A Sand Control and Development Model in Sandy Land Based on Mixed Experiments of Arsenic Sandstone and Sand: A Case Study in Mu Us Sandy Land in China

Serious desertification caused by human activity and climate change,in addition to water loss and soil erosion related to arsenic sandstone in the Mu Us Sandy Land,lead to severe scarcity of soil and water resources,which causes worse local agricultural conditions accordingly.Many physical properties of arsenic sandstone is complementary with that of sand,arsenic sandstone is therefore supposed to be blended to enhance water productivity and arability of sandy land.Container experiments are carried out to study the enhancement of water holding capacity of the mixture,the blending ratio of arsenic sandstone and sand,and the proper size of the arsenic sandstone particles,respectively.The results of the experiments show that particle size of 4 cm with a ratio of 1∶2 between arsenic sandstone and sand are the proper parameters on blending.Both water content and fertility increase after blending.Water use efficiency in the mixture is 2.7 times higher than that in sand by the water release curves from experiments.Therefore,a new sand control and development model,including arsenic sandstone blending with sand,efficient water irrigation management and reasonable farming system,is put forward to control and develop sandy land so that water-saving agriculture could be developed.Demonstration of potato planting about 153.1 ha in area in the Mu Us Sandy Land in China indicates that water consumption is 3018 m3/ha in the whole growth period.It means that about 61%of irrigation water can be saved compared with water use in coarse sand without treatment.Recycle economic mode and positive feedback of sand resource-crop planting-soil resource are constructed,which changes sand into arable soil and make it possible to develop water-saving agriculture on it.The proposed model will be helpful for soil-water resources utilization and management in the Mu Us Sandy Land.

Microcystis aeruginosa aggravated arsenic accumulation in silver carp during silver carp controlling algal bloom in arsenic-contaminated water

Silver carp mediated biological control techniques are often advocated for controlling cyanobacteria blooms in eutrophic water,which are often enriched with arsenic(As).How-ever,the transfer and fate of As during the biological control of cyanobacteria blooms by silver carp in As-rich eutrophic water remain unclear.Based on the simulated ecosystem experiment,the accumulation of As in silver carp and the transfer and fate of As in the water-algae-silver carp system during Microcystis aeruginosa blooms controlled by silver carp were investigated.Microcystis aeruginosa showed high tolerance to As(V).The accumulation of As in different tissues of silver carp was different,as follows:intestine>liver>gill>skin>muscle.After silver carp ingested As-rich Microcystis aeruginosa,As accumulation in the intestine,liver,gill,and skin of silver carp was enhanced under the action of digestion and skin contact.Compared with the system without algal,As accumulation in the intestine,liver,gill,and skin of silver carp increased by 1.1,3.3,3.3,and 9.6 times,respectively,after incubation for 30 days in the system with Microcystis aeruginosa,while the accumulation of As in the muscle was only slightly increased by 0.56 mg/kg.This work revealed the transfer and fate of As during algal control by silver carp,elucidated the accumulation mechanism of As in water-algae-silver carp system,enriched our understanding of As bioaccumulation and transformation in As-rich eutrophication water,and provided a scientific basis for as-sessing and predicting As migration and enrichment in water-algae-silver carp system.

Occurrence of Rice Dry Straight Head Disease and Its Control

[Objective] Cause of disease and control measures of rice dry straight head disease in Chuzhou area was discussed. [Method] Field investigation and comprehensive analysis of the literature were conducted to study the reason of dry straight head disease in Chuzhou area, some common control measures were summarized. [Result] The characteristic of main symptoms included incidence of single plant, incidence of cluster, inclusive incidence between clusters. Sporadic normal rice grains existed in diseased spikes under the incidence of grains. The main pathogenic factors of dry straight head disease were concentration of arsenic or lack of elements, belonging to physiological disease, while the effect of other pathogenic factors could not be excluded. Heavy application of organic fertilizer and crop rotation should be conducted, white soil field should be paid more attention about the changes of disease condition with more wet and dry roasting over fields. Application time of micro fertilizer should be chosen properly, while tillering final stage and pollen formation stage must be adjusted to avoid high temperature, irrigation management should also be improved. [Conclusion] The study could provide reference for preventing rice dry straight head disease.

