Chronic inhalation of H2S in low concentration induces immunotoxicity and inflammatory effects in lung tissue of rats.

Hydrogen sulfide (H2S) is a typical odour compound mainly causing respiratory and central nervous system symptoms. However, the immunotoxicity of inhaled H2S and the underlying mechanisms remain largely unknown. In this study, a low-dose inhalation exposure to H2S was arranged to observe inflammatory response and immunotoxicity in lung tissue of rats. Low concentrations of H2S exposure affected the immune level of pulmonary tissue and peripheral blood. Significant pathological changes in lung tissue in the exposure group were observed. At low concentration, H2S not only induced the upregulation of AQP-4 and MMP-9 expression but also stimulated immune responses, initiating various anti-inflammatory and inflammatory factors, altering tissue homeostatic environments. The TNF and chemokine signaling pathway played an important role which can promote the deterioration of pulmonary inflammatory processes and lead to lung injury and fibrosis. Excessive immune response causes an inflammatory effect and blood-gas barrier damage. These data will be of value in evaluating future occupational health risks and providing technical support for the further development of reliable, sensitive, and easy-to-use screening indicators of exposure injury.

Sediment-water distribution and potential sources of polyhalogenated carbazoles in a coastal river locating at a north metropolis, China.

The fate and transformation of PHCZs in the coastal river environment are not yet comprehensively understood. Paired river water and surface sediment were collected, and 12 PHCZs were analyzed to find out their potential sources and investigate the distribution of PHCZs between river water and sediment. The concentration of ∑PHCZs varied from 8.66 to 42.97 ng/g (mean 22.46 ng/g) in sediment and 17.91 to 81.82 ng/L (mean 39.07 ng/L) in river water. 18-B-36-CCZ was the dominant PHCZ congener in sediment, while 36-CCZ was in water. Meanwhile, the logKoc values for CZ and PHCZs were among the first calculated in the estuary and the mean logKoc varied from 4.12 for 1-B-36-CCZ to 5.63 for 3-CCZ. The logKoc values of CCZs were higher than those of BCZs, this may suggest that sediments have a higher capacity for accumulation and storage of CCZs than highly mobile environmental media.

Occurrence and distribution of polyhalogenated carbazoles in eastern Tibetan Plateau soils along the slope of Mt. Qionglai.

Polyhalogenated carbazoles (PHCZs), are considered as potential persistent organic pollutants (POPs), which have been frequently detected in the environment. However, the altitudinal distribution characteristics and possible sources of PHCZs in high mountain soils are still unknown. The present study was the first to analyze PHCZs in soil samples collected along the eastern slope of Mt. Qionglai (MQ), the east edge of the Tibetan Plateau. The concentration of ΣPHCZs (based on dry weight) ranges from 14.4 to 107 ng/g (median value of 40.9), which was at high end of the range reported in soils and sediments to date in the literature. The composition profiles of PHCZs in the soils of MQ were dominated by 3,6-dichlorocarbazole (36-CCZ), 3-chlorocarbazole (3-CCZ), and 2-bromocarbazole (2-BCZ). The mean TOC-normalized concentrations of ΣPHCZs in soil samples from below-treeline (2092 ng/g TOC) were higher than those from alpine meadow (1124 ng/g TOC), probably due to the forest filter effect. The decreasing trend of the PHCZs TOC-normalized concentrations with altitude shows that accumulation of PHCZs from the alpine meadow samples was not affected by the mountain cold-trapping effect. Significantly positive correlations were observed between the concentrations of more than half of detected PHCZ congeners and TOC. In addition, PHCZs show the potential to represent a class of POPs with the frequent occurrence and wide distribution, as the abundance and environmental behavior of PHCZs are similar to some POPs in MQ.

Occurrence and potential sources of polyhalogenated carbazoles in farmland soils from the Three Northeast Provinces, China.

