金属离子对纤维素酶活性影响的研究

通过金属离子对纤维素酶系中3大组分（β-葡萄糖苷酶、内切葡聚糖酶和外切葡聚糖酶）酶活的影响,探讨金属离子对纤维素酶活影响的作用机理。试验结果表明,金属离子Co2＋、Zn2＋、Mn2＋对内切葡聚糖酶酶活具有促进作用;Co2＋和K＋对外切葡聚糖酶的酶活具有促进作用;Co2＋、Mn2＋、Ca2＋和Mg2＋对β-葡萄糖苷酶具有促进作用,来源不同的纤维素酶,因其酶系组分不一样,酶促离子对纤维素酶的促进作用有所差异。     

Cu2+、Zn2 、Pb2 对七带石斑鱼(Epinephelus septemfasciatus)胚胎和初孵仔鱼的毒性效应

在(21.0±0.5)℃条件下,研究了Cu2+、Zn2+、Pb2+3种金属离子对七带石斑鱼胚胎和初孵仔鱼的毒性效应。结果表明:1)随着3种金属离子浓度的升高,受精卵的孵化速率和孵化率逐渐降低,畸形率逐渐增加。重金属引发胚胎发育发生各种畸形,如胚体增生异常而死亡、尾芽弯曲,仔鱼不能正常出膜而死亡,初孵仔鱼脊椎弯曲多呈L、S、V型或尾部未展开呈逗号状畸形。综合孵化速率、孵化率和畸形率等指标,可以看出,3种金属离子对胚胎发育的毒性大小依次为Cu2+Zn2+Pb2+;2)初孵仔鱼的毒性试验周期为96 h,随着时间加长,仔鱼的存活率逐渐降低,且金属离子浓度越大,其下降幅度越大。此外,仔鱼出现脊椎S、V型弯曲等畸形也越来越多。通过计算各时间段的半致死浓度(LC50)和安全浓度得出,3种金属离子对初孵仔鱼的毒性大小依次为Cu2+Pb2+Zn2+。本研究的一系列数据可以为新渔业水质标准的制定和水环境的监测提供理论参数,为七带石斑鱼等鱼类繁育养殖中的重金属监测与治理提供重要科学依据。     

冀北山区矿区周边镉铅污染农田钝化修复研究

为了筛选出一种适用于冀北山区矿区周边铅镉污染农田的土壤调理剂配方,本研究采用室内土壤培养试验,以石灰、蒙脱石、生物炭、沸石为材料,研究不同组合方式和添加量(0.5％、1％、3％、5％)对土壤中有效态Cd和Pb含量的影响.结果 表明,土壤有效态Cd含量、有效态Pb含量和土壤pH因土壤调理剂不同组合方式和不同添加量呈现不同...     

重金属污染土壤的植物修复技术

文章介绍了植物提取、植物挥发和植物钝化三种重金属污染土壤的植物修复技术的研究动态。     

用快速干灰法处理样品测定奶粉中金属元素的含量

本文叙述用快速干灰法处理样品测定奶粉中金属元素的含量,并与常规的干法和湿法处理进行对比试验,用三种方法进行的回收试验和精密度试验所得结果,经统计分析表明,快干法测定的结果准确可靠,准确度、精密度以快速干灰法为最好。     

超声振动在金属塑性加工的应用

用超声振动进行金属塑性加工是金属在冷加工过程中加上超声频振动,以促进工艺过程和改善产品质量的一种新工艺。经过多年的发展、研究,已用于工业生产上的有超声振动冷拔金属管、丝、棒,拉伸成型、铆镦、超声弯管和矫直;超声粉末压缩治金处理,超声振动滚轧和冷锻等。本文简单介绍国内外利用超声振动金属性加工的现状,水平和效益。对一些应用研究和作用原理作了简单介绍。     

Single and mixture toxicity of gold nanoparticles and gold(III) to Enchytraeus buchholzi (Oligochaeta)

