添加奶粉对土壤中铬、镍、锰、铜生物可给性的影响

为了探究不同成分的奶粉对土壤中Cr、Ni、Mn、Cu生物可给性的影响,本文通过in vitro实验研究了添加全脂或脱脂奶粉后,胃肠阶段土壤中Cr、Ni、Mn、Cu的生物可给性的变化.结果表明,胃阶段,土壤中Cr、Ni、Mn、Cu的生物可给性分别为3.9%—46.2%、4.5%—64.0%、21.2%—72.5%、4.5%—69.5%;添加奶粉后,4种金属的生物可给性均有升高,是未加奶粉的1.1—1.5倍、1.3—2.2倍、1.1—2.1倍、1.0—3.6倍(全脂奶粉)和1.1—1.4倍、1.4—2.4倍、1.2—2.5倍、1.0—4.2倍(脱脂奶粉).小肠阶段,土壤中Cr、Ni、Cu的生物可给性有一定上升,但Mn的生物可给性相比胃阶段降低了;奶粉的添加使Cr、Ni、Mn、Cu等4种金属的溶出量增加,分别是未添加的1.2—1.3倍、1.3—2.3倍、2.0—4.5倍、1.0—1.5倍(全脂奶粉)和1.1—1.5倍、1.6—2.5倍、2.5—6.9倍、1.2—1.8倍(脱脂奶粉),其中Ni、Mn的生物可给性增加显著,且Ni、Mn的生物可给性的增加率高于胃阶段.由此可见,奶粉的添加,尤其是脱脂奶粉,促进了土壤中Cr、Ni、Mn、Cu的溶出释放,可能增大了其对人体的健康风险.     

袁河水系溶解态痕量金属元素分布特征及来源分析

为研究袁河水系水体溶解态痕量金属元素污染来源与水质状况,分别于2018年7月和2019年1月在袁河干流和支流采集38个表层水样,检测了痕量金属元素Cr、Fe、Mn、As、Al、Cd、Ni和Tl的浓度.采用单因素方差分析分析袁河水系痕量金属元素的时空特征,基于痕量金属元素水质指数评价袁河痕量金属元素污染程度,采用相关分析、主成分分析探讨痕量金属元素污染的主要来源.结果表明,袁河部分金属元素时间或空间差异显著,Cr、Cd、As浓度在丰、枯水期之间差异显著,Fe、Cd、Tl浓度在干、支流之间差异显著.袁河丰、枯水期污染程度相似,主要污染河段位于宜春河段和新余河段,重度污染采样点基本上位于支流.痕量金属元素中Cr、Fe、As主要来源于城市废水,工业活动和采矿活动;Ni、Cd、Tl主要来源于生活污水和工业废水;Mn、Al主要来源于自然活动和采矿活动.本研究可以为袁河流域的痕量金属元素污染治理提供科学依据.     

肠道微生物对土壤中铜、锌、锰生物可给性的影响

为了更全面、准确地评价土壤中金属元素对人体的健康风险,研究土壤中金属元素在结肠阶段的生物可给性具有重要意义。通过采集我国一些地区的6种土壤,利用in vitro方法(PBET和SHIME联用)研究土壤中Cu、Zn、Mn在胃、小肠、结肠阶段的生物可给性。研究显示,土壤中Cu、Zn、Mn在胃阶段的生物可给性分别为23.8%~63.0%、21.2%~64.4%、11.7%~35.6%;从胃阶段到小肠阶段,土壤中Cu的生物可给性提高了0.4%~14.4%,而土壤中Zn在小肠阶段的生物可给性降低了6.7%~38.7%。结肠阶段,土壤中Cu、Zn、Mn的生物可给性分别为2.4%~12.9%、5.7%~18.7%、6.2%~18.9%,与小肠阶段相比,分别降低了21.7%~56.9%、0.4%~36.8%、4.5%~19.1%。结果表明,在肠道微生物存在的情况下,土壤中Cu、Zn、Mn在结肠阶段有较低的人体健康风险。     

