耕作土壤非交换性钾有效性的研究

采用２种化学连续提取法及连续耗钾实验。研究了几种耕作土壤非交换性钾释放特性及有效性。结果表明,供试土壤非交换性钾释放特性和有效性与粘土矿物密切相关。富含伊利石的土壤非交换性钾的释放量大,速率快,有效性高;黑麦草吸收该土壤的非交换性钾量及总吸钾量高,生物量大。而富含高岭石或蒙脱石的土壤非交换性钾有效性明显较低;非交换性钾的释放量和速率、黑麦草吸收该土壤的非交换性钾量、总吸钾量及生物量的均值分别仅为富含伊利石上壤的４６．９６％、４５．５０％、４１．６５％、４３．９０％和６７．５２％。供试土壤耗竭前期非交换性钾有效性高,供钾量大;黑麦草生长良好,生物量大。     

Clam‐sediment accumulation factors for polychlorinated biphenyl congeners at a contaminated estuarine marsh

Clam‐sediment accumulation factors for hexa‐, hepta‐ and octa‐chlorobiphenyls were estimated at an intertidal marsh that has been contaminated with Aroclor 1268. Accumulation factors for PCB congeners with K _ow > 6.5 were in the range of 0.07–0.88, indicating that their uptake was hindered by steric factors, contamination levels, non‐equilibrium conditions and stronger affinity to sediment organic carbon. Biota‐sediment accumulation factors (BSAFs) were negatively correlated with log K _ow of superhydrophobic PCB congeners. BSAFs estimated based on 2,3,7,8‐TCDD equivalents of PCBs were 2‐fold greater than those derived from total PCB concentrations.     

腐殖酸作用下沉积物中纳米氧化铜对铜锈环棱螺生态毒性的影响

为了探讨不同水平腐殖酸作用下沉积物中纳米氧化铜(CuO-NPs)对底栖生物生态毒理学效应的影响,以铜锈环棱螺(Bellamya aeruginosa)为受试生物,通过腐殖酸和CuO-NPs加标沉积物的慢性(28 d)生物测试,研究了肝胰脏中Cu的生物积累、Na+K+-ATP酶(ATPase)、超氧化物歧化酶(SOD)以及过氧化氢酶(CAT)活性的变化规律.结果表明,在低浓度CuO-NPs处理组(60 μg·g1),沉积物中腐殖酸水平对Cu的生物积累以及ATPase、SOD和CAT活性均没有显著影响.在中、高浓度CuO-NPs处理组(≥180 μg·g-1),Cu的生物积累均随腐殖酸水平的增加而显著升高;肝胰脏ATPase活性随腐殖酸水平的增加而显著下降;当腐殖酸水平为0.05 g·g-1时,SOD活性显著高于未添加腐殖酸组,表现为显著诱导,当腐殖酸水平≥0.1g·g-1时,SOD活性开始下降,并具有浓度依赖性;随腐殖酸水平的增加,肝胰脏CAT活性总体上表现为浓度依赖性显著下降.由于沉积物中腐殖酸的存在,显著增加CuO-NPs在沉积物中的分散稳定性,更容易被铜锈环棱螺摄取,从而通过增加CuO-NPs的生物积累而增强对铜锈环棱螺的生态毒性.     

Degradation of Polylactide by Commercial Proteases

Fifty-six commercially available proteases were tested for polylactide-degrading activity. Little or no activity was found in acid and neutral proteases, while some alkaline proteases formed appreciable amounts of lactic acid from polylactide. These polylactide-degrading proteases were derived from Bacillus species and had catalytic activity even under neutral, as well as alkaline, conditions. Savinase (Novo Nordisk) degraded polylactide the fastest among the enzymes tested and its specific activity corresponded to about one-half of proteinase K. Polylactide-degrading activity was not always present in the enzymes that affected keratin, while polylactide-degrading proteases commonly hydrolyzed keratin. A significant correlation was observed between degrading activities of polylactide and keratin in alkaline proteases.     

Changes of plasma membrane AtPase activity, membrane potential and transmembrane proton gradient in Kandelia candel and Avicennia marina seedlings with various salinities

The salt-secreting mangrove, Avicennia marina, and non-salt-secreting mangrove, Kande/ia candel were cultivated in sand with various salinities(0‰, 100‰, 20‰, 30‰, 40‰) for 60 d. Plasma membrane vesicles of highpurity in leaves and roots of A. marina and K. candel seedlings were obtained by two-phase partitioning. The function of the plasma membranes, the activity of ATPase, membrane potential and transmembrane proton gradient, at various salinities were investigated. The results showed that within a certain range of salinity( A. marina and roots of K. candel: 0-30‰; leaves of K. candel: 0-20‰), the activity of ATPase increased with increasing salinity, while high salinity (above 30‰ or 20‰) inhibited ATPase activity. In comparison with A. marina, K.candel appeared to be more sensitive to salinity. The dynamics of membrane potential and transmembrane proton gradient in leaves and roots of A. marina and K. candel seedlings were similar to that of ATPase. When treated directly by NaCl all the indexes were inhibited markedly: there was a little increase within 0-10‰( K. candel) or 0-20‰( A. marina) followed by sharp declining. It indicated that the structure and function of plasma membrane was damaged severely.     

