土壤溶液性质对Zn的形态变化及其微生物毒性的影响

采集了我国具有代表性的12种不同性质土壤,利用基础诱导硝化(SIN)方法测定了不同土壤中锌的微生物毒性阈值,同时利用850离子色谱仪与WHAM6.0模型,测定了溶液不同阴离子组成及自由Zn2+含量,建立了基于不同土壤性质与溶液离子的土壤中Zn毒性预测模型.结果表明,基于SIN测定的不同土壤Zn微生物毒性阈值在不同土壤间有显著差异,其中EC50从196mg/kg至1310mg/kg;EC10值从48mg/kg增加至682mg/kg,不同土壤EC50与EC10的最大值与最小值的比例分别达到了6.68及14.3倍,表明土壤性质对Zn的微生物毒性有非常显著的影响;基于SIN的Zn的毒性阈值ECx(x=10,50)与溶液自由Zn2+浓度的负对数p(Zn2+)间呈正相关关系,表明随着土壤溶液中自由Zn2+值的升高,Zn的毒性逐渐增加.土壤pH值、OC、CEC、F-、Cl-、Ca2+及Mg2+与Zn的毒性阈值ECx(x=10,50)及p(Zn2+)呈正相关关系,其中土壤pH值为最重要的影响因子,偏相关系数均达到极显著水平(P<0.01),其次为OC、CEC及F-,ECx与溶液中NO3-, SO42-呈负相关关系.基于不同主控因子的土壤中Zn毒性阈值(ECx)及P(Zn2+)的预测模型表明,pH值、OC、CEC、F- 四个变量因子分别解释了log(EC50)、log(EC10)及p(Zn2+)预测模型变异的89.9%、81.2%和92.3%.     

超声场中活性炭上Zn2+的吸附/脱附

采用静态条件,考察了超声波对活性炭上Zn2+吸附/脱附性能的影响.结果表明,有/无超声作用下,活性炭对Zn2+的吸附率均随Zn2+初始浓度的增加而减少,该吸附过程属于优惠吸附, Langmuir模型能更好描述该过程,超声的引入对活性炭吸附Zn2+有一定抑制作用.脱附研究发现,在蒸馏水介质中,Zn2+脱附率仅为2.11%,加入超声后Zn2+的脱附率提高至20.8%,添加NaOH后脱附率明显增加,有/无超声作用下的脱附率分别为40.1%和33.1%.动力学分析表明,Zn2+在活性炭上的吸附/脱附均符合2级反应动力学.     

羟基化锌催化臭氧氧化去除水中痕量磺胺嘧啶

以实验室制备的羟基化锌(ZnOOH)为催化剂,研究了其催化臭氧化去除水中痕量磺胺嘧啶(SD)的效能,通过研究叔丁醇对催化效果的影响,推断了催化反应机理,探讨了臭氧投加量、水质因素、催化剂投加量和使用次数对催化性能的影响因素.结果表明,ZnOOH对臭氧氧化水中的SD有较强的催化活性.催化剂表面结合的羟基基团有利于催化反应.在优化的实验条件下,蒸馏水中反应30min时,催化臭氧化比单独臭氧化对SD的去除率提高了47.7%.催化过程遵循自由基反应机理,SD的去除效果随催化剂投加量的增加而提高,催化剂在重复使用后催化效果基本不变,水中的氯离子可以明显降低催化剂的活性,偏碱性条件下,催化效果更佳.     

Application of rotating cylinder method for ecotoxicological evaluation of antifouling paints