模拟酸雨对泉州市区大气降尘重金属的淋溶

以泉州市区受污染的大气降尘为研究对象,开展大气降尘中重金属(Cu,Pb,Cr,Cd,Zn,Mn,Fe,Ni,V,As,Co)在不同酸度(pH=2.5、3.5、4.5、5.6)酸雨淋溶下的溶出行为研究.结果表明:由于降尘样品本身的中和作用,淋出液的pH呈现出先升后降的趋势,并最终接近淋溶液原始pH.在模拟酸雨作用下,污染降尘中不同重金属呈现不同的溶出规律,金属Cu、Pb、Fe、Ni、Mn、Cd的淋出量随pH的升高而降低,各重金属的溶出基本可分为快速溶出阶段、缓慢溶出阶段或稳定阶段,重金属的溶出不仅与总量有关,还与模拟酸雨pH、环境温度、淋溶时间等因素有关.在pH2.5的酸雨下,累积释放量由大到小的顺序为交通区降尘:FeZnMnCoCuCrNiPbAsVCd,工业区降尘:MnFeZnPbCrCuNiAsVCoCd.     

包头市南海湿地土壤重金属污染评价及来源解析

包头市南海湿地位于中国西北地区的高纬度寒旱区,具有独特的河流湿地生态系统。以南海湿地土壤为研究对象,对湿地28个点位表层土壤(0~20 cm)中As、Cd、Cr、Cu、Ni、Mn、Pb、Zn 8种重金属进行检测分析,采用环境质量指数与Hakanson环境生态潜在风险指数相结合的方法,探讨土壤中8种重金属的累积污染现状及潜在生态风险,利用相关性分析、主成分分析和聚类分析区分了南海湿地重金属的来源,以期为南海湿地土壤环境保护提供理论依据。结果表明,As、Cd、Cr、Cu、Ni、Mn、Pb和Zn重金属平均值分别为75.18、1.27、56.98、111.18、87.67、622.71、54.10和209.33 mg·kg~(-1)。以包头市南海公园树木林土壤重金属含量为评价基准,南海湿地土壤重金属普遍超标,研究区域所有样方中As、Cd、Cu、Mn和Pb均超标,Cr有64.29%的样点超标,Ni有96.43%的样点超标,Zn有89.29%的样点超标。单因子污染指数表明,Cd处于中度污染;As、Cu、Pb和Zn处于轻度污染;Cr、Ni和Mn处于轻微污染。农田区和景观大道两侧处于重污染水平,鱼塘区和湿地植物区处于中污染水平。潜在生态风险指数表明,Cd处于强风险等级;As、Cr、Cu、Ni、Mn、Pb、Zn处于低风险等级。;研究区整体上都属于中等风险等级。来源解析表明:As、Cd、Cu、Ni、Mn的来源受到周边工业活动和农业活动的影响;Pb和Zn的来源与道路交通有关,Pb还受到工业活动的影响;Cr来源与土壤母质和农业活动有关。     

淮北煤矿周边土壤重金属生物可给性及人体健康风险

为了探究煤矿周边农田土壤重金属污染状况以及评估可能对人体带来的健康危害,本研究以安徽省淮北地区3座主要煤矿为研究区,对土壤重金属含量进行分析,并采用体外胃肠模拟方法(PBET),计算土壤中重金属的生物可给性,并以此修正健康风险评价计算方法.结果表明,土壤中重金属含量平均值(mg·kg~(-1))分别为Cd (0.16)、Cr (11.82)、Cu (12.03)、Ni (21.86)、Pb (55.09)、Zn (41.46),与国内不同类型矿区相比,淮北煤矿区周边土壤重金属含量较低;重金属的生物可给性平均值大小顺序是:胃阶段:Pb (61.69%)Cu (51.88%)Cd (43.88%)Cr (26.48%)Zn (17.45%)Ni (14.57%),小肠阶段为:Cr (58.80%)Cu (55.71%)Zn (51.40%)Ni (39.44%)Pb (7.59%)Cd (7.32%);由生物可给性校正后,成人和儿童不同重金属非致癌风险暴露量均小于1,说明成人和儿童均不存在非致癌风险,不同种类重金属的致癌风险为:CrCdNi,其中,Cr的致癌风险介于10~(-6)—10~(-4)之间,表明Cr对人群有一定的致癌风险,但在可接受的范围内,且儿童的致癌风险高于成人,经手-口无意摄入是土壤重金属最主要的暴露途径.     

