氟化氢对植物抗氧化酶活性的影响

采用人工熏气方法研究ＨＦ污染条件下大豆和菜豆叶片中４种抗氧化酶的活性变化，结果表明它们对氟的敏感性差异很大：超氧化物歧化酶最为敏感，抗坏血酸过氧化物酶和非特异性过氧化物酶次之，而过氧化氢酶活性基本无变化，就两种供试植物而言，大豆的抗氧化酶对氟更为敏感；就植物生长阶段而言，开花期的抗氧化酶对氟的敏感性较苗期为大。在此基础上提出，氟污染环境中植物ＳＯＤ、Ａ－ＰＯＤ和Ｎ－ＰＯＤ的活性受抑与植物氟害有关。     

“颗颗灵”矫治金川雪梨树缺铁黄叶病

本文采用树干深层埋植铁剂“颗颗灵”对金川雪梨缺铁黄叶病进行了同株异枝的对比试验，结果表明经过埋植处理的缺铁黄化叶１５天均匀复绿，叶绿素、叶厚、百叶重、百叶体积和百叶面积等叶片生理、生长指标比对照增加显著或极显著，黄化叶、褐变叶发病率和黄化、褐变指数等生理病害指标下降到０值。     

MODELING WATER BALANCE WITH THE ERHYM MODEL ON SOUTH TEXAS RANGELANDS1

ABSTRACT: Understanding the hydrologic processes of rangeland plant communities is essential to determine if water augmentation through shrub management is feasible. Vegetation manipulation studies are costly, difficult to accurately replicate, and often require more than 10 years to determine treatment effect on the water budget. If properly applied, hydrologic simulation models are an attractive alternative for assessing vegetation manipulation practices. The ERHYM-II model was evaluated to determine if it was capable of simulating the water balance for honey mesquite shrub clusters, grass interspaces, and bare soil in south Texas. The simulated water budget was within 2 percent of the measured evapotranspiration for the shrub clusters and grass interspaces. The model underestimated the number of runoff events and overestimated runoff volume for the grass interspace and shrub clusters. Simulated runoff was overestimated by approximately twofold for the grass interspace and threefold for the shrub clusters. Although simulated runoff was substantially overestimated, observed and simulated runoff only accounted for 3 to 6 percent of annual rainfall for the grass and shrub dominated areas, respectively. Simulated evapotranspiration was underestimated by 18 percent and soil water content was overestimated by 82 percent for the bare soil. The model underestimated evapotranspiration for the bare soil as a result of restricting evaporative losses to the first soil layer. Based on our analysis, the ERHYM-II model has the potential for simulating the annual water balance for semiarid rangeland plant communities where runoff and deep drainage are limited components of the water balance.     

Declines in Woodland Salamander Abundance Associated with Non-Native Earthworm and Plant Invasions

Abstract:  Factors that negatively affect the quality of wildlife habitat are a major concern for conservation. Non-native species invasions, in particular, are perceived as a global threat to the quality of wildlife habitat. Recent evidence indicates that some changes to understory plant communities in northern temperate forests of North America, including invasions by 3 non-native plant species, are facilitated by non-native earthworm invasion. Furthermore, non-native earthworm invasions cause a reduction in leaf litter on the forest floor, and the loss of forest leaf litter is commonly associated with declines in forest fauna, including amphibians. We conducted a mark-recapture study of woodland salamander abundance across plant invasion fronts at 10 sites to determine whether earthworm or plant invasions were associated with reduced salamander abundance. Salamander abundance declined exponentially with decreasing leaf litter volume. There was no significant relationship between invasive plant cover and salamander abundance, independent of the effects of leaf litter loss due to earthworm invasion. An analysis of selected salamander prey abundance (excluding earthworms) at 4 sites showed that prey abundance declined with declining leaf litter. The loss of leaf litter layers due to non-native earthworm invasions appears to be negatively affecting woodland salamander abundance, in part, because of declines in the abundance of small arthropods that are a stable resource for salamanders. Our results demonstrate that earthworm invasions pose a significant threat to woodland amphibian fauna in the northeastern United States, and that plant invasions are symptomatic of degraded amphibian habitat but are not necessarily drivers of habitat degradation.     

Laser Radiation Can Retard Leaf Senescence of Isatis Indigotica Seedlings Exposed to Elevated UV-B

以菘蓝(Isatis indigotica Fort)幼苗为实验材料,比较研究了He-Ne激光对增强UV-B(辐射强度:10.08kJ·m-2;照射时间8h·d-1;共照射8d)辐射损伤菘蓝叶片衰老的延缓作用.结果表明:与对照相比,UV-B辐射可导致环丁烷嘧啶二聚体(CPD)形成,显著降低蛋白酶、转氨酶、游离氨基酸、可溶性蛋白质含量,同时降低了叶绿素含量、气孔导度、水分利用率和生物量;而菘蓝幼苗经UV-B辐射处理后再用激光辐照(波长:633nm;功率密度:5.23mW·mm-2;束径:1.5mm;照射时间:5min·d-1),叶片中CPD含量显著降低,蛋白酶、转氨酶、游离氨基酸、可溶性蛋白质含量、叶绿素含量、气孔导度、水分利用率和生物量与单独UV-B处理组相比显著提高.上述结果表明激光辐照可以显著延缓UV-B损伤菘蓝叶片的衰老。     

