水泥窑协同处置过程中Pb、Cd的挥发特性

对铅、镉2种重金属的氧化物开展了热重实验、熟料煅烧以及熟料消解实验，以重金属的挥发率为主要指标，研究了水泥窑协同处置过程中铅、镉在等温条件下随时间的挥发特性。结果表明，2种重金属的挥发率均是随温度的升高，时间的增加而增大。Pb的挥发率为96%，Cd的挥发率达到98%，根据等温动力学及阿累尼乌斯方程，对Pb，Cd的挥发率随时间变化的规律进行动力学模拟，得到较好的线性拟合效果，其中，Pb挥发反应的表观活化能E为88.73 kJ/mol，Cd挥发反应可以分2个部分：1 200℃以下的表观活化能E为61 kJ/mol；1 250℃以上的表观活化能E为184.6 kJ/mol。     

生活垃圾焚烧飞灰重金属的受热特性

研究了飞灰重金属在不同煅烧温度下的挥发情况及其存在形态.结果表明:重金属挥发能力由强到弱依次为Hg＞Pb＞As、Cd＞Zn＞Cr、Ni、Cu;其中Hg、Pb、As和Cd属易挥发重金属,在1 150 ℃时几乎全部挥发;Zn属较易挥发重金属,1 150 ℃时的挥发率在40%～50%;Cr、Ni和Cu属难挥发重金属,在1 150 ℃的挥发率不超过10%;在400～1 150 ℃,随温度的升高,部分Zn、Hg、Cu、Pb、Cd、Ni和As由可溶态向残渣态、铁锰氧化态转化;在400～900 ℃,随温度的升高Cr可溶态比例减少,而在900～1 150 ℃,随温度的升高其可溶态比例增加.     

燃烧条件对灰渣中重金属元素形态的影响

根据改进了的BCR连续提取法,重金属元素形态分为酸可提取态、氧化物结合态、有机物结合态和残渣态,实验研究了不同燃烧温度、空气流量和燃烧气氛对燃煤重金属(Cr、Mn、Ni、Cu、Zn、As、Cd和Pb)的形态分布和挥发特性的影响规律。结果表明:在原煤和灰渣中,各重金属元素均主要以稳定的残渣态存在;8种重金属元素的挥发性难易程度顺序为Pb、Cd、ZnAs、Cr、Ni、CuMn;燃烧温度从650℃升至1 050℃过程中,各重金属元素4种存在形态的逸出率逐渐升高,逸出率最低增大幅度为20%,最高达60%;随空气流量的增大,重金属元素的有机物结合态和残渣态加速分解和挥发,各重金属元素的逸出率不断增大;除元素Mn和Ni较易于在贫氧气氛中挥发外,元素Cr、Cu、Zn、As、Cd和Pb均在富氧气氛中比较易于挥发气化。     

水泥窑共处置废物过程中重金属的流向分布

为了探索水泥窑共处置危险废物过程中重金属流向分布规律,研究了不同温度条件下Cr、As、Pb在煅烧熟料、颗粒物和尾气中的残留率。在900、1 000、1 100、1 200、1 300和1 450℃温度条件下,将添加Cr、As和Pb化学试剂的生料分别进行煅烧,模拟重金属在水泥窑内不同温度带的煅烧过程。结果表明,6个温度条件下,Cr主要分布在熟料中并且呈现不规则变化;颗粒物中的Cr在1 200℃条件下分布量最大,所占比例为32.79%(w);在900℃和1450℃条件下,烟气中的Cr分布量最大,所占比例为0.24%(w)。6个温度条件下As主要分布在熟料中并且1 000~1 450℃条件下稳定在81%~83%之间;在900℃条件下,As在熟料中的残留率最大,所占比例为97%(w);在1450℃条件下,As在尾气中的分布达到最大值,所占比例为0.0023%(w)。6个温度条件下,Pb在熟料中的残留率随着温度升高而逐渐减少,挥发颗粒物中的含量呈现相反的趋势;尾气中Pb的含量随着温度的升高逐渐增加。     

