Occurrence of phthalates in sediment and biota: relationship to aquatic factors and the biota-sediment accumulation factor

Phthalate compounds in sediments and fishes were investigated in 17 Taiwan's rivers to determine the relationships between phthalate levels in sediment and aquatic factors, and biota-sediment accumulation factor (BSAF) for phthalates. Mean concentrations (range) of di(2-ethylhexyl) phthalate (DEHP), butyl benzyl phthalate (BBzP) and di-n-butyl phthalate (DBP) in sediment at low-flow season were 4.1 (<0.05-46.5), 0.22 (<0.05-3.1) and 0.14 (<0.05-1.3)mgkg(-1)dw; those at high-flow season were 1.2 (<0.05-13.1), 0.13 (<0.05-0.27) and 0.09 (<0.05-0.22)mgkg(-1)dw, respectively. Trace levels of dimethyl phthalate (DMP), diethyl phthalate (DEP) and di-n-octyl phthalate (DOP) in sediment were found in both seasons. Concentrations of DEHP in sediments were significantly affected by temperature, suspended solids, ammonia-nitrogen, and chemical oxygen demand. The highest concentration of DEHP in fish samples were found in Liza subviridis (253.9mgkg(-1)dw) and Oreochromis miloticus niloticus (129.5mgkg(-1)dw). BSAF of DEHP in L. subviridis (13.8-40.9) and O. miloticus niloticus (2.4-28.5) were higher than those in other fish species, indicating that the living habits of fish and physical-chemical properties of phthalates, like logKow, may influence the bioavailability of phthalates in fish. Our data suggested that DEHP level in river sediments were influenced by water quality parameters due to their effects on the biodegradation processes, and that the DEHP level in fish was affected by fish habitat and physiochemical properties of polluted contaminants.     

Effects of rare earth elements on the distribution of mineral elements and heavy metals in horseradish

In order to investigate the effects of rare earth elements (REEs) on horseradish, the distribution of the mineral elements and heavy metals in different organs of horseradish have been studied by using inductively coupled plasma-atomic emission spectrometry (ICP-AES). Meanwhile, three variable major parameters, namely the concentration of REEs, the type of REEs, and the growth stage of plant were chosen. The results indicated that the test REEs, Ce(III) and Tb(III), could be accumulated in leaves, stems and roots of horseradish. In addition, we found that the content of mineral elements was increased in horseradish treated with 20mgl(-1) of Ce(III), but not those with the 20mgl(-1) of Tb(III). Moreover, the content of mineral elements in horseradish was decreased with the increasing concentration of REEs (100, 300mgl(-1)). Furthermore, we found that there were the opposite effects on the content of the heavy metals in horseradish treated with REEs. Finally, we found that the effect of REEs on the accumulation of REEs, and the content of mineral elements or heavy metals of horseradish during vigorous growth stage, no matter positive or negative, was more obvious than that of the other growth stages. These results demonstrated that the distribution behaviors of mineral elements and heavy metals in horseradish can be affected by the type and concentration of REEs, and the growth period of plant.     

A rapid spectrophotometric determination of persulfate anion in ISCO

Due to a gradual increase in the use of persulfate as an in situ chemical oxidation (ISCO) oxidant, a simple measurement of persulfate concentration is desirable to analyze persulfate distribution at designated time intervals on/off a site. Such a distribution helps evaluate efficacy of ISCO treatment at a site. This work proposes a spectrophotometric determination of persulfate based on modification of the iodometric titration method. The analysis of absorption spectra of a yellow color solution resulting from the reaction of persulfate and iodide in the presence of sodium bicarbonate reveals an absorbance at 352 nm, without significant interferences from the reagent matrix. The calibration graph was linear in the range of persulfate solution concentration of 0-70 mM at 352 nm. The proposed method is validated by the iodometric titration method. The solution pH was at near neutral and the presence of iron activator does not interfere with the absorption measurement. Also, analysis of persulfate in a groundwater sample using the proposed method indicates a good agreement with measurements by the titration method. This proposed spectrophotometric quantification of persulfate provides a simple and rapid method for evaluation of ISCO effectiveness at a remediation site.     

Ozonation of pentachlorophenol in unsaturated soils

A heterogeneous model was developed to describe interactions between ozone and hydrophobic organic compounds, exemplified by pentachlorophenol, in highly gas-saturated vadose zones where water moisture was limited to a thin film on soil particle surfaces. The soil was assumed to be free of soil organic matter. The model included a set of transient equations considering diffusion with simultaneous chemical reaction and hydrophobic partitioning. From dimensionless analysis, it was found that the film concentrations of ozone and the hydrophobic organic component were dependent on the Damk?hler numbers. Effects of Damk?hler numbers on the film profiles of components were examined. With the interfacial flux of ozone calculated from film profiles, dimensionless governing equations of ozone transport and contaminant removal across an experimental column were established. These equations were dependent on the Stanton number. One-dimensional column experiments were conducted to test the model. The optimal time for flow rate adjustment during the process was approximated. Finally, effects of ozone velocity and ozone gas concentration on the Stanton number were evaluated.     

