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20世纪90年代中期以来,斯里兰卡旱区(Dry Zone)不明原因慢性肾病(chronic kidney disease of unknown etiology, CKDu)高发,患者约占全国总人口的0.2%,标化患病率高达12%~15%,已成为该国亟需解决的重大民生问题。当地主要饮用水源为地下水,世界卫生组织(World Health Organization, WHO)的初步研究结果表明,地下水中污染物可能是重要的致病原因[1-2]。但近年来,针对地下水特别是CKDu病区地下水的系统性调研工作开展的较少,特别是地下水中溶解性有机物(dissolved organic matter,DOM)的研究一直处于空白状态。因此,在斯里兰卡CKDu病区开展系统的地下水水质调研,了解当地地下水水质情况、水质类型、关键组成,以及DOM的组成、来源、特性和分布,对于确定地下水深度处理与饮用水安全保障技术方案具有重要的指导意义,也助于进一步了解水质与CKDu之间的关联,促进CKDu的追因研究。
本研究在斯里兰卡CKDu高发的北中省(North Central Province,NCP)展开,按照CKDu发病率,考察不同区域地下水在干湿季节的水化学特征。采用CODMn/DOC、SUVA等指标评估DOM的可生物利用性,结合应用三维荧光光谱(3DEEM)和平行因子分析(PARAFAC)方法分析DOM的组成、分布特征及来源,明确斯里兰卡CKDu病区地下水源饮用水的关键问题。针对主要污染特征,提出有效的解决策略,以期为当地饮用水安全保障和CKDu追因工作提供基础数据。
斯里兰卡CKDu病区地下水源饮用水关键问题及解决策略
Critical challenges and solutions on ground drinking water in chronic kidney disease of unknown etiology (CKDu) affected regions in Sri Lanka
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摘要: 不明原因肾病(CKDu)是斯里兰卡亟需解决的重要民生问题,其地下水源饮用水中的溶解性污染物可能是重要的致病原因。系统分析了北部中心省内高、低、非发病区及对照区 (HR、LR、NR、CR)干湿季地下水的水化学特征和DOM特性,结果表明:地下水主要呈Ca-Mg-HCO3型,硬度和F−超标率较高,是地下水作为饮水安全保障最关键的指标;地下水中DOM主要为自生源,芳香性和腐熟化程度较低,主要为富里酸、腐殖酸和小分子蛋白质类物质;湿季DOM浓度较高,是Fe浓度增加的关键原因;而干季地下水中微生物活性较高,腐殖质和蛋白质发生分解,小分子络氨酸/赖氨酸的浓度增加。同时,发现不同区域地下水中DOM的生物利用性表现为HR<LR<NR<CR。其中,HR区地下水中的DOM最稳定,SUVA为(3.29±0.44) L·(mg·m)−1,芳香性较高。有机无机的相互作用导致赋存形态、生物可利用性的变化可能是CKDu致病的重要原因。针对以上问题,提出“吸附-除F-软化-NF-消毒”的处理策略,通过有机物吸附处理、阴离子交换除F、软化除硬分离预处理及NF深度处理等技术有效解决地下水中DOM、F−、Ca2+和Mg2+超标的问题,实现饮用水的供给。本研究全面分析了CKDu病区地下水中的污染物组成,并提出解决策略,可为斯里兰卡饮用水安全保障提供支撑。Abstract: Chronic kidney disease of unknown etiology (CKDu) has been a key livelihood issue in Sri Lanka for years, and the dissolved contaminants in ground drinking water source was regarded as the main potential contributor. In this study, the hydrochemical characteristics and dissolved organic matters (DOM) properties of groundwater in several areas in Sri Lanka were investigated in terms of high, low, none CKDu prevalence (referred to as HR, LR, NR, respectively, hereafter), with a no CKDu areas set as control (CR). The investigated groundwater mainly exhibited a Ca-Mg-HCO3 type with high Ca2+ and Mg2+, hardness, and F−, which were the main problems affecting safe water supply. The bio-availability of DOM showed a tendency of HR<LR<NR<CR, while DOM in HR also has highest aromaticity with a SUVA of (3.29±0.44) L·(mg·m)−1. The DOM was main endogenous-sourced and showed low aromaticity and maturity, fulvic acid, humic acid, and protein were main components. DOM has high concentration in wet season, and Fe concentration increase. Bioactivity was higher in dry season, humics and proteins degradation happened and tyrosine and lysine presenting high concentration. No significant difference was found in DOM between CKDu related areas and control area, and it can be inferred that the interaction between inorganic and organic matters, which influence the speciation and bio-availability, can be the reason for CKDu. Adsorption-ion exchange- NF-disinfection coupled technology was designed for groundwater treatment for DOM, F and hardness control. This work systematically analyzed the water quality in CKDu region in Sri Lanka and offer an effective groundwater treatment strategy for safeguarding drinking water supply in Sri Lanka.
