乙酸铜对银鲳幼鱼急性毒性及抗氧化酶活性的影响

为评价乙酸铜对银鲳的安全性及毒性效应,采用静水急性暴露实验,研究了8个乙酸铜浓度梯度(0、0.150、0.206、0.282、0.387、0.531、0.729、1.00 mg·L~(-1))对银鲳幼鱼的急性毒性,以肝脏和鳃组织的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化酶(GSH—PX)以及谷胱甘肽巯基转移酶(GST)活性为指标研究乙酸铜对银鲳幼鱼的毒理作用,并进行安全评价。结果表明,高浓度乙酸铜会对银鲳幼鱼产生了较大的毒性,48 h和96 h-LC_(50)分别为0.898 mg·L~(-1)、0.264 mg·L~(-1),安全质量浓度为0.026 mg·L~(-1);不同浓度乙酸铜胁迫下银鲳幼鱼组织中的SOD、CAT、GSH-PX和GST活性均表现为低浓度被诱导而高浓度受抑制的规律,与乙酸铜浓度呈抛物线型剂量效应关系,此外,肝脏中4种抗氧化酶活性普遍高于鳃组织。研究发现,乙酸铜胁迫对抗氧化酶的影响,可以反映银鲳幼鱼机体的受损状况,其中SOD可较灵敏地指示早期低浓度的铜污染。     

氧化钙燃烧固硫添加剂的研究

在寻找钙基燃烧固硫加剂，并探讨其机理的试验中，研究了碱金属化合物在不同含量，不同温度下对氧化钙固硫率的影响，试验结果表明，一些碱金属化合物能使固硫率增加约１０个百分点左右，采用ＳＥＭ和热天平分析了固硫率提高的原因，提出碱金属化合物提高固硫率的机理在于：低熔点液相共熔物的形成导致ＣａＯ微观结构的改变。     

石灰预处理和干发酵对稻草热解特性影响

深入研究生物质热解有助于热解机理的理解,利用热重分析来探讨石灰预处理和干发酵对稻草热解特性的影响。结果表明:预处理使木质素和半纤维素含量增加,而干发酵使VS、半纤维素和纤维素含量降低;预处理和干发酵改变稻草热解特性,但未改变稻草的热反应机理;热解一级动力学方程很好模拟稻草热解的主失重阶段,稻草热解活化能数值为42.3～47.8 kJ/mol,属于正常范围;预处理降低反应活化能,而干发酵增加反应活化能。这为秸秆及其干发酵残渣的气化提供了重要的设计依据。     

Level and distribution of DDT in surface soils from Tianjin, China

One hundred and eighty eight surface soil samples were collected from the Tianjin area to study the contamination of DDT and its metabolites. Measurements were taken for p,p'-DDE, p,p'-DDD, p,p'-DDT, o,p'-DDE, o,p'-DDD and o,p'-DDT for all samples. The results indicated that p,p'-DDT and p,p'-DDE were the predominant contaminant compounds in the surface soil samples, with mean concentrations of 27.5 and 18.8 ng g(-1) respectively. No significant differences in DDT concentrations were found between the soils from wastewater treated irrigated areas and other areas, suggesting that wastewater irrigation is not an important source of DDT in the area. However, the spatial distribution of soil DDTs levels in the area did correlate well with early direct application rates of pesticides. In addition, both pH level and organic carbon content are also known factors affecting the level of DDT and its metabolites. Although it was assumed that the use of these chemicals was banned in the early 1980s, the current concentration levels appear to be too high to be mere residuals after 20 years degradation.     

新乡市城市污水对泥鳅的生理毒性与遗传毒性研究

采用鱼体外周血细胞微核技术研究新乡市城市污水对泥鳅的遗传毒性,实验各组(A组、B组、C组、D组)中微核率明显高于对照组(P<0.01).以黄嘌呤氧化酶法检测泥鳅肝组织中的超氧化物歧化酶(SOD)酶活力变化,以赖氏法检测肝组织和血清中的谷草转氨酶(GOT)和谷丙转氨酶(GPT)酶活力变化,研究该污水对泥鳅的生理毒性.结果表明,实验各组肝组织中SOD、GOT和GPT酶活力均低于对照组.且随城市污水浓度升高而减小;血清中的SOD、GOT和GPT酶活力均高于对照组,且随城市污水浓度升高而增强.由此可知,直接排放的城市污水对泥鳅有显著的遗传毒性与生理毒性,水样中有致突变酶活力物质存在.     

