四种植物材料对废水中铅离子的吸附特征

为解决重金属废水处理问题,寻找高效低成本的生物吸附剂,本文选用了野菊杆（Dendranthema indicum, DI）、艾杆（Artemisia argyi, AA）、薄荷杆（Mentha haplocalyx, MH）和柠檬皮（Citrus limon, CL）四种植物材料对水中铅离子进行吸附研究。并利用SEM、BET和FTIR对材料进行表征,探讨了吸附剂投加量、溶液初始pH和共存阳离子对吸附量的影响。结果表明,四种材料对模拟废水中铅的吸附量随投加量的增加呈对数下降（P<0.05）;随初始pH的升高,四种材料呈现先增加后逐渐趋于稳定的趋势。准一级动力学能更好地描述野菊杆对Pb²⁺的动力学吸附过程,准二级动力学能更好描述艾杆、薄荷杆和柠檬皮对Pb²⁺的动力学吸附过程。野菊杆和艾杆对铅的吸附是以化学吸附为主的单层吸附,符合Langmuir模型;薄荷杆和柠檬皮对铅的吸附过程主要为不规则的多分子层吸附,更符合Freundlich模型。共存阳离子Mg²⁺、Cu²⁺、Al³⁺与Pb²⁺产生竞争吸附,显著降低材料对Pb²⁺的吸附量（P<0.05）。四种植物材料吸附性能大小顺序为薄荷杆 > 艾杆 > 柠檬皮 > 野菊杆。因此,四种植物材料是吸附废水中铅离子的潜在材料。     

Inhibition of erythrocyte delta-aminolevulinic acid dehydratase (ALAD) activity in fish from waters affected by lead smelters

We assessed the effects on fish of lead (Pb) released to streamsby smelters located in Trail, BC (Canada), E. Helena, MT, Herculaneum, MO, and Glover, MO. Fish were collected by electrofishing from sites located downstream of smelters and from reference sites. Blood from each fish was analyzed for -aminolevulinic acid dehydratase (ALAD) activity and hemoglobin (Hb), and samples of blood, liver, or carcass were analyzed for Pb, zinc (Zn), or both. Fish collected downstreamof all four smelters sites had elevated Pb concentrations, decreased ALAD activity, or both relative to their respectivereference sites. At E. Helena, fish from the downstream site also had lower Hb concentrations than fish from upstream. Differences among taxa were also apparent. Consistent with previous studies, ALAD activity in catostomids (Pisces: Catostomidae-northern hog sucker, Hypentelium nigricans;river carpsucker, Carpiodes carpio; largescale sucker, Catostomus macrocheilus; and mountain sucker, C. platyrhynchus) seemed more sensitive to Pb-induced ALAD inhibition than the salmonids (Pisces: Salmonidae-rainbow trout,Oncorhynchus mykiss; brook trout, Salvelinus fontinalis) or common carp (Cyprinus carpio). Some of these differences may have resulted from differential accumulation of Zn, which was not measured at all sites. We detected no ALAD activity in channel catfish (Ictaluruspunctatus) from either site on the Mississippi River at Herculaneum, MO. Our findings confirmed that Pb is releasedto aquatic ecosystems by smelters and accumulated by fish, andwe documented potentially adverse effects of Pb in fish. We recommend that Zn be measured along with Pb when ALAD activityis used as a biomarker and the collection of at least 10 fish ofa species at each site to facilitate statistical analysis.     

Roadside Concentration of Gaseous and Particulate Matter Pollutants and Risk Assessment in Dar-Es-Salaam, Tanzania

This study used manual air sampling method to assess the contribution of road traffic to air pollution level in Dar-es-Salaam City, Tanzania. Samples were collected from 11 different sites. Parameters measured were: sulphur dioxide using pararosaniline method, nitrogen dioxide using saltzman method, particulate matter and particulate lead using filtration method and atomic absorption spectrometric method, respectively. Results showed that hourly average sulphur dioxide concentration range from 127 to 1385 g/m³. The measured values of sulphur dioxide were above the recommended WHO guidelines with an hourly objective value of 350 g/m³ at 87% of the sampling sites. The hourly average nitrogen dioxide concentration ranged from 18 to 53 g/m³. The maximum hourly nitrogen dioxide concentration at 53 g/m³ was below the WHO guideline value of 200 g/m³. The hourly average suspended particulate matter (SPM) ranged from 98 to 1161 g/m³, exceeding the recommended value of 230 g/m³ by WHO at 87% of the sampling sites. The hourly average lead concentration was found to range from 0.60 to 25.6 g/m³, exceeding again the WHO guideline value of 1.5 g/m³at 83% of the sampling sites. Results predicted by Gaussian model when compared with the measured values were found to have a correlation coefficient of 0.8, signifying a good correlation. The risk assessment was undertaken considering the people who spend a significant portion of their time near the roads, such as the Uhuru primary school pupils and the adult population who reside by the roadside. The unit risk realised was 18.2 × 10^–6 for adult population and 2.2 × 10^–6 for pupils, both scenarios showing risk higher than the United Sates of America Environmental Protection Agency (USEPA) acceptable limit of 1× 10^–6. Considering the magnitude of the problem at hand, this study recommends an introduction of mandatory emission tests of SPM, lead and sulphur dioxide (SO₂). The study further recommends the introduction of continuous and/or regular air quality monitoring and the use non-leaded petrol in Tanzania.     