Polyhalogenated carbazoles (PHCZs) have been detected in various environments frequently and have attracted increasing attention for their multiple toxicities. However, only a few reports record the occurrence of PHCZs in farmland soils, and the sources of which were not yet been implemented. In this study, 12 PHCZs and carbazole (CZ) were screened in farmland soil samples from the Three Northeast Provinces, and the ∑PHCZs were in the range of 18.16-219.67 ng/g dw. 36-CCZ was the dominant congener (40.67%) in farmland soils, followed by 3-CCZ (14.51%), and average percentages of other congeners were lower than 10%. A concrete analysis of the sources of PHCZs in the soil was conducted, revealing the diversity of PHCZs sources. Potential toxic effects associated with the levels of PHCZs were evaluated via the toxic equivalency (TEQ) approach, and the TEQs of PHCZs (TEQPHCZs) were in the range of 2.24-14.06 pg TEQ/g dw. Notwithstanding the 1368-CCZ with a low concentration level, the mean contribution to TEQPHCZs was up to 24.24%, preceded only by 36-CCZ (39.69%), showing the congeners with low concentration also may pose potential risks to the environment. Partial PHCZs congeners (2-BCZ, 3-BCZ, 36-CCZ, 136-BCZ, and 2367-BCZ) showed significant correlations (r = 0.45-0.63, p < 0.05) with the total organic carbon (TOC). Significant correlations were shown between PHCZ congeners replaced by halogens of the same species and quantity (r = 0.40-0.99, p < 0.01). In view of the fact that the high concentration level of PHCZs in the soil and their source diversity, more environmental monitoring and risk assessments of PHCZs should be of particular concern.

Assembly strategies of the wheat root-associated microbiome in soils contaminated with phenanthrene and copper.

Plants can cope with stressful conditions by indirectly regulating root-associated microbial structures. However, the recruitment strategies of the root-associated microbiome in combined organic and inorganic contaminated soils are not well known, especially for common agricultural crops. In this study, we performed greenhouse experiments to investigate the interactive effects of joint copper (Cu) and phenanthrene (PHE) pollution on wheat growth and microbial detoxication processes. Results show that heavy metals did not affect PHE dissipation in the rhizosphere but significantly enhanced the accumulation of PHE in the endosphere. In contrast, the addition of PHE did not influence the absorption of Cu by wheat roots. Cu was the primary factor affecting the variation of microbial communities in cocontaminated treatments among each rhizocompartment while the interactive effects of combined pollutants were only detected in unplanted bulk soil. Microbes are known to degrade polycyclic aromatic hydrocarbons and tolerant heavy metal stress e.g. Novosphingobium, Sphingomonas, Sphingobium and Pseudomonas enriched in the contaminated treatments. Our results provide an integrated understanding of the synthetic effects of combined pollutants on the root-microbial assemblage process in plant-soil systems and offer useful information on the selection of effective bioremediating root-associated microbes for the application of self-remediation by common crops.

Complete genome sequence of Exiguobacterium mexicanum A-EM, isolated from seafloor hydrothermal vents in Atlantic Ocean.

Exiguobacterium mexicanum A-EM was isolated from seafloor hydrothermal vents(Caifan field, 14.0S 14.4 W) and was shown to degrade toxins and contaminants. Here, we present the complete genome sequence of A-EM, consisting of 2,412,492 bp, with a GC content of 53.16%. A-EM sequence contains genes encoding enzymes that degrade toxins and contaminants. Complete genome sequence of the strain A-EM can further provide insights into microbial adaption to the seafloor hydrothermal system and the genomic basis for the biotechnological application of strain A-EM as an efficient agent to degrade environmental contaminants.

Spatial distribution and influencing factors on the variation of bacterial communities in an urban river sediment.

