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斯里兰卡CKDU 地区浅层地下水中溶解有机碳特征及其与钙的相互作用研究
Alternative TitleCharac terization of DOC and its interaction with Calcium in s hallow g roundwater of CKDu zones in Sri Lanka
MADHUBHASHINI MAKEHELWALA
Subtype博士
Thesis Advisor魏源送
2019-06
Degree Grantor中国科学院生态环境研究中心
Place of Conferral北京
Degree Name工学博士
Degree Discipline环境工程
Keyword溶解性有机碳 硫酸盐 纳滤膜污染 CKDu Dissolved organic carbon, calcium, sulfate, nano-membrane fouling, CKDu
Abstract

    斯里兰卡中北省不明原因慢性肾病(Chronic Kidney Disease Unknown Aetiology,CKDu )病患者人数不断增加,已成为一个亟待解决的民生问题,其中地下水是影响CKDu 病因的主要因素之一。所以,安全供水是 CKDu 防治和控制的关键措施之一。因此,本研究选择斯里兰卡的三个 CKDu 风险区( high risk, HR; low risk, LR and no risk, NR )和一个对照区 control zone, CR ),通过现场调研,考察了不同季节 旱季和湿季 斯里兰卡 CKDu 病区浅层地下水水质和溶解性有机物 (Dissolved OrganicCarbon, DOC) 的特征,同时考察了杀虫剂及其代谢产物,研究了 DOC 和 Ca 2+ 、 SO 42-的相互作用关系,并据此研究了 DOC 和 Ca 2+ 、 SO 42- 相互作用对纳滤膜污染的影响。取得的主要研究成果如下:
1,明确了不同季节斯里兰卡 CKDu 病区浅层地下水的溶解性有机物分布特征。在干湿季节, HR 地下水中 DOC 的 (𝐶𝑂𝐷𝑀𝑛/𝐷𝑂𝐶)最小值分别为 0.60 +-0.19 和 0.5 8 +- 0.17,该 DOC 组分包含难生物降解和高芳香性的有机化合物 (SUVA 254 =3.29 L.mg-1 m -1 。D OC 中可生物降解组分含量大小依次是 𝐶𝑜𝑥𝑖𝐻𝑅<𝐶𝑜𝑥𝑖𝐿𝑅<𝐶𝑜𝑥𝑖𝑁𝑅<𝐶𝑜𝑥𝑖𝐶𝑅。 3D-EEM 分析结果表明, HR 地下水中 DOC 组分主要是不可生物降解的富里酸 (FA )、色氨酸、酪氨酸。不可生物降解有机物的基本组成主要集中在表观分子量( A MW II 900 1800Da)的有机物和较高同位素  13 C DOC 值 22 ‰ to 11 ‰) 。所有地下水中的 DOC 源于本土碳源(荧光指数 > 1.8 ),并在 HR 的地下水检测到了一定量的五氯苯酚( PCP )。主成分分析 (PCA )结果表明 HR 地下水中的 DOC 与 SO 42- , Ca 2+,总铁 PCP 之间呈正相关。这些结果说明,在碱性 pH 7.4 )下 HR 地下水中丰富的二价阳离子( Ca 2+ ,   Mg 2+)可与 DOC 中的苯酚和羧酸官能团发生相互作用。

2,采用模型化合物和多种分析手段,揭示了 DOC- Ca 的相互作用关系。 市售腐植酸 SHA )和 HR 区地下水 DOC 样品的比较结果表明,两 者具有很多的相似性,它们的分子量分别 3350Da 和 3100Da ,两者均含有更多的芳香族和脂肪族有机物, DOC 样品中 C 、 O 、 N 的比例分别是 87.9 %、 11.4 %、 0.7 SHA 中 C 、O 、 N 的比例分别是 73.8 %、 24.7 %、 1.6 %。因此,本研究采用 SHA 为模型化合物揭示了揭示了DOC与与Ca 2+的螯合机制。Ca 2+和 SO 42- -通过羧基通过羧基(COOH)和酯基(COOR)与SHA结合。在NaCl存在的条件下,Ca 2+与羧基的=O及––O键配位结合,而在Na2 SO4 存在的条件下,Ca 2+与酯基与(COOR)配位结合。SO 42- 的四面体结构与SHA上的酯基––O键作用,这促进了几何d轨道的弱π键形成,因而形成了O=O的结构,FTIR结果表明 SO 42- 在与有机物表面作用后形成了还原态有机磺酸盐官能团(1100--1200cm-1),进而),进而SO32-上形成的上形成的=O、酯基中的=O与Ca 2+形成了双配位键螯合物,该螯合物推测可能是一种尿毒素物质。IR 光谱(~866 cm-1)分析结果表明,在pH=7.4和和NaCl的条件下形成了CaCO3晶体。

