Green remediation of mercury-contaminated soil using iron sulfide nanoparticles: Immobilization performance and mechanisms, effects on soil properties, and life cycle assessment.

Mercury (Hg) pollution in soil has grown into a severe environmental issue. Effective in situ immobilization techniques are crucially demanded. In this study, we explored the application of carboxymethyl cellulose stabilized iron sulfide nanoparticles (CMC-FeS) for in situ immobilization of Hg in soil. CMC-FeS (a CMC-to-FeS molar ratio of 0.0004) was prepared via the reaction between FeSO4 and Na2S using CMC as a stabilizer. Remedying the Hg-polluted soil using 0.03 % CMC-FeS via batch experiments effectively reduced the acid leachable Hg by 97.5 % upon equilibrium after 71 days. Column elution tests demonstrated that the addition of CMC-FeS decreased the peak Hg concentration by 89.9 % and the total Hg mass eluted by 94.9 % after 523 pore volumes. CMC-FeS immobilized Hg in soil via chemical precipitation, ion exchange, and surface complexation. After the CMC-FeS treatment, Hg was transformed from more available exchangeable, carbonate-bound, and organic material-bound forms into the less available residual fraction, reducing the environmental risk of soil Hg from medium to low. The application of CMC-FeS boosted the soil enzyme activities and enhanced the soil bacterial diversity whereas decreased the production of methylmercury. CMC-FeS also facilitated long-term immobilization of Hg in soil. The acid leachable Hg and relative Hg bioaccessibility was decreased. Lift cycle assessment indicated that the preparation and application of CMC-FeS for in situ Hg remediation in soil met green chemistry principles. The present study confirms that CMC-FeS can be applied as an efficient and "green" amending agent for long-term Hg immobilization in soil/sediment.

Correlations between microbial communities in stool and clinical indicators in patients with metabolic syndrome.

AIM: To analyze the bacterial community structure and distribution of intestinal microflora in people with and without metabolic syndrome and combined these data with clinical indicators to determine relationships between selected bacteria and metabolic diseases. METHODS: Faecal samples were collected from 20 patients with metabolic syndrome and 16 controls at Cangnan People's Hospital, Zhejiang Province, China. DNA was extracted and the V3-V4 regions of the 16S rRNA genes were amplified for high throughput sequencing. Clear reads were clustered at the 97% sequence similarity level. α and ß diversity were used to describe the bacterial community structure and distribution in patients. Combined with the clinical indicators, further analysis was performed. RESULTS: Bacteroidetes, Firmicutes, Actinobacteria, Proteobacteria, Fusobacteria were the dominant phyla, and Prevotella, Bacteroides and Faecalibacterium was the top three genera in faecal samples. α diversity analysis showed that the species richness of metabolic syndrome samples (group D) was significantly higher than the control (group C) (P < 0.05), and the microbial diversity of group C was greater than that of group D. According to the principal co-ordinates analysis, the samples of group C clustered more tightly, indicating that the distribution of bacteria in healthy patients was similar. The correlation analysis showed that alkaline phosphatase was negatively correlated with the abundance of Prevotella (P < 0.05). There was a negative correlation between low-density lipoprotein and the abundance of Ruminococcus (P < 0.05) and a positive correlation between the high-density lipoprotein and the abundance of Ruminococcus (P < 0.05). The total protein and the alanine aminotransferase was positively correlated with the abundance of Peptostreptococcus (P < 0.05). CONCLUSION: The changes microbial communities can be used as an indicator of metabolic syndrome, and Prevotella may be a target microorganism in patients with metabolic syndrome.

[Purification of eutrophic wastewater by Cyperus alternifolius, Coleus blumei and Jasminum sambac planted in a floating phytoremediation system].

In a greenhouse study, Cyperus alternifolius, Coleus blumei and Jasminum sambac were cultured in a floating phytoremediation system with plantation cups inserted into a polyfoam plate that floated in the upper part of a tank filled with 100 L domestic wastewater. The contents of chemical oxygen demand (CODCr), total P (T-P), total N (T-N), soluble P(S-P), ammonia-nitrogen (NH4+ -N) and nitrate-nitrogen (NO3- -N) in the domestic wastewater were tested during the growth of these three plants. The results showed that Cyperus alternifolius and Coleus blumei could grow well in the floating phytoremediation system, their dry weight being 285.8% and 371.4% of the initial weight of planting, respectively, but Jasminum sambac could not grow well, being 125.0% of the initial weight of planting. The removal rate of TN by these 3 plants was 68.0%, 62.0% and 45.0%, and that of NO3- -N, CODCr and TP was 98.0%, 80.0% and 92.0%, 78.0%, 66.0% and 55.0%, and 90.6%, 90.5% and 88.0% respectively. Cyperus alternifolius and Coleus blumei had good effects on the removal of pollutants in the floating phytoremediation system.