平江县生态弹性度定量分析评价研究

根据生态弹性力的概念,体会其深刻内涵及意义,根据区域实际情况,科学合理的构建平江县生态系统弹性力评价指标体系,运用综合评价的方法计算分析平江县生态系统弹性力,结果显示从2008年至2013年间,平江县生态系统弹性力呈下降趋势,主要原因是水资源总量下降,并对之后生态系统可持续发展和经济发展提出建议.     

恩诺沙星与Cu复合污染对白菜和西红柿根及芽伸长的抑制作用

抗生素恩诺沙星和重金属Cu是当今我国土壤中较常见的污染物。本研究考察了恩诺沙星与Cu复合污染对砖红壤中白菜和西红柿种子的根及芽伸长的影响,以评估恩诺沙星和Cu复合污染潜在的生态风险。结果表明,加入不同浓度的Cu时,土壤中的恩诺沙星浓度与2种作物的根伸长和芽伸长的抑制率均显著相关(P0.05);白菜的敏感性均大于西红柿;白菜和西红柿的根伸长对复合污染的生态毒性的敏感性均较芽伸长更高;与单一恩诺沙星胁迫相比,在恩诺沙星与Cu(100 mg·kg~(-1))或Cu(300 mg·kg~(-1))复合污染下,二者对白菜和西红柿的根及芽伸长抑制效应均表现为协同作用。试验结果在揭示恩诺沙星与Cu复合污染的生态毒性效应的同时,也为重金属和抗生素复合污染的生态风险评价提供科学依据。     

崇明东滩湿地植被类型和沉积特征对土壤碳、氮分布的影响

滨海湿地碳、氮储量的分布可能受盐沼植被和外源沉积物的综合影响.本文以长江口典型滨海湿地为研究对象,分别在崇明东滩湿地北部、中部和南部设置3条样线,根据外源沉积物的区域特征研究了3种主要盐沼植被(芦苇(Phragmites australis)、互花米草(Spartina alterniflora)、海三棱藨草(Scirpus mariqueter))和土壤中的有机碳(TOC)、总氮(TN)的季节变化及空间特征.结果显示,崇明东滩湿地北、中部为淤积型滩涂,南部呈侵蚀态势.盐沼植被中芦苇和互花米草生物量TOC、TN累积量均显著高于海三棱藨草带.北、中样线的相同植被类型中的土壤TOC、TN显著高于南样线.高潮滩的芦苇带土壤TOC储量高于中潮滩的互花米草带,而互花米草带土壤TN储量略高于芦苇带,海三棱藨草带和光滩土壤TOC、TN储量最低.盐沼植被类型显著影响土壤各层次TOC和TN储量的分布,其中,0~10 cm层次储量受植被类型和表层外源沉积物空间特征的交互作用影响.     

Heterogeneous uptake of NO2 on soils under variable temperature and relative humidity conditions

Heterogeneous reactions of nitrogen dioxide (NO₂) on soils collected from Dalian (S1) and Changsha (S2) were investigated over the relative humidity (RH) range of 5%-80% and temperature range of 278-328 K using a horizontal coated-wall flow tube. The initial uptake coefficients of NO₂ on S2 exhibited a decreasing trend from (10 ± 1.3) × 10^-8 to (3.1 ± 0.5) × 10^-8 with the relative humidity increasing from 5% to 80%. In the temperature effect studies, the initial uptake coefficients of S1 and S2 decreased from (10 ± 1.2) × 10^-8 to (3.8 ± 0.5) × 10^-8 and from (16 ± 2.2) × 10^-8 to (3.8 ± 0.4) × 10^-8 when temperature increased from 278 to 288 K for S1 and from 278 to 308 K for S2, respectively. As the temperature continued to increase, the initial uptake coefficients of S1 and S2 returned to (7.9 ± 1.1) × 10^-8 and (20 ± 3.1) × 10^-8 at 313 and 328 K, respectively. This study shows that relative humidity could influence the uptake kinetics of NO₂ on soil and temperature would impact the heterogeneous chemistry of NO₂.     

