不锈钢管的焊接技术

汽轮机润滑油系统油管道焊接是汽轮机专业焊接的一个重点.为了保证汽轮杌润滑油管道系统的清洁度及汽轮机主机润滑系统、调节保安系统安全可靠地工作,其材质全部由不锈钢组成,所以油管道安装的内在质量格外重要.总结出一套焊接组装工艺措施,提高了生产效能,满足了汽轮机油管的质量要求.     

微生物在铬污染土壤中的分布及铬累积菌株的初步筛选

通过现场采集土样及室内培养测定，对铬矿渣堆放区污染土壤的微生物分布进行了分析。结果表明，微生物的数量分布随污染程度的降低而上升，距离中心污染区越远，微生物CFU的数量就越多；地下样品的CFU数量明显低于表土CFU数量，显示铬污染向地下迁移的趋势。从污染土壤中分离到的抗铬微生物，主要为细菌和霉菌。细菌多为革兰氏阳性菌，且以芽孢菌为主。其中有4株细菌抗总铬能力可达1000mg·L^-1并显示出一定的降铬趋势，在100mg·L^-1实验条件下，采用二苯碳酰二肼显色法检测结果显示，试验组低于无菌空白对照50％以上。     

Cr6+小白菜种子萌发及生理生化指标的影响

以0.050 mg/L,0.125 mg/L,1.250 mg/L的Cr6+溶液盆栽处理研究Cr6+对小白菜萌发、生长及生理指标的影响.结果表明:随着Cr6+处理浓度的增大,种子的发芽率和发芽势均呈下降的趋势,平均发芽天数均有所增加;不同浓度Cr6+对小白菜幼苗的根和叶均产生了不同程度的毒害影响;随Cr6+处理浓度的增加叶绿素含量趋于下降,细胞膜透性及游离脯氨酸含量均呈上升趋势,过氧化氢酶的活性受到抑制.     

NPK不同配比对笋瓜(印度南瓜)果实中铬(Cr~(3+))、果胶和戊糖含量的影响

以笋瓜(印度南瓜)龙园栗香为材料,研究了N、P、K不同肥料配比对笋瓜果实中铬(Cr3+)、果胶、戊糖3种物质含量的影响。结果表明:高氮肥(尿素450kg·hm-2)的各组合下果实中Cr3+、果胶和戊糖含量均显著降低。在正常追肥(N1P1K1)前提下,仅增施钾肥的处理(N1P1K2)果实中3种物质均显著增加,仅增施磷肥的处理(N1P2K1)果实中Cr3+和戊糖含量显著增加,同时增施钾肥和磷肥的处理(N1P2K2)更有利于果实中Cr3+的积累。综合来看,生产中采用N1P1K2(尿素225kg·hm-2+磷酸铵225kg·hm-2+硫酸钾300kg·hm-2)处理进行追肥,可提高笋瓜果实中Cr3+、果胶、戊糖的含量。     

低浓度重金属Cr~(6+)对紫狼尾草生理生化特性的影响

为探讨污水中Cr6+对紫狼尾草(Pennisetum purpureum Schum.)生理生化特性的影响,将其幼苗置于含不同浓度Cr6+(0、1、10、20、30、40、50 mg/L K2Cr2O7)生活污水中培养.分别在不同时期测定植株叶片Pro、MDA、可溶性糖、SOD、POD活性及植株总铬含量.结果表明:经不同时期处理后,叶片Pro含量、可溶性糖含量、POD活性均随Cr6+理浓度的增大而先上升后下降;SOD活性没有受到明显的抑制;MDA含量随着铬处理浓度的升高、时间延长而逐渐升高.20mg/L Cr6+处理14d后植株生长速率最快,1～40mg/L Cr6+能有效促进紫狼尾草对铬的吸收与积累;而50mg/L Cr6+则对根系有毒害效应,抑制植株生长.这些结果显示,低浓度Cr6+能有效促进紫狼尾草生长,从而使其在受Cr6+污染环境中的植物修复方面具有一定的应用前景.     

高浓度铬对克氏原螯虾抗氧化酶系统的影响

采用毒性实验方法,研究了50mg·L~(-1)铬(Cr~(6 ))在14d内对克氏原螯虾鳃和肝胰腺抗氧化酶系统的影响。结果表明,肝胰腺比鳃的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性、总抗氧化能力(T-AOC)和丙二醛(MDA)含量均要高。Cr6 对鳃和肝胰腺SOD和CAT活性的影响各异,鳃SOD活性先受抑制再被激活,最后再被抑制;而肝胰腺SOD活性始终受到抑制。鳃CAT活性先增高后下降,肝胰腺CAT活性先下降后上升,最后均下降至低于对照组。鳃和肝胰腺T-AOC随Cr~(6 )处理时间而出现的变化呈总体一致的趋势:在暴露的7d内,T-AOC与暴露时间呈正相关,在暴露14d后显著下降;而MDA含量几乎全部低于对照组。结果显示,肝胰腺比鳃对高浓度Cr~(6 )的毒性影响更为敏感,高浓度Cr~(6 )在短期内可能对抗氧化防御功能起促进作用;同时,高浓度下克氏原螯虾抗氧化能力的提高可能并非由抗氧化酶活性的提高引起,而主要通过调动机体的非酶促系统来完成。     

