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首页> 外文学位 >Comparaison de quatre procedures d'extraction pour evaluer les concentrations en arsenite et arseniate dans les sols contamines.
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Comparaison de quatre procedures d'extraction pour evaluer les concentrations en arsenite et arseniate dans les sols contamines.

机译：比较四种评估污染土壤中砷和砷浓度的提取程序。

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摘要

The research hypotheses for this project are : (1) the methods employed for the extraction of inorganic arsenic in contamined soils have an influence on the oxidation of As(III) to As(V) during the extraction, (2) the physico-chemical properties of contamined soils have an influence on the oxidation of As(III) to As(V) during the extraction of inorganic arsenic species. The first objective of this research is to identify, among the published extraction procedures, an extraction method which preserves the oxidation state of arsenic. The second objective of this study is to assess the influence of the physiochemical properties of soils on the performance of the extraction method.;The results of the characterization of the CCA-contamined soils have shown that the total arsenic content was between 93+/-9 mg/kg and 147+/-112 mg/kg. These values were two or three times higher than the criteria set in the province of Quebec (50 mg/kg) for commercial and industrial use.;After the first stage, the results have shown that there was no speciation change of the standard As(III) solution for the three extraction method : 15% (v/v) H3PO4, 10 mM Phosphate + 0,5% (p/v) NaDDC and 1M H3PO4 + 0,5M C6H8O 6. However, for the 10M HCl extraction method, there was 18+/-1% of the As(III) which were oxidized in As(V). These results have shown that the 10M HC1 was responsible for the oxidation of As(III). It was therefore concluded that this method was not adapted to extract inorganic arsenic from soils. This method was eliminated for the others stages.;In the second stage, the arsenic extracted in all CCA-contamined soils was As(V). The soils were collected in surface immediately adjacent to the CCA-treated utility poles with CCA-C solution which contained arsenate. Generally, As(V) is a major arsenic species under oxidizing conditions, therefore, the presence of As(V) in the five subsurface collected soils was to be expected. For the two reference materials, the five collected soils, the 15% (v/v) H 3PO4, 10mM Phosphate + NaDDC 0.5% (w/v), and 1M H3PO 4 + 0,5M C6H8O6 extraction methods, total As was 107+/-18%, 13+/-8%, 83+/-11%, respectively. The two extraction methods which used phosphoric acid in the extraction solution allowed the extraction of the totality or quasi-totality of total arsenic in the soils. On the other hand, the 10 mM Phosphate + 0,5% (p/v) extraction method was too weak to extract arsenic from soils.;After the third stage, the same results were found for the extraction of total arsenic. For the 15% (v/v) H3PO4 extraction method, an important oxidation of the doped As(III) was observed while for the 10 mM Phosphate + 0,5% (p/v) extraction method, the doped As(III) was well preserved. Theses results have shown that these extraction methods were able to extract ancient or recent contamination but not in the same time. These two extraction methods were not adapted for the extraction of inorganic arsenic from soils. For the 1M H3PO4 + 0,5M C6 H8O6 extraction method, between 0% and 40+/-1% of the doped As(III) were oxidized. These results have shown that this extraction method seem adapted because it minimises the oxidation of As(III) during extraction.;The oxidation of As(III) was more important for soils C and D. These soils have a high content of Fe and Mn, which may have an influence on the oxidation of As(III). The results have shown that the manganese oxides were responsible because high correlations were found between manganese fractions extracted by citrate dithionine (CD), ammonium oxalate (AO), hydroxylamine hydrochloride (HH) and the extracted As(V) (r = 0,90, p = 0,01, n = 6) as well as the total Mn content (r = 0,91, p = 0,01, n = 7). The soil C high clay content (18%) could be responsible of the oxidation of As(III). The manganese proved to be an effective oxidant of As(III), more so than the others soils physicochemical properties. As a matter of fact, it was the most important factor on the performance of extraction methods. (Abstract shortened by UMI.)
机译：该项目的研究假设是：（1）污染土壤中无机砷的提取方法会对提取过程中As（III）氧化为As（V）产生影响，（2）物理化学污染土壤的性质对无机砷物质萃取过程中As（III）氧化为As（V）有影响。这项研究的第一个目标是在公开的提取程序中确定一种保留砷氧化态的提取方法。这项研究的第二个目的是评估土壤的理化性质对提取方法性能的影响。CCC污染土壤的表征结果表明，总砷含量在93 +/-之间9 mg / kg和147 +/- 112 mg / kg。这些值比魁北克省设定的用于商业和工业用途的标准（50 mg / kg）高出两倍或三倍。;在第一阶段之后，结果表明标准砷的形态没有变化（ III）三种萃取方法的溶液：15％（v / v）H3PO4、10 mM磷酸盐+ 0.5％（p / v）NaDDC和1M H3PO4 + 0.5M C6H8O6。但是，对于10M HCl萃取方法，有18 +/- 1％的As（III）在As（V）中被氧化。这些结果表明，10M HCl负责As（III）的氧化。因此得出结论，该方法不适用于从土壤中提取无机砷。第二阶段，在所有CCA污染的土壤中提取的砷都是As（V）。用含有砷酸盐的CCA-C溶液将土壤收集在紧邻经CCA处理的电线杆附近的表面。通常，As（V）在氧化条件下是主要的砷物质，因此，可以预期在五种地下收集的土壤中都存在As（V）。对于这两种参考材料，这五种收集的土壤分别为15％（v / v）H 3PO4、10mM磷酸盐+ 0.5％（w / v）NaDDC和1M H3PO 4 + 0.5M C6H8O6提取方法，总砷为107分别为+/- 18％，13 +/- 8％，83 +/- 11％。两种在提取液中使用磷酸的提取方法可以提取土壤中总砷的总含量或准总含量。另一方面，10 mM磷酸盐+ 0.5％（p / v）萃取方法太弱，无法从土壤中萃取砷。第三阶段后，总砷的萃取结果相同。对于15％（v / v）的H3PO4提取方法，观察到掺杂的As（III）发生了重要的氧化，而对于10 mM磷酸盐+ 0.5％（p / v）的提取方法，掺杂的As（III）保存完好。这些结果表明，这些提取方法能够提取古老的或最近的污染，但不能同时提取。这两种提取方法不适用于从土壤中提取无机砷。对于1M H3PO4 + 0.5M C6 H8O6萃取方法，氧化了0％至40 +/- 1％的掺杂As（III）。这些结果表明，这种提取方法似乎很适合，因为它在提取过程中将As（III）的氧化减至最小。 ，这可能会影响As（III）的氧化。结果表明，锰氧化物是主要原因，因为在柠檬酸二硫氨酸（CD），草酸铵（AO），羟胺盐酸盐（HH）和提取的As（V）提取的锰馏分之间发现高度相关性（r = 0.90 ，p = 0,01，n = 6）以及总锰含量（r = 0,91，p = 0,01，n = 7）。土壤C的高粘土含量（18％）可能是As（III）氧化的原因。锰被证明是一种有效的As（III）氧化剂，比其他土壤更具有理化特性。事实上，它是萃取方法性能的最重要因素。 （摘要由UMI缩短。）

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