The water and sediments of urban rivers are spatially heterogeneous because of the influence of environmental and anthropogenic factors. However, the spatial and functional diversity of bacterial communities in urban river sediments are unclear. We investigated the spatial distribution of microbial compositions in sediments in Qingdao section of the Dagu River, and the effects of sediment physiochemical properties on the variation were explored. Among the seven heavy metals analyzed, only the average concentration of Cd significantly exceeded the safety limit for sediments. The detailed composition and spatial distribution of bacterial communities fluctuated substantially between sites along the river. Bacterial datasets were separated into three clusters according to the environmental characteristics of sampling areas (the urbanized, scenic, and intertidal zones). For the urbanized zone, Acidobacteria, Firmicutes, Gemmatimonadetes, Bacteroidetes, and Gammaproteobacteria were significantly enriched, implying the effects of human activity. In the intertidal zone, Alphaproteobacteria and Deltaproteobacteria were significantly enriched, which are associated with S redox processes, as in the marine environment. Variation partitioning analysis showed that the amount of variation independently explained by variables of Na, Al, total S and Zn was largest, followed by sediment nutrients, while heavy metals and pH explained independently 13% and 9% of the variance, respectively. Overall, microbial structures in the Dagu River exhibited spatial variation and functional diversity as a result of natural and anthropogenic factors. The results will enable the prediction of the changes in urban river ecosystems that maintain their ecological balance and health.

Distribution and ecotoxicological effects of polyhalogenated carbazoles in sediments from Jiaozhou Bay wetland.

A suite of eight polyhalogenated carbazole (PHCZ) congeners were detected in sediments of the Jiaozhou Bay wetland. 3,6-dichlorocarbazole (36-CCZ), and 3,6-dibromocarbazole (36-BCZ) were detected in all samples. The concentrations of ΣPHCZs ranged from 6.9 to 33.4 ng/g dry weight (dw). The recovery of surrogate standard ranged from 85 to 109%. Significant relationships were found between the concentrations of 36-CCZ and those of the other three detected compounds (36-BCZ, 36-ICZ, and 1368-BCZ). However, with regard to the other chemicals, only 1368-BCZ was related to 36-ICZ. The toxic equivalent (TEQ) was used to assess the relative toxicity of PHCZs, which ranged within 0.1-3.9 pg TEQ/g dw in sediment. The inventory of ΣPHCZs was 58.9 kg. These results indicate that PHCZs are widely distributed in the Jiaozhou wetland and the dyeing and finishing industries may be important contamination sources of PHCZs.

Sorption of polyhalogenated carbazoles (PHCs) to microplastics.

The sorption of 5 Polyhalogenated carbazoles (PHCs) [3,6-dibromocarbazole (3,6-BCZ), 3,6-dichlorocarbazole (3,6-CCZ), 3,6-diiodocarbazole (3,6-ICZ), 2,7-dibromocarbazole (2,7-BCZ) and 3-bromocarbazole (3-BCZ)] on to three microplastics [polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC)] in a simulated seawater system are studied. Sorption isotherms demonstrated that PVC had the maximum sorption capacity, which can be attributed to polar-polar interaction. The sorption kinetics model showed that the sorption process was controlled by both intraparticle and film diffusion. The sorption of PHCs to microplastics was significantly influenced by temperature, the sorption capacity first increased gradually and then decreased with the increasing temperature. Increasing the salinity decreased the sorption of PHCs onto PP, PE, PVC microplastics. Our results indicated that all three kinds of microplastics can serve as carriers for PHCs in the aquatic environment, which put marine ecosystems at higher risks.

Levels and distribution of synthetic musks in farmland soils from the Three Northeast Provinces of China.

The levels and distribution of synthetic musks (ADBI, AHMI, ATII, HHCB, AHTN, MX and MK) were investigated in farmland soils from the Three Northeast Provinces of China. The total concentrations of SMs ranged from 2.40 ng/g to 12.2 ng/g (dry weight). HHCB and AHTN were the main pollutants that were detected in all samples, accounting for 99.35% of the total SMs. The hazard quotients were 0.0700 and 0.102 for AHTN and HHCB, respectively. Although the results indicate there is no serious environmental impact, the detection frequency of SMs in the farmland soil is high, which demonstrated that SMs are widely used in the Three Northeast Provinces of China. Therefore, more attention should be given to synthetic musks during environment monitoring and risk assessments for their bioaccumulation, lipophilicity and persistence.