Recycling MSWI bottom and fly ash as raw materials for Portland cement

Municipal solid waste incineration (MSWI) ash is rich in heavy metals and salts. The disposal of MSWI ash without proper treatment may cause serious environmental problems. Recently, the local cement industry in Taiwan has played an important role in the management of solid wastes because it can utilize various kinds of wastes as either fuels or raw materials. The objective of this study is to assess the possibility of MSWI ash reuse as a raw material for cement production. The ash was first washed with water and acid to remove the chlorides, which could cause serious corrosion in the cement kiln. Various amounts of pre-washed ash were added to replace the clay component of the raw materials for cement production. The allowable limits of chloride in the fly ash and bottom ash were found to be 1.75% and 3.50% respectively. The results indicate that cement production can be a feasible alternative for MSWI ash management. It is also evident that the addition of either fly ash or bottom ash did not have any effect on the compressive strength of the clinker. Cement products conformed to the Chinese National Standard (CNS) of Type II Portland cement with one exception, the setting time of the clinker was much longer.     

Optimization of sprayed lime amount in the semi-dry scrubbing system of MSWI

This paper reports the characterization of residues collected from air pollution controlling devices (APCDs) at seven large-scale municipal solid wastes (MSW) incineration plants. The amount of lime being sprayed in plants is a function of free CaO content in scrubber residues; a higher free CaO content in scrubber residue causes more leaching of lead. The proper amount of lime in the semi-dry scrubbing system was found to be 5kg/ton of MSW waste. Under these conditions, both the free CaO content and lead leaching became extremely low in scrubber residue.     

黑藻对铅离子的生物吸附

研究了黑藻对Pb^2＋的生物吸附作用,考察了溶液pH、Pb^2＋初始质量浓度、黑藻加入量和吸附时间对吸附效果的影响。实验结果表明,溶液pH在2．5～5．0时吸附效果最好,吸附20min基本达到平衡。在溶液pH为4．0、黑藻加入量为2g／L、吸附时间为60min、Pb^2＋初始质量浓度为100mg／L的条件下,黑藻对Pb^2＋的吸附量为47．5mg／g。通过元素分析和等温吸附模型对黑藻吸附Pb^2＋的机理进行了研究,发现黑藻吸附Pb“是阳离子交换过程,吸附符合Langmuir、Freundlich和D—R等温吸附模型。考察了Cd^2＋、Cu^2＋和Ni^2＋对黑藻吸附Pb^2＋的影响,结果表明,Cd^2＋、Cu^2＋和Ni^2＋的存在不干扰黑藻对Pb^2＋的吸附。     

结晶紫褪色分光光度法测定SO_2的研究

在碱性介质中,ＳＯ２能使结晶紫褪色且褪色的程度随ＳＯ２量的增加而呈线性关系,据此建立了分光光度法测定ＳＯ２的新方法,确定了显色测定的最佳条件。方法的最大吸收波长在６００ｎｍ处,表观摩尔吸光系数为７３×１０３Ｌ／ｍｏｌ·ｃｍ。ＳＯ２量在０～１００μｇ／２５ｍｌ范围内符合比尔定律     

水样中有机磷的微波消解

采用微波消解系统对水样中有机磷进行消解,考察了消解时间、功率等不同实验条件对样品微波消解的影响;并将该法与总磷测定的常规消解方法进行了比较,结果表明,微波消解法简便、快速、准确、可靠     

广东省杨村华侨柑桔场土壤微量元素含量与分布的研究

采集并分析全场不同母质形成的有代表性的土壤样本142个.研究结果表明,各类土壤全B、Mo、Zn和Mn含量的平均值均低于全国平均值,全量Cu平均值高于全国平均值.有效B、Mo、Zn和Mn含量的平均值均低于临界值,有效Cu的平均值稍高于临界值;但66.7％的土样有效Cu含量低于临界值.硼、钼、锌和锰严重缺乏,铜多数缺乏.全场各类土壤的微量元素含量差异较大,各类土壤微量元素的垂直和水平分布特征不尽相同,尤其是垂直分布差异明显.从土壤微量元素的全量与母质的关系来看,以玄武岩、紫色砂页岩母质形成的土壤全量较高,砂砾岩母质形成的土壤全量中等,砂页岩和冲积物母质形成的土壤全量较低.