Evidence for a mutual effect of biofilms, suspended particles and sediments on DDT sorption

This report shows that biofilms and suspended particles double DDT sorption capacity on surface sediments. Sorption of pollutants by solid materials, such as biofilms, suspended particles and sediments, is a major process controlling the fate of hydrophobic pollutants in natural waters. Most previous studies focused on the sorption of hydrophobic pollutants by single-solid material, whereas few studies considered the mutual effect of different solids on the sorption. Various solid materials often interact with each other when they coexist in the same system. Therefore, pollutants sorption could be different from that in the single-solid sorption system. Here we studied the mutual effect of biofilms, suspended particles and surface sediments on the sorption of dichlorodiphenyltrichloroethane (DDT). Results showed that biofilms and suspended particles double DDT sorption capacity on surface sediments. The different effects were mainly determined by distinct components and structures of the three solid materials, particularly by organic components. Here we show the mutual effect of biofilms, suspended particles and sediments on DDT sorption.     

Mechanisms mediating plant distributions across estuarine landscapes in a low-latitude tidal estuary

Understanding of how plant communities are organized and will respond to global changes requires an understanding of how plant species respond to multiple environmental gradients. We examined the mechanisms mediating the distribution patterns of tidal marsh plants along an estuarine gradient in Georgia (USA) using a combination of field transplant experiments and monitoring. Our results could not be fully explained by the "competition-to-stress hypothesis" (the current paradigm explaining plant distributions across estuarine landscapes). This hypothesis states that the upstream limits of plant distributions are determined by competition, and the downstream limits by abiotic stress. We found that competition was generally strong in freshwater and brackish marshes, and that conditions in brackish and salt marshes were stressful to freshwater marsh plants, results consistent with the competition-to-stress hypothesis. Four other aspects of our results, however, were not explained by the competition-to-stress hypothesis. First, several halophytes found the freshwater habitat stressful and performed best (in the absence of competition) in brackish or salt marshes. Second, the upstream distribution of one species was determined by the combination of both abiotic and biotic (competition) factors. Third, marsh productivity (estimated by standing biomass) was a better predictor of relative biotic interaction intensity (RII) than was salinity or flooding, suggesting that productivity is a better indicator of plant stress than salinity or flooding gradients. Fourth, facilitation played a role in mediating the distribution patterns of some plants. Our results illustrate that even apparently simple abiotic gradients can encompass surprisingly complex processes mediating plant distributions.     

Systematical strategies for wastewater treatment and the generated wastes and greenhouse gases in China

China now faces double challenges of water resources shortage and severe water pollution. To resolve Chinese water pollution problems and reduce its impacts on human health, economic growth and social development, the situation of wastewater treatment was investigated. Excess sludge and greenhouse gases (GHGs) emitted during wastewater treatment were also surveyed. It is concluded that Chinese water pollution problems should be systematically resolved with inclusion of wastewater and the solid waste and GHGs generated during wastewater treatment. Strategies proposed for the wastewater treatment in China herein were also adequate for other countries, especially for the developing countries with similar economic conditions to China.     

发酵液回流对餐厨垃圾厌氧消化的影响

针对厌氧发酵液回流可提高厌氧系统性能,而不适的回流比例又会造成系统酸化的现象,采用单相连续反应器研究了发酵液回流及不同回流比对餐厨垃圾厌氧消化过程的影响。结果表明:在1 gVS/L的有机负荷下进行三种比例(10%、30%、50%)的发酵液回流使系统日平均产气量比不回流阶段分别提高0.7%、13.0%、4.9%,且对气体甲烷含量无显著影响。回流使VFA降解更充分,也使系统缓冲能力得到调节,但在较高的回流比(50%)下会造成Na+积累从而抑制系统产气性能。     

Metals and metalloids in PM10 in Nandan County,Guangxi, China,and the health risks posed

Intense mining, smelting, and tailing activities of polymetallic ore deposits have affected the environment in Nandan County, Guangxi, China. Samples of particulates with aerodynamic diameters low or equal 10 μm (PM₁₀) were collected in Nandan County to investigate the concentrations of and health risks posed by 17 metals and metalloids in the PM₁₀. The metal and metalloid concentrations were lower than those found in other industrial cities. The mean Cr concentration was 7.48 ng/m³. Significant higher metal and metalloid concentrations were found in PM₁₀ from mining areas (Dachang and Chehe) than from the control area (Liuzhai) (p < 0.05). Principal component analysis indicated that the main sources of Ba, Co, Cr, Fe, K, Mg, Mo, Na, and Sr were resuspension of the soil produced through mineral erosion, the main sources of As, Cd, Cu, Pb, Sb, and Zn were smelting and mining activities, and the main source of Ni was fossil fuel combustion. Higher non-carcinogenic and carcinogenic risks were posed in Dachang and Chehe than in Liuzhai. The non-carcinogenic risks posed to adults and children by individual metals and metalloids in PM₁₀ at all the sites were low, but the non-carcinogenic risks posed to children by all the metals and metalloids together exceeded the safe level (i.e., risk value > 1). The carcinogenic risks posed by Cd, Ni, and Pb were negligible at all sites, while As, Co, and Cr posed potential carcinogenic risks to the residents.