控制Na~+转运以及维持Na~+/K~+平衡有助于提高植物的耐盐性

盐害(包括土壤次生盐渍化)造成的日益严重的环境问题已在世界范围内引起了广泛关注。大量针对植物耐盐分子机制的研究已开展,旨在更好地了解植物自身的耐盐机制。到目前为止,已获取了大量关于植物耐盐性机制的信息。同时,人们正在形成一个共识,即植物维持自身细胞离子平衡的能力是其具有耐盐性的关键。Na+/H+、K+/H+和Na+/K+逆向转运蛋白及其同源蛋白在植物细胞维持离子平衡中的关键作用受到了人们越来越多的关注。结合前人的研究结果和最新的研究动态,着重阐述了Na+转运控制和维持细胞离子平衡在植物耐盐过程中的机理及其重要作用。     

Correlations between potassium, rubidium and cesium ((133)Cs and (137)Cs) in sporocarps of Suillus variegatus in a Swedish boreal forest

An analysis of sporocarps of ectomycorrhizal fungi Suillus variegatus assessed whether cesium (¹³³Cs and ¹³⁷Cs) uptake was correlated with potassium (K) or rubidium (Rb) uptake. The question was whether intraspecific correlations of Rb, K and ¹³³Cs mass concentrations with ¹³⁷Cs activity concentrations in sporocarps were higher within, rather than among, different fungal species, and if genotypic origin of sporocarps within a population affected uptake and correlation. Sporocarps (n = 51) from a Swedish forest population affected by the fallout after the Chernobyl accident were studied. The concentrations were 31.9 ± 6.79 g kg⁻¹ for K (mean ± SD, dwt), 0.40 ± 0.09 g kg⁻¹ for Rb, 8.7 ± 4.36 mg kg⁻¹ for ¹³³Cs and 63.7 ± 24.2 kBq kg⁻¹ for ¹³⁷Cs. The mass concentrations of ¹³³Cs correlated with ¹³⁷Cs activity concentrations (r = 0.61). There was correlation between both ¹³³Cs concentrations (r = 0.75) and ¹³⁷Cs activity concentrations (r = 0.44) and Rb, but the ¹³⁷Cs/¹³³Cs isotopic ratio negatively correlated with Rb concentration. Concentrations of K and Rb were weakly correlated (r = 0.51). The ¹³³Cs mass concentrations, ¹³⁷Cs activity concentrations and ¹³⁷Cs/¹³³Cs isotopic ratios did not correlate with K concentrations. No differences between, within or, among genotypes in S. variegatus were found. This suggested the relationships between K, Rb, ¹³³Cs and ¹³⁷Cs in sporocarps of S. variegatus is similar to other fungal species.     

Solving mercury (Hg) speciation in soil samples by synchrotron X-ray microspectroscopic techniques

Direct mercury (Hg) speciation was assessed for soil samples with a Hg concentration ranging from 7 up to 240 mg kg⁻¹. Hg chemical forms were identified and quantified by sequential extractions and bulk- and micro-analytical techniques exploiting synchrotron generated X-rays. In particular, microspectroscopic techniques such as μ-XRF, μ-XRD and μ-XANES were necessary to solve bulk Hg speciation, in both soil fractions <2 mm and <2 μm. The main Hg-species found in the soil samples were metacinnabar (β-HgS), cinnabar (α-HgS), corderoite (Hg₃S₂Cl₂), and an amorphous phase containing Hg bound to chlorine and sulfur. The amount of metacinnabar and amorphous phases increased in the fraction <2 μm. No interaction among Hg-species and soil components was observed. All the observed Hg-species originated from the slow weathering of an inert Hg-containing waste material (K106, U.S. EPA) dumped in the area several years ago, which is changing into a relatively more dangerous source of pollution.     

三甲基氯化锡对斑马鱼(Danio rerio)生理生化特性的影响

为初步探讨三甲基氯化锡(trimethyltin chloride,TMT)对鱼类的毒性效应以及评价环境中TMT的安全性,采用静态鱼类急性毒性试验法测定了TMT对斑马鱼(Danio rerio)生理生化指标的影响;参考TMT的96 h-LC50值,设定3个浓度(0.39、0.78和1.17 mg·L-1)处理斑马鱼,测...     

Radiological monitoring: terrestrial natural radionuclides in Kinta District,Perak, Malaysia

Natural background gamma radiation and radioactivity concentrations were investigated from 2003 to 2005 in Kinta District, Perak, Malaysia. Sample locations were distant from any ‘amang’ processing plants. The external gamma dose rates ranged from 39 to 1039 nGy h⁻¹. The mean external gamma dose rate was 222 ± 191 nGy h⁻¹. Small areas of relatively enhanced activity were located having external gamma dose rates of up to 1039 ± 104 nGy h⁻¹. The activity concentrations of ²³⁸U, ²³²Th and ⁴⁰K were analyzed by using a high-resolution co-axial HPGe detector system. The activity concentration ranges were 12–426 Bq kg⁻¹ for ²³⁸U, 19–1377 Bq kg⁻¹ for ²³²Th and <19–2204 Bq kg⁻¹ for ⁴⁰ K. Based on the radioactivity levels determined, the gamma-absorbed dose rates in air at 1 m above the ground were calculated. The calculated dose rates and measured dose rates had a good correlation coefficient, R of 0.94. To evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity, the gamma-absorbed dose rate and the mean population weighted dose rate were calculated. An isodose map for the Kinta District was also produced.