外源Mo降低As(III)和As(V)对水稻的毒性及As的积累

通过溶液培养试验,研究外源添加Mo对2种价态砷(As(III)和As(V))胁迫下水稻吸收积累Mo和As的影响。结果表明,这2种价态的As对水稻生长均有抑制作用,As(III)比As(V)对水稻毒害更明显,添加Mo可缓解As对水稻的毒害。As添加可影响水稻根系和茎叶对Mo的吸收积累,但是不同价态As对Mo积累量的影响不一致。同时,Mo的添加也可以显著地降低水稻根系和茎叶对2个价态As的吸收积累。在100 μmol?L^-1 As(III)处理下,添加0.1和0.5 mg?L^-1的Mo可导致水稻根系As积累量分别比对照处理降低38.8%和52.8%,茎叶As积累量分别降低5.1%和10.6%;当As(V)浓度为100 μmol?L^-1时,添加0.1和0.5 mg?L^-1的Mo可导致水稻根系As积累量分别比对照处理降低15.4%和62.4%,茎叶As积累量分别降低11.9%和23.7%。Mo的添加还能显著地降低2种价态As在水稻根系和茎叶中的富集系数。因此,通过施用适量的Mo肥可以用来防治农田As污染,降低As对人体健康的危害。     

甲醛暴露时间延长加剧小鼠哮喘模型肺氧化损伤并促进IL-17表达

为了探究不同暴露时间甲醛对小鼠哮喘模型肺氧化应激及IL-17表达的影响,用浓度为3.0 mg·m~(-3)的甲醛气体吸入染毒,同时将48只雄性Balb/c小鼠随机分为6组:(1)对照组(生理盐水组);(2)ovalbumin(OVA)致敏组;(3)0.5 h甲醛+OVA组;(4)1h甲醛+OVA组;(5)1.5 h甲醛+OVA组;(6)2 h甲醛+OVA组,以不同时间长度进行甲醛暴露,连续35 d。OVA致敏组、0.5 h甲醛+OVA组、1 h甲醛+OVA组、1.5 h甲醛+OVA组、2 h甲醛+OVA组均在第11、18及25天腹腔注射OVA致敏液(5 mg OVA+175 mg Al(OH)_3+30 mL生理盐水),第29~35天(共计1周)进行1%OVA雾化(30 min·d~(-1)),每日1次,诱发哮喘。第36天进行以下操作:取肺组织测定肺系数并制作肺匀浆,检测肺组织中活性氧自由基(ROS)、丙二醛(MDA)和还原型谷胱甘肽(GSH)的含量,并采用ELISA法检测肺组织中IL-17的水平。同时,采用HE染色法观察小鼠肺部气道的病理学变化。结果显示,在浓度为3.0 mg·m~(-3)的甲醛气体吸入染毒条件下,与对照组相比,1.5 h甲醛+OVA染毒组、2 h甲醛+OVA染毒组ROS、MDA、IL-17含量上升,具有统计学意义(P0.01)。同时,随着暴露时间长度的增加,小鼠肺部气道出现明显病理学变化。综上所述,每天2 h甲醛+OVA染毒能对小鼠肺造成损伤并恶化OVA对小鼠肺的损伤,产生炎症反应,并通过氧化应激反应介导。     

外源Mo降低As(Ⅲ)和As(Ⅴ)对水稻的毒性及As的积累

通过溶液培养试验,研究外源添加Mo对2种价态砷(As(Ⅲ)和As(Ⅴ))胁迫下水稻吸收积累Mo和As的影响。结果表明,这2种价态的As对水稻生长均有抑制作用,As(Ⅲ)比As(Ⅴ)对水稻毒害更明显,添加Mo可缓解As对水稻的毒害。As添加可影响水稻根系和茎叶对Mo的吸收积累,但是不同价态As对Mo积累量的影响不一致。同时,Mo的添加也可以显著地降低水稻根系和茎叶对2个价态As的吸收积累。在100μmol·L~(-1)As(Ⅲ)处理下,添加0.1和0.5 mg·L~(-1)的Mo可导致水稻根系As积累量分别比对照处理降低38.8%和52.8%,茎叶As积累量分别降低5.1%和10.6%;当As(V)浓度为100μmol·L~(-1)时,添加0.1和0.5 mg·L~(-1)的Mo可导致水稻根系As积累量分别比对照处理降低15.4%和62.4%,茎叶As积累量分别降低11.9%和23.7%。Mo的添加还能显著地降低2种价态As在水稻根系和茎叶中的富集系数。因此,通过施用适量的Mo肥可以用来防治农田As污染,降低As对人体健康的危害。     

The impacts of Robinia pseudoacacia litter cover and roots on soil erosion in the Loess Plateau,China

The impacts of vegetation on soil erosion are closely associated with the combined effects of above- and below-ground components. In this study, we explore the effects and contributions of Robinia pseudoacacia litter cover and roots on soil erosion. Experiment sites under natural conditions with vegetation cover, plant roots and bare ground plots were investigated for overland flow discharges of 0.5, 1.0 and 2.0?L?s^?1 and slope gradients of 8.7%, 17.6%, 26.8%, 36.4% and 46.6%. Results indicate that litter cover and roots have a significant impact on sediment reduction; soil loss was reduced by about 57% and plant roots had a greater impact on the reduction of soil erosion than litter cover. The combination of litter cover and plant roots had a significant effect on decreasing K_r, increasing τ_c and consequently strengthening soil resistance capacity to erosion. When plants and roots existed on the slopes, K_r decreased by 81% and 66%, and τ_c increased by 319% and 246%, respectively, in comparison with bare slopes. These results illustrate the importance of high-forest in controlling soil erosion by quantifying the specific contributions of litter cover and plant roots in erosion reduction in the Loess Plateau.     

