An improved Back Propagation Neural Network framework and its application in the automatic calibration of Storm Water Management Model for an urban river watershed.

The use of the Storm Water Management Model (SWMM) to simulate flows in urban river watersheds necessitates the proper calibration of the various parameters involved in the process. Back Propagation Neural Network (BPNN) is often used to establish relationship between two sets of multivariate variables, such as parameters and simulation results of SWMM. The aim of this study is to establish an improved BPNN to calibrate SWMM. It was found that when using gauged flow data obtained from the urban river management system as calibration data, only using BPNN was not sufficient. An improved BPNN framework was proposed with integrating Principal Component Analysis (PCA) and Genetic Algorithm (GA) process, abbreviated as PCA-GA-BPNN. It was proved to be effective for calibration. The BPNN combined with GA process made 90 % of the predicted parameters within reasonable range, which was only 8 % using BPNN alone. The PCA process reduced the training time up to 64 %. Using a hydrograph of 196 h, compared with the nondominated sorting genetic algorithm (NSGA), PCA-GA-BPNN training time can be reduced from 18,142 s down to 4.5 s. Nash efficiency coefficients (NSE) of hydrographs fitting was 0.75. Including more rainfall events data in calibration achieved better fitting than including more gauging station data.

Levels, tissue distribution and isomer stereoselectivity of Dechlorane Plus in humans: A critical review.

Exposure of human tissues to Dechlorane Plus (DP) has raised public concern because of the multiple health threats it may pose to humans. Therefore, it is important to summarize the main findings of previous studies on DP in human tissues and to provide potential guidance for future studies. In this paper, DP levels in different populations and human tissues worldwide since 2009 were systematically reviewed. DP levels in human tissues of workers in e-waste dismantling sites in Guangdong Province, China (median 190 ng·g-1 lw in serum) and DP manufacturing plants in Jiangsu Province, China (mean 857 ng·g-1 lw in whole-blood) are the highest reported worldwide. DP levels in tissues of the general population in recent studies are close to those of residents near e-waste dismantling sites, which should be of concern. DP levels in different human tissues were found to be positively correlated with a pattern of blood > breast milk > adipose tissue. The distribution of DP in different human tissues is mainly lipid-driven and may also be influenced by the interaction of DP with proteins such as human serum albumin. Most of the past studies determined the isomer stereoselectivity of DP in human tissues only by comparing the composition of DP in commercial DP products and human tissues, which lacks evidence of mechanism. Recently, a significantly different affinity of DP isomers for proteins was found, which seems to confirm the isomer selectivity of DP in human tissues. We simulated the binding of DP to human serum albumin and DP to thyroid hormone receptor ß by molecular docking and found differences in the binding behavior of syn-DP and anti-DP to the selected proteins. Molecular docking seems to be a feasible approach for future studies to predict and reveal the mechanisms of DP behavior and health effects in human tissues.

Polychlorinated naphthalene concentrations and temporal trends in serum from the general Chinese adult population and effects of polychlorinated naphthalenes on thyroid function.

Polychlorinated naphthalenes (PCNs) have stopped being produced and used but have been detected in human serum around the world. Investigating temporal trends in PCN concentrations in human serum will improve our understanding of human exposure to PCNs and the risks posed. We determined the PCN concentrations in serum collected from 32 adults in five consecutive years (2012-2016). The total PCN concentrations in the serum samples were 0.00-5443 pg/g lipid weight. We found no significant decreases in the total PCN concentrations in human serum and even found that the concentrations of some PCN congeners (e.g., CN20) increased over time. We found differences in the PCN concentrations in serum from males and females, the CN75 concentration being significantly higher in serum from females than males, meaning CN75 poses more serious risks to females than males. We found, using molecular docking techniques, that CN75 interferes with thyroid hormone transport in vivo and that CN20 affects thyroid hormone binding to receptors. These two effects are synergistic and can cause hypothyroidism-like symptoms.

A Pilot Study on the Concentration, Distribution and Bioaccumulation of Polybrominated Diphenyl Ethers (PBDEs) in Tissues and Organs of Grassland Sheep.