土壤/沉积物中14种金属元素的ICP-MS准确测定方法

建立了微波和湿法两种消解方式的不同条件下土壤/沉积物中V、Cr、Co、Ni、Cu、Zn、Se、As、Sr、Mn、Pb、Cd、Ba和Fe共14种金属元素的ICP-MS准确测定方法.比较了微波消解不同称样量及湿法不同消解体系、温度对不同金属元素的消解效果.以103Rh和195Pt作为ICP-MS测定时的内标元素,针对不同测定元素选择合适的监测质量数及碰撞/反应模式.结果表明,微波消解称样量为0.10 g、消解体系为硝酸-盐酸-氢氟酸时,除Mn、Sr、Ba、Fe等半金属外大部分金属元素消解效果良好;湿法消解采用硝酸-盐酸-高氯酸-氢氟酸(5∶1∶1∶5)体系、消解最高温度为180℃时消解效果最佳,14种金属元素测定结果均在标准值范围内,但需防止少数易挥发元素如As、Se、Pb等在蒸酸过程中挥发损失.分别采用上述两种消解体系对湖底沉积物和两种国际比对土壤样品进行了前处理,并以ICP-MS进行了准确测定,14种金属元素的RSD均在0.10%—3.32%范围之间,国际比对中As、Cd、Pb、Mn的测定结果与初步公布结果一致.该方法重复性好、准确度高,适用于常规土壤/沉积物样品的准确测定.     

应用四种体外消化方法比较研究场地土壤中重金属的生物可给性及其人体健康风险

本研究采用PBET(physiologically based extraction test)、DIN(Deutsches Institut für Normung)、IVG(Invitro Gastrointestinal)和UBM(Unified BARGE Method)等4种体外消化方法,比较8个工矿废弃场地土壤中6种典型重金属的生物可给性并进行健康风险评估分析.结果显示,在4种方法的胃阶段,土壤Co、Ni、Cu、Zn、As和Cd的生物可给性范围分别为1.57%—88.07%、6.69%—129.78%、8.68%—122.62%、18.55%—128.75%、4.17%—61. 14%和32. 22%—118. 44%;小肠阶段分别为0—43. 49%、3. 12%—61. 94%、4. 75%—123. 91%、1.48%—99.02%、5.93%—39.70%和8.48%—67.83%.总体而言,采集的场地土壤中多数重金属生物可给性在各方法的胃阶段均显著高于小肠阶段.土壤重金属在胃阶段的生物可给性分析显示,Co、Ni、Cu和As在UBM和IVG方法中较高,Zn在DIN方法中最高,Cd在UBM和DIN方法中高于其他方法.土壤重金属在小肠阶段的生物可给性分析显示,Co和Ni在UBM方法中最高,Cu在DIN和UBM方法中高于PBET和IVG方法; Zn生物可给性的顺序为DINPBETIVGUBM; As和Cd在IVG方法中均较高.与基于总量的重金属健康风险评估相比,采用生物可给性为评估参数,对8个场地土壤进行的评估分析显示风险水平显著降低,本研究中的场地土壤若采用基于总量的评估方法可能会高估重金属污染的风险.     

三峡库区主要粮食作物和土壤中重金属的相关性及富积特征分析

采用野外采样和室内分析,试验结果表明三峡库区土壤中重金属Cu、Zn、Pb、Cd、Fe、Cr的变异系数小于50%,重金属的含量比较稳定。稻谷（Oryza sativa）中Cu、Zn、Pb、Cd、Fe、Mn、Cr,玉米（Zea mays）中Pb、Cd、Fe、Mn、Cr和小麦（Triticum aestivum）中Cu、Pb、Cd、Fe、Mn、Cr的变异系数大于50%。土壤、稻谷、玉米、小麦中大部分重金属呈偏态分布。土壤中重金属间均为正相关,且极显著正相关性明显。稻谷、玉米、小麦中重金属间有正相关,也有负相关,但正相关明显多于负相关;稻谷、玉米、小麦中Mn同其它重金属间均有显著正相关性,协同作用明显。稻谷、玉米、小麦中Pb、Cd、Cr的样本超标率较大,污染明显,并且稻谷中Cd与土壤中Cd有直线关系。     

广东某垃圾焚烧炉周边空气颗粒物中金属浓度特征及源解析研究

以广东某垃圾焚烧炉为研究对象,应用富集因子法、主成分分析法对其周边环境空气中金属(Fe、Al、Mg、Cu、Zn、Mn、Ba、Pb、Cr、Ni、Bi和Cd)含量及来源进行分析.结果如下:研究区域环境空气中各金属含量(各点均值)(ng·m-3)为:Fe(1092—3487)Al(939—3126)Mg(716—1339)Cu(63.4—995)Zn(227—427)Mn(162—291.1)Ba(61.4—372)Pb(21.9—41.8)Cr(12.3—25.7)Ni(5.70—15.5)Bi(0.70—1.22)Cd(0.42—0.82).相关分析和主成分分析发现,研究区域Fe与Ni、Cr、Mn、Ba主要来自于焚烧炉释放,Zn、Cd、Pb、Bi和Cu则来自于研究区域周边的交通污染源,而Al和Mg则主要来自于地壳或土壤背景值.     