膜浓缩液淋滤飞灰后灰渣重金属热处理特性分析

垃圾焚烧飞灰与垃圾渗滤液膜浓缩液协同处理能够解决2种废物处置难的问题,但二者协同处理产生的灰渣往往仍需进一步无害化处理。在分析灰渣的物理化学性质基础上,研究灰渣中重金属在热处理过程中的迁移转化特性,进而探讨灰渣热处理无害化的可行性。实验考察了不同热处理温度(300、600、800、1 000和1 200℃)对灰渣中重金属(Pb、Zn、Cu和Cd)的挥发率的影响,并分析热处理后灰渣的矿物相转化及重金属浸出毒性变化。结果表明:随着热处理温度的升高,重金属Pb、Cd的挥发率显著增大,Zn、Cu挥发率的增幅相对较小。热处理过程中,Pb、Zn、Cu、Cd在1 200℃时挥发率最大,分别为94.6%、68.9%、69.4%和97.7%。浸出实验结果表明,当热处理温度高于800℃时,热处理后灰渣中重金属Pb、Zn、Cu、Cr、Cd的浸出浓度均达到GB 16889-2008相关限值要求。研究结果显示,对飞灰协同处理后的灰渣进行热处理实现其无害化具有一定的可行性。     

危险废物焚烧灰渣熔融过程中重金属元素热力学平衡计算

熔融固化是目前危废焚烧灰渣处置的有效方法之一。为了能够有效地控制熔融过程中重金属元素的迁移,采用HSC Chemistry软件模拟研究了重金属元素As、Pb、Zn、Cu、Ni、Cr等在熔融过程中的物质变化历程,考察了不同气氛、温度、氯化物种类的影响。结果表明:在还原性气氛下,As、Pb几乎100%以As S(g)和Pb S(g)的形式挥发进入气相;Zn主要以气态金属挥发,1 500℃时90.8%的Zn进入气相;Cu、Ni、Cr与灰渣中的Fe2O3、Al2O3等形成不易挥发的化合物,几乎完全被熔渣固化。氧化性气氛有利于各重金属元素的固化,除46.47%的Pb以Pb Cl2(g)、Pb Cl(g)、Pb O(g)的形式挥发外,其余重金属元素均能被固溶在渣中。与灰渣中Na Cl相比,Ca Cl2不影响As、Cr的平衡形态分布,但能促进Pb、Zn、Cu、Ni以气态氯化物的形式挥发进入气相,不利于重金属元素的固化。     

间歇浸取对废物水泥窑共处置产品中Cr和As释放的影响

研究间歇浸取条件下废物水泥窑共处置产品中重金属Cr、As的释放,对水泥产品在实际应用中的环境安全性评价有重要意义.通过模拟煅烧实验制取含Cr和As的水泥熟料,并制取混凝土样品,采用pH影响实验和扩散浸出实验,研究了混凝土中Cr和As的溶解特性及其间歇浸取对混凝土中Cr和As释放的影响.结果表明,浸取方式对浸取液pH有较...     

模拟陈腐垃圾掺烧过程中P/Cl/S对6种重金属迁移特性的影响

通过管式炉焚烧实验,探究了在陈腐垃圾与城市生活垃圾(MSW)掺烧过程中,P/Cl/S对6种重金属(Cd、Zn、Ni、Cu、Cr、Pb)迁移规律的影响,并考察了陈腐垃圾掺混比例、含特征元素的添加剂种类及焚烧温度对6种重金属挥发率的影响.结果 表明,当陈腐垃圾掺烧比例与温度相同时,NaH2PO4和Na2SO4的协同作用对Cd挥发有显著的抑制作用,但对Ni、Cu的挥发起促进作用;NaCl对Zn的挥发有明显的抑制作用,但对Cr的挥发起促进作用;而NaCl和Na2SO4的协同作用促进了Pb的挥发.随着焚烧温度在设定范围(600～800℃)内的增加,Cd、Ni、Cr和Pb的挥发率整体呈增加的趋势.相比添加剂种类,陈腐垃圾掺混比例对Cd、Cr、Cu挥发率的影响更显著.本研究结果可为制定有效的重金属控制策略提供参考.     

