基于液相31P-NMRNMRNMR技术的沉积物中有机磷分析方法构建及其应用研究
文献类型：学位论文
| 作者 | 张文强
|
| 学位类别 | 博士 |
| 答辩日期 | 2014-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 单保庆 |
| 关键词 | 沉积物 有机磷 液相 P-NMR NaOH-EDTA Sediment Organic phosphorus 31 P-NMR NaOH-EDTA |
| 其他题名 | The analytical method establishment based on solution 31P-NMR for sediment organic phosphorus analysis |
| 学位专业 | 环境工程 |
| 中文摘要 | 核磁共振（NMR）技术是现代科学中用途广泛的分析工具，它可以快速准确的用于土壤、动植物组织、沉积物等环境样品的分析。自然界中的磷仅有一种稳定同位素（31P），31P原子核质量数为奇数，原子核的自旋量子数为半整数，在外加磁场件下可以产生核磁共振现象。31P-NMR技术被应用于环境样品Po分析，但是 Po提取效率较低和核磁共振图谱质量不高等问题仍有待于进一步完善。本研究以 Fe/Al型沉积物为研究对象，通过逐步优化的方式，构建了包括样品保存方法、样品前处理方法、提取剂选择与配比、浸提比例与浸提时间优化等内的沉积物中 Po液相 31P-NMR分析方法，并在河流、湖泊等沉积物中 Po分析上进行了应用验证。利用构建的液相 31P-NMR分析方法，不仅揭示了沉积物中 Po形态特征，而且探索了沉积物中 Po的转化规律及驱动因素。期望为深入探讨沉积物中磷生物地球化学循环过程及影响机制提供技术支撑。主要研究内容和结果如下： （1）构建了一套适合于 Fe/Al型沉积物的有机磷液相 31P-NMR分析方法，实现了沉积物中有机磷化合物的精确定量分析。 以 Fe/Al型沉积物为研究对象，分别从沉积物样品保存方式、沉积物的前处理方式、沉积物提取剂的选择和提取剂的配比、沉积物与提取液的浸提比例、浸提时间和提取液的浓缩方式等方面对液相 31P-NMR分析方法进行了优化。研究发现：①样品保存方法：沉积物取样后采用隔氧保护层法进行样品保存可以有效的降低沉积物中 Po的降解和转化；②样品前处理方式：沉积物带回实验室后，采用冷冻干燥的方法对样品进行处理，冷干法不仅可以避免沉积物中 Po的转化，而且可以批量处理样品；③提取剂选择与配比：从提取效率和图谱质量等分析来看，0.25 M NaOH+50 mM EDTA混合溶液可以得到较为理想的提取效果；④浸提时间与提取比例：研究结果表明，浸提时间以 16小时，浸提比例为 1:10（w:v）为最优配比；⑤提取液浓缩：浸提液冷冻干燥后研磨过筛，溶解到 0.6 mL D2O+0.1mL 10 M NaOH混合溶液中，上机检测；⑥NMR分析与图谱解译：根据沉积物中磷含量，弛豫时间选择 3.6秒，扫描次数 20000次左右。获得图谱后，确定Po化合物峰值，对图谱进行积分计算有机磷化合物浓度。 （2）利用构建的液相 31P-NMR技术，结合 H-J磷分级方法，在滏阳新河和滏阳河沉积物中检测到 Mono-P、PL-P和 DNA-P等有机磷化合物，并发现沿河流流向，有机磷化合物种类和含量呈衰减趋势。 利用 31P-NMR在滏阳新河沉积物 NaOH-EDTA提取液中共检测到 6种磷化合物。磷酸单酯（Mono-P：8.96-29.58%）是生物物质磷（Biogenic-P）的主要组成部分。其他 Biogenic-P包括焦磷酸（Pyro-P：0.22-0.86%），DNA-P（0.75-2.03%），膦酸盐（Phon-P：0-1.57%）和磷脂（Lipids-P：0-2.66%）。沿河流流向，TP和Biogenic-P含量降低。磷分级过程中 NaOH-Po的种类和含量低于提取液 31P-NMR分析所得结果。滏阳河沉积物的分析表明：滏阳河沉积物累积了大量磷；不同形态磷含量为：H2SO4-P>NaOH-Pi>Res-P>NaOH-Po>KCl-P；利用 31P-NMR技术在NaOH-EDTA提取液中共检测到七种磷化合物。正磷酸盐（Ortho-P：45.16-92.35%）和磷酸单酯（Mono-P： 6.57-45.70%）是沉积物中磷的主要成分，其次是 Pyro-P（0.13-6.58%），DNA-P（0.33-3.96%），Phon-P（0-3.34%），Lipids-P（0-2.74%）和多聚磷酸盐（Poly-P：0-0.04%）；基于磷分级和 31P-NMR分析结果，Pi中的35%为活性 Pi，主要包括 KCl-P和 NaOH-Pi（Fe-P和 Al-P），Biogenic-P占到沉积物中总磷的 24%。 （3）利用构建的液相 31P-NMR分析方法，在巢湖沉积物中检测到包括Mono-P和 Diesters-P在内的多种有机磷化合物。在沉积物剖面上，有机磷化合物种类和含量呈递减趋势，且磷酸二酯类物质衰减速度要高于磷酸单酯类物质。 液相 31P-NMR分析发现，巢湖表层沉积物主要包括 Ortho-P、Mono-P、Lipids-P、DNA-P、Pyro-P、Phon-P。Mono-P占 Po总量的 70%以上，为 Po的主要组成部分。巢湖东西部湖区磷形态及含量存在差异：巢湖表层沉积物中 TP平均含量为 686.93±254.94 mg∙kg-1，西部湖区沉积物中 TP高于东湖。沉积物中Po平均占 TP的 27.47±6.05%。与 TP不同，东部湖区的 Po百分含量大于西部湖区，其中 Mono-P和 DNA-P含量明显高于西部湖区。随着沉积柱深度的增加，磷的种类和含量都逐步降低，且西部湖区的降低速率要大于东部湖区。Po化合物的降低速率差异显著，磷酸二酯（ Diesters-P）类化合物随深度增加含量和种类降低的速率要高于 Mono-P类化合物。 （4）液相 31P-NMR方法结合 SMT分级方法揭示了湖泊沉积物中有机磷含量高于湿地和河流沉积物，河流 Mono-P的平均含量要高于湖泊与湿地；对于东部所有水系，引起流域沉积物中磷差别的主要是 Pi；在区域尺度上，沉积物 pH、LOI和 TC/TN都会影响液相 31P-NMR的分析效率。 液相 31P-NMR分析方法可以科学有效的应用于区域尺度的磷化合物分析。结果显示，在区域尺度上，当提取效率低于 60%时，ER与 LOI呈正相关关系，当 ER高于 60%时，ER与 LOI无相关关系；ER与 pH存在负相关关系，即在酸性沉积物中 ER较高，而在碱性沉积物中，ER较低；当 TC/TN比值低于 20时，ER较高，但随着 TC/TN比值升高，ER逐步降低，表明沉积物有机质来源不同会影响 NaOH-EDTA的提取效率。在不同生态系统沉积物中， Pi中的稳态磷（Ca-P）在河流沉积物中含量最高，而作为磷的重要储库，Po在湖泊沉积物中含量最高，可以占到全部沉积物中磷的 27%。在 Po形态上，稳定性较高的 Mono-P 在河流沉积物中含量高于湖泊和湿地沉积物，而活性较高的 Diesters-P主要存在于湖泊和湿地沉积物中。 |