Uptake of isoprene, methacrylic acid and methyl methacrylate into aqueous solutions of sulfuric acid and hydrogen peroxide

Multiphase acid-catalyzed oxidation by hydrogen peroxide has been suggested to be a potential route to secondary organic aerosol formation from isoprene and its gas-phase oxidation products, but the lack of kinetics data significantly limited the evaluation of this process in the atmosphere. Here we report the first measurement of the uptake of isoprene, methacrylic acid and methyl methacrylate into aqueous solutions of sulfuric acid and hydrogen peroxide. Isoprene cannot readily partition into the solution because of its high volatility and low solubility, which hinders its further liquid-phase oxidation. Both methacrylic acid and methyl methacrylate can enter the solutions and be oxidized by hydrogen peroxide, and steady-state uptake was observed with the acidity of solution above 30 wt.% and 70 wt.%, respectively. The steady-state uptake coefficient of methacrylic acid is much larger than that of methyl methacrylate for a solution with same acidity. These observations can be explained by the different reactivity of these two compounds caused by the different electron-withdrawing conjugation between carboxyl and ester groups. The atmospheric lifetimes were estimated based on the calculated steady-state uptake coefficients. These results demonstrate that the multiphase acid-catalyzed oxidation of methacrylic acid plays a role in secondary organic aerosol formation, but for isoprene and methyl methacrylate, this process is not important in the troposphere.     

乳化油电破乳研究进展与物性参数优化

为获取不同物性参数对油水乳状液电破乳效率的联合作用规律,系统分析国内外电破乳油水分离的前沿成果,归纳含水率、温度、无机盐、酸碱等参数对电破乳的作用,并得到优化油水乳状液电破乳分离的物性参数:含水率过大易造成乳状液的电导率发生剧增,统筹考虑油水分离的电能耗,一般将含水率控制在25%为宜;避免升温分散液滴产生电分散,破乳剂达到浊点的影响,以及热负荷增加,油水乳状液的电破乳温度控制在70℃为佳;无机盐能显著降低油水乳状液的稳定性,但过高的含盐浓度,使得乳状液的电导率增加,能耗也有所上升;控制乳状液中固体微粒的粒径不小于几十微米,避免掺混与油湿润角小、具有亲油特性的固体微粒,易于电破乳的进程。     

Distribution of heavy metals in the water column, suspended particulate matters and the sediment under hydrodynamic conditions using an annular flume

Sediment resuspension plays an important role in the transport and fate of heavy metals in the aquatic environment. In the present study, the release and binding forms of Cr, Cu, Zn, Pb under hydrodynamic conditions were investigated using an annular flume. Two sediments located at YLZ and GBD from Liangshui River, Beijing were resuspended for 10 hr at 0.159 and 0.267 m/sec, respectively. The concentrations of suspended particulate matters of YLZ were higher than those of GBD during resuspension, indicating that the former sediment is more sensitive to the velocity. Cr in the dissolved phase stayed nearly constant at about 2.25 and 1.84 μg/L for YLZ and GBD, respectively, due to the high percentage of its stable binding fractions in both sediments, while Cu, Zn, and Pb showed a fast release in the initial period of time. However, their concentrations in SPM generally decreased with time and were higher at the lower velocity of 0.159 m/sec, which resulted from the entrainment and depressing effect of larger size particles with lower heavy metal content, commonly referred to as the "particle concentration effect". In addition, the binding form and heavy metal fractions were also found to vary during the resuspension event. A decrease in the sulphide/organic matters bounded form in GBD sediment was observed, whereas no visible changes were perceived in YLZ site samples. This phenomenon is due to the oxidation of heavy metal-sulphide binding forms, which originated from its high acid volatile sulphide content in GBD sediment.     