污泥与煤、木屑燃烧过程中重金属排放特性研究

为了考察燃料燃烧过程中重金属的迁移转化规律，对污泥、煤与木屑及其混合物在不同温度下氧气中燃烧灰渣中的重金属元素进行分析。结果表明，燃料中重金属在高温燃烧时表现出不同的挥发特性，大部分元素随着温度的升高挥发率增加，其中Cd、Pb和Zn元素挥发性较强，Cr、Cu和Ni挥发性较弱。污泥与木屑混合燃烧灰渣仍以污泥灰为主，重金属含量与污泥灰相近，污泥中混入煤后使灰中大部分重金属含量有所降低。燃烧过程会改变重金属存在形态，污泥与煤原料中以酸溶态和可还原态存在的重金属含量较高，具有较强的生物有效性和迁移性，而燃烧灰渣中酸溶态和可还原态含量显著下降，混合燃烧灰渣中除As外的其他重金属几乎全部以残渣态存在，其含量达到90％以上，焚烧过程有效降低了燃料灰渣中重金属的生物毒性。     

城市生活垃圾焚烧飞灰水泥固化技术研究

用硫铝酸盐水泥对城市垃圾焚烧飞灰(简称飞灰)进行固化实验,研究了飞灰重金属浸出特性,分析了飞灰掺量、浸提剂p H值对重金属浸出特性以及飞灰掺量对不同龄期(3、7、28 d)飞灰固化体抗压强度的影响,并对飞灰及其固化体进行XRD分析。结果表明,在HJ/T 299-2007和HJ/T 300-2007两种不同浸出体系下,飞灰中Cu、Zn、Cd、Pb、Cr和Mn等重金属浸出浓度差别较大,建议应根据评价目标合理选择重金属浸出测量方法。其中,飞灰中Pb的浸出浓度超过《危险废物鉴别标准浸出毒性鉴别》(GB 5085.3-2007)限值的3.35倍,因此被列为危险废物,应妥善处理。除飞灰掺量小于40%时的固化体Cd符合标准,其余飞灰固化体Pb和Cd的浸出浓度仍超过《生活垃圾填埋场污染控制标准》(GB 16889-2008)限值,故达不到卫生填埋的要求。固化体抗压强度随飞灰掺量增大而降低,重金属浸出浓度与之相反。飞灰掺量为40%时,固化体中重金属浸出浓度随浸提剂p H值降低而增大,但p H值大于5时,未测出重金属浸出。XRD结果表明:飞灰中可溶性盐参与水泥水化反应,重金属Cr以CrO_2-4的形式固化于钙矾石中。     

Radionuclides and trace elements in fish collected upstream and downstream of Los Alamos national laboratory and the doses to humans from the consumption of muscle and bone

Abstract

The purpose of this study was to determine radionuclide and trace element concentrations in bottom‐feeding fish (catfish, carp, and suckers) collected from the confluences of some of the major canyons that cross Los Alamos National Laboratory (LANL) lands with the Rio Grande (RG) and the potential radiological doses from the ingestion of these fish. Samples of muscle and bone (and viscera in some cases) were analyzed for ³H, ⁹⁰Sr, ¹³⁷Cs, ^totU, ²³⁸Pu, ^239,240Pu, and ²⁴¹Am and Ag, As, Ba, Be, Cr, Cd, Cu, Hg, Ni, Pb, Sb, Se, and Tl. Most radionuclides, with the exception of ⁹⁰Sr, in the muscle plus bone portions of fish collected from LANL canyons/RG were not significantly (p<0.05) higher from fish collected upstream (San Ildefonso/background) of LANL. Strontium‐90 in fish muscle plus bone tissue significantly (p<0.05) increases in concentration starting from Los Alamos Canyon, the most upstream confluence (fish contained 3.4E‐02 pCi g^‐1 [126E‐02 Bq kg^‐1]), to Frijoles Canyon, the most downstream confluence (fish contained 14E‐02 pCi g^‐1 [518E‐02 Bq kg^‐1]). The differences in ⁹⁰Sr concentrations in fish collected downstream and upstream (background) of LANL, however, were very small. Based on the average concentrations (±2SD) of radionuclides in fish tissue from the four LANL confluences, the committed effective dose equivalent from the ingestion of 46 lb (21 kg) (maximum ingestion rate per person per year) of fish muscle plus bone, after the subtraction of background, was 0.1 ± 0.1 mrem y^‐1 (1.0 ± 1.0 μSv y^‐1), and was far below the International Commission on Radiological Protection (all pathway) permissible dose limit of 100 mrem y^‐1 (1000 μSv y^‐1). Of the trace elements that were found above the limits of detection (Ba, Cu, and Hg) in fish muscle collected from the confluences of canyons that cross LANL and the RG, none were in significantly higher (p<0.05) concentrations than in muscle of fish collected from background locations.     

