Notes

[Research as well as application of fresh methods for early on carried out caries].
Influences of post depositional changes of sedimentary organic matter (SOM) on chromium (Cr) speciation in continental slope sediments from the east and west coast of India are presented in this study. Average concentrations of total sedimentary Cr (CrT) in the slope areas of both the coasts were not elevated and ranged from 56.8 to 163 mg·kg-1 (avg. 97.3 ± 28.3 mg·kg-1). The geology of adjacent land masses influenced sedimentary Cr concentration in the slope areas. Geochemical fractionation study showed that a major fraction (51.6-159 mg·kg-1; avg. 89.6 ± 24.3 mg·kg-1) of the total sedimentary Cr was present in residual part of the sediments. Prime hosting phase for non-residual sedimentary Cr was oxidizable binding phase (SOM) (1.4-23.9 mg·kg-1; avg. 6.7 ± 6.3 mg·kg-1) followed by reducing binding phase (Fe/Mn-oxyhydroxide phase) (0.1-1.7 mg·kg-1; avg. 0.7 ± 0.3 mg·kg-1). Concentration of Cr (VI) in the slope sediments, varied from 0.2 to 8.3 mg·kg-1 (avg. 1.2 ± 1.0 mg·kg-1), was also predominantly associated with the SOM. The δ13Corg values of the SOM (ranged from -19.4 to -21.4‰; avg. -20.3 ± 0.5‰) suggests that they were derived from marine sources. Based on molar C/N ratio (ranged from 6.3-12.9; avg. 9.0 ± 2.0), the SOM were classified as labile organic matter. Increasing molar C/N ratio in the studied sediments was used as a proxy to reflect post depositional changes of the SOM. Association of normalized Cr (VI) (with respect to CrT) increased with increasing SOM concentration by 0.008 mg·kg-1. One unit increase of sedimentary molar C/N ratio was found to increase normalized Cr (VI) (w.r.t. CrT) by 0.003 mg·kg-1 in the sediments. This study suggests that post-depositional changes of SOM may increase Cr binding capacity and control its speciation and mobility in marine sediment system.The effects of adding zero-valent iron nanoparticles (nZVI) on the physicochemical, biological and biochemical responses of a semi-continuous anaerobic digestion of sewage sludge have been assessed. Two sets of consecutive experiments of 103 and 116 days, respectively, were carried out in triplicate. nZVI were magnetically retained in the reactors, and the effect of punctual doses (from 0.27 to 4.33 g L-1) over time was studied. Among the different parameters monitored, only methane content in the biogas was significantly higher when nZVI was added. However, this effect was progressively lost after the addition, and in 5-7 days, the methane content returned to initial values. The increase in the oxidation state of nanoparticles seems to be related to the loss of effect over time. Higher dose (4.33 g L-1) sustained positive effects for a longer time along with higher methane content, but this fact seems to be related to microbiome acclimation. Changes in microbial community structure could also play a role in the mechanisms involved in methane enhancement. In this sense, the microbial consortium analysis reported a shift in the balance among acetogenic eubacterial communities, and a marked increase in the relative abundance of members assigned to Methanothrix genus, recognized as acetoclastic species showing high affinity for acetate, which explain the rise in methane content in the biogas. This research demonstrates that biogas methane enrichment in semicontinuous anaerobic digesters can be achieved by using nZVI nanoparticles, thus increasing energy production or reducing costs of a later biogas upgrading process.Straw addition can increase the content of soil organic carbon (SOC), and affect the content of aggregates and organic carbon fractions. The changes in aggregates and organic carbon fractions in the natural salt marsh, 10-year and 15-year freshwater pumping areas in the Yellow River Estuary were studied by 120-day field in situ culture experiments with Phragmites australis straw addition. The results showed that straw addition mainly enhanced the soil aggregate stability in the 10-year freshwater pumping area, and the organic carbon content of small macro-aggregates increased significantly by 26.36% (P less then 0.05). In particular, the content of coarse particulate organic carbon (cPOC) with small macro-aggregates in all areas increased significantly with the addition of straw (P less then 0.05). For small macro-aggregates in the 10-year pumping area, the cPOC contents increased significantly by 21.73 g/kg (P less then 0.05); and were significantly higher than the fine particulate organic carbon (fPOC) and mineral-associated organic carbon (mSOC) contents, as the fPOC contents in micro-aggregates increased by 85.92% (P less then 0.05). selleck Additionally, the cPOC contents of small macro-aggregates and fPOC contents of micro-aggregates increased by 34.59% and 43.24% in the 15-year pumping area. The contents of mSOC were the lowest in different aggregates across all areas. Thus, straw addition had a significant effect on the contents of cPOC and fPOC, while freshwater pumping in the YRE could affect the distribution of fPOC and mSOC with aggregates.Novel brominated flame retardants (NBFRs) have emerged as an alternative to traditional brominated flame retardants (BFRs); however, they may pose risks to the environment and human health. To investigate the occurrence, temporal trends, and human exposure of seven typical NBFRs (∑7 NBFRs), seven species of mollusks (n = 329) were collected from coastal cities in the Chinese Bohai Sea area from 2011 to 2018. The ∑7 NBFRs ranged from 1.52 to 154 ng/g dry weight (dw) (mean 14.9 ± 21.21 ng/g dw), higher than in other areas worldwide. Decabromodiphenylethane (DBDPE) was the main contaminant, contributing to 33% of the NBFRs. Temporal trends indicate that the DBDPE and 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE) concentrations in mollusks increased significantly (P less then 0.05) at rates of about 26% and 5.4%, respectively. This suggests that these NBFRs are continuously released into the environment of the Bohai Sea area. The higher NBFR concentrations in the southern sampling sites relative to the northern sampling sites were consistent with the spatial distribution of the NBFR industry in the Bohai Rim Economic Circle. Chlamys farreri possessed the highest ∑7 NBFR concentrations compared with the other species, while the lowest concentrations were found in Neverita didyma and Rapana venosa, suggesting interspecific differences in bioaccumulation. The estimated daily intake of NBFRs was low, and as the main contaminant, DBDPE was unlikely to pose significant human health risks. Overall, this is the first study to comprehensively assess the occurrence, spatial distribution, and temporal trends of NBFRs in mollusks.
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