宝鸡城市街尘、土壤及河流沉积物重金属形态迁移特征

在宝鸡城市街尘、土壤及河流沉积物基本理化性质和重金属元素含量分析的基础上,重点研究了重金属元素在街尘、土壤及河流沉积物中的赋存形态和迁移特征.结果表明:在街尘中Cu主要以可氧化态和残余态形式存在,Pb主要以可还原态和可氧化态形式存在,Zn和Cd主要以乙酸可提取态形式存在,Mn、Fe、Co、Ni和Cr主要以残余态形式存在...     

Ecological and human health risks from metal(loid)s in peri-urban soil in Nanjing,China

In order to investigate the ecological and human health risks of metal(loid)s (Cu, Pb, Zn, Ni, Cd, Mn, Cr, and As) in peri-urban soils, 43 surface soil samples were collected from the peri-urban area around Nanjing, a megacity in China. The average contents were 1.19, 67.8, 37.6, 105, 167, 44.6, 722, and 50.8 mg kg^?1 for Cd, Cr, Ni, Pb, Zn, Cu, Mn, and As, respectively. A significant positive correlation was found between Cu, Pb, Zn, Cd, Mn, and As (p < 0.01), and Cr had a significant positive correlation with Ni (p < 0.01). Geoaccumulation indices indicate the presence of Cd and As contamination in all of the peri-urban soil samples. Potential ecological risk indices show that the metal(loid)s in the soil could result in higher ecological risks. Cd is the main contributor to the risk, followed by As. The levels of Cu, Pb, Zn, Cd, Mn, and As in stomach and intestinal phases show a positive linear correlation with their total contents. Mn, Zn, Ni, Cd, and Pb in stomach phase showed higher bioaccessibility, while in intestinal phase, Cu, Cr, and As had the higher bioaccessibility. The carcinogenic risk in children and adults posed by As, Pb, and Cr via ingestion was deemed acceptable. The non-carcinogenic risks posed by these metal(loid)s via ingestion to children are higher than to adults and mainly result from As.     

Accumulation and translocation of heavy metals in soil and plants from fly ash contaminated area

The present investigation deals with the accumulation of heavy metals in fields contaminated with fly ash from a thermal power plant and subsequent uptake in different parts of naturally grown plants. Results revealed that in the contaminated site, the mean level of all the metals (Cd, Zn, Cr, Pb, Cu, Ni, Mn and Fe) in soil and different parts (root and shoots) of plant species were found to be significantly (p<0.01) higher than the uncontaminated site. The enrichment factor (EF) of these metals in contaminated soil was found to be in the sequence of Cd (2.33) > Fe (1.88) > Ni (1.58) > Pb (1.42) > Zn (1.31) > Mn (1.27) > Cr (1.11) > Cu (1.10). Whereas, enrichment factor of metals in root and shoot parts, were found to be in the order of Cd (7.56) > Fe (4.75) > Zn (2.79) > Ni (2.22) > Cu (1.69) > Mn (1.53) > Pb (1.31) > Cr (1.02) and Cd (6.06) approximately equal Fe (6.06) > Zn (2.65) > Ni (2.57) > Mn (2.19) > Cu (1.58) > Pb (1.37) > Cr (1.01) respectively. In contaminated site, translocation factor (TF) of metals from root to shoot was found to be in the order of Mn (1.38) > Fe (1.27) > Pb (1.03) > Ni (0.94) > Zn (0.85) > Cd (0.82) > Cr (0.73) and that of the metals Cd with Cr, Cu, Mn, Fe; Cr with Pb, Mn, Fe and Pb with Fe were found to be significantly correlated. The present findings provide us a clue for the selection of plant species, which show natural resistance against toxic metals and are efficient metal accumulators.     