| 英文摘要 | Nuclear magnetic resonance (NMR) is a powerful analysis tool for environmental science, and phosphorus-31 nuclear magnetic resonance (31P-NMR) spectroscopy distinguishes different P groups based on specific resonance frequencies, reflecting the chemical environment surrounding the P nuclei. 31P-NMR is a non-destructive, non-invasive technique for identifying chemical forms that has the advantage of enabling multiple P compounds to be characterized simultaneously with distinct binding properties. The extractant and extraction procedure used are critical to the P recovery and the reliable determination of individual P components, but the physical and chemical properties of soils and sediments vary widely, so the analytical method has to be adjusted to suit a particular set of samples. The main contents and detail results are as follows: (1)The analytical method establishment based on solution 31P-NMR Fe/Al-rich river sediments that were highly polluted with P were used in tests to determine the optimum preparation techniques for measuring Po using solution 31P-NMR. The optimum pre-treatment, extraction time, sediment to solution ratio and sodium hydroxide-ethylenediaminetetraacetic acid (NaOH-EDTA) extractant solution composition were determined. The total P(TP) and Po recovery rates were higher from freeze- and air-dried samples than from fresh samples. An extraction time of 16 h was adequate for extracting Po, and a shorter or longer extraction time led to lower recoveries of TP and Po, or led to the degradation of Po. An ideal P recovery rate and good-quality NMR spectra were obtained at a sediment:solution ratio of 1:10,showing that this ratio is ideal for extracting Po. An extractant solution of 0.25 M NaOH and 50 mM EDTA was found to be more appropriate than either NaOH on its own, or a more concentrated NaOH-EDTA mixture for 31P-NMR analysis, as this combination minimized interference from paramagnetic ions and was appropriate for the detected range of Po concentrations. The most appropriate preparation method for Po analysis, therefore, was to extract the freeze-dried and ground sediment sample with a 0.25 M NaOH and 50 mM EDTA solution at a sediment:solution ratio of 1:10, for 16 h, by shaking. As lyophilization of the NaOH-EDTA extracts proved to be an optimal pre-concentration method for Po analysis in the river sediment, the extract was lyophilized as soon as possible, and analyzed by 31P-NMR. (2) Pyro-P, DNA-P, Phon-P and Lipids-P were detected by 31P-NMR.The TP and biogenic-P decreased along the direction of flows. The Fuyangxin river sediments accumulated significant Pi and Po; in the P fractionation, the rank order of the P fractions was as follows: H2SO4-Pi>NaOH-Pi >Res-P>KCl-P>NaOH-Po. Six P compounds were detected in the NaOH-EDTA extract by 31P-NMR. Mono-P (8.96 - 29.58%) was the dominant forms of biogenic-P, and other smaller fractions of biogenic-P were also observed, including Pyro-P (0.22 - 0.86%), DNA-P (0.75 - 2.03%), Phon-P (0 - 1.57%), and Lipids-P (0 - 2.66%). The TP and biogenic-P decreased along the direction of flows. The concentration and species of Po in NaOH-Po were lower than found in 31P-NMR analysis in this research. Thus the use of 0.25 M NaOH and 50 mM EDTA extracts and solution 