Amendment of drilling fluid-affected soils with calcium salts

Land disposal of waste drilling fluid is an environmental concern because of the high salt content and the presence of potential toxic elements. A water-based drilling fluid was tested in a laboratory column study to determine the feasibility of leaching excessive salt without mobilizing chromium (Cr). The drilling fluid-affected two Alfisols with similar mineralogy, acidity, and texture were treated with gypsum (CaSO₄ · 2H₂O), calcium carbonate (CaCO₃), or calcium phosphate (CaHPO₄) (0 to 2% of weight). The electrical conductivity (EC) increased and the sodium adsorption ratio (SAR) decreased with increasing Ca-salt concentration. The pH did not vary significantly with the changes in the concentrations of gypsum and calcium phosphate. The pH of the mixtures increased in proportion to the concentration of added calcium carbonate. The hydraulic conductivity increased and the mobility of the soil particles decreased with increasing Ca-salt concentration. The Cr mobility decreased by gypsum and CaCO₃ treatments but it increased by calcium phosphate treatment. The soil with a higher content of organic matter and cation exchange capacity (CEC) showed a higher hydraulic conductivity and lower Cr mobility than the other soils at the same levels of the treatment. The results of this study suggest that the amendment of drilling fluid-affected soils with CaCO₃ and gypsum can enhance the leaching of excessive salt and reduce the Cr mobility. Among loamy soil, those with a higher CEC and organic matter content are more suitable for land disposal of drilling fluid.     

Subcellular distribution and chemical forms of chromium in rice plants suffering from different levels of chromium toxicity

The subcellular distribution and chemical forms of different heavy metals in rice are correlated with their bio‐toxicity. An experiment was conducted to investigate the subcellular distribution and chemical forms of chromium (Cr) in two rice genotypes (Oryza sativa L. cv. Xiushui 113 and cv. Dan K5) differing in Cr accumulation, to understand the mechanisms of Cr toxicity and resistance in rice plants. The results show that Cr in the roots of rice plants exposed to Cr stress was mainly localized in cell walls, whereas Cr in leaves and stems was mainly present in both cell walls and vacuoles, suggesting that both compartments act as important protective barriers against Cr toxicity in rice plants. Although Cr ions in all plant tissues exist predominantly in the forms extracted by 80% ethanol and distilled water, the amount of Cr in the chemical forms extracted by 2% HAc, 0.6 M HCl, and in residues was significantly increased under the highest Cr level (100 μM Cr) compared to the plants grown under lower Cr levels. These results indicate that excess Cr accumulated in rice plants under Cr stress is bound to undissolved or low‐bioavailable compounds, such as undissolved phosphate and oxalate, being beneficial for rice plants to alleviate Cr toxicity. In addition, under the highest Cr level (100 μM), Dan K5 had a higher percentage of Cr in the chemical forms extracted by 2% HAc, 0.6 M HCl, and in residues compared to Xiushui 113 in both stems and leaves, indicating that more Cr ions in shoots of Dan K5 were bound to undissolved or low‐bioavailable compounds, in comparison with those of Xiushui 113. It is evident that the low bioavailability of Cr in the shoots of Dan K5 is related to a high Cr accumulation.     

改性花生壳处理废水中Cr^6＋的实验研究

简述了农林废弃物处理废水中重金属离子的研究现状,实验研究了改性花生壳对废水中Cr6 的去除效果,并探讨了溶液的pH值、Cr6 初始浓度、吸附时间、温度及改性花生壳用量等因素对Cr6 吸附效果的影响.结果表明,改性花生壳对Cr6 有很好的吸附作用,在温度33℃,改性花生壳用量1.0 g,20 mg·L-1的Cr6 溶液50 mL,溶液的pH值2.0,振荡吸附120 min的条件下,Cr6 的吸附去除率达到了98.4%.     

西宁市不同功能区土壤重金属铬和镍的形态研究

采取Tessier连续提取法对西宁市6个功能区城市土壤中重金属Cr和Ni的形态进行研究.结果表明,西宁市各功能区土壤中Cr和Ni的全量分别是全国土壤几何平均值的2.6～3.2,1.3～2.1倍.各功能区Cr的含量均无显著差异(P＞O.05);Ni的含量表现出矿冶区与风景区和开发区差异显著(P＜0.05),但与其他功能区差异不显著(P＞0.05),并且除矿冶区外其他功能区间也均无显著差异(P＞0.05).Cr的各形态分布趋势为:残渣态＞铁锰氧化物结合态＞有机结合态＞可交换态＞碳酸盐结合态;Ni的各形态分布趋势为:残渣态＞铁锰氧化物结合态＞有机结合态＞碳酸盐结合态＞可交换态.重金属Cr为:不可利用态＞潜在可利用态＞可利用态;重金属Ni为:潜在可利用态＞不可利用态＞可利用态.研究表明土壤中重金属Cr和Ni的生物有效性和潜在生态危害性较大.