Patterns of volatile metabolites and nonvolatile trichothecenes produced by isolates of <Emphasis Type="Italic">Stachybotrys,Fusarium, Trichoderma,Trichothecium</Emphasis> and <Emphasis Type="Italic">Memnoniella</Emphasis>

We reported previously that trichodiene, a volatile trichothecene derivative, was produced by a Stachybotrys isolate, also known to produce highly cytotoxic, non-volatile, macrocyclic trichothecenes (satrotoxins). We investigated the relationship between the production of trichodiene and various non-volatile trichothecenes for several molds. Volatile metabolites were concentrated by adsorption on Tenax TA and analyzed by GC/MS, while non-volatile metabolites were separated by HPLC, derivatized and analyzed by GC/MS. Stachybotrys chartarum isolates producing macrocyclic trichothecenes secreted significantly larger amounts of trichodiene and other sesquiterpenes than isolates which only produced simple trichothecenes. The amounts of secreted trichodiene were relatively small in all cases. With the exception of Memnoniella, which excreted small amounts of sesquiterpenes, the other isolates produced varying amounts of sesquiterpenes, including trichodiene, as well as simple tricothecenes, no detectable trichodiene, but large amounts of griseofulvin derivatives. In Stachybotrys there is apparently a correlation between trichodiene and macrocyclic trichothecene production. In the remaining isolates, there was no simple relationship between trichodiene and non-volatile trichothecene synthesis. Trichodiene is produced in larger amounts by Stachybotrys isolates, which also produce satratoxins, but it will be difficult to utilize this metabolite to detect toxic isolates in buildings due to the relatively small amounts excreted.     

Radionuclides in deer and elk from Los Alamos national laboratory and the doses to humans from the ingestion of muscle and bone

Abstract

This paper summarizes radionuclide concentrations (³H, ⁹⁰Sr, ¹³⁷Cs, ²³⁸Pu, ^239,240Pu, ²⁴¹Am, and ^totU) in muscle and bone tissue of mule deer (Odocoileus hemionus) and Rocky Mountain elk (Cervus elaphus) collected from Los Alamos National Laboratory (LANL), Los Alamos, New Mexico, lands from 1991 through 1998. Also, the committed effective dose equivalent (CEDE) and the risk of excess cancer fatalities (RECF) to people who ingest muscle and bone from deer and elk collected from LANL lands were estimated. Most radionuclide concentrations in muscle and bone from individual deer (n = 11) and elk (n = 22) collected from LANL lands were either at less than detectable quantities (where the analytical result was smaller than two counting uncertainties) and/or within upper (95%) level background (BG) concentrations. As a group, most radionuclides in muscle and bone of deer and elk from LANL lands were not significantly higher (p<0.10) than in similar tissues from deer (n = 3) and elk (n = 7) collected from BG locations. Also, elk that had been radio collared and tracked for two years and spent an average time of 50% on LANL lands were not significantly different in most radionuclides from road kill elk that have been collected as part of the environmental surveillance program. Overall, the upper (95%) level net CEDEs (the CEDE plus two sigma for each radioisotope minus background) at the most conservative ingestion rate (50 lbs of muscle and 13 lbs of bone) were as follows: deer muscle = 0.22 mrem y^‐1 (2.2 μSv y^‐1), deer bone = 3.8 mrem y^‐1 (38 μSv y^‐1), elk muscle = 0.12 mrem y^‐1 (1.2 μSv y^‐1), and elk bone = 1.7 mrem y^‐1 (17 μSv y^‐1). All CEDEs were far below the International Commission on Radiological Protection guideline of 100 mrem y^‐1 (1000 μSv y^‐1), and the highest muscle plus bone net CEDE corresponded to a RECF of 2E‐06, which is far below the Environmental Protection Agency upper level guideline of 1E‐04.     