Mechanism research on arsenic removal from arsenopyrite ore during a sintering process

The mechanism of arsenic removal during a sintering process was investigated through experiments with a sintering pot and arsenic-bearing iron ore containing arsenopyrite; the corresponding chemical properties of the sinter were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray diffraction (XRD), and scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS). The experimental results revealed that the reaction of arsenic removal is mainly related to the oxygen atmosphere and temperature. During the sintering process, arsenic could be removed in the ignition layer, the sinter layer, and the combustion zone. A portion of FeAsS reacted with excess oxygen to generate FeAsO4, and the rest of the FeAsS reacted with oxygen to generate As2O3(g) and SO2(g). A portion of As2O3(g) mixed with Al2O3or CaO, which resulted in the formation of arsenates such as AlAsO4and Ca3(AsO4)2, leading to arsenic residues in sintering products. The FeAsS component in the blending ore was difficult to decompose in the preliminary heating zone, the dry zone, or the bottom layer because of the relatively low temperatures; however, As2O3(g) that originated from the high-temperature zone could react with metal oxides, resulting in the formation of arsenate residues. © 2017, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.

Tungsten and arsenic substance flow analysis of a hydrometallurgical process for tungsten extracting from wolframite

In this study,the metabolism of a hydrometallurgical process for tungsten extracting from wolframite was studied through substance flow analysis.The mass balance accounts,substance flow charts of tungsten and arsenic were established to evaluate the metabolism efficiency of the investigated system.The results showed that,the total tungsten resource efficiency of the system was 97.56%,and the tungsten recovery of unit process autoclaved alkali leaching,ion exchange,Mo removing,concentration and crystallization was 98.16%,98.94%,99.71%,99.89%,respectively.Meanwhile,for extracting 1 ton of tungsten into the qualified ammonium paratungstate,10.0414 kg of arsenic was carried into the system,with the generation of 7.2801 kg of arsenic in alkali leaching residue,1.5067 kg of tungsten in arsenic waste residue,and 1.2312 kg of tungsten in Mo residue.Besides,7.9 g of arsenic was discharged into nature environment with waste water,15.5 g of arsenic was entrained into the final APT.The distribution and transformation behaviors of arsenic during production were analyzed through phases change analysis,and some recommendations for improving the resource efficiency of tungsten and pollution control during production were also proposed based on the substance flow analysis in this study.

铜顶吹熔炼过程中砷元素的走向调控研究

随着铜精矿品位逐渐下降,精矿中的杂质元素越来越多,其中有害元素砷在冶炼过程中很难脱除,且在铜熔炼系统中循环累积,最终影响阴极铜的质量。某冶炼企业铜顶吹熔炼生产实践中,有害砷元素在烟尘中的分配比例为55%~75%,在铜锍相中分配比例为5%~15%,在渣相中分配比例为20%~35%。本文主要对铜顶吹熔炼过程中砷的分布与走向调控手段进行了理论分析,并在实验室条件下探究了熔渣中Fe/SiO_(2)、富氧浓度、铜锍品位、渣中CaO含量等工艺参数对不同产出物中砷分配率的影响规律,获得了砷进入渣相的有效调控措施。优化工艺参数后,As在渣中占比为30%~40%,烟尘中占比为50%~60%,铜锍中占比为10%~20%,解决了铜冶炼过程砷进入硫酸系统形成大量污酸的问题,从而控制各个产品中砷的含量。

使用控制图法对原子荧光法测定土壤中砷进行不确定度评定

根据《检测实验室中常用不确定度评定方法与表示》(GB/T 27411-2012)中控制图法,在期间精密度测量条件下按照《土壤和沉积物汞、砷、硒、铋、锑的测定微波消解/原子荧光法》(HJ 680-2013)对土壤中砷进行重复测量,得到34组测量数据。首先计算其正态统计量(A^(2*)),并判断数据的正态性、独立性和分辨力适宜性;其次再绘制控制图,使用失控准则判断测量系统处于受控状态;最后使用t检验判断数据统计上的偏倚受控。三者均满足的情况下,可视期间精密度标准偏差为实验室土壤中砷的测量不确定度。

非法炼金废渣和污染土壤风险管控实例

从应用研究出发提出了一种矿山遗留废渣及污染土壤处置的技术和工程方案。通过前期的调查和评估,对历史遗留的非法金矿开采点的污染状况进行了定性和定量分析,确认了需对调查中发现的矿渣及周边污染土壤进行风险管控,砷管控目标值为60 mg/kg,采用“集中填埋—生态恢复—制度控制”的风险管控措施。通过以上管控措施,控制了遗留矿渣对周边农田和水体的污染风险,尤其是对饮用水水源点的污染风险。项目实施过程中积累的技术和工程经验,可为其他类似项目提供参考。

Reaction mechanism of arsenic capture by a calcium-based sorbent during the combustion of arsenic-contaminated biomass: A pilot-scale experience