The ecotoxicity of gold nanoparticles (Au-NPs), gold(III) and their mixtures was assessed in the potworm Enchytraeus buchholzi after 14-day bioassays. The worms were exposed at 20 °C in OECD artificial soil to 0, 9.37, 18.7, 28.1 and 37.5 mg/kg Au-NPs or Au(III) and 0, 9.37 + 9.37, 18.7 + 18.7, 28.1 + 28.1, 37.5 + 37.5 mg Au-NPs + Au(III)/kg. The results indicated that the range of Au-NPs concentrations used in the present study was not deleterious to the survival and reproduction of E. buchholzi. Au(III) showed no significant effect on survival but was significantly deleterious to reproduction in the highest treatment (p ≤ 0.01). A 14-day EC50_Au(III) = 35.5 mg/kg was estimated for effects on reproduction. Au-NPs/Au(III) mixtures essentially caused the same effects as Au(III) except for 18.7 mg Au(III)/kg vs. 18.7 + 18.7 mg Au-NPs + Au(III)/kg where the mixture treatment was significantly more toxic to reproduction (p < 0.02). Mixture results suggested a seemingly additive effect between Au-NPs and Au(III), although the conventional toxic unit approach could not be used to ascertain this conclusively because of the lack of Au-NPs toxicity. The order of toxicity between Au-NPs, Au(III) and their mixtures was Au-NPs = Au(III) = Au-NPs/Au(III) for survival and Au-NPs < Au(III) ≤ Au-NPs/Au(III) for reproduction.     

Microbial properties and attributes of ecological relevance for soil quality monitoring during a chemical stabilization field study

Chemical stabilization is a soil remediation technique based on the incorporation of organic and/or inorganic amendments to metal contaminated soil in order to decrease metal bioavailability and improve soil quality. Consequently, the establishment of follow-up monitoring programmes is essential to ensure the long-term effectiveness of chemical stabilization in terms of both metal bioavailability reduction and soil quality improvement. In this study, three doses (20, 40 and 80 t ha⁻¹) of a lime-treated sewage sludge, that meets legal standards regarding metal contents, were added to a metalliferous mine soil and a variety of physicochemical and microbial indicators of soil quality were measured over time (immediately before treatment application and one and six months after such application). Soil CaCl₂-extractable and plant metal concentrations were also measured. We carried out a complementary interpretation of soil microbial properties through their grouping within a set of ecosystem attributes of ecological relevance: vigour, organization, stability, suppressiveness and redundancy. Sewage sludge addition led to an increase in soil pH, but this beneficial effect was transient. The addition of sewage sludge had a more pronounced effect on parameters used here to estimate soil vigour (dehydrogenase activity, basal and substrate-induced respiration). On the contrary, the addition of sewage sludge did not significantly alter the composition of soil microbial communities, as reflected by PCR-DGGE data. Chemical stabilization was only partly successful: it did improve soil quality but the expected reduction in soil metal bioavailability (as reflected by the values of CaCl₂-extractable metal concentration) was clearly observed only for Cd (not for Pb or Zn); however, SL addition led to a significant reduction in shoot metal concentration for the three metals under study. The assessment of soil quality at the attribute level has proven useful for the interpretation of the effect of chemical stabilization on soil functioning.     

Cu~(2+)和Cd~(2+)对草履虫的毒性试验

[目的]为水体环境监测中废水排放安全性评价提供参考依据。[方法]通过单一急性毒性试验和联合毒性试验,研究了金属离子Cu2+和Cd2+对草履虫的急性毒性和联合毒性。[结果]在单离子急性毒性试验中,Cu2+和Cd2+对草履虫的毒性随浓度的增高而增大,且均呈明显的剂量效应。Cu2+的1h半致死浓度(LC50)为0.32mg/L,而Cd2+的1h半致死浓度(LC50)为0.96mg/L。当Cu2+和Cd2+共存时,Cu2+的1h半致死浓度(LC50)为0.24mg/L,Cd2+的1h半致死浓度(LC50)为0.19mg/L,2种金属离子表现为协同作用。[结论]在废水排放中,不但要考虑单种金属离子对水生生物的毒害作用,而且要重视2种或多种金属离子共存时它们对水生生物的毒害作用。     

福建沿海地区不同用地土壤重金属污染及其评价

对福建沿海地区4种不同用地类型的8种重金属元素进行了检测和评价,结果表明:水田污染最严重是Pb,菜园地是Hg,果园是As,旱地是As。在多项综合指数评价中,菜园土污染最严重,综合污染指数(P)达到1.18,其余依次为水田0.64,果园0.59,旱地0.47。在单项污染综合指数中,Hg和Cd污染最严重,其污染指数(I)分别达到0.86和0.61,其余依次为Cr、Pb、Cu、As、Zn、Ni。评价结果为进一步的土壤污染与治理提供了科学依据。