     

Epigenetic effect of long-term bisphenol A exposure on human breast adenocarcinoma cells

In this research, epigenetic effects of bisphenol A (BPA) on human breast cancer MCF-7 cells were analyzed. Genome-wide DNA methylation and gene expression were analyzed in MCF-7 cells exposed to BPA (10^?5 and 10^?6 mol/L for 5 weeks). No significant changes in the global level of 5-methyl-2′-deoxycytidine and 5-hydroxymethyl-2′-deoxycytidine were observed. DNA methylation profiling analysis indicated that BPA exposure resulted in the hypermethylation of FOXK2, LKB1, LMX1A and CUGBP2 and the hypomethylation of PTPRN2, TRIM27, BCAS3 and ZNF423. Decreased expression of apoptosis genes (P38 and BCL2L1) and increased expression of chemokine (Cxcl2 and ccl20) were detected. Changes of these genes were speculated to affect the ERα-related cell growth as well as cell apoptosis.     

Effects of different mowing frequencies on soil carbon and nitrogen changes in leymus chinensis steppe of Hulun Buir北大核心CSCD

Mowing is the main management of Hulun Buir grasslands in Inner Mongolia; therefore, understanding the changes of soil organic carbon (SOC), total nitrogen (TN), and carbon sequestration under different mowing frequencies will provide an important scientific basis for grassland carbon sink management in Inner Mongolia. Three treatment plots were devised in the study area, including enclosed sample (Y), mowing every other year (2G), and mowing once a year (1G), where SOC, TN content and storage were investigated. The results showed that with increased mowing frequency, the SOC and TN content showed a decreasing trend in the 0-30 cm depth soil layer. The SOC and TN content were different in each soil layer, which decreased gradually with increasing soil depth in Y and 2G plots, whereas increased gradually in 1G plots. The soil carbon storage was significantly correlated with the soil nitrogen storage, and both showed a significant linear decrease with increased mowing frequency, which showed as carbon and nitrogen loss. In 2G plots, the soil carbon storage decreased by 17.1% and soil nitrogen storage decreased by 20.8%. In 1G plots, the soil carbon storage decreased by 21.6% and soil nitrogen storage decreased by 29.3%. The results showed that the change of soil carbon and nitrogen was sensitive to mowing frequency for the Hulun Buir grassland. It is possible to reduce the loss of carbon and nitrogen by reasonably controlling mowing frequency, and the sustainable use of grassland could be achieved with appropriate fertilization. Keywords. © 2018 Science Press. All rights reserved.     

Cd~(2+)暴露对斑马鱼肝脏和卵巢抗氧化和免疫系统的影响及蓝LED光预暴露的保护作用

本研究探讨了急性镉暴露(Cd~(2+))对斑马鱼抗氧化和免疫系统的影响及蓝LED光源(LDB)预暴露的缓解作用。斑马鱼均分为2组,分别用白炽灯和LDB处理4周(辐照度为0.9 W·m-2)。4周后每组再分为2个小组,分别在白炽灯下用0和0.97 mg·L~(-1)Cd~(2+)的水体处理4 d。结果表明:Cd~(2+)暴露导致肝脏和卵巢丙二醛(MDA)和一氧化氮(NO)含量的显著升高。在肝脏中,Cd~(2+)暴露下调了铜锌超氧化物歧化酶(Cu/Zn-SOD)和过氧化氢酶(CAT)的酶活和m RNA表达水平,上调了环氧化酶2(COX-2)和诱导型一氧化氮合酶(i NOS)的表达和酶活。在卵巢中,Cd~(2+)导致Cu/Zn-SOD和CAT的表达,CAT、COX-2和i NOS的酶活显著升高。在卵巢中,LDB预暴露可显著缓解Cd~(2+)引起的MDA和NO含量、Cu/Zn-SOD的表达、CAT的表达和酶活、COX-2和i NOS的酶活的升高。在肝脏中,LDB预暴露不能影响Cd~(2+)引起的MDA和NO含量的升高,但是显著缓解了Cd~(2+)引起的Cu/Zn-SOD和CAT表达和酶活的下降和COX-2和i NOS表达的升高。在这些过程中,核转录相关因子2(Nrf2)和核转录因子-κB(NF-κB)与其目标基因的表达及其抑制因子Kelch样ECH联合蛋白1(Keap1a和Keap1b)和抑制蛋白激酶(IκBαa和IκBαb)显示了紧密的关联性。综上结果表明,斑马鱼急性Cd~(2+)暴露后,机体处于氧化应激状态,导致肝脏和卵巢氧化性损伤和炎症的产生,而LDB预暴露能够改善机体这种不利状态。这个过程可能分别涉及Nrf2和NF-κB诱导的抗氧化和免疫系统。     

低剂量丙烯酰胺多世代持续暴露对秀丽隐杆线虫的损伤作用

论文研究了丙烯酰胺(acrylamide,AA)低剂量多代持续暴露对模式生物秀丽隐杆线虫(Caenorhabditis elegans,C.elegans)的发育、生殖、寿命和捕食行为能力的影响。将线虫暴露于不同剂量水平的AA中,检测对当代线虫的发育周期、后代数量、寿命和捕食行为的影响,结果显示,1.0 mmol·L~(-1)AA水平可诱发当代线虫发育周期延长和后代数量减少(P 0.05),0.05mmol·L~(-1)和0.001 mmol·L~(-1)水平可分别诱发捕食行为能力下降和寿命缩短(P0.05)。进一步选取对当代线虫不产生明显损伤效应的AA剂量,将线虫进行多代持续暴露处理,结果显示,0.01 mmol·L~(-1)AA分别可在第2代g1和第3代g2诱发发育周期延长和后代数量减少(P0.05),0.005 mmol·L~(-1)AA可在第2代g1引起摄食行为能力下降,0.0001 mmol·L~(-1)(约7μg·L~(-1),低于推测人的平均AA暴露水平)的AA在第2代g1即可诱发寿命缩短(P0.05)。以上结果表明AA生物学毒性可以在后代间积累,极低剂量AA多代持续暴露仍可诱发生物学损伤。