Heavy metal pollution in vegetables grown in the vicinity of a multi-metal mining area in Gejiu,China: total concentrations,speciation analysis,and health risk

A field survey was conducted to investigate the present situation and health risk of arsenic (As), lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn) in soils and vegetables in a multi-metal mining area, Gejiu, China. Furthermore, three vegetables (water spinach, potato, and summer squash) containing high metal concentrations were selected to further analyze metal speciation. The results showed that the average concentrations of five metals in soil exceeded the limiting values, and their bioavailable concentrations were significantly positively correlated to the total ones. Heavy metals in the edible parts of vegetables also exceeded the corresponding standards. The leaves of pakchoi, peppermint, and coriander had a strong metal-accumulative ability and they were not suitable for planting. Except the residue forms, the main forms of metals in the edible parts of three selected vegetables were ethanol-, NaCl-, and HAc-extractable fractions for As, Pb, and Cd, respectively; however, Cu was mainly presented as NaCl-extractable and Zn as HAc-extractable fractions. A high proportion of ethanol-extractable As showed that As bioactivity and toxic effects were the highest. Although the total and bioavailable Cd were high in soil, its speciation in vegetables was mainly presented as HAc-extractable fraction, which has a relatively low bioactivity. Lead and arsenic were imposing a serious threat on the local residents via vegetable consumption.     

玉米秸秆活性炭的制备及其吸附动力学研究

以玉米秸秆为原材料,采用ZnCl2活化法制备玉米秸秆活性炭,吸附次甲基蓝染料废水,进行动力学分析。本实验用Langmuir和Freundlich模型对吸附等温线进行拟合,结果表明,玉米秸秆活性炭对次甲基蓝的吸附与Langmuir方程拟合良好,R2=0.9857。采用Lagergren准一级速率模型、Lagergren准二级速率模型、Bangham动力学方程和Elovich动力学方程分别对秸秆活性炭吸附次甲基蓝溶液进行吸附动力学拟合,通过分析得出吸附过程与Lagergren准二级速率模型拟合最好,R2=0.9979。秸秆活性炭对次甲基蓝的最大吸附量达到909.09 mg/g,具有很高的吸附能力。     

大型蚤标志酶用于城市二级出水毒性的评价

大型蚤是一种国际公认的标准实验生物,广泛应用于污水、地表水等水质毒性检测。毒性水平较低的城市二级出水,对大型蚤往往无急性毒性效应,而具有慢性毒性效应,但慢性毒性检测周期过长,因此探索一种更灵敏的指标,实现快速检测,对于控制二级出水的水质风险具有重要意义。本研究考察了大型蚤在短期暴露于城市二级出水条件下,其体内乙酰胆碱酯酶、超氧化物歧化酶、过氧化氢酶、ATP酶、羧酸酯酶和碱性磷酸酯酶的酶活变化特征,从中筛选出对二级出水毒性响应灵敏的标志酶指标。实验结果表明,碱性磷酸酯酶、过氧化氢酶对二级出水毒性响应相对较灵敏,具有成为标志酶的潜力,研究结果为城市二级出水生物毒性评价方法优化提供新的思路。     

2008年江苏持续性降雪中的水汽和动力抬升机制分析

2008年1月下旬江苏省出现了历史罕见的持续性暴雪过程,研究发现,降雪量的大小与低空急流的日变化相对应,暴雪过程中700 hPa西南急流对水汽的输送起着重要的作用,作为大尺度天气系统,700 hPa急流的加速发生在降雪量增大之前,其值阈大小与6 h降雪量之间没有对应关系,急流减弱在暴雪结束以后;降雪的发生和发展与南北风的增大和冷暖平流有关,低层偏北风作为冷垫对暖湿气流的抬升和水汽的凝结起到了一定的作用;江苏降雪过程中水汽主要来源于700～500 hPa,低层东风气流对黄海南部的水汽输送非常有限;强降雪的发生与700 hPa水汽通量散度相对应,水汽通量散度辐合增大,降雪量增大;在降雪过程中垂直运动对降雪量的大小有很好的指示意义。     

Quantifying air pollution attenuation within urban parks: an experimental approach in Shanghai, China

Parks with various types of vegetations played an important role in ameliorating air quality in urban areas. However, the attenuation effect of urban vegetation on levels of air pollution was rarely been experimentally estimated. This study, using seasonal monitoring data of total suspended particles (TSP), sulfur dioxide (SO(2)) and nitrogen dioxide (NO(2)) from six parks in Pudong District, Shanghai, China, demonstrated vegetations in parks can remove large amount of airborne pollutants. In addition, crown volume coverage (CVC) was introduced to characterize vegetation conditions in parks and a mixed-effects model indicated that CVC and the pollution diffusion distance were key predictors influencing pollutants removal rate. Therefore, it could be estimated by regression analysis that in summer, urban vegetations in Pudong District could contribute to 9.1% of TSP removal, 5.3% of SO(2) and 2.6% of NO(2). The results could be considered for a better park planning and improving air quality.     