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表 1 斯里兰卡地下水采样信息
Table 1. Sampling information of groundwater in Sri Lanka
样品序号 地区 类型 样品序号 地区 类型 样品序号 地区 类型 1 Palagala LR 28 Nochchiyagama MR 56 Padaviya HR 2 Palagala LR 29 Nochchiyagama MR 57 Padaviya HR 3 Palagala LR 30 Nochchiyagama MR 58 Padaviya HR 4 Palagala LR 31 Nochchiyagama MR 59 Padaviya HR 5 Palagala LR 32 Nochchiyagama MR 60 Padaviya HR 6 Palagala LR 33 Nochchiyagama MR 61 Padaviya HR 7 Palagala LR 34 Nochchiyagama MR 62 Padaviya HR 8 Palagala LR 35 Nochchiyagama MR 63 Kebithigollawa HR 9 Galnewa LR 36 Nochchiyagama MR 64 Kebithigollawa HR 10 Galnewa LR 37 Nochchiyagama MR 65 Kebithigollawa HR 11 Galnewa LR 38 Nochchiyagama MR 66 Kebithigollawa HR 12 Galnewa LR 39 Thabuththegama MR 67 Kebithigollawa HR 13 Galnewa LR 40 Thalawa MR 68 Kebithigollawa HR 14 Galnewa LR 41 Thalawa MR 69 Kebithigollawa HR 15 Galnewa LR 42 Thalawa MR 70 Kebithigollawa HR 16 Galnewa LR 43 Thalawa MR 71 Medawachchiya HR 17 Galnewa LR 44 Thalawa MR 72 Medawachchiya HR 18 Monaragala NR 45 Thalawa MR 73 Medawachchiya HR 19 Monaragala NR 46 Thalawa MR 74 Medawachchiya HR 20 Monaragala NR 47 Mihintale MR 75 Medawachchiya HR 21 Monaragala NR 48 Mihintale MR 76 Medawachchiya HR 22 Monaragala NR 49 Mihintale MR 77 Medawachchiya HR 23 Digana CR 50 Mihintale MR 78 Medawachchiya HR 24 Digana CR 51 Mihintale MR 79 Medawachchiya HR 25 Digana CR 52 Mihintale MR 80 Medawachchiya HR 26 Digana CR 53 Mihintale MR 81 Kahatagasdigiliya HR 27 Digana CR 54 Mihintale MR 82 Kahatagasdigiliya HR 55 Thirappane MR 83 Kahatagasdigiliya HR 84 Kahatagasdigiliya HR 85 Kahatagasdigiliya HR 86 Kahatagasdigiliya HR 87 Kahatagasdigiliya HR 88 Kahatagasdigiliya HR 89 Kahatagasdigiliya HR 90 Kahatagasdigiliya HR 表 2 不同地区干湿季地下水中水化学特性
Table 2. Hydro geochemical data in wet and dry seasons in different zone
区域 数据
类型pH 电导率/(μS·cm−1) K+/(mg·L−1) Ca2+/(mg·L−1) Na+/(mg·L−1) Mg2+/(mg·L−1) 碱度/(mg·L−1) 硬度/(mg·L−1) 湿季 干季 湿季 干季 湿季 干季 湿季 干季 湿季 干季 湿季 干季 湿季 干季 湿季 干季 HR 最低 6.6 5.7 35.2 147.0 n.d n.d 5.28 6.63 61.72 10.5 3.85 n.d 11.2 23.9 29.0 37.9 最高 8.8 8.2 2 080.0 2 250.0 25.3 24.1 73.1 124 430.6 233.6 52.9 74.6 387.0 656.0 525.8 604.5 平均 7.8 7.2 729.4 872.2 2.0 1.8 42.5 68.2 172.6 71.9 25.4 32.0 242.5 282.2 231.0 280.2 MR 最低 7.2 6.7 149.0 180.0 n.d n.d 16.7 14.9 6.5 18.8 14.2 2.6 24.4 43.7 32.0 47.9 最高 8.7 