Polybrominated diphenyl ether (PBDE) concentrations in various tissues and organs of grassland sheep from Inner Mongolia, China, were determined. The abilities of PBDEs binding to ovine serum albumin (OSA) and Cytochrome P450 enzyme (CYP3A24) were assessed by fluorescence spectroscopy and molecular docking simulations. The PBDE concentrations in the sheep tissue and organ samples were 33.4-167 pg/g dw. The distribution of PBDEs in sheep organs and tissues is affected not only by the function of organs and tissues, but also by the characteristics of PBDEs. Adipose tissue tends to bioaccumulate more-brominated BDEs (BDE-154, -153, and -183), but muscle tissues and visceral organs mainly bioaccumulate less-brominated BDEs. The distribution of PBDEs in visceral organs is mainly affected by the transport of ovine serum albumin (OSA) and the metabolism of CYP3A24 enzyme. The distribution of PBDEs in adipose tissue and brain is mainly affected by their logKOW.

Concentration, Distribution and Biomagnification of Novel Brominated Flame Retardant in Grassland Food Chain and Sheep from Inner Mongolia, China.

Novel brominated flame retardants (NBFRs) have been of great concern in the past few years due to their ubiquity in the environment and potential bioconcentration characteristics. This study takes Xilingol grassland in Inner Mongolia as the research area to analyze the pollution characteristics of NBFRs (pTBX, HBB, PBT, PBBz, and PBEB) in the grassland food chain. pTBX was more likely to be biomagnified in the food chain of amphibians, reptiles, and birds, whereas PBT and HBB were more likely to be biomagnified in the food chain of mammals. This may be because these animals have different diets and metabolic patterns. According to the concentration distribution of NBFRs in sheep organs and tissues, PBT, HBB, and PBBz easy bioaccumulated in sheep. The biomagnification effect of sheep adipose tissue and internal organs on NBFRs was inconsistent, so the biomagnification of chemicals in organisms cannot be determined only by the biomagnification of adipose tissue.

Factors Influencing Dechlorane plus Distributions in Various Sheep Tissues.

Dechlorane plus (DP) is a potential persistent organic pollutant and its distribution in various tissues and organs of terrestrial organisms is currently unknown. DP concentrations in sheep tissues were determined in this study. The DP concentrations in the tissues decreased in the following order: abdominal fat > liver > stomach > heart > outer tenderloin > lung > hind leg meat > kidney > small intestine > tail fat > spleen > brain. Apart from brain and fat, anti-DP is enriched more readily than syn-DP in sheep tissues, but syn-DP is more readily enriched in brain and abdominal fat. The factors influencing DP distributions in sheep tissues were assessed by determining the DP to sheep serum albumin binding forces, binding types, and binding sites by fluorescence spectroscopy. The results indicated that anti-DP more readily binds to sheep serum albumin than does syn-DP. Therefore, sheep serum albumin will more readily transport anti-DP than syn-DP to sheep tissues, and anti-DP will be enriched more than syn-DP in the tissues. The molecular diameter of DP is the main factor affecting DP concentrations in sheep brain and fat because of the blood−brain barrier and because the main source of DP to abdominal fat is dermal contact.

New emerging polybromobiphenyls in serum of general population and their disruption on thyroid hormone receptor ß1.

After the PBBs pollution incident in Michigan, a large number of studies focused on the exposure of people to 2,2',4,4',5,5'-hexabromobiphenyl (BB-153), but paid less attention to other PBBs congeners in human serum. In this study, three monobromobiphenyls (BB-1, BB-2 and BB-3), five dibromobiphenyls (BB-4, BB-7, BB-9, BB-10 and BB-15), decabromobiphenyl (BB-209) and BB-153 in the serum of the general population in Wuxi from 2012 to 2016 were detected by GC-MS/MS. The most abundant congeners in serum samples were BB-1(median 254 ng·g-1 lw), BB-10 (median 141 ng·g-1 lw) and BB-209 (median 68.4 ng·g-1 lw). The detection rate of BB-153 is less than 10%, and the concentration is far lower than that in other areas. The concentrations of BB-1, BB-10 and BB-209 are 3-4 orders of magnitude higher than the maximum concentration of BB-153. Serum concentrations of BB-209 increased significantly from 2012 to 2016 (p = 0.025). In addition, the concentrations of BB-1 in serum of females were significantly higher than that of males, and the concentrations of BB-1, BB-10 and BB-209 in serum of young adults were significantly higher than that of middle-aged adults. Finally, we found that BB-1 and BB-10 may have similar disruption on the binding of T3 and TRß1 as BB-153, while BB-209 has little effect on the binding of T3 and TRß1. This suggests that we should pay more attention to the damage of BB-1 and BB-10 to thyroid in the future.