Sorption of 3,6-dibromocarbazole and 1,3,6,8-tetrabromocarbazole by microplastics.

Microplastics and organic pollutants are typical contaminants in the marine environment. However, little is known about their interactions. In this study, the sorption of 3,6-Dibromocarbazole(3,6-BCZ) and 1,3,6,8-Tetrabromocarbazole (1,3,6,8-BCZ) by Polypropylene microplastic in simulated seawater was studied. Factors, including particle size, salinity and concentration, were investigated, and the experimental results were simulated using a mathematical model. Results showed that the pseudo-second-order kinetic model was more suitable to describe the sorption of polyhalogenated carbazole by microplastics, with equilibrium sorption times of 6 h and 8 h for 3,6-BCZ and 1,3,6,8-BCZ, respectively. Sorption capacity increased with decreasing particle size and the adsorption capacity increased initially and then decreased with increasing salinity, with a maximum sorption occurring at salinity of 14%. Moreover, the sorption amount increased with the increasing concentration of polyhalogenated carbazole. The sorption isotherms were confirmed as the extended Langmuir model and the extended Freundlich model, both of which were S-type.

Sorption behaviors of tris-(2,3-dibromopropyl) isocyanurate and hexabromocyclododecanes on polypropylene microplastics.

In recent years, microplastics in oceans have become a serious environmental problem and the focus of attention. In the present study, the sorption of TBC and HBCDs by microplastics in simulated seawater is examined. The effects of particle size, temperature, salinity, and concentration on the adsorption of TBC and HBCDs by microplastics are studied. Results indicate that the first-order adsorption kinetic model is more suitable than the pseudo-second-order kinetic model to describe adsorption. The equilibrium adsorption times are 15 h and 10 h for TBC and HBCDs, respectively. The adsorption capacity increases with the decrease in particle size. The adsorption capacity gradually increases at first and then decreases with the increase in salinity and temperature. The maximum adsorption capacity is at 15 °C and 14% salinity. Compared with the linear and Freundlich models, the Langmuir model is more suitable; this indicates that the main adsorption mechanism might be chemical adsorption.

High level of tris-(2,3-dibromopropyl) isocyanurate (TBC) and hexabromocyclododecanes (HBCDs) in sediments from the intertidal zone of New River Estuary-a polluted and degraded wetland.

The levels and distribution of tris-(2,3-dibromopropyl) isocyanurate (TBC) and hexabromocyclododecanes (HBCDs) in sediments in the intertidal zone of the New River Estuary were investigated. The concentration of TBC ranged from 2.78 to 35.1 ng·g-1dw, and the concentration of total HBCDs ranged from 10.3 to 43.5 ng·g-1dw. The composition of the three HBCD isomers, α-, ß-, and γ-HBCD, was 6.23%, 8.00% and 85.8%, respectively. Moreover, the mass inventory of TBC, α-, ß-, γ-HBCD, and total HBCDs in sediments were estimated to be about 1465.49, 124.64, 154.98, 1707.54, 1987.16 kg, respectively. Compared to previous studies, the concentrations of TBC and HBCDs in the intertidal zone of the New River Estuary were relatively high. Therefore, more concern of the potential public health and environmental risks of TBC and HBCDs is necessary.

Sorption of three synthetic musks by microplastics.

Microplastics and synthetic musks (SMs) are two typical organic pollutants in the marine environment. In this study, the sorption of three SMs to microplastics in a simulated seawater environment was examined. Tonalide (AHTN), musk xylene (MX), and musk ketone (MK) were the musks investigated, while polypropylene (PP) was used as the microplastic. It was found that the equilibrium sorption time was about 10h and the adsorption kinetics model conformed to a Lagergren adsorption model. The adsorption capacity increased with decreasing particle size. Adsorption reached a peak at 25°C, and the adsorption capacity was not sensitive to the concentration of sodium chloride. There is a need for more research and monitoring of microplastics in the marine environment due to their strong ability to absorb organic pollutants.