Mercury distribution in seawater discharged from a coal-fired power plant equipped with a seawater flue gas desulfurization system

Background and purpose  

More and more coal-fired power plants equipped with seawater flue gas desulfurization systems have been built in coastal areas. They release large amount of mercury (Hg)-containing waste seawater into the adjacent seas. However, very limited impact studies have been carried out. Our research targeted the distribution of Hg in the seawater, sediment, biota, and atmosphere, and its environmental transportation.     

Distribution characteristics of organochlorine pesticides in surface and vertical sediments from the Zha Long Wetland, China

Introduction

The Zha Long Wetland, the first water bird conservation area in China, lies on the northern bank of the Song Nen Plain with an area of 2,100 km². In many areas of the Zha Long Wetland, water pollution has led to a decrease in the wetland??s ecological function, vegetation degradation, a decrease in the number of bird species, and the depletion of fish resources.

Materials and methods

The sediments used in this study were collected from the surface sediment of seven sites and from different depths in three types of marshes in the Zha Long Wetland in northeast China in late October 2006. The levels and distribution patterns of 17 organochlorine pesticides (OCPs; ??-HCH, ??-HCH, ??-HCH, ??-HCH, p,p??-DDE, p,p??-DDD, p,p??-DDT, endosulfan I, endosulfan II, endosulfan sulfate, heptachlor, heptachlor epoxide, aldrin, dieldrin, endrin, endrin aldehyde, and methoxychlor) in surface sediments as well as hexachlorocyclohexane (HCH) and 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) in vertical sediments were investigated.

Results and discussion

The concentrations of HCHs, DDTs, endosulfans, heptachlors, aldrin, and methoxychlor in surface sediments ranged from 10.44 to 41.97 ng/g, nd (undetectable levels) to 211.88 ng/g, nd to 69.89 ng/g, nd to 28.10 ng/g, 9.81 to 623.83 ng/g, and from nd to 3.99 ng/g, respectively. The highest levels of OCPs were detected in Tangtugangzi at a total concentration of 727.72 ng/g, where the dominant compound was endrin at a concentration of 483.04 ng/g. In the vertical sediments, the HCHs and DDTs were in the ranges of nd?C136.00 and nd?C214.06 ng/g, respectively.

Conclusions

Different distributions of HCHs, DDTs, and other OCPs indicated that they originated from different contamination sources. Composition analyses in surface sediments indicated recent OCP usage or discharge at some sample sites in the Zha Long Wetland.     

Comparison of inclined plate sedimentation and dissolved air flotation for the minimisation of subsequent nitrogenous disinfection by-product formation

The formation of disinfection by-products (DBPs), including both nitrogenous disinfection by-products (N-DBPs) and carbonaceous disinfection by-products (C-DBPs), was investigated upon chlorination of water samples following two treatment processes: (i) coagulation-inclined plate sedimentation (IPS)-filtration and (ii) coagulation-dissolved air flotation (DAF)-filtration. The removal of algae, dissolved organic nitrogen (DON), dissolved organic carbon (DOC) and UV₂₅₄ by coagulation-DAF-filtration was superior to coagulation-IPS-filtration. On average, 53%, 53% and 31% of DOC, DON and UV₂₅₄ were removed by coagulation-DAF-filtration process, which were higher than 47%, 31% and 27% of that by coagulation-IPS-filtration process. Additionally, coagulation-IPS-filtration performed less well at removing the low molecular weight organics than coagulation-DAF-filtration process. The concentrations of chloroform, dichloroacetamide (DCAcAm) and dichloroacetonitrile (DCAN) formed during chlorination after coagulation-DAF-filtration reached their maximum values of 13, 1.5 and 4.7 μg L⁻¹, respectively, and were lower than those after coagulation-IPS-filtration with the maximum detected levels of 17, 2.9 and 6.3 μg L⁻¹. However, the trichloronitromethane (TCNM) concentration after the two processes was similar, suggesting that DON may have less of a contribution to TCNM formation than DCAcAm and DCAN.     

Column study of Cr(VI) removal by cationic hydrogel for in-situ remediation of contaminated groundwater and soil

Column experiments were conducted for examining the effectiveness of the cationic hydrogel on Cr(VI) removal from groundwater and soil. For in-situ groundwater remediation, the effects of background anions, humic acid (HA) and pH were studied. Cr(VI) has a higher preference for being adsorbed onto the cationic hydrogel than sulphate, bicarbonate ions and HA. However, the adsorbed HA reduced the Cr(VI) removal capacity of the cationic hydrogel, especially after regeneration of the adsorbents, probably due to the blockage of adsorption sites. The Cr(VI) removal was slightly influenced by the groundwater pH that could be attributed to Cr(VI) speciation. The 6-cycle regeneration and reusability study shows that the effectiveness of the cationic hydrogel remained almost unchanged. On average, 93% of the adsorbed Cr(VI) was recovered in each cycle and concentrated Cr(VI) solution was obtained after regeneration. For in-situ soil remediation, the flushing water pH had an insignificant effect on the release of Cr(VI) from the soils. Multiple-pulse flushing increased the removal of Cr(VI) from the soils. In contrast, more flushing water and longer operation may be required to achieve the same removal level by continuous flushing.