Effect of Affinity between Dechlorane Plus and Human Serum Albumin on Its Serum Concentration in a General Population.

Dechlorane Plus (DP) has been detected in human serum around the world. Determining how DP binds to human serum albumin (HSA) could improve our understanding of the effects of DP in humans. The results of a fluorescence titration experiment indicated that DP binds to HSA at the interface between domains IIA and IIB, and HSA has more affinity for anti-DP than syn-DP. The DP concentrations in serum from 33 people living in Wuxi City, China, were determined in five consecutive years (2012-2016). The total concentrations of the two DP isomers were 1.73-16.3 ng·g-1 lipid weight (mean 4.7 ng·g-1 lipid weight). No clear increasing or decreasing temporal trend was found in the DP concentrations in serum over the study period. The affinity between DP and HSA will increase as the amount of fatty acids combined with HSA increases. This explained the syn-DP and anti-DP concentrations in serum being higher for overweight people than for normal weight people. Ethanol can occupy the DP binding sites on HSA. This explained the syn-DP and anti-DP concentrations being lower for alcoholic people than for nonalcoholic people.

[Pollution Distribution and Ecological Risk Assessment of Heavy Metals in River Sediments from the Ancient Town of Suzhou].

The contents of heavy metals (Cd, Cu, Cr, As, Mn, Ni, Pb, and Zn) in sediments from 20 representative sections of the ancient town of Suzhou were analyzed to determine the pollution degree and potential ecological risk, and pollution sources were identified. The results showed that the average concentrations of Cd, Cu, Cr, As, Mn, Ni, Pb, and Zn in river sediments from the ancient town of Suzhou were 1.1, 142.6, 90.2, 17.2, 800.1, 63.3, 199.1, and 384.2 mg·kg-1, respectively, and the proportions of sampling points that exceeded the soil background value of Jiangsu Province were 100%, 100%, 65%, 95%, 70%, 100%, 95%, and 100%, respectively. The geo-accumulation index indicated that the pollution degree of heavy metals followed the order of Pb > Cd > Cu > Zn > Cr > Ni > As > Mn. In general, high Pb pollution, moderate Cd, Cu, Zn, and Cr pollution, slight Ni and As pollution, and no Mn pollution were observed. The potential ecological risk index for heavy metals was determined to follow the order of Cd > Pb > Cu > As > Ni > Zn > Cr > Mn. Generally, Cd, Pb, and Cu presented moderate potential ecological risk, and the others presented low potential ecological risk. The average concentration of heavy metals, geo-accumulation index, and potential ecological risk index of river sediments in the northern and southern of ancient town were all higher than that of Ganjiang River and Huancheng River, indicating that the control of heavy metals should focus on the inner part of the ancient town. According to correlation analysis and principal component analysis, Cd, Cu, Cr, As, Ni, Pb, and Zn might be derived from man-made factors such as fertilizer, road aging, tire wear, exhaust emissions and so on, which Mn was mainly derived from natural factors.

Uptake and translocation of polybrominated diphenyl ethers in the rhizosphere soil-crop-atmosphere system in e-waste dismantling areas in Taizhou, China.