3,明确了,明确了NFNF过程钙与有机物复合污染的化学机制。采用Ca和腐殖酸作为模型污染物,分析了斯里兰卡CKDu干区中地下水NF处理过程中的膜污染机制。NF膜表面具有氨基((––N––C) 和磺基(O=S=O),SHA-Caa结构可以与其结合导致膜污染。污染膜表面的FTIR结果中非键合-OH基团的存在表明存在物理吸附。XPS中两个Ca峰(2p3/2 和2p1/2)证实了SHA-Ca在膜表面的吸附。因此,膜污染主要机理是极性有机吸附,在膜表面形成亲水层及亲水疏水复合层的双层结构。

Other Abstract

    Number of Chronic Kidney Disease patients with no identifiable cause (Chronic Kidney Disease Unknown Aetiology, CKDu) as a burning issue is escalating in the North Central Province (NCP) of Sri Lanka, and the groundwater factor is believed as one of main causes of the CKDu disease. Therefore, the provision of safe and palatable water is one of the essential remedial measures for disease prevention and control. In this study, selected three risk areas ((high risk, HR; low risk, LR and no risk, NR) and control zone (CR) in Sri Lanka to investigate groundwater quality in two different seasons (wet and dry season). The shallow groundwater quality, dissolved organic carbon (DOC)characteri zation in different risk zones, measurement of herbicide and their metabolites and interaction between DOC and Ca 2+2+, SO 42 were investigated in this study. The interaction of DOC and Ca 2+2+, SO 42 was effected to the nano filtration membrane fouling. The main research results are shown as follows;

1. DOC characterization and distribution in shallow groundwater have identified in different CDKu risk zones and climatic seasons.Two sample sets, each time with 50 samples during wet season (Dec 2016) and dry season (May 2017) were collected in Sri Lanka. T he lowest (𝐶𝑂𝐷𝑀𝑛𝐷𝑂𝐶) values of the DOC at 0.60  0.19, 0.58  0.17 were reported in the HR zone during the wet and dry seasons, respectively. This DOC fraction was encompassed with the non  iodegradable C f raction and highly aromatic organic compounds (SUVA 254 =3.29 L.mg 1 m 1 ) in HR zone. The chemically and biologically active fraction of DOC was in the order of 𝐶𝑜𝑥𝑖𝐻𝑅<𝐶𝑜𝑥𝑖𝐿𝑅<𝐶𝑜𝑥𝑖𝑁𝑅<𝐶𝑜𝑥𝑖𝐶𝑅. Results of the 3D EEM analysis identified tha t the DOC fraction in HR zone were mainly as non biodegradable humic substances (mixture of humic acid, HA and fulvic acid, FA), tryptophan and tyrosine. The building blocks of non biodegradable C were concentrated into apparent molecular weight (AMW) frac tion II (900 1800 Da) and higher isotope  13 C DOC value ( 22 ‰ to 11 ‰ was indicated the formation of humic substances in groundwater . The DOC source in all groundwater was identified as autochthonous (fluorescence index>1.8) C source. The appreciable quantities (2.11  6.84 2.76  4.59) of pentachlorophenol (PCP) was detected in HR zone. The principal component analysis(PCA) results showed a positive correlation between DOC and SO 42 -, Ca 2+, total iron, PCP in the HR groundwater. Accordingly, the divalent cations (Cacations (Ca2+2+, Mg, Mg2+2+) abundant in the HR ) abundant in the HR groundwater interacted with carboxylate functional groups in DOC due to the carboxylate groundwater interacted with carboxylate functional groups in DOC due to the carboxylate anion (O=Canion (O=C––OO--) formation at alkaline pH (>7.4).) formation at alkaline pH (>7.4).