Leaching of seven pesticides currently used in cotton crop in Mato Grosso State—Brazil

This study aimed to evaluate the leaching of pesticides and the applicability of the Attenuation Factor (AF) Model to predict their leaching. The leaching of carbofuran, carbendazim, diuron, metolachlor, α and β endosulfan and chlorpyrifos was studied in an Oxisol using a field experiment lysimeter located in Dom Aquino – Mato Grosso. The samples of percolated water were collected by rain event and analyzed. Chemical and physical soil attributes were determined before pesticide application to the plots. The results showed that carbofuran was the pesticide that presented a higher leaching rate in the studied soil, so was the one representing the highest contamination potential. From the total carbofuran applied in the soil surface, around 6 % leached below 50 cm. The other pesticides showed lower mobility in the studied soil. The calculated values to AF were 7.06E-12 (carbendazim), 5.08E-03 (carbofuran), 3.12E-17 (diuron), 6.66E-345 (α-endosulfan), 1.47E-162 (β-endosulfan), 1.50E-06 (metolachlor), 3.51E-155 (chlorpyrifos). AF Model was useful to classify the pesticides' potential for contamination; however, that model underestimated pesticide leaching.     

Endosulfan in China 2—emissions and residues

Background, aim, and scope  Endosulfan is one of the organochlorine pesticides (OCPs) and also a candidate to be included in a group of new persistent organic pollutants (UNEP 2007). The first national endosulfan usage inventories in China with 1/4° longitude by 1/6° latitude resolution has been reported in an accompanying paper. In the second part of the paper, we compiled the gridded historical emissions and soil residues of endosulfan in China from the usage inventories. Based on the residue/emission data, gridded concentrations of endosulfan in Chinese soil and air have been calculated. These inventories will provide valuable data for the further study of endosulfan. Methods  Emission and residue of endosulfan were calculated from endosulfan usage by using a simplified gridded pesticide emission and residue model—SGPERM, which is an integrated modeling system combining mathematical model, database management system, and geographic information system. By using the emission and residue inventories, annual air and soil concentrations of endosulfan in each cell were determined. Results and discussion  Historical gridded emission and residue inventories of α- and β-endosulfan in agricultural soil in China with 1/4° longitude by 1/6° latitude resolution have been created. Total emissions were around 10,800 t, with α-endosulfan at 7,400 t and β-endosulfan at 3,400 t from 1994 to 2004. The highest residues were 140 t for α-endosulfan and 390 t for β-endosulfan, and the lowest residues were 0.7 t for α-endosulfan and 170 t for β-endosulfan in 2004 in Chinese agricultural soil where endosulfan was applied. Based on the emission and residue inventories, concentrations of α- and β-endosulfan in Chinese air and agricultural surface soil were also calculated for each grid cell. We have estimated annual averaged air concentrations and the annual minimum and maximum soil concentrations across China. The real concentrations will be different from season to season. Although our model does not consider the transport of the insecticide in the atmosphere, which could be very important in some areas during some special time, the estimated concentrations of endosulfan in Chinese air and soil derived from the endosulfan emission and residue inventories are in general consistent with the published monitoring data. Conclusions  To our knowledge, this work is the first inventory of this kind for endosulfan published on a national scale. Concentrations of the chemical in Chinese air and agricultural surface soil were calculated for each grid cell. Results show that the estimated concentrations of endosulfan in Chinese air and soil agree reasonably well with the monitoring data in general. Recommendations and perspectives  The gridded endosulfan emission/residue inventories and also the air and soil concentration inventories created in this study will be updated upon availability of new information, including usage and monitoring data. The establishment of these inventories for the OCP is important for both scientific communities and policy makers.     