地衣芽孢杆菌γ-谷氨酰转移酶的分离和纯化

γ-谷氨酰转移酶(GTE)是聚γ-谷氨酸生物合成的关键酶,地衣芽孢杆菌QBL-033是目前合成聚γ-谷氨酸的主要菌种,其γ-谷氨酰转移酶的研究尚未见报道.分离纯化该菌中的γ-谷氨酰转移酶,研究其辅酶组成,对揭示γ-谷氨酰转移酶的分子结构和性质,提高聚γ-谷氨酸产率很有必要.将培养至对数期中期的细胞离心收集并用缓冲液洗涤,细胞破碎、离心去除菌体碎片得无细胞抽提液.经DEAE-纤维素柱(HIC)、G-200凝胶过滤柱层析得到纯化大约70倍的以NADPH为辅酶的GTE和部分纯化的以NADH为辅酶的GTE,这两个酶分别对NADPH、NADH高度专一.经HPLC和SDS-PAGE测得前一种酶的分子量和亚基相对分子质量分别为235×103和39×103,表明该酶为具有相同亚基的六聚体.酶活性测定使用HLTACHI U-3000分光光度计利用NAD(P)H在340nm氧化的初速度进行.纯化结果表明,QBL-033中确实存在两种GTE.QBL-033是以NADPH为辅酶的GTE参与聚γ-谷氨酸的合成代谢,以NADH为辅酶的GTE参与聚γ-谷氨酸的分解代谢.同时发现以NADPH为辅酶的GTE在280 nm吸收很弱,在215 nm吸收很强,说明此酶中酪氨酸、苯丙氨酸含量较低.GTE最适作用温度和最适反应pH值分别为50 ℃和6.0,具有较宽的pH稳定性,并且在50℃以下较稳定.Ca2 、Co2 、Cu2 、Mn2 、Pb2 、K2 、Zn2 ,以及EDTA对酶有不同程度的抑制作用,Fe2 和Mg2 对酶有轻微的激活作用.图4表1参16     

Impact of maximum sustainable yield on independent populations

We investigate a community of independent logistically growing populations under a common harvesting effort which leads to the total maximum sustainable yield (TMSY). It is surprising that in the case of two populations with approximately equal carrying capacities, TMSY is reached while both populations persist, although their biotic potential may differ substantially. In general, however, TMSY with a common harvesting effort implies suboptimal fishing of some populations, overfishing of others and extinction of the rest of the populations. Since extinction of populations is a rule rather than an exception and since a community of independent populations is more robust than an ecosystem with multiple trophic levels, we call for urgent retraction of all legal documents advocating MSY in ecosystems.     

Study of Ni adsorption on NKF-6 zeolite

The adsorption of ⁶³Ni from aqueous solutions using NKF-6 zeolite was investigated by a batch technique under ambient conditions. The adsorption was investigated as a function of contact time, pH, ionic strength, foreign ions, humic substances (FA/HA) and temperature. The kinetic adsorption was well described by the pseudo-second-order rate equation. The adsorption of ⁶³Ni on NKF-6 zeolite was strongly dependent on pH and ionic strength, and the adsorption of ⁶³Ni increased with increasing NKF-6 zeolite content. At low pH values, the presence of FA enhanced the adsorption of ⁶³Ni on NKF-6 zeolite, but the presence of HA had no drastic effect. At high pH values, the presence of FA or HA decreased the adsorption of ⁶³Ni on NKF-6 zeolite. The adsorption isotherms were well represented by the Langmuir model. The thermodynamic parameters (i.e., ΔH⁰, ΔS⁰and ΔG⁰) for the adsorption of ⁶³Ni were determined from the temperature dependent isotherms at 293.15, 313.15 and 333.15 °K, respectively, and the results indicate that the adsorption reaction was favored at high temperature. The results suggest that the adsorption process of ⁶³Ni on NKF-6 zeolite is spontaneous and endothermic.