Air, crop, and rhizosphere soil samples were collected from e-waste dismantling areas in Taizhou City (Zhejiang Province, China). The mean PBDEs (Polybrominated diphenyl ethers) concentrations in air in the Fengjiang and Binhai areas were 27.8 and 25.1 pg m-3, respectively (no significant difference, P > 0.05). The mean PBDE concentrations in rhizosphere soil from Fengjiang and Binhai were 9.19 × 104 and 1.34 × 103 pg g-1 dry weight, respectively (no significant difference, P > 0.05). The mean PBDE concentrations in the crop samples from Fengjiang and Binhai were 1.38 × 103 and 6.64 × 102 pg g-1 dry weight, respectively (no significant difference, P > 0.05). PBDEs with≥6 bromine atoms (BDEs-153, -154, -183, and -190) were not translocated from the crop roots to other tissues. PBDEs were taken up by crops selectively. The root epidermis effectively prevented PBDEs from entering edible crop parts and kept the PBDE concentrations in edible roots low. PBDEs with≤5 bromine atoms (BDEs-15, -28, -47, -66, -85, -99, and -100) were selectively enriched from the rhizosphere soil into crop roots, but PBDEs with more bromine substituents were not transferred from the rhizosphere soil to the crop roots. PBDEs with≥6 bromine atoms were selectively enriched from the atmosphere into crop leaves. Crop roots and leaves took up PBDEs with ortho bromine substituents more readily than PBDEs with meta bromine substituents because the octanol-water partition coefficients are lower for ortho-brominated than meta-brominated PBDEs.

Uptake and distributions of polycyclic aromatic hydrocarbons in cultivated plants around an E-waste disposal site in Southern China.

Polycyclic aromatic hydrocarbons (PAHs) in air, soil, and cultivated plants at e-waste disposal sites in Taizhou, Zhejiang Province, were determined to allow PAH uptake by and distributions in plants to be investigated. The PAH distributions in air, rhizosphere soil, and surface soil were markedly different. This indicated that root morphology variations and root exudates may affect PAH compositions in soil around plants. The PAH concentrations in the plant samples were 29.7-2170 ng/g. The lowest PAH concentration was found in a peeled taproot sample. The PAH concentration gradients from the plant shoots to roots suggested that PAHs entered the plants through various pathways. The three- and four-ring PAHs were found to be absorbed more readily than the higher-molecular-weight (five- and six-ring) PAHs. This indicated that high-molecular-weight PAHs in soil can be prevented from entering plants, particularly taproots, via root exudates and the root peel. For most plants, the highest PAH concentrations were found in leaves, indicating that atmospheric deposition may strongly affect PAH concentrations in aerial plant parts. High-molecular-weight PAHs are more readily absorbed from ambient air by leaves than other parts. Lower PAH concentrations were found in fruits than other plant parts. This and the differences in PAH distributions between fruits and other aerial parts indicated that PAHs may be selectively absorbed by fruits.

Dechlorane Plus Biomagnification and Transmission through Prairie Food Webs in Inner Mongolia, China.

Dechlorane Plus (DP) is found widely in the environment. It is important to study DP enrichment and biomagnification in terrestrial ecosystems to improve our understanding of the possible effects of DP on the environment and human health. A total of 90 samples, including plant and animal tissues, were collected from Xilingol Prairie in Inner Mongolia, China. The DP concentrations in different species were assessed, and transmission of DP through food webs containing ectotherms and endotherms was assessed. The compound was detected in the biotic samples (plant; range 0.133-0.422 ng/g dry wt), in animal muscle (range: not dected-5.70 ng/g lipid wt), and in animal hair (range: not dected-2.03 ng/g dry wt), indicating that DP is present in remote environments such as Xilingol Prairie. These findings suggest that DP can undergo long-distance transport in the environment. Biomagnification factors (ectotherms: range 0.146-88.0, endotherms: range 0.866-17.2) and anti-DP/total DP concentration ratios (fanti values of 0.412-0.787) for the prairie animals were calculated. Ectotherms were found to selectively enrich syn-DP, and stereoselective enrichment increased moving up the food web. Lower-trophic-level endotherms strongly stereoselectively enriched syn-DP, and higher-trophic-level endotherms stereoselectively enriched anti-DP. Environ Toxicol Chem 2021;40:413-421. © 2020 SETAC.

High surface area for La1-xSrxFeO3 (x=0, 0.4, 0.6) as bifunctional catalyst for rechargeable Li-O2 batteries.

Three-dimensionally mesoporous La1-xSrxFeO3 (x = 0, 0.4, 0.6) precursors have been synthesized through a facile solvothermal process. After high-temperature sintering, La1-xSrxFeO3 still exhibits uniform morphology and good dispersibility, which provides a porous structure and favorable surface area. Particularly, La0.4Sr0.6FeO3 shows the biggest surface area of 58 m2 g-1. Doping also induces the generation of oxygen vacancies and Fe4+, which is beneficial for the conductivity and catalytic activity of the materials. Complete with favorable structure and electrochemical activity, La0.4Sr0.6FeO3 exhibits bifunctional catalytic activity in alkaline solution. Applied as a cathode catalyst in Li-O2 batteries, it shows a larger discharge capacity of 23 905 mA h g-1 and a better cycling stability of 100 cycles.