重庆市菜地土壤和蔬菜中Hg、Pb的污染特征及相关性分析

通过对重庆市菜地土壤和蔬菜 Hg、Pb的含量分析 ,发现土壤 Hg含量远远大于背景值 ,并且土壤 Hg的含量与菜地周围的环境密切相关 ;土壤 Pb的含量同背景值相差不大。Hg、Pb在土壤和蔬菜中的污染特征表现为主城区 >近郊区 >远郊区 ;并且不同蔬菜品种中 Hg、Pb的含量差异较大 ,在不同蔬菜种类表现为叶菜类 >果菜类 >根菜类。相关性分析表明同一菜地土壤和蔬菜中 Hg、Pb含量无相关性 ;不同菜地土壤和蔬菜 Hg、Pb含量不具有相关性。     

Evaluation of Lead Availability in Amended Soils Monitored Over a Long-Term Time Period

Two different soil amendment processes were evaluated for reducing lead availability from a contaminated soil at a demonstration study site, to reduce potential public health and environmental concerns. A limited variety of in vitro laboratory “availability” tests (relative bioaccessible and environmental mobility) were performed to determine if the available lead in the contaminated soil would be less available after in situ soil amendment (chemical treatment). The relative bioaccessibility results were evaluated in both a short-term period (within 24 h after treatment) and over a long-term time period (quarterly basis for 5 years). Reduction in relative bioaccessibility was noted for one of the treatments immediately after treatment; however, both treatments indicated a significant upward trend in bioaccessibility values over a 5-year time period after treatment. The comparison between the treated units and the control units indicated that the long-term effectiveness of the treatment processes could not be demonstrated.     

新型二氧化铅电极处理有机染料废水的研究

研究了高压塑片法制备新型二氧化铅电极的工艺,通过循环伏安、X衍射和扫描电镜等手段对电极性能的考察表明,该电极不仅具有高电催化活性,还有很好的抗腐蚀性能.通过与普通石墨电极的对比实验,进一步探讨了该电极降解中性枣红染料的机制和工艺条件.结果表明,该电极在脱色和COD降解方面都有明显的优越性.在含磷酸盐和氯离子的体系中,降解效率尤为突出.     

AQUATIC TRANSPORT OF HEAVY METALS IN THE URBAN ENVIRONMENT1

ABSTRACT: A study has been conducted for the past two years on a 4.6 mile stretch of the Saddle River near Lodi, New Jersey. The primary objectives of this study were two fold; initially, the amounts of various heavy metals being contributed to the Saddle River by stormwater runoff, rainfall, and individual tributaries, etc., were investigated to better delineate the distribution of various sources of heavy metals to the aquatic environment. Secondly, a series of benthal deposits from the Saddle River were analyzed to determine the fate of these metals once introduced into the receiving stream. A mass balance analysis of heavy metals in the Saddle River was performed to determine the amount of these materials contributed from unrecorded sources. The results of this study seemed to demonstrate the importance of considering the potential scouring of river sediments as a secondary source of metals in determinations of this type. The distribution of metals in precipitation samples collected in this study was found to be similar to that in runoff, with lead and zinc predominating. Relative concentrations of metals in precipitation as compared to those of stormwater were relatively insignificant. Metal concentrations of bottom sediments were found to vary considerably from sample to sample.     

TRENDS IN LEAD CONCENTRATIONS IN MAJOR U.S. RIVERS AND THEIR RELATION TO HISTORICAL CHANGES IN GASOLINE-LEAD CONSUMPTION1

ABSTRACT: Declines in concentrations of dissolved lead occurred at nearly two-thirds of 306 locations on major U.S. rivers from 1974 to 1985. Declines in dissolved lead concentrations are statistically significant (p < 0.10) at approximately one-third of the sampling locations. Statistically significant increases in dissolved lead concentrations occurred at only 6 percent of the sites, but are clustered in the Texas-Gulf and Lower Mississippi regions. Possible explanations for the observed trends in lead concentrations are tested through comparisons with (1) records of lead discharges from major sources including leaded-gasoline consumption and municipal- and industrial-point source discharges, (2) trends in various water-quality constituents such as pH and total alkalinity, and (3) basin characteristics such as drainage area. Statistically significant declines in lead concentrations in streams and gasoline lead (i.e., the largest source of lead at these sites) are highly coincident for the 1979 to 1980 period at most sampling locations. The greatest amount of decline in gasoline lead occurred at sites showing statistically significant downtrends in stream concentrations of lead from 1974 to 1985. No more than 5 percent of the trends in stream lead are influenced by municipal- and industrial-point sources of lead. Factors that affect the transport of dissolved lead, including lead solubility, suspended sediment, and basin characteristics such as drainage basin size, are not significantly related to trends in dissolved lead. Trends in streamflow explain no more than 7 percent of the downtrends in concentrations of lead and may partly explain the frequent increases in lead concentrations in the Texas-Gulf and Lower Mississippi regions.     

镉、铅、汞在体外对氨基酸掺入微粒体蛋白中的影响

将从未经处理大鼠体内分离出来的肝微粒体与蛋白合成能量系统,同位素标记氨基酸以及各种浓度镉、铅、汞在体外一起温育以测定镉、铅、汞对氨基酸掺入微粒体蛋白中的影响.实验结果表明,上述三种金属都抑制氨基酸向肝微粒体蛋白中的掺入.随着这些金属在体外浓度的增加,此种抑制作用,也越明显.