西南典型地下河系统无机-有机指标特征及健康风险评价

朱丹尼; 周长松; 李军; 邹胜章; 卢海平; 樊连杰; 林永生

doi:10.15898/j.cnki.11-2131/td.202201310018

西南典型地下河系统无机-有机指标特征及健康风险评价

Inorganic-Organic Characteristics and Health Risk Assessment of Typical Underground River System in Southwest China

摘要

摘要: 岩溶地下水为全球约25%的人口提供饮用水源，地下河作为主要岩溶地下水类型，是中国西南岩溶区重要供水水源，掌握其水质污染状况及人体健康风险，对岩溶区水资源保护与安全用水具有重要意义。本文以广西桂林会仙狮子岩地下河系统为例，采集地下河水样品22组(无机和有机样品各11组)，采用电感耦合等离子体质谱、离子色谱、气相色谱-质谱等方法测定11项无机离子、10项金属元素及41项有机指标的质量浓度，运用单指标污染标准指数法、健康风险评价模型揭示了研究区无机与有机指标分布、污染及健康风险。结果表明：①狮子岩地下河水中无机超标指标有NH₄⁺(1.33倍)、Fe(1.2倍)、Al(1.5倍)和Mn(1.01倍)，超标点多位于地下河排泄区；检出18项有机物，其中挥发性有机物(VOCs)、半挥发性有机物(SVOCs)和有机氯农药(OCPs)检出率分别为18.75%、30.77%和91.67%，研究区存在普遍的农药残留(49.14~109.83ng/L)。②与地下水对照值相比，研究区受到10项无机指标的轻度~中度污染、14项有机指标的轻度污染，个别采样点受到NO₃^-、Fe、Al和Mn的较严重~严重污染，一处采样点遭受苯并a芘的极严重污染。③经饮用水和皮肤接触两种途径暴露的非致癌健康风险(成人9.98×10^-3a^-1，儿童1.09×10^-2a^-1)和致癌健康风险(成人1.33×10^-7a^-1，儿童2.82×10^-7a^-1)均在可接受范围内。本文认为研究区存在不同程度的无机和有机污染，但污染物指标对人体暂不构成非致癌和致癌健康风险。

Abstract:
BACKGROUND Karst groundwater provides drinking water for about 25% of the world's population. As the main type of karst groundwater, underground rivers are an important water supply source for karst areas in Southwest China. It is of great significance to master the water quality, pollution status and human health risk for water resources protection and safety use in southern karst areas.
OBJECTIVES To reveal the chemical compositions, pollution degree and health risk of underground river water.
METHODS 22 groups of underground river water samples (half inorganic and half organic samples) from the underground river system of Shiziyan in Huixian, Guilin, Guangxi were collected. The concentrations and spatial distribution of 21 inorganic ions and 41 organic indices were analyzed by inductively coupled plasma-mass spectrometry (ICP-MS), ion chromatography (IC) and gas chromatography-mass spectrometry (GC-MS).The single index pollution standard index method was used to evaluate the pollution of 17 inorganic ions and 15 detected organic compounds. The health risk assessment model recommended by the United States Environmental Protection Agency (US EPA) was used to study the human health risk of 10 major pollutants.
RESULTS The results showed that: (1) Ca²⁺ and HCO₃^- were the dominant ions in the Shiziyan underground river. The concentrations of NH₄⁺, Fe, Al and Mn in the underground river exceeded the groundwater quality standard by 1.33, 1.2, 1.5 and 1.01 times, respectively, and the exceeding points were mostly located in the discharge area of the underground river. 18 organic compounds were detected, of which the detection rates of volatile organic compounds (VOCs), semi volatile organics (SVOCs) and organochlorine pesticides (OCPs) were 18.75%, 30.77% and 91.67% respectively. (2) Compared with the groundwater background values, the underground river water in the study area was slightly-moderately polluted by 10 inorganic indicators and 14 organic compounds. Some sampling points were seriously polluted by NO₃^-, Fe, Al and Mn, and one sampling point (UR8) was extremely polluted by benzo a pyrene. (3) According to the results of health risk assessment, the non-carcinogenic health risks of being exposed to drinking water and for skin exposure were 9.98×10^-3 per year for adults and 1.09×10^-2 per year for children, and carcinogenic health risks were 1.33×10^-7 per year for adults and 2.82×10^-7 per year for children, which were within acceptable levels.
CONCLUSIONS There are various degrees of inorganic and organic pollution in the study area, but the pollutant indicators do not pose a non-carcinogenic or carcinogenic health risk to the population.

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