Large quantities of contaminated biomass due to phytoremediation were disposed through combustion in low-income rural regions of China.This process provided a solution to reduce waste volume and disposal cost.Pilot-scale combustion trials were conducted for in site disposal at phytoremediation sites.The reaction mechanism of arsenic capture during pilot-scale combustion should be determined to control the arsenic emission in flue gas.This study investigated three Pteris vittata L.biomass with a disposal capacity of 600 kg/d and different arsenic concentrations from three sites in China.The arsenic concentration in flue gas was greater than that of the national standard in the trial with no emission control,and the arsenic concentration in biomass was 486 mg/kg.CaO addition notably reduced arsenic emission in flue gas,and absorption was efficient when CaO was mixed with biomass at 10% of the total weight.For the trial with 10% CaO addition,arsenic recovery from ash reached 76%,which is an ~8-fold increase compared with the control.Synchrotron radiation analysis confirmed that calcium arsenate is the dominant reaction product.

燃煤电站砷的全流程控制技术研究进展

采用文献计量学方法对近18年燃煤砷的文献进行整理,分析其研究特点和趋势,综述了燃煤砷在燃烧前、燃烧中和燃烧后控制技术的相关研究进展,总结当下燃煤电站砷污染控制技术的不足,并对未来燃煤砷控制技术的研究提出建议。

高砷背景土壤风险分级与管控技术研究

由于华南地区土壤类型独特,主要是以赤红壤和红壤为主,这些土壤中含有高量的砷,这种现象对生态环境和人类健康构成了严重的威胁。本研究着重对高砷背景土壤的风险进行分析与分级,并探索相应的管控技术,这不仅为高砷背景土壤的风险管理提供了科学依据,同时也对其他地区的土壤污染管控提供了有益的参考。

2002年中国大陆饮水型地方性砷中毒防治状况与防治工作思路

目的 总结和分析中国饮水型地方性砷中毒的病区范围和防治措施进展。方法 通过现场调查 ,发现高砷地区。利用 Mapinfo系统分析中国地方性砷中毒病区分布。结果 2 0 0 2年我国新确认饮水型地方性砷中毒病区县 2 5个 ,病区村 2 3 5个。病区村人口增加 3 4 .2 7万。结论 尽快建立综合防治策略 ,采取社区干预措施 。

我国地方性砷中毒的地理流行病学规律及防治对策

本文报道我国地方性砷中毒病区的分布、类型和地理流行病学特征。研究了不同类型砷中毒病区砷从环境到人体的传输途径、通量和环境 -剂量效应。对环境剂量 -效应的研究表明 ,饮水型砷中毒病区的环境剂量效应因地质环境背景不同而异 ,提示不同环境地质背景下砷的赋存形态、价态不尽相同。

老化土壤中As的人体可给性控制因素及健康风险

采用UBM（unified bioaccessibility model）模拟胃肠消化的方法测试了来自湖南省、广西壮族自治区和大连市的13个不同理化参数污染土壤中As的人体可给性,分析了考虑As人体可给性对风险评估结果的影响.结果表明：①供试土壤样品模拟胃提取阶段As的人体可给性因子为3.9%-49.5%,平均值为19.6%;模拟肠提取阶段的人体可给性因子为1.2%-10.8%,平均值为6.0%,前者是后者的1.2-9.1倍.②影响供试土壤样品胃提取阶段As人体可给性浓度的最显著性因素是w（TAs）（R^2=0.94,P〈0.01,n=13）,其次为w（TP）（R^2=0.82,P〈0.01,n=13）和w（TMn）（R^2=0.79,P〈0.01,n=13）;影响肠提取阶段As人体可给性浓度的显著因素依次为土壤w（TAs）（R^2=0.83,P〈0.01,n=13）、w（TP）（R^2=0.80,P〈0.01,n=13）、胃提取阶段As的人体可给性浓度（R^2=0.76,P〈0.01,n=13）、pH（R^2=0.74,P〈0.01,n=13）、w（TMn）（R^2=0.65,P〈0.02,n=13）以及w（TOM）（TOM为有机质）（R^2=0.59,P〈0.04,n=13）.③基于土壤w（TAs）和w（黏粒）构建的模型能较好地预测As在胃提取阶段的人体可给性浓度,预测值与实测值的R^2达到0.97,ME（平均误差）、RMSE（均方根误差）、rp^2（可决系数）分别为0.02、0.17、0.95;仅基于土壤w（TAs）构建的模型能较好地预测As在肠提取阶段的人体可给性浓度,R^2达到0.90,ME、RMSE、rp^2分别为-0.03、0.26、0.80.④以供试土壤样品中w（TAs）为暴露浓度计算的健康风险分别是考虑As在胃及肠提取阶段人体可给性因子的2.0-15.0和7.3-81.0倍.可见,基于土壤w（TAs）所制定的风险管理对策可能过于保守.

