Leaching variations of heavy metals in chelator-assisted phytoextraction by Zea mays L. exposed to acid rainfall

Chelant-enhanced phytoextraction method has been put forward as an effective soil remediation method, whereas the heavy metal leaching could not be ignored. In this study, a cropping-leaching experiment, using soil columns, was applied to study the metal leaching variations during assisted phytoextraction of Cd- and Pb-polluted soils, using seedlings of Zea mays, applying three different chelators (EDTA, EDDS, and rhamnolipid), and artificial rainfall (acid rainfall or normal rainfall). It showed that artificial rainfall, especially artificial acid rain, after chelator application led to the increase of heavy metals in the leaching solution. EDTA increased both Cd and Pb concentrations in the leaching solution, obviously, whereas EDDS and rhamnolipid increased Cd concentration but not Pb. The amount of Cd and Pb decreased as the leaching solution increased, the patterns as well matched LRMs (linear regression models), with R-square (R ²) higher than 90 and 82% for Cd and Pb, respectively. The maximum cumulative Cd and Pb in the leaching solutions were 18.44 and 16.68%, respectively, which was amended by EDTA and acid rainwater (pH 4.5), and followed by EDDS (pH 4.5), EDDS (pH 6.5), rhamnolipid (0.5 g kg⁻¹ soil, pH 4.5), and rhamnolipid (pH 6.5).

     

可见光下氮掺杂罗丹明B分子印迹TiO_2的选择性光催化性能

采用溶胶-凝胶法和分子印迹技术,以尿素为氮源、罗丹明B为模板分子制备了氮掺杂罗丹明B分子印迹TiO_2粉末(N-TiO_2-RhB),并对样品进行了XRD、UV-Vis DRS和BET表征。表征结果显示:氮掺杂和分子印迹一定程度改善了样品的孔隙结构和孔径分布,N-TiO_2-RhB的比表面积和孔体积分别为TiO_2的1.9倍和1.5倍;氮掺杂使TiO_2的光吸收带边发生红移,而分子印迹不能改变催化剂的光吸收带边。N-TiO_2-RhB具有最佳的可见光活性和选择性,对罗丹明B的降解率高达92.7%。对罗丹明B、罗丹明6G、甲基紫和甲基绿的降解过程均符合一级反应动力学方程。     

灭幼脲Ⅲ号杀虫剂在大白菜和土壤中持久性及残留的研究

本文报道灭幼脲Ⅲ号杀虫剂在大白菜和土壤中的残留试验结果.经在南北两地连续两年的田间试验表明,灭幼脲Ⅲ号属非持久性农药,在作物和土壤中都较快地消失,在大白菜上的半衰期为3.8—14.0d,在土壤中为8.8—27.0d.用25％灭幼脲Ⅲ号胶悬剂稀释2500倍,每亩每次按常规用药10g或加倍药量20g(有效成分)施药,喷施2或3次,距最后一次施药三周时,灭幼脲Ⅲ号杀虫剂在大白菜的最大残留量为2.67ppm,在土壤中为13.81ppm.建议该农药在大白菜上的最高允许残留量(MRL)为3ppm,安全间隔期为21d.     

一种新的处理甲基汞废水的树脂:石油亚砜萃淋树脂

本文对从高硫原油很容易制取的一种新的廉价萃取剂——石油亚砜(PSO)所合成的树脂,即PSO萃淋树脂处理低浓度甲基汞废水的可能性进行了研究。研究结果表明:在中性范围内(pH5—8)树脂对甲基汞的吸附能力很强,吸附率≥99％(废水浓度为10—20ppb);随着流速的增加,吸附率下降幅度很小;树脂易再生, 十倍树脂体积的再生剂(4mol HCl),洗脱率可达97.9％,再生五个周期后,净化率未见明显变化;Mg~(2+)、Fe~(2+)(Fe~(3+)、Ag+、cu~(2+)、Hg~(2+)、PA(黄腐酸)及Cl~-的干扰实验表咀除Hg~(2+)、Ag+外,其他离子基本没有影响。     

Study on low-temperature plasma γ-Al2O3 catalytic viscosity reduction of polyacrylamide solution