Correlations between dechlorane plus concentrations in paired hair and indoor dust samples and differences between dechlorane plus isomer concentrations in hair from males and females.

Dechlorane plus (DP) is found widely in environmental media. Determining DP concentrations in dust and hair and identifying relationships between the concentrations in dust and hair could improve our understanding of the effects of DP in humans. DP concentrations in 48 hair samples from male and female students and in 30 indoor dust samples from dormitories and classrooms used by the students were determined. The objective was to determine the difference of DP concentration between indoor dust and hair, and to explore the effect of DP in dust on DP in hair of male and female students. The mean DP concentration was significantly higher in male dormitory dust than female dormitory dust, and the estimated DP dose through exposure to dust was also significantly higher for males than females. However, the mean DP concentration was significantly higher for hair from females than from males. The median DP fanti was significantly lower for hair than dust, indicating DP may be stereoselectively metabolized by humans. The median DP fanti was significantly higher for hair from females than from males, indicating DP may be metabolized differently by males and females. Human serum albumin preferred combination with anti-DP, rather than syn-DP. DP in indoor dust was not a major direct source of the DP in the hair, meaning DP in hair mainly came from within the body. There may be significant differences in DP, particularly anti-DP, metabolism in males and females.

Different organophosphate flame retardant and metabolite concentrations in urine from male and female university students in Beijing and an assessment of exposure via indoor dust.

Organophosphate flame retardants (OPFRs) have been found in human samples and associated with adverse health effects. In the present study, OPFR and dialkyl and diaryl phosphate (DAP) concentrations in human urine were determined and differences in the concentrations in urine from males and females were investigated. Urine samples from 22 male and 26 female university students, paired dust samples from the dormitories (13 each for males and females), and 10 dust samples from university teaching buildings were analyzed. The tri-o-cresyl phosphate (TOCP), tri-p-cresyl phosphate (TPCP), and tris(2-chloroisopropyl)phosphate (TCIPP) concentrations were significantly higher (p = 0.049, 0.023, and 0.027, respectively) in urine from the female students than in urine from the male students. Similar differences were found between males and females in terms of OPFR exposure and OPFR concentrations in urine for three-fourths of the OPFRs. Questionnaire answers and calculations indicated that disparities in OPFR concentrations in urine were mainly caused by females spending much more time than males in dormitories. Organophosphate flame retardants may pose degrees of health risk similar to those of polybrominated diphenyl ethers (PBDEs), and this must be considered when making decisions about controlling flame retardants. We are not aware of any previous studies that simultaneously monitor OPFRs and DAPs in human urine in China. Environ Toxicol Chem 2019;38:760-768. © 2019 SETAC.

Human exposure to brominated flame retardants through dust in different indoor environments: Identifying the sources of concentration differences in hair from men and women.

Brominated flame retardants (BFRs) can accumulate in humans and are associated with adverse health effects. The study was conducted to determine the differences in Polybrominated diphenyl ethers (PBDEs) and alternative brominated flame retardant (Alt-BFR) concentrations between men and women. We analyzed hair samples from 14 male and 20 female university students, paired dust samples from their dormitories (10 for males and 8 for females), and six dust samples from university teaching buildings. The total PBDE concentrations in hair from females were significantly (three times) higher (p = 0.012) than that from males (means 372 and 109 ng/g, respectively). The mean total PBDE concentrations in classroom and dormitory dust were 36100 and 2012 ng/g, respectively. The PBDE patterns were different in the male and female hair samples, as were the patterns in the classroom and dormitory dust. There are no reports concerning human exposure to BFRs through dust that was assessed considering academic and residential environments simultaneously. The differences between BFR exposure for males and females and the differences between BFR concentrations in hair samples from males and females were consistent for 71.4% of the compounds. However, using only dormitory dust in the calculations gave consistent differences only for 28.6% of the compounds, suggesting that the BFR concentration differences in hair were mainly because females spent much more time than males in classrooms.