会泽某铅锌矿周边农田土壤重金属生态风险评价

为了了解云南会泽某铅锌矿废周边农田土壤中重金属含量及潜在的生态危害程度,利用野外采样与实验室分析相结合的方法,以会泽某铅锌矿周边农田土壤（0-20 cm）为研究对象,分析其中7种的重金属（Cd、As、Pb、Cr、Cu、Zn和Hg）含量,并采用风险评价代码法和Hankanson潜在生态风险指数法评价对重金属污染程度与潜在生态风险进行评价。结果表明：7种重金属都存在超标或污染,其中Pb、As、Cd等的污染较为严重。统计学分析结果表明,Pb、As、Hg、Zn、Cd来源相同,铅锌矿冶炼污染物的排放可能是导致研究区域农田土壤重金属含量升高的主要原因。7种重金属化学形态也不尽相同：在重金属有效态中,Cd的水溶态和可提取态较高（平均值达到31.2%）;Pb、Cu和Zn可还原态、可氧化态这两部分含量较高,两部分之和的平均值分别可达到27.9%、30%和27.2%;Hg、As和Cr的残渣态含量较高,平均值分别为90.4%、72.9%和76.8%。风险评价代码评价结果表明,54.4%的样点Cd为高生态风险,45.6%的样点Cd为中度生态风险;100%的样点Zn为中度生态风险;Cu有41.2%的点位属于低生态风险,58.8%的点位属于中度生态风险;As和Pb主要以低生态风险为主（所占比例分别为92.6%和91.8%）;Hg主要以无生态风险为主（所占97.1%）。Hakanson潜在生态风险指数法结果表明,7种重金属潜在生态危害大小顺序为：Cd（331）〉Hg（127.5）〉Pb（43.6）〉As（14.9）〉Cu（9.3）〉Zn（2.3）〉Cr（2.1）。7种重金属的综合潜在生态风险指数（RI）的范围为58.2-1839.3。11%的采样点处于轻微生态风险程度,27.1%的采样点处于中等生态风险程度,46.3%的的采样点处于强生态风险程度,15.6%的采样点处于很强的生态风险程度。综上所述,该矿区周边农田土壤受到了严重的重金属污染,由此引起的重金属生态风险不容忽视?     

芜湖市区土壤重金属污染评价及来源分析

对芜湖市区153个土壤样品中9种重金属的含量进行测定和评价,利用多元地统计方法进行污染来源分析。结果表明：芜湖市区土壤Zn、Fe、Mn、Cu、Pb、Co、Cd、Ni、Cr的平均含量分别为96.8、30600.1、466.1、35.0、29.1、16.7、1.2、26.3、78.3mg/kg;除Fe、Mn、Ni外,其他元素均高于相应土壤背景值,Zn、Cu、Pb、Co、Cd、Cr分别是背景值的1.26、1.09、1.17、1.20、6.11、1.29倍,说明这些元素出现了一定程度的积累。单因子评价结果表明Cd污染最为严重,Zn、Cu、Pb、Co和Cr为轻度污染,Fe、Mn和Ni没有污染。综合相关性、聚类及主成分分析可知,Fe和Mn为＂自然源因子＂,不同功能区分布主要受成土母质控制;Zn、Cu、Pb和Cd为＂交通及工业活动因子＂,Cu、Cd高值区均分布在开发区,Zn和Pb的高值区分布在镜湖区;Ni、Co和Cr为＂农业活动因子＂,其空间变异受成土母质及农业活动等因素影响。     

Enrichment and solubility of trace metals associated with magnetic extracts in industrially derived contaminated soils

Magnetic fractions (MFs) in industrially derived contaminated soils were extracted with a magnetic separation procedure. Total, soluble, and bioaccessible Cr, Cu, Pb and Zn in the MFs and non-magnetic fractions (NMFs) were analyzed using aqua regia and extraction tests, such as deionized water, toxicity characteristic leaching procedure (TCLP), and gastric juice simulation (GJST) test. Compared with the non-magnetic fractions, soil MFs were enriched with Fe, Mn, Pb, Cd, Cr, Cu, and Ni. Extraction tests indicated that soil MFs contained higher water, TCLP, and GJST-extractable Cr, Cu, Pb, and Zn concentrations than the soil NMFs. The TCLP-extractable Pb concentration in the MFs exceeded the USEPA hazardous waste criteria, suggesting that soil MFs have a potentially environmental pollution risk. Solubility of trace metals was variable in the different extraction tests, which has the order of GJST?>?TCLP?>?water. TCLP test showed Cu and Zn were more mobile than Cr and Pb while bioaccessibility of trace metal defined by GJST test showed the order of Cu?≈?Cr?≈?Zn?>?Pb. These findings suggested that the MFs in the industrially derived contaminated soils had higher possibility of polluting water bodies, and careful environmental impact assessment was necessary.     