Determination and environmental risk assessment of synthetic musks in the water and sediments of the Jiaozhou Bay wetland, China.

Human activity in estuarine areas has resulted in pollution of the aquatic environment, but little is known about the levels of synthetic musks (SMs) in river water and sediments in estuarine areas. This study investigated the concentrations and distribution of SMs in the Jiaozhou Bay wetland, including celestolide, phantolide, traseolide, galaxolide (HHCB), tonalide (AHTN), musk xylene and musk ketone (MK). The SMs HHCB, AHTN and MK were detected at concentrations of 10.7-208, not detected (ND)-59.2 and ND-13.6 ng/L, respectively, in surface water samples and 13.1-27.3, 3.06-14.5 and 1.33-18.8 ng/g (dry weight; dw), respectively, in sediment samples. Based on the calculated total organic carbon (TOC) concentrations, there was no significant correlation between SMs and TOC in sediment samples (p > 0.05). The hazard quotients were 0.204, 0.386 and 0.059 for AHTN, HHCB and MK, respectively, which indicated no serious environmental impact, because these values are all less than 1. The concentrations of SMs decreased as the distance to the Xiaojianxi refuse landfill increased in both surface water and sediments. Compared with previous studies, the concentration of SMs in the Jiaozhou Bay wetland was relatively high. Therefore, more attention should be paid to SMs because of their persistent impact on human health and the environment.

Levels and distribution of tris-(2,3-dibromopropyl) isocyanurate and hexabromocyclododecanes in surface sediments from the Yellow River Delta wetland of China.

The levels and distribution of tris-(2,3-dibromopropyl) isocyanurate (TBC) and hexabromocyclododecanes (HBCDs) of surface sediments in the Yellow River Delta wetland had been investigated. The concentrations of TBC and ∑HBCDs ranged from 0.20 to 29.03ng·g-1dw and below limits of detections (LODs) to 20.25ng·g-1dw. The average composition profile of three HBCDs isomers were 10.1%, 6.1% and 83.8% for α-, ß- and γ-HBCD, respectively. Moreover, correlation analysis indicated there are similar sources among three isomers and positive correlations between total organic carbon (TOC) content and concentrations of TBC and HBCDs. The mass inventory of TBC,α-, ß-, γ-HBCD, ΣHBCDs in surface sediments of Yellow River Delta wetland were estimated about 725.50, 72.76, 44.29, 548.34, 665.39kg. Therefore, further investigations on potential human health and environmental risk assessments of TBC and HBCDs were needed.

Determination of heterocyclic brominated flame retardants tris-(2, 3-dibromopropyl) isocyanurate and hexabromocyclododecane in sediment from Jiaozhou Bay wetland.

The concentration and distribution of tris-(2,3-dibromopropyl) isocyanurate (TBC) and the three isomers of hexabromocyclododecane (HBCDs) were analyzed in the sediment of Jiaozhou Bay wetland in China. The concentrations of TBC and the three isomers of HBCDs (α-HBCD, ß-HBCD, γ-HBCD) were in the ranges of 1.20 to 8.76, 1.03 to 5.69, 1.13 to 5.46, and 1.18 to 15.04ng·g-1 dw (dry weight), respectively. γ-HBCD was the predominant congener with an average proportion of 52.42% of ΣHBCDs, average inventory of HBCDs was about 93.53ng∙cm-2. Depending on the function of wetland, the concentration of HBCDs tended to decrease as the distance to the Xiaojianxi refuse landfill increased. Compared with previous research studies, the concentration of TBC and HBCDs in the Jiaozhou Bay wetland was at a relatively high level. Therefore, more attention should be paid to TBC and HBCDs on account of their persistent impact on human health and the environment.