2. The interaction between DOC-Ca was revealed by using model compound (SHA) with different background electrolytes, and the sulfate and low molecular weight DOC fraction complexation was postulated as uremic toxicant.
The comparison of molecular weight fraction of commercially available humic acid (sigma(sigma--humic acid, SHA) in different humic acid, SHA) in different background electrolyte (SObackground electrolyte (SO4422--, Cl, Cl--) and groundwater ) and groundwater DOC was shown some similarity in each other as MW<3100 Da in HR zone and MW<3350 DOC was shown some similarity in each other as MW<3100 Da in HR zone and MW<3350 Da in SHA (after 12 h equilibration). The comparison of surface functional groups in SHA Da in SHA (after 12 h equilibration). The comparison of surface functional groups in SHA and groundwater DOC samples in HR and groundwater DOC samples in HR zone were shown that both contained more aromatic zone were shown that both contained more aromatic and aliphatic organic matter, and the proportion of C, O, N were 87.9%, 11.4%, 0.7% and aliphatic organic matter, and the proportion of C, O, N were 87.9%, 11.4%, 0.7% respectively in DOC while 73.8%, 24.7%, 1.6% respectively in SHA. The use of SHA as a respectively in DOC while 73.8%, 24.7%, 1.6% respectively in SHA. The use of SHA as a model compound was revealed the compmodel compound was revealed the complexation mechanism of Calexation mechanism of Ca2+2+ on organic matter on organic matter under different background electrolyte. The Caunder different background electrolyte. The Ca2+2+ and SOand SO4422-- ions in water were bonded to ions in water were bonded to SHA through carboxyl (COOH) and ester (COOR) groups. The CaSHA through carboxyl (COOH) and ester (COOR) groups. The Ca2+2+ was nonwas non--competitively interacted with carboxylic =O and competitively interacted with carboxylic =O and ––O unO under NaCl electrolyte while der NaCl electrolyte while competitive bonding with ester group (COOR) under Nacompetitive bonding with ester group (COOR) under Na22SOSO44 electrolyte. Foremost, the electrolyte. Foremost, the improper geometrical dimproper geometrical d--orbital with weak orbital with weak  bonding =O on tetrahedral structure of the bonding =O on tetrahedral structure of the SOSO4422-- interacted with ester interacted with ester ––O on SHA, thus forming an O=O molecule. Therefore, SOO on SHA, thus forming an O=O molecule. Therefore, SO4422-- interaction on the surface of organic matter to form a reduced organic sulfonate. The FTIR interaction on the surface of organic matter to form a reduced organic sulfonate. The FTIR band at band at 1170 cm1170 cm--11 was also was also identified the identified the formation of sulfonate groups (1100formation of sulfonate groups (1100--1200 c1200 cmm--11) ) on SHA. Different sulfur oxidation states correspond to SOon SHA. Different sulfur oxidation states correspond to SO3322-- and SOand SO4422-- binding energies binding energies at 168.9 eV and 170.1 eV by XPS, respectively were proved formation of organic sulfonate at 168.9 eV and 170.1 eV by XPS, respectively were proved formation of organic sulfonate on SHA. on SHA. The =O formed on this sulfonate and the =O on ester group was proThe =O formed on this sulfonate and the =O on ester group was promoted the moted the CaCa2+2+ to form a bidentate bonding (to form a bidentate bonding (Ca 2pCa 2p3/23/2 and Ca 2pand Ca 2p1/21/2 binding energies at ~347 eV and binding energies at ~347 eV and ~351 eV~351 eV). ). This sulfate and low molecular weight DOC fraction complexation (DOCThis sulfate and low molecular weight DOC fraction complexation (DOC--CaCa--SOSO33) was postulated as uremic toxicant in HR zone due to tryptophan and tyrosine DOC sine DOC fractions metabolized uremic toxicants with sulfate by human gut microbiota in elsewhere. fractions metabolized uremic toxicants with sulfate by human gut microbiota in elsewhere.The IR band at ~866 cm--11 was significant evidenced of the CaCOwas significant evidenced of the CaCO33 crystal formation after crystal formation after pH 7.4 under NaCl electrolyte. pH 7.4 under NaCl electrolyte.

3. The chemical fouling mechanism with the complexed pollution of Ca2+ and DOC in nanofiltration membrane process was clarified, and is polar organic fouling by hydrophilic first layer and hydrophilic, hydrophobic multilayer at next layer.The chemical mechanism of the Ca2+ and humic acid complexation was identified to and humic acid complexation was identified to understand as a model of the NF membrane fouling mechanism to supply safe drinking understand as a model of the NF membrane fouling mechanism to supply safe drinking water to CKDu endemic areas in dry zone of Sri Lanka. The surface of the NF membrane water to CKDu endemic areas in dry zone of Sri Lanka. The surface of the NF membrane has an amide (has an amide (––NN––C) and sulfone (O=S=O) gC) and sulfone (O=S=O) groups and these groups were participated to roups and these groups were participated to form physical bonding with the SHAform physical bonding with the SHA--Ca complex to fouled the NF membrane. The FTIR Ca complex to fouled the NF membrane. The FTIR data showed the narrow three peaks for nondata showed the narrow three peaks for non--bonding bonding ––OH groups on the fouled membrane OH groups on the fouled membrane surface which denoted the physical adsorptionsurface which denoted the physical adsorption. The two Ca peaks in XPS (2p. The two Ca peaks in XPS (2p3/23/2 and 2pand 2p1/21/2) ) were confirmed the adsorption of SHAwere confirmed the adsorption of SHA--Ca complex onto the membrane surface. Therefore, Ca complex onto the membrane surface. Therefore, the main mechanism of membrane fouling was polar organic fouling by the main mechanism of membrane fouling was polar organic fouling by hydrophilic first hydrophilic first layer and hydrophilic, hydrophobic multilayer at next layer.

    

Pages147
Language中文
Document Type学位论文
Identifierhttp://ir.rcees.ac.cn/handle/311016/42174
Collection水污染控制实验室
Recommended Citation
GB/T 7714
MADHUBHASHINI MAKEHELWALA. 斯里兰卡CKDU 地区浅层地下水中溶解有机碳特征及其与钙的相互作用研究[D]. 北京. 中国科学院生态环境研究中心,2019.
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