31P-NMR analysis was a more accurate method for quantifying biogenic-P in the river sediments than P fractionation. In Fuyang river sediment, the rank order of the P fractions was as follows: H2SO4-P>NaOH-Pi>Res-P>NaOH-Po>KCl-P. Seven P compounds were detected by the 31P-NMR analysis. Ortho-P (45.2 - 92.4%) and Mono-P (6.6 - 45.7%) were the dominant forms. Smaller amounts of Pyro-P (0.1 - 6.6%), DNA-P(0.3 - 3.9%), Phon-P(0 - 3.3%), Lipids-P(0 - 2.7%) and Poly-P(0 - 0.04%) were observed in the sediments. Results of P fractionation and 31P-NMR analysis showed that 35% of Pi was labile P, including KCl-P and NaOH-Pi. Biogenic-P accounted for 24% of P in the sediments. (3) Mono-P was the majority Po compounds in the Chaohu Lake sediments. For sediment cores, the contents of Lipids-P and DNA-P declined more rapidly than that of Mono-P and Pyro-P as sediment depth increased, with these compounds primarily occurring in the top 10 cm of sediment. For the surface sediments, TP in the NaOH-EDTA extracts was dominated by Pi, with higher levels being observed in the heavily eutrophic western lake (79.1 ± 1.7%)than in the eastern lake (68.1 ± 2.4%). These findings were opposite to those for Po. Pi (Ortho-P and Pyro-P) and Po (Phon-P, Mono-P, Lipids-P and DNA-P) were detected in the NaOH-EDTA extracts of the sediments by 31P-NMR. The majority of Po consisted of Mono-P (80.2 ± 2.7%). For sediment cores, the contents of Lipids-P and DNA-P declined more rapidly than that of Mono-P and Pyro-P as sediment depth increased, with these compounds primarily occurring in the top 10 cm of sediment. (4) The concentation of Mono-P was higher in the river sediment than lakeand wetland, but the Diesters-P mainly existed in lake and wetland sediment. LOI, pH and TC/TN effected the ER of 31P-NMR in the surface sediment. Surface sediments in different ecosystems (lake, river, wetland) in Eastern China were extracted with NaOH-EDTA, and the extracts were analyzed by 31P-NMR to reveal the P species distribution. Positive relationship between ER and LOI under the condition of ER under 60% (R2=0.10, p<0.05). The ER and the LOI show no correlation when the ER exceed 60%. Negative relationship was found between EDTA-NaOH extraction rate and the pH of the sediments (R2=0.38, p<0.01), which means the ER was increased with the decrease of the pH of the sediment. The ER show negative exponent with the TC/TN(R2=0.65, p<0.01), which means the origin of OM affect the NaOH-EDTA extraction efficiency in the sediment.The concentration of Ca-P was higher in river sediment than that in lake and wetland sediment. As P pool, the Po was dominant in lake sediment, which was accounted for 27% of TP. The concentation of Mono-P was higher in the river sediment than lake and wetland, but the Diesters-P mainly existed in lake and wetland sediment. |
| 公开日期 | 2015-07-08 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/15644]  |
| 专题 | 生态环境研究中心_环境水质学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 张文强. 基于液相31P-NMRNMRNMR技术的沉积物中有机磷分析方法构建及其应用研究[D]. 北京. 中国科学院研究生院. 2014. |
入库方式： OAI收割
来源：生态环境研究中心
浏览0
下载0
收藏0
其他版本
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。