贵州省地方性砷中毒防治现状及对策

贵州省燃煤污染型砷中毒病区主要分布于4县9乡镇32个行政村,暴露人口约4万人,8700余户,现症病人2848人。其主要流行特点为室内砷暴露水平与煤含砷量、用煤量、燃煤时间、房屋大小及通风情况、食物干燥储存方式等多种因素有关;通过消化道、呼吸道和皮肤等多途径摄砷;多在冬季发病,起病较急,首先出现亚急性砷中毒表现;肝硬化腹水是主要死因之一;氟、砷、二氧化硫等多重污染共存。该病在贵州省发生与流行已久,虽采取一定的防治措施,未能得到完全控制,建议在病区政府领导下,制定限期控制行动计划,采取以健康教育为基础,禁采高砷煤、改炉改灶为主的综合防治措施,尽快控制病区砷污染。

控制电位氧化法铅阳极泥脱砷

采用压缩空气和双氧水作氧化剂,通过控制氢氧化钠体系中的电位来氧化浸出铅阳极泥中的砷。试验中考察电位、NaOH浓度、反应温度、反应时间和液固质量比对脱砷效果的影响,确定碱性浸出过程中预脱砷的最佳工艺条件:NaOH浓度为2 mol/L,温度为80℃,液固质量比为5:1,通入0.2 MPa的压缩空气4 h后用双氧水调节体系的电位至-180 mV,反应时间为2 h。在此条件下,砷的浸出率可达98%以上。碱浸液经冷却过滤掉结晶砷酸钠后,返回浸出过程,砷的浸出率达98%以上,实现碱浸液的循环利用以及砷与其他金属的有效分离。

水产品中砷的质量控制研究进展

水产生物资源的开发利用一直是生物资源可持续发展研究的重要部分,但某些水产食品由于养殖捕捞水域环境质量劣化、自身易富集重金属的原因,含砷量较高,不仅具有潜在的食用危险性,也限制了其作为加工原料的使用,因此对水产食品中无机砷进行检测并减低其砷含量尤为重要。就水产品中无机砷的分析检测技术、含量控制方法以及砷脱除技术研究现状和发展前景进行了总结和展望,并提出具有较好应用前景的水产品脱砷方法。

陕西省饮水氟砷测定实验室间质量控制结果与分析

目的评价实验室对饮水氟、砷分析的能力。方法参加实验室对2种质量浓度的氟、砷质控样品进行测定,采用方框图评价质控结果。结果对参考值为1．00、2．00 mg／L氟质控样品的测定结果分别为 (1．005±0．057)mg／L和(1．972±0．128)mg／L,室间相对标准差分别为5．0％和6．5％,室间相对误差分别为0．5％和1．4％;55个实验室中有50个合格,合格率为90．9％。对参考值为0．100、0．200 mg／L砷质控样品的测定结果分别为(0．098±0．022)和(0．196±0．043)mg／L,室间相对标准差为22．4％和21．9％,室间相对误差均为 2．0％;32个实验室中有29个合格,合格率为90．6％。结论通过饮水氟、砷测定室间质量控制,为陕西省饮水氟、砷筛查项目筛选出了合格的实验室。

中国燃煤大气砷排放及其污染控制

砷是煤中使人致癌的有害物质之一。在煤燃烧过程中,砷以不同的形态进入大气环境,对环境及公众健康造成危害。中国煤中的砷赋存形式多样,主要以无机结合态为主,也存在有机结合态的砷;中国煤中砷总体含量不高,但贵州等部分地区的高砷煤成为燃煤型砷污染的主要来源;在煤燃烧过程中,砷挥发富集于微细颗粒并主要以飞灰形式排放进入大气环境。从煤中砷的赋存状态、分布、燃烧过程中砷的形态转化及砷污染控制措施等方面对中国燃煤砷排放及其控制进行了分析研究。目前,控制燃煤砷排放污染的技术措施主要包括燃烧前洗煤脱砷、使用固砷剂及发展动力配煤技术等。

普通克里格评估土壤污染物空间分布精度控制研究

从数据的统计特征分析、异常值筛选及处理、实验半变异函数计算及拟合等方面对普通克里格计算过程中的精度控制问题进行了初步研究,并以天津市东南郊区土壤砷(As)空间分布评估为例,分析了在多步骤精度控制下普通克里格法估计土壤污染物空间分布的可靠性。结果表明,研究区土壤As表现出了明显的累积特征,且监测值为正态分布,异常值较少且为局部异常值,实验半变异函数表现出明显的各向异性。在较严格的精度控制下,普通克里格估值的最优无偏特性可以得到较好的体现,其对土壤As的空间分布的估计精度可以达到较高的水平。