The wide use of polyacrylamide (PAM) in enhanced oil recovery generates a large amount of polymer-bearing wastewater featuring high viscosity and difficult viscosity reduction, making the treatment of wastewater increasingly difficult. In this paper, the experimental study on reducing the viscosity of wastewater containing polyacrylamide by using the plasma generated by dielectric barrier discharge (DBD) and the synergistic effect of catalyst γ-Al₂O₃ is carried out. The law of plasma reducing the viscosity of wastewater containing polyacrylamide is studied under the different conditions of amounts of γ-Al₂O₃ catalyst, discharge voltages, and initial concentrations of polyacrylamide-containing wastewater. The mechanism of viscosity reduction of polyacrylamide is studied through environmental scanning electron microscope (ESEM), Fourier transform infrared (FTIR) spectrometer, and X-ray photoelectron spectroscopy (XPS). The results show that the catalytic viscosity reduction is the best when the discharge voltage is 18 kV and the discharge time is 15 min. With the increase in the input of the γ-Al₂O₃ catalyst, the viscosity of the PAM solution decreases gradually. When the amount of γ-Al₂O₃ is 375 mg, the shear rate changes from 0.5 1/sec to 28 1/sec, and the viscosity of the solution containing polyacrylamide changes from 434.5 mPa·s to 40.2 mPa·s. The viscosity reduction rate of the PAM solution is 90.7%. After the catalytic viscosity reduction, the functional groups of polyacrylamide do not change much. The elemental composition of the catalyst has not changed, which is still Al, C, and O.

     

Artificial aging induced changes in biochar,s properties and Cd2+ adsorption behaviors

Environmental Science and Pollution Research - Fresh biochar has been widely applied to the remediation of heavy metals in soil by its property of adsorption, but the changes in its physicochemical...     

微生物磁效应及其强化废/污水生物处理的研究进展

介绍了微生物磁效应的现象、原理及其在强化废/污水生物处理过程应用的研究进展,包括磁场对微生物运动、微生物生长、微生物酶活力以及对活性污泥法或生物接触氧化法处理废/污水过程的影响。提出生物亲和亲水磁性填料以及磁粉的合理运用,可能是实现微生物磁效应在废/污水生物处理中应用的有效途径。     

Spatial distribution and seasonal variation of char-EC and soot-EC in the atmosphere over China

A previous study on PM_2.5 carbonaceous aerosols measured with the thermal optical reflectance (TOR) method in fourteen Chinese cities is extended by subdividing total EC into char-EC and soot-EC. Average char-EC concentrations show great differences between the fourteen cities and between winter and summer periods, with concentrations of 8.67 and 2.41 μg m^?3 in winter and summer, respectively. Meanwhile spatial and seasonal soot-EC variations are small, with average concentrations of 1.26 and 1.21 μg m^?3 in winter and summer, respectively. Spatial and temporal distributions of char-EC, similar to EC, are mainly influenced by local fuel consumption, as well as the East Asian monsoon and some meteorological factors such as the mixing height and wet precipitation. The small spatial and seasonal variation of soot-EC is consistent with its regional-to-global dispersion, which may suggest that soot carbon is not local carbon, but regional carbon. Char-EC/soot-EC ratios show summer minimum and winter maximum in all cities, which is in good agreement with the difference in source contributions between the two periods. As OC/EC ratio is affected by the formation of the secondary organic aerosol (SOA), char-EC/soot-EC ratio is a more effective indicator for source identification of carbonaceous aerosol than previously used OC/EC ratio.     

废铸砂作为建筑材料资源化再利用研究进展

废铸砂是铸造工业在金属制品的生产过程中次生出来的一种细颗粒固体废弃物。研究其作为一种资源进行合理再利用是当前处置废铸砂、保护生态环境的良好对策。本文对废铸砂的环境特征、物理性质及废铸砂作为建筑材料在多种建筑制品及工程中的资源化再利用进行了综述研究,涉及的再利用领域包括混凝土、热拌沥青混合料、低强度填料、水泥、路基、路堤、阻水帷幕（屏障）和衬垫。调查发现,次生于黑色金属（铁和钢）铸造生产线的废铸砂是一种无害固体废弃物,正确处置和科学利用,对环境不会产生二次污染,在以上建筑制品及工程中的应用能满足相关技术、性能要求,可以替代相关的材料进行资源化再利用。     

提高法律地位 强化征收力度 ——谈排污费费改税的必要性

阐述了我国排污收费制度的现状和发展趋势,针对当前排污费征收工作中遇到的问题,提出了排污费费改税的必要性。指出,在我国实行排污费费改税的条件已经具备,应当把排污收费制度的改革提高到作为我国社会经济可持续发展长期战略的一个组成部分的高度来认识和考虑。