The environmental impact of two biocide-free antifouling paints, fluoropolymer and silicone types, painted on a test cylinder was assessed using a battery of ecotoxicity test and chemical analyses for organic micro-pollutants such as perfluoroalkyl substances (PFAS). A biocide paint containing zinc pyrithione (ZnPT₂) and cuprous oxide was assessed as a positive control. A standardized laboratory rotating-cylinder method using each test cylinder with artificial seawater was performed for 45 days. After 1?h rotation, the leaked seawater was subjected for bioassay and chemical analyses twice weekly. The seawater extracts from the biocide paint showed adverse effects on bacteria, algae, and crustaceans, but those from the biocide-free paints did not. The leakage seawater from biocide-free paints, after 7-day continuous rotation, contained the same concentration levels of PFAS as blank seawater used to conduct the tests. Thus, no significant toxicities of the biocide-free paints were found under the conditions of this study. Simultaneous analysis of ZnPT₂ and copper pyrithione (CuPT₂) was developed using an HPLC with a polymeric resin column, showing that ZnPT₂ was converted to CuPT₂ by trans-chelation in the leakage seawater from the positive control paint. The experimental results using a laboratory rotating-cylinder method demonstrated that biocide-free paints did not markedly affect three species tested and no PFAS was detected. In contrast, biocide paint was significantly toxic to test species and toxicity of the extract on bacteria was partly responsible for CuPT₂ produced in leakage seawater. Thus, a laboratory rotating-cylinder method may be applied for ecotoxicological assessment of antifouling paints.     

Correlation between lead and iron in children's blood in Jordan

A total of 200 Jordanian children were classified into two groups: 100 Fe replete and 100 Fe deficient with ages ranging between 3.0 and 12.0 years (6.9 ± 2.7 years). All participants were chosen according to proper selection criteria followed by the sample collection: the samples were analyzed for hemoglobin and red blood cells; ferritin, an immunoassays-based instrument; and levels of Pb, Cu, and Zn. There were no significant differences between genders regarding Fe-deficiency (p = 0.57 and χ2 = 0.33), with a significant association of younger individuals (3.0–9.1 years) with Fe-deficiency (p < 0.05 and χ2 = 22.7).

In addition, there is a significant positive correlation between Fe-deficiency with blood levels of Pb, Cu, and Zn (p < 0.05), (r = 0.43, 0.35, and 0.42, respectively) as compared to control group, this findings supported, by comparing the levels of the examined metals in both groups, in individuals whom close to heavy metals source (highway traffic or oil gas station), and found that the mean of the heavy metals level in close Fe-deficient group higher than in close Fe-replete group.     

Mechanistic aspects of the thermal formation of halogenated organic compounds including polychlorinated dibenzo‐p‐dioxins. Part V†: Hypotheses and summary

The hypotheses on the de novo syntheses of polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo‐p‐dioxins (PCDDs), based on known literature, are presented. Polychlorinated benzenes and polychlorinated phenols are probably key intermediates.

In the present article, hypotheses that may account for the presence of polychlorinated dibenzofurans (PCDFs) and dibenzo‐p‐dioxins (PCDDs) in the effluents from municipal and industrial incinerators are put forward. These hypotheses are based on the previously surveyed literature (Ref. 203–206) and experimental results on laboratory scale and thermodynamic calculations are considered. The interconnections of various reaction steps are speculative and no technological information was added to account for conditions in real incinerators. Conclusion of the discussions on the related subject matter, presented in the Parts I‐IV (Ref. 203–206), are also described in this paper.     

Polarographic investigations on the complexation of cadmium and zinc by thiol peptides

Complex formation of Cd²⁺ and Zn²⁺ with thiol derivatives has been investigated by differential pulse polarography. The binding of Cd²⁺ and Zn²⁺ with cysteine (CySH), glutathione (GSH) and the model peptide N‐acetyl‐cysteine‐methylamide (ASH) reveals different stoichiometry. Thus, Cd²⁺ forms 1:1 and 1:2 complexes with CySH while 1:2 and 1:4 complexes have been observed with GSH and ASH, respectively. Overall formation constants of Cd²⁺ with CySH (Iogβ ₂ 15.3) and with GSH (Iogβ5₂ 14.4) have been estimated using competitive complexation with nitrilotriacetic acid (NTA). Investigation of competition between Zn²⁺ and Cd²⁺ for the thiol complexation has underlined the role played by the amino group in CySH for the stabilization of Zn complexes in contrary to Cd complexes.     