南京市15种树木叶片对铅锌的吸收吸附能力

运用ICP仪对南京市15种主要绿化树木的叶片吸收吸附铅、锌的能力进行了研究。结果表明:15种树木叶片对铅、锌具有一定的吸收净化能力,并依污染物和树种的不同差异明显。在被研究的15个树种中,对铅吸收量较高的树种是雪松和圆柏,对锌吸收量较高的树种是杨树。对铅吸附能力强的树种是雪松,对锌吸附能力强的树种是海桐。叶片吸收和吸附铅的能力强的树种是雪松,叶片吸收和吸附锌的能力强的树种是杨树。最后,通过综合分析得出,杨树和雪松叶片中重金属铅和锌的累积量,可作为铅锌污染监测和评价的重要依据。     

High Immobilization of NH4+ in Danish Heath Soil Related to Succession,Soil and Nutrients: Implications for Critical Loads of N

During recent decades heathlands havechanged into grasslands in regions with high atmosphericnitrogen deposition. In regions with intermediatedeposition level (e.g., Denmark) changes have been lesspronounced which may be due to delay or decrease inresponse of the ecosystem. The mor layer (O horizon) mayplay an important role for this delay due to high sinkstrength for N. In this study, the capacity for netNH₄ ⁺ immobilization and mineralization wasstudied during short- and long-term incubations (2–36 days)of mor samples from Danish dry inland heaths. High short-term capacity for net NH₄ ⁺ immobilization wasfound to be a general characteristic of Danish heath morlayers both under heather (Calluna vulgaris) andcrowberry (Empetrum nigrum ssp nigrum), the latterdominating late stages in heathland succession. The netNH₄ ⁺ immobilization was higher under youngcompared to old or dead vegetation, and higher on lessnutrient poor soils than on extremely nutrient poor soils.The addition of N, P and C stimulated CO₂ productionand net NH₄ ⁺ immobilization, but not net Nmineralization. The immobilization of ¹⁵NH₄ ⁺caused release of dissolved organic N, increased N anddecreased C/N ratio in the microbial biomass, and indicatedgrowth of microorganisms with other metabolic abilitiesthan the indigenous population. No evidence was obtained ofstabilization of immobilized ¹⁵NH₄ ⁺ intosoil organic matter during the experiment. On background ofthe results and current knowledge it was concluded that therecognition of the high capacity for net NH₄ ⁺immobilization in mor layers does not allow for a raiseof critical loads for N for northern dry inland heaths.     

豆制品生产废水处理技术

简介豆制品生产废水的来源、废水水质及废水资源概况,着重介绍了豆制品废水处理的工艺,讨论了UASB反应器及在此基础上开发出的新型厌氧反应器及应用前景。     

Permethrin induced oxidative stress and neurotoxicity on the freshwater beetle Laccophilus minutus

Biomonitoring has become a useful tool in environmental risk assessment of anthropogenic activities releasing disturbing pollutants. Permethrin, used worldwide to control a wide range of pest insects, can threaten aquatic biota, potentially useful as precocious bioindicators in ecotoxicology. This study seeks to assess the acute toxicity permethrin to the freshwater beetle, its availability in water, as well as, its uptake. The acute toxicity of permethrin to non-target species was studied under laboratory conditions to assess its effect, after the exposure 48 h, on the freshwater beetle Laccophilus minitus considering changes in some enzymatic activities; a specific biomarker of neurotoxicity (acetylcholinesterase) and a non-specific biomarker of oxidative stress (superoxide dismutase and catalase). The rates of permethrin in water and insects were determined using gas chromatography. The low measured concentration of the pesticide 0.0013 μg/L didńt modify the SOD and CAT activities in comparison with controls, only the high concentrations (0.023 and 0.18 μg/L) induced a significant increase in the enzyme activity. A similar profile was recorded for the H₂O₂ level. The permethrin treatment induced a drastic depletion of AChE activity. As outcomes, uptake at a low level (<6.8 ± 0.43 ng/g dry weight) showed to be the factor underlying the alterations in the beetles exposed to permethrin. Such findings provide information on the behaviour of permethrin within the environment and its biological target through its neurotoxicity and induction of oxidative stress in a freshwater beetle.     

Biosynthesis of iron nanoparticles and their application in removing phosphorus from aqueous solutions

This paper reports the biosynthesis of nanoscale zero-valent iron (nZVI) using the extracts of Shirazi thyme leaf (Th-nZVI) and pistachio green hulls (P-nZVI). Scanning electron microscopy verified the successful synthesis of the poorly crystalline nZVI with a spherical shape and diameter in the range of 40–70 nm. According to X-ray diffraction and Fourier transform infrared spectroscope analyses, the synthesised nZVI were composed of iron oxides nanoparticles and ployphenol obtained from Shirazi thyme leaf and pistachio green hulls extracts acting as both reducing and capping agents. The phosphorus removal efficiency of Th-nZVI and P-nZVI increased with time and reached equilibrium at about 4 and 2h, respectively. Sorption of phosphorus on both sorbents was observed to be pH-dependent with maximum phosphorus removal occurring in the pH range of 2–5. Langmuir, Freundlich, Redlich–Peterson, and Temkin models were used to describe phosphorus sorption at pH 5 and maximum sorption capacity for Th-nZVI and P-nZVI was about 40.52 and 29.33?mg?g^?1, respectively. Correlation coefficient (R²) and standard errors of estimate showed that the Elovich model was better than other models at describing the kinetic data. These results suggested that the synthesised nZVI with Shirazi thyme leaf and pistachio green hulls extracts could be employed as an efficient sorbent for the remediation of phosphorus from contaminated water sources.