8.6 2 730.0 2 890.0 5.3 5.9 168.6 177.1 73.1 437.4 71.1 86.0 571.0 819.0 637.3 738.8 平均 7.9 7.4 1 200.3 1 298.1 1.7 1.5 64.4 69.7 59.7 142.4 40.1 42.9 295.4 349.0 285.1 345.3 LR 最低 7.5 6.4 110.1 147.0 n.d n.d 8.1 7.2 11.78 9.4 3.2 1.8 13.0 21.6 19.1 25.6 最高 8.2 8.4 1 356.0 1 133.0 31.3 26.4 66.7 95.4 143.1 148.5 54.8 58.5 419.0 391.0 348.1 350.4 平均 7.8 7.3 664.0 677.6 5.9 2.8 40.2 45.3 48.9 58.6 18.5 22.6 228.6 172.6 208.6 205.8 NR 最低 7.4 6.5 294.0 303.0 0.2 0.3 19.7 23.3 19.7 18.2 10.8 12.2 106.0 94.8 99.1 108.3 最高 8.0 7.7 669.0 815.0 7.5 7.5 50.1 74.2 50.1 64.6 43.3 54.0 247.5 232.0 250.1 308.0 平均 7.8 7.1 490.4 565.0 3.1 3.6 37.6 48.1 26.43 30.0 21.2 27.6 156.8 135.4 180.9 233.5 区域 数据
类型$ {\rm{SO}}_{\rm{4}}^{{\rm{2 - }}}$ /(mg·L−1)Cl−/(mg·L−1) $ {\rm{NO}}_{\rm{3}}^{\rm{ - }}$ /(mg·L−1)$ {\rm{NO}}_{\rm{2}}^{\rm{ - }}$ /(mg·L−1)$ {\rm{PO}}_{\rm{4}}^{{\rm{3 - }}}$ /(mg·L−1)Fe/(ng·mL−1) F−/(mg·L−1) COD/(mg·L−1) 湿季 干季 湿季 干季 湿季 干季 湿季 干季 湿季 干季 湿季 干季 湿季 干季 湿季 干季 HR 最低 4.3 1.8 7.1 2.5 n.d n.d n.d n.d n.d n.d 2.3 1.0 0.5 0.7 1.4 1.8 最高 66.3 53.1 160.7 525.4 4.9 24.7 5.9 0.2 0.6 — 462.4 23.9 5.3 6.0 11.3 8.1 平均 23.7 19.9 49.6 69.5 — — — — — — 168.1 9.7 2.3 2.8 6.4 5.4 MR 最低 7.1 7.5 42.5 2.5 n.d n.d n.d n.d n.d n.d 25.5 7.4 0.6 0.6 3.2 4.3 最高 97.3 98.5 267.9 489.2 10.3 17.2 4.8 0.7 0.4 n.d 697.3 38.0 5.2 4.7 11.0 10.3 平均 33.9 31.0 168.4 144.5 — — — — — — 224.9 13.9 2.5 2.2 5.5 6.3 LR 最低 7.1 3.9 18.3 4.6 n.d n.d n.d n.d n.d n.d 73.0 4.6 0.2 0.3 2.5 0.1 最高 62.6 38.9 103.5 121.2 6.38 15 5.8 0.3 0.7 0.7 220.3 37.2 3.7 3.5 10.0 6.8 平均 27.3 16.7 41.6 44.3 — — — — — — 146.1 12.1 2.1 2.4 6.2 3.9 NR 最低 6.5 6.0 7.9 6.6 n.d n.d n.d n.d n.d n.d 66.7 7.6 0.7 0.5 2.9 3.0 最高 90.9 82.9 37.7 85.8 n.d 17.9 n.d n.d 0.3 n.d 221.0 15.7 3.3 2.8 5.5 7.1 平均 27.9 27 27.9 36.4 — — — — — — 142.9 10.1 2.0 1.5 3.7 4.2 注:n.d. 为未检出,“—”为未计算。 表 3 湿季典型地下水常规指标和金属含量
Table 3. Water quality and concentration of metals in groundwater in wet season
采样点 区域 pH 电导率/
(μS·cm−1)碱度 /
(mg·L−1)COD/
(mg·L−1)硬度/
(mg·L−1)F−/
(mg·L−1)Al/
(ng·mL−1)Mn/
(ng·mL−1)Fe/
(ng·mL−1)Cu/
(ng·mL−1)Zn/
(ng·mL−1)As/