Bisphenol S induces oxidative stress and DNA damage in rat spermatozoa in vitro and disrupts daily sperm production in vivo

Bisphenol S has been introduced into some industrial applications and it may act as a xeno-estrogen that can alter endocrine functions and reproduction. The present study was carried out to examine the effect of bisphenol S exposure on oxidative stress, generation of reactive oxygen species, and DNA integrity in rat spermatozoa in vitro and daily sperm production and sperm DNA damage in vivo. Sperm were incubated with bisphenol S at concentrations of 0.5, 1, 10, and 100 µg/L. At the highest concentration, bisphenol S induced formation of reactive oxygen species, caused lipid peroxidation, affected superoxide dismutase levels, and increased DNA fragmentation. Adult rats were exposed to doses of 0.5, 5, 25, and 50 µg/kg/d for 28 days. Decrease in daily sperm production and an increase in sperm DNA damage was observed at the highest dose in the 50 µg/kg/d treated group, but sperm motility was not reduced.     

Recycling and utilization of metabolic wastes for energy production is an index of biochemical adaptation of fish under environmental pollution stress

The activity levels of lactate dehydrogenase andlactic acid were assessed in various tissues of the fishduring exposure to lethal concentration of group-IIPyrethroids (deltamethrin, cypermethrin, fenvalerate andfluvalinate) for a period of 72 hours. The results showedsteady increased levels in all the tissues (blood,muscle, brain and liver) with response patterncharacteristic of their own. The increased LDH activityand lactic acid levels indicate the shifting of aerobicglycolysis to anaerobiosis and its further utilizationfor energy production during adaptation to toxic stress.     

Incidence of stress in benthic communities along the U.S. Atlantic and Gulf of Mexico coasts within different ranges of sediment contamination from chemical mixtures

Synoptic data on concentrations of sediment-associated chemical contaminants and benthic macroinfaunal community structure were collected from 1,389 stations in estuaries along the U.S. Atlantic and Gulf of Mexico coasts as part of the nationwide Environmental Monitoring and Assessment Program (EMAP). These data were used to develop an empirical framework for evaluating risks of benthic community-level effects within different ranges of sediment contamination from mixtures of multiple chemicals present at varying concentrations. Sediment contamination was expressed as the mean ratio of individual chemical concentrations relative to corresponding sediment quality guidelines (SQGs), including Effects Range-Median (ERM) and Probable Effects Level (PEL) values. Benthic condition was assessed using diagnostic, multi-metric indices developed for each of three EMAP provinces (Virginian, Carolinian, and Louisianian). Cumulative percentages of stations with a degraded benthic community were plotted against ascending values of the mean ERM and PEL quotients. Based on the observed relationships, mean SQG quotients were divided into four ranges corresponding to either a low, moderate, high, or very high incidence of degraded benthic condition. Results showed that condition of the ambient benthic community provides a reliable and sensitive indicator for evaluating the biological significance of sediment-associated stressors. Mean SQG quotients marking the beginning of the contaminant range associated with the highest incidence of benthic impacts (73–100% of samples, depending on the province and type of SQG) were well below those linked to high risks of sediment toxicity as determined by short-term toxicity tests with single species. Measures of the ambient benthic community reflect the sensitivities of multiple species and life stages to persistent exposures under actual field conditions. Similar results were obtained with preliminary data from the west coast (Puget Sound).     

Prediction of Annual Streambank Erosion for Sequoia National Forest,California

Many bank erosion models have limitations that restrict their use in wildland settings. Scientists and land managers at the Sequoia National Forest would like to understand the mechanisms and rates of streambank erosion to evaluate management issues and post‐wildfire effects. This study uses bank erosion hazard index (BEHI) and near‐bank stress (NBS) methods developed in Rosgen (2006 Watershed Assessment of River Stability and Sediment Supply [WARSSS]) for predicting streambank erosion in a geographic area that is dominated by colluvium and in which streambank erosion modeling has not been previously evaluated. BEHI evaluates bank susceptibility to erosion based on bank angle, bank and bankfull height, rooting depth and density, surface protection, and stratification of material within the banks. NBS assesses energy distribution against the bank measured as a ratio of bankfull near‐bank maximum depth to mean bankfull depth. We compared BEHI classes and NBS to actual bank erosion measured from 2008 to 2012. This index predicted streambank erosion with clear separation among BEHI ratings with R² values of 0.76 for extreme, 0.37 for high/very high, 0.49 for moderate, and 0.70 for low BEHI. The relationships between measured erosion and BEHI extend the application of BEHI/NBS to a new region where they can inform management priorities, afforestation, stream/riparian restoration projects, and potentially burned area rehabilitation.