Organo-chlorine pesticide (DDT and HCH) residues in the Taihu Lake Region and its movement in soil-water system I. Field survey of DDT and HCH residues in ecosystem of the region

The use of organo-chlorine (DDT and HCH) has been banned in China for 20 years. A field survey was carried out during 1999-2000 in the Taihu Lake Region. Organo-chlorine pesticide (OCP) residues in soil, water, fish and sediment samples were investigated. DDT was detected in 5 out of 10 samples with concentration ranging from 0.3 to 5.3 microg/kg in the surface (0-15 cm) layer, 6 out of 10 with 0.5 to 4.0 microg/kg in the subsoil layer (16-30 cm), and 4 of 10 with 0 to 2.7 microg/ kg in the deep soil layer (31-50 cm). Results for HCH residues in soil samples were similar to those of DDT. These results indicate that OCP residues in 0-50 cm profile had been leached out or degraded to safe level. In river water DDT was detected in 10 out of 13 samples ranging from 0.2 to 9.3 microg/l, with an average of 1.0 microg/l. While HCH was detected in 12 out of 13 samples ranging from 0.02 to 36.1 microg/l, with an average 5.6 microg/l. DDT residues in sediment ranged from 0.1 to 8.8 microg/kg, while HCH ranged from 0.3 to 66.5 microg/kg. DDT residues in fish body ranged from 3.7 to 23.5 microg/kg and HCH ranged from 3.7 to 132 microg/kg. These results demonstrate an accumulation through food chain (from soil-water-sediment-microbes-crop-fish-... etc.), also that HCH residues are generally more persistent than DDT residues. However, all these data are well below than the state warning standard limit.     

Assessment of the bioavailability of rare earth elements in soils by chemical fractionation and multiple regression analysis

The bioavailability of rare earth elements (REEs) in soils was evaluated, based on the combination of chemical fractionation and multiple regression analysis. REEs in soils were partitioned by a sequential extraction procedure into water soluble (F(ws)), exchangeable (F(ec)), bound to carbonates (F(cb)), bound to organic matter (F(om)), bound to Fe-Mn oxides (F(fm)) and residual (F(rd)) fractions. Alfalfa (Medicago Staiva Linn.) had been grown on the soils in a pot-culture experiment under greenhouse conditions for 35 days. The concentrations of REEs in fractions and plant were determined by inductively coupled plasma-mass spectrometry (ICP-MS). Chemical fractionation showed that (F(ws)) fraction of REEs was less than 0.1% and residual (F(rd)) was the dominant form, more than 60% in soils. Bioaccumulation of REEs was observed in Alfalfa. REE availability to the plant was evaluated by multiple regression analysis. F(ws), F(ec), F(cb) and F(om) fractions were significantly correlated with REE uptake by alfalfa. But the exchangeable Pr(F(ec)) was significantly correlated with Pr concentration in alfalfa. F(ec), F(cb) and F(om) greatly contributed to La and Nd bioavailability; F(ec) and F(om) to Ce, Gd and Dy; F(ec) and F(cb) to Yb; and F(ws), F(ec) and F(om) to total REEs. This meant that the bioavailability of different species of REEs varied with individual REE. The results of this study indicated that the sequential extraction procedure, in conjunction with multiple regression analysis, may be useful for the prediction of plant uptake of REEs from soils.     

冬季低温条件下浮床植物对富营养化水体的净化效果

在冬季低温条件下,采用浮床无土栽培技术,研究了水芹菜、多花黑麦草以及大蒜3种耐寒植物对富营养化水体的净化效果。试验结果表明,3种植物在水温4.0～10．1℃的条件下均生长良好,对水体中TN、NH4^＋-N、TP、CODMn污染物的去除率分别为59.3％～29.2％、65、2％～39.3％、55.6％～33.9％,55．7％～49．5％．对藻类的抑制率为88．4%～92．3％。通过比较,水芹菜净化能力最强,多花黑麦草次之,大蒜最弱。本项研究丰富了冬季低温条件下治理富营养化水体的方法．也为冬季浮床植物的选择提供了依据。     

铁酸锌纳米晶的合成及其催化脱色性能研究

采用改进的共沉淀法与溶剂热法相结合制备了ZnFe2O4纳米晶,利用X射线衍射(XRD)、透射电镜(TEM)对ZnFe2O4的晶型和形貌进行了表征,讨论了其表面的光伏效应,以酸性橙Ⅱ的光催化脱色性能作为探针反应,详细地考察了催化剂的用量、底物浓度及溶液pH等因素对其脱色效果的影响.结果表明,制备的ZnFe2O4为正尖晶石型结构,平均粒径为7 nm左右,样品具有一定的捕获电子能力,在外加电场下光伏响应变化明显,在正电场下有最佳响应值,而当负电场达到一定值时,外电场的光伏响应占据主导地位.在酸性橙Ⅱ为20 mg/L、催化剂用量为1.0 g/L的中性条件下,其脱色效率达95%左右,而且经过4次重复使用后催化剂仍然具有一定的脱色性能.     

乙草胺对土壤微生物的影响研究

研究了乙草胺在6种不同浓度下对土壤微生物种群数量及土壤中细菌、放线菌、真菌生长速率的影响.采用密闭法测定乙草胺对土壤微生物呼吸的影响.结果表明,乙草胺对土壤微生物种群数量及土壤中细菌、放线菌、真菌生长速率均有一定的抑制作用,对土壤微生物呼吸作用具有明显的抑制作用.