(ng·mL−1)1 LR 8.0 1 143 411.0 10.0 332.6 2.4 n.d 0.3 147.5 3.7 6.7 1.7 4 LR 7.5 259.0 48.4 7.6 52.9 3.7 91.8 0.5 82.5 1.8 4.4 1.4 7 LR 7.6 582.0 168.5 9.4 243.3 3.2 0.0 0.2 180.5 2.4 4.1 0.8 8 LR 7.6 153.0 25.1 6.0 43.0 2.9 2.1 0.3 n.d 0.3 3.8 0.2 9 MR 7.8 544.0 124.0 4.9 144.3 4.0 0.9 0.5 86.8 2.1 7.4 0.7 32 MR 8.7 1 981.0 571.0 11.0 169.9 5.2 0.3 0.1 25.5 11.8 6.1 4.3 37 MR 8.0 1 440.0 232.5 6.4 332.7 0.6 2.3 145.2 278.5 5.3 8.2 4.0 43 MR 7.4 2 350.0 157.0 6.2 637.3 1.8 n.d 0.4 697.3 6.0 6.5 6.8 46 MR 7.5 776.0 259.5 4.0 265.4 1.8 n.d 0.3 245.1 1.6 6.3 0.9 58 HR 8.1 477.0 183.0 11.0 202.2 0.8 3.2 0.5 117.5 2.8 3.9 1.0 59 HR 7.9 1 050.0 378.5 10.2 336.3 2.8 n.d 1.1 181.4 3.0 6.3 1.2 65 HR 7.6 123.0 11.2 3.3 29.0 4.8 1.9 0.6 n.d 0.9 7.0 0.1 83 HR 7.7 600.0 193.5 4.0 214.4 1.0 n.d 0.1 130.7 1.4 11.7 0.5 19 NR 7.5 668.0 158.5 9.7 211.5 2.4 0.9 76.5 166.7 51.1 21.5 0.4 23 CR 7.8 2 080.0 266.0 5.0 525.8 5.3 2.0 0.4 462.4 7.6 10.1 5.6 国标 6.5~8.5 — 200.0 — 250.0 1.0 200.0 100.0 300.0 — 3 000.0 10.0 WHO 6.5~8.5 — — — — 1.5 — — — 2 000.0 — 10.0 注:n.d. 为未检出,“—”为标准未涉及。 表 4 不同地区地下水DOM荧光峰、组成及荧光指数
Table 4. DOM fluorescence peaks, composition and fluorescence indexes of groundwater from different areas.
季节 区域 组分1 组分2 FI 370 HIX BIX 峰位置(Ex/Em) 物质 峰位置1(Ex/Em) 峰位置2(Ex/Em) 物质 湿季 LR 250/425 类富里酸 230/400 290/400 类腐殖酸 1.973±0.162 1.024±0.131 0.616±0.164 MR 250/450 类富里酸 240/375 275/375 溶解性微生物代谢产物 1.958±0.090 1.012±0.077 0.710±0.070 HR 250/425 类富里酸 230/400 290/400 类腐殖酸 1.905±0.129 1.030±0.128 0.653±0.101 NR — — — — — 1.975±0.134 1.036±0.062 0.647±0.232 CR — — — — — 1.989±0.198 1.087±0.089 0.538±0.142 干季 LR 225/400 290/400 类富里酸 220/325 275/325 类蛋白质 1.983±0.123 1.151±0.225 0.477±0.242 MR 230/400 280/400 类富里酸 220/325 275/325 类蛋白质 2.033±0.166 1.125±0.221 0.599±0.097 HR 225/400 290/400 类富里酸 220/325 275/325 类蛋白质 2.022±0.189 1.126±0.384 0.384±0.213 NR — — — — — — 2.048±0.125 1.071±0.068 0.673±0.139 CR — — — — — — 2.060±0.169 1.192±0.170 0.550±0.135 表 5 地下水有机物指标
Table 5. DOM concentration in groundwater
地区 DOC/ (mg·L−1) CODMn/ (mg·L−1) CODMn/DOC UVA254 /cm−1 SUVA/ (L·(mg·m)−1) HR区湿季 1.68±0.69 1.12±0.42 0.60±0.19 0.031±0.023 3.29±7.44 HR区干季 2.02±1.60 1.26±1.23 0.58±0.17 0.044±0.055 1.91±0.45 LR 区湿季 2.08±0.74 1.32±0.58 0.65±0.13 0.034±0.021 1.49±0.42 LR 区干季 1.35±0.17 0.92±0.24 0.70±0.19 0.022±0.004 1.66±0.21 NR区湿季 1.54±0.28 0.95±0.22 0.61±0.11 0.019±0.007 1.25±0.33 NR 区干季 1.87±0.36 1.43±0.69 0.73±0.23 0.037±0.016 1.92±0.54 CR区湿季 1.37±0.28 0.59±0.31 0.41±0.17 0.014±0.002 1.05±0.10 CR区干季 1.62±0.65 1.49±0.85 0.89±0.35 0.016±0.018 0.78±0.61 -
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