is successfully regenerated and collected by magnet. -- Abstract: Three adsorbents, namely, original biochar (CLB), montmorillonite (MMT)-biochar composite (MBC), and magnetic MMT-biochar composite (MMBC) were successfully fabricated by one step pyrolysis of original cauliflower (Brassica oleracea L.) leaves, mixture of cauliflower leaves and MMT, and FeCl₃-laden mixture of cauliflower leaves and MMT under limited oxygen atmosphere, respectively. The characterizations of samples indicated that substantial MMT mineral particles and Fe₃O₄ nanoparticle were dispersed on the surface of MMBC. Due to the introduction of Fe₃O₄, MMBC performed excellent magnetization property. The adsorption experiments of oxytetracycline (OTC) indicated that the maximum adsorption ability of MMBC was 58.85 mg·g⁻¹, which was 2.63 times as large as CLB, also, larger than that of MBC. Meanwhile, pH, ionic strength, and humic acid (HA) performed slight effects for adsorption of OTC on MMBC. In addition, MMBC still removed 92% OTC after five regeneration cycles. Finally, primary mechanisms of OTC adsorption onto MMBC were attributed to hydrogen bonding and π-π reaction, and ion exchange reaction was considered to exist. Meanwhile, functional groups including Si-O-Al, Si-O-Si, Si-O, and Fe₃O₄ nanoparticles would provide extra binding sites for OTC adsorption. Therefore, MMBC had an obvious potential to apply into water purification as a reliable, low-cost, and environmentally friendly adsorbent.

[en] Highlights: • Half-lives of three fungicides after single and alternate spraying were similar. • Half-life of pyraclostrobin after alternate repeated spraying was shorter. • The risk of exceeding the MRL was reduced after alternate repeated spraying. • Potential cumulative dietary risk might increase after alternate repeated spraying. Repeated spraying of fungicides is a common phenomenon in greenhouse strawberry cultivation, and the continuous harvest of strawberries makes them prone to contamination by accumulated fungicides. Despite this, very few residue safety assessments of fungicides on greenhouse strawberries are conducted after repeated spraying of fungicides, and no research exists on fungicide dissipation and accumulation mechanism. Therefore, the present study investigated the dissipation and accumulation of four fungicides (pyraclostrobin, pyrimethanil, procymidone, and cyprodinil) after two typical repeated sprayings (a single fungicide repeated spraying and two fungicides sprayed using an alternate repeated technique). The half-life of pyraclostrobin after three single repeated sprayings was 18 d; however, its average half-life decreased to 9 d after alternate repeated spraying with cyprodinil. The shortened half-life may be attributed to cyprodinil water solution washing during alternate repeated spraying. The other three fungicides showed similar half-lives after single and alternate repeated spraying, following the order of cyprodinil (12 d and 10 d) > procymidone (11 d and 10 d) > pyrimethanil (6 d and 7 d). The octanol-water partition coefficient was a more efficient indicator of the half-life order of the fungicides than vapor pressure and water solubility. Pyraclostrobin showed the highest deposition efficiency but negligible residue accumulation; further, the residue accumulation of the four fungicides followed the order of procymidone > cyprodinil > pyrimethanil > pyraclostrobin after both single and alternate repeated spraying. A safety assessment demonstrated that the maximum number of times cyprodinil could be sprayed after single spraying was one; however, this number doubled after alternate spraying. The risk of exceeding the maximum residue limits of the fungicides on greenhouse strawberries decreased; however, the combined dietary risks of fungicides after alternate spraying might be high. Alternate repeated spraying of procymidone and pyrimethanil may be the optimal repeated spraying combination for greenhouse strawberries.

[en] Highlights: • This paper focuses on potentially toxic trace elements in urban topsoil in China. • Spatiotemporal analysis was conducted for the pollution features in the two time periods 2000–2009 and 2010–2019. • Pollution level, pollution pattern, and pollution sources were addressed from multiple spatial scales. • Cd and Hg were heavily accumulated in the urban topsoil in Chinese cities. • Although the comprehensive pollution remained severe, it has shown a momentum towards improvement. The Chinese government has launched a critical battle against soil pollution in recent years to establish an effective pollution prevention and control framework. This study sought to investigate the long-term pollution status of potentially toxic trace elements in urban topsoil nationwide, and to further investigate the effectiveness of pollution control over the past decade. The concentrations of 8 elements (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in urban topsoil in China between 2000–2009 and 2010–2019 were separately collected for comparative analysis. Individual and comprehensive pollution levels of the elements were evaluated at the city, provincial, regional, and national scales, and further spatially mapped using GIS. Combined with PCA, the main factors influencing these elements in soil nationwide were identified. The results revealed a severe situation in terms of potentially toxic trace element accumulation in urban topsoil, where the NNIPIs surpassed 3 in both periods. The elements As, Cd, and Hg were closely associated with industrial activity and coal burning. Hg and, in particular, Cd pollution (NPI > 3) were found to be severe in most of the cities studied. For the elements As, Cu, Pb, and Zn, pollution ranged from slight to moderate (1.0 < NPI ≤ 3.0), and Cu, Pb, and Zn were related to a significant degree with vehicle use. Soil Cr and Ni were mainly controlled by parent materials of lithogenic origin, and slight pollution was identified (1.0 < NPI ≤ 2.0). Pollution patterns showed different characteristics across the regions, and those of the same region and the nation hardly changed over time. Mercury pollution was dominant in the northern regions (NW, MYeR, NE, and NC), while Cd pollution was more severe for the south (EC, MYaR, SC, and SW). Notably, the country's comprehensive pollution level was stable across the two periods, with momentum towards improvement observed over the past decade.

[en] Highlights: • Anthropogenic metal contamination in the Bernese Alps dates back to the Iron Age. • Sediments exhibited the most significant metal peak anomalies in the last 500 yrs. • Shifts in metal trends correspond with socioeconomic changes in central Europe. • Similar anthropogenic pollution trends are observed across the Alpine region. • Other archives and knowledge of ancient mining validated sediment metal trends. The geochemical analysis of natural archives can improve our knowledge of past mining activities and their environmental imprint. The sedimentary records from the Hasli-Aare floodplain (Bernese Alps) over the last 2500 years were analysed for metals. Evidence of past mining contamination was obtained from the XRF analyses of iron, copper, zinc and lead. These results were analytically and statistically processed to produce a metal content index. Positive metal anomalies indicate four major pulses of contamination coinciding with the end of the Iron Age, from the end of the Roman Period to the Early Medieval Period, the Late Medieval Period, and the Modern Period. These pulses show good agreement with local historical sources of mining in the Hasli-Aare catchment, dating back to the beginning of the 15th century. Furthermore, they are in phase with anthropogenic pollution trends inferred from glacier ice cores, lake sediments and peat bogs across the Western Alps, most notably during the Roman, Late Medieval and Modern Periods. However, close comparison between these records can show some differences, suggesting local variations in mining activities and/or a lag in metal transfer. The reconstructed periods of anthropogenic metal pollution are located in their political, economic and social contexts and compared with the climate periods of central Europe.