Determination of total and bioaccessible metals in airborne particulate matter from an urban and a rural area at Sarajevo

Airborne particulate matter of up to 10 µm collected at an urban and a rural area at Sarajevo in 2013 and 2014 was acid digested for determination of total concentrations or extracted with synthetic gastric juice for the bioaccessible fractions of Cd, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn and determined by graphite furnace and flame atomic absorption spectrometry. The total concentrations of Cr, Cu, Fe, Mn, Pb, and V were higher at the urban site, while those of Cd, Ni, and Zn were virtually equal at both sites. The average bioaccessible fractions exhibited the following trend at both sites: Fe > Zn > Cu > Mn > Pb > Cr > V > Ni > Cd. Enrichment factors and daily intake of metals by inhalation were calculated.     

Some characteristics of the distribution of heavy metals in urban topsoil of Xuzhou,China

An assessment is presented of distribution characteristics of heavy metals in the urban topsoil from the city of Xuzhou. The concentrations of Ag, Al, As, Au, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, Ga, Hg, Li, Mn, Mo, Ni, Pb, Pd, Pt, Sb, Sc, Se, Sn, V and Zn have been determined from 21 soil samples. Examination of lognormal distribution plots indicates that the diagrams of Al, Be, Fe, Ga, Li, and V are almost linear suggesting that these metals are almost unaffected by anthropogenic activities while the plots for As, Cd, Cu, Pb, Pd, Pt, Se, Zn and others are not linear probably due to anthropogenic activities from which these metals are delivered to the soils. Al is used for mineralogical normalization of these data. An evaluation of background values for topsoil is also carried out by means of lognormal distribution plots. The results show our background values obtained from the lognormal distribution plots are comparable to those values of uncontaminated soils of Xuzhou obtained by previous work except for Cd and Hg. At present, no explanation for the exceptions Cd and Hg can be given.     

The relationship between soil geochemistry and the bioaccessibility of trace elements in playground soil

A total of 32 samples of surficial soil were collected from 16 playground areas in Madrid (Spain), in order to investigate the importance of the geochemistry of the soil on subsequent bioaccessibility of trace elements. The in vitro bioaccessibility of As, Co, Cr, Cu, Ni, Pb and Zn was evaluated by means of two extraction processes that simulate the gastric environment and one that reproduces a gastric?+?intestinal digestion sequence. The results of the in vitro bioaccessibility were compared against aqua regia extractions (“total” concentration), and it was found that total concentrations of As, Cu, Pb and Zn were double those of bioaccessible values, whilst that of Cr was ten times higher. Whereas the results of the gastric?+?intestinal extraction were affected by a high uncertainty, both gastric methods offered very similar and consistent results, with bioaccessibilities following the order: As?=?Cu?=?Pb?=?Zn?>?Co?>?Ni?>?Cr, and ranging from 63 to 7?%. Selected soil properties including pH, organic matter, Fe and CaCO₃ content were determined to assess their influence on trace element bioaccessibility, and it was found that Cu, Pb and Zn were predominantly bound to organic matter and, to a lesser extent, Fe oxides. The former fraction was readily accessible in the gastric solution, whereas Fe oxides seemed to recapture negatively charged chloride complexes of these elements in the gastric solution, lowering their bioaccessibility. The homogeneous pH of the playground soils included in the study does not influence trace element bioaccessibility to any significant extent except for Cr, where the very low gastric accessibility seems to be related to the strongly pH-dependent formation of complexes with organic matter. The results for As, which have been previously described and discussed in detail in Mingot et al. (Chemosphere 84: 1386–1391, 2011), indicate a high gastric bioaccessibility for this element as a consequence of its strong association with calcium carbonate and the ease with which these bonds are broken in the gastric solution. The calculation of risk assessments are therefore dependant on the methodology used and the specific environment they address. This has impacts on management strategies formulated to ensure that the most vulnerable of society, children, can live and play without adverse consequences to their health.