Impact of spiked concentrations of Cd,Pb, As and Zn in growth medium on elemental uptake of Nasturtium officinale (Watercress)

This study is aimed at investigating the impact of water quality on the uptake and distribution of three non-essential and toxic elements, namely, As, Cd and Pb in the watercress plant to assess for metal toxicity. The plant was hydroponically cultivated under greenhouse conditions, with the growth medium being spiked with varying concentrations of As, Cd and Pb. Plants that were harvested weekly for elemental analysis showed physiological and morphological symptoms of toxicity on exposure to high concentrations of Cd and Pb. Plants exposed to high concentrations of As did not survive and the threshold for As uptake in watercress was established at 5 ppm. Translocation factors were low in all cases as the toxic elements accumulated more in the roots of the plant than the edible leaves. The impact of Zn on the uptake of toxic elements was also evaluated and Zn was found to have an antagonistic effect on uptake of both Cd and Pb with no notable effect on uptake of As. The findings indicate that phytotoxicity or death of the watercress plant would prevent it from being a route of human exposure to high concentrations of As, Cd and Pb in the environment.     

Butyltin compounds in sediment and fish from the Polish Coast of the Baltic Sea

Concentrations of mono- (MBT), di- (DBT), and tri-(TBT) butyltin compounds were measured in eggs, liver, and muscle of nine species of fish from four regions of the Baltic Sea - the Firth of Vistula, the Gulf of Gdańsk, Puck Bay, and the mouth of the Vistula River. The overall concentration ranges among all the fish sampled from the four sites were: < 7 to 79 ng/g for MBT, 6 to 1100 ng/g for DBT, 7 to 3600 ng/g for TBT, and 16 to 4800 ng/g for total BTs, on a wet wt basis. The highest concentration of total BTs was found in herring liver from the Firth of Vistula (4800 ng/g, wet wt) and in roach muscle from Puck Bay (3300 ng/g, wet wt), while the least concentration was found in burbot eggs and liver from the Vistula River (39 and 32 ng/g, wet wt, respectively). TBT was the major form of BTs present in most samples analyzed. Sediment samples collected from shipyards in the Gulf of Gdańsk contained butyltin concentrations ranging from 1.2 to 46 μg/g (dry wt) for MBT, 2.0 to 42 μg/g for DBT, and 2.6 to 40 μg/g for TBT. As with the fish, the majority of the BTs in sediment were present as TBT, which suggested recent exposure of the aquatic environment of the region to TBT.     

Malathion-induced sublethal toxicity on the hematology of cricket frog (Fejervarya limnocharis)

The effect of malathion [diethyl(dimethoxythiophosphorylthio)succinate] at sublethal concentration (0.006 ppm) on hematological parameters of the cricket frog (Fejervarya limnocharis) was studied for 24 hrs to 240 hrs of exposure and remarkable hematological alterations were observed. The study on hematological parameters revealed a highly significant decrease (P < 0.01) in the total erythrocytes count in malathion-exposed animals from 24 hours to 96 hrs of exposure as compared to control. Significant decreases (P < 0.01) of hemoglobin and packed cell volume were also observed from 48 hrs to 240 hrs. A significant increase (P < 0.01) in leucocytes count was noted throughout the exposure period. Elevated numbers of lymphocytes and eosinophils as found in the present study revealed lymphocytosis as well as eosinophilia, suggesting that this was a result of direct stimulation of the immunological defense due to the presence of a toxic substance or may be associated with tissue damage. The cytomorphological and cytopathological study of erythrocytes and leucocytes in malathion-exposed frogs at 0.006 ppm concentration revealed various cytotoxic effects at different exposure times. It was noted that the size and the shape of the erythrocytes were subjected to variation in different blood disorders.     

Relation between forest vegetation, atmospheric deposition and site conditions at regional and European scales

Several monitoring programs have been set up to assess effects of atmospheric deposition on forest ecosystems. The aim of the present study was to evaluate effects on the understorey vegetation, based on the first round of a regional (the Netherlands) and a European forest monitoring program. A multivariate statistical analysis showed surprisingly similar results for both data sets; the vegetation appeared to be largely determined by the ‘traditional’ factors soil, climate, and tree species, but there was a small but statistically significant effect of atmospheric deposition. The effects of deposition include a slight shift towards nitrophytic species at high N deposition in the European network, and towards acidophytic species at high S-deposition in the Dutch network. The relatively small effect of atmospheric deposition is understandable in view of the very large natural variation in environmental conditions. Time series of both vegetation and environment are needed to assess deposition effects in detail.