Large plasmids governing multiple resistances to heavy metals: A genetic approach∗

Gram negative bacteria classified as Alcaligenes eutrophus and carrying large resistance plasmids (generally two) were found in various industrial sites highly contaminated by heavy metals (Zn⁺⁺, Cu⁺⁺, Co⁺⁺,...). These strains were detected by DNA hybridization with a probe made with a 9kb fragment (ccz⁺ fragment) encoding for resistances to Cd⁺⁺, Co⁺⁺ and Zn⁺⁺, and cloned from plasmid pMOL30. This plasmid was isolated from the representative strain A. eutrophus CH34 which harbours the plasmids pMOL30 (240 kb) and pMOL28 (165 kb). Phenotypes related to pMOL28 and pMOL30 include the tolerance to Cd⁺⁺, Co⁺⁺, Cr0₄ ⁼, Cu⁺⁺, Hg⁺⁺, Ni⁺⁺, Pb⁺⁺ and Zn⁺⁺. The described genetic properties of these plasmids refer to some cloned or mapped functions and to some plasmid rearrangements. Plasmid pMOL85 (250 kb) which is related to pMOL30 was also described. Its host (A. eutrophus DS185) was isolated from a zinc desert. pMOL85 can efficiently self transfer in plasmidfree derivatives.     

Preliminary Evaluation of the Use of Phosphogypsum for Reef Substrate. I. A Laboratory Study of Bioaccumulation of Radium and Six Heavy Metals in an Aquatic Food Chain

Phosphogypsum (PG), a solid by-product of phosphoric acid production, contains radionuclides and trace metals in concentrations which may pose a potential hazard to human health and the environment. to investigate the possibility of bioaccumulation of radium and six heavy metals over time when aquatic organisms experience both trophic and environmental exposure to PG, we designed a laboratory experiment representing three levels of an aquatic food chain. During the 135 day experiment, a meiobenthic copepod species (Amphiascoides atopus) was cultured in the presence of PG. the copepods were subsequently fed to grass shrimp (Palaemonetes vulgaris and P. pugio) which were in turn fed to gulf killifish (Fundulus grandis); both the grass shrimp and the killifish also experienced an environmental PG exposure. Other than elevated radium levels in the experimental grass shrimp, the experiment demonstrated little effect of environmental or trophic exposure to PG on microinvertebrates, macroinvertebrates, or fishes that could be attributed to PG. in all cases where increased concentrations were indicated within the experimental group, roughly equivalent increases in metal concentrations also occurred in the control group.     

Effects of nanoparticles on Daphnia magna population dynamics

Spherical TiO₂ nanoparticles (npTiO₂) were prepared by controlled hydrolysis of tetraethoxy orthotitanate under a nitrogen atmosphere. ZnO nanoparticles (npZnO) were prepared using hydrothermal methods. The crystal structure, chemical, thermal and morphological properties of npZnO and npTiO₂ were characterised using Fourier Transform Infrared Spectrometer, enery-dispersive X-ray spectroscopy, X-ray diffraction, and scanning electron microscope techniques. The short- and long-term experiments were started with neonates taken from the same culture and laboratory condition. In the acute experiments, npTiO₂, npZnO, and cocktail concentrations were applied. 96h-LC₅₀ values were 1.8, 0.7, and 0.1?mg?L^?1, respectively (p?<?.05). For the chronic experiments, different npTiO₂ concentrations were performed. 21d-LC₅₀ value was 1.0?mgL^?1 (p?<?.05). Morphometry became progressively worse in concentrations of more than 1?mgL^?1 npTiO₂. Neonate and young individuals were more sensitive to death because of their low tolerance. This result was affected by population progeny and growth rates (p?<?.05). While control and 0.5?mgL^?1 npTiO₂ groups were determined as growing population, 1.5 and 2?mgL^?1 npTiO₂ groups had decreased population size as R₀ values. Consequently, the relationships between nanoparticle accumulation within Daphnia magna and its population structure and body morphometry for each concentration were important indicators. Its tolerance level to nanoparticles under laboratory conditions reflected its replacement and behaviour in the ecosystem.