However, with the growth of the world population, the change of land use types and the rapid development of industrialization, the harm to groundwater has been accelerated. In some areas, the content of natural substances in groundwater is too high, which limits its use. For example, seawater may invade aquifers, and groundwater may also contain some soluble natural substances, such as arsenic, fluorine, nitrate or sulfate. For health reasons, these substances restrict or even prevent the direct use of groundwater.
This conference did not list hydrogeology or environmental geology as the theme of the conference, but integrated water (groundwater as a part), health and environment into one theme, and spent one day discussing and expounding the relationship between water, health and environment, which has become a major hot issue for all countries in the world to pay attention to and improve people's livelihood.
First, high arsenic groundwater and healthy geological environment
This is one of the hottest environmental geological problems in investigation and study, which exists in five continents and has the most threatened population (65.438+0.5 billion people in the Bay of Bengal alone). The high arsenic groundwater in the Bay of Bengal is still a hot spot for scientists all over the world. Facing the health problems concerned by human beings, Centeno thinks that geologists and public health scientists need to work together, and the coping strategy is that geologists should determine the existing forms, migration and transmission characteristics of arsenic in soil, water and other environmental media; Geologists, medical geographers and hydrogeologists * * * make geological risk assessment maps, especially in areas where the arsenic concentration in groundwater is greater than 10 μ g/L; Environmental health workers and public health workers study the relationship between low-dose arsenic exposure and arsenic metabolism in drinking water, and carry out molecular research on the transformation of arsenic components, the interaction between arsenic polymorphs and nutrients, and the carcinogenesis of arsenic.
Two. Geological background (rock and soil) and indoor radon risk assessment
Exposure of human body to indoor high radon gas and high radon groundwater environment often leads to high incidence of lung cancer and gastric cancer. It is estimated that 30,000 lung cancer deaths in Europe are related to radon inhalation every year, accounting for about 9% of lung cancer deaths; The population of the United States is about 18200 (1995). In Britain, 50% of people's radioactive radiation comes from radon. Therefore, the investigation and evaluation of geological background (bedrock and soil) and indoor radon risk has become one of the hot issues of international geologists, especially developed countries and regions.
During the period of 1978, the houses built in Skovad, Sweden, had radon health problems, which attracted the attention of the Swedish government. From 65438 to 0979, Sweden established a special radon research committee, which initiated the worldwide geological background and indoor radon investigation and risk assessment. Up to now, more than a dozen countries and regions such as Britain, the United States, Norway and Sweden have carried out geological background (rocks, soil and groundwater) and indoor radon survey and risk assessment. The survey and quantitative analysis methods commonly used in western developed countries include airborne radioactive detection technology and Bayesian conditional probability statistics.
In addition, the EU formulated the radon water supply standard in 200 1 year: public or commercial water supply is per liter100 bq; Less than 50 people or the daily water supply is insufficient 10 cubic meter, per liter 1000 Bq. Indoor radon standard is per cubic meter 100 Bq.
At present, there are three methods to remove radon from groundwater: aeration, filtration and activated carbon adsorption.
Three. Unreasonable fluorine ion content in groundwater and its water resources utilization
The harsh requirements of groundwater resources for fluoride ion content (high fluoride water and low fluoride water), as well as the investigation, substitution and treatment of such water sources, are still problems that international hydrogeologists and environmental sanitation workers have to work hard for a long time. Therefore, W.M.Edmunds put forward the following work directions: (1) the evaluation of groundwater resources needs to delineate high fluorine areas and low fluorine areas in the geological background; Find out the variation of groundwater with depth and age in fluorine anomaly area; In high-risk areas, it is more suitable to replace drinking water sources than to treat high arsenic water sources; In the small-scale water supply of local wards, rainwater and aquifer recharge can be given priority, or solar desalination can be used to improve water quality; The research experiment in Britain shows that the fluorination treatment of low fluorine water has achieved good results and is worth learning. It is necessary to strengthen environmental education, public participation and dialogue between government and NGOs.
Four. Health problems caused by groundwater flowing through carbonaceous sediments
Coal, oil and shale all contain many toxic organic compounds (such as polycyclic aromatic hydrocarbons, aliphatic hydrocarbons, terpenoids, heterocyclic compounds, aromatic amines and so on). The solubility of these organic compounds in natural water is relatively small, but long-term exposure to low-level toxic substances may also lead to health problems.
Drinking groundwater flowing through carbonaceous sediments (such as lignite beds) is likely to lead to high incidence of chronic renal failure and renal pelvis cancer. Countries or regions that may have such problems include Romania, Bulgaria, Croatia, the United States, Australia, Canada, Germany, Russia, China, India, Brazil, Turkey, Hungary, Poland, Thailand and Scotland. For this reason, Bob Finkelman and others suggested that we should pay special attention to drinking groundwater that flows directly from or comes into contact with carbonaceous sediments. Continue to observe and study the relationship between toxic organic compounds derived from carbonaceous sediments in drinking water and endemic nephropathy and similar endemic nephropathy in other parts of the world.
Verb (abbreviation of verb) groundwater resources management
Globally, 50% of domestic water, 40% of industrial water and 20% of irrigation water come from groundwater. At the same time, the over-exploitation and pollution of groundwater resources have become a serious problem in the current development and utilization of groundwater. Although groundwater is so important, it is still basically ignored in the discussion of water resources management compared with the emphasis on surface water in many countries and regions in the world. Anders Berntell believes that these problems are the products of "ordinary tragedies" and "tragedies that we can't see or imagine"; Financial repression and lack of knowledge of groundwater resources hinder the effective management of groundwater; Although many aquifers have been studied in depth, in most cases, the existing management mechanism does not include the responsibility of monitoring and managing water resources.
Roisin Rooney discussed the risk management of groundwater pollution in the Water Security Plan, and thought that in Europe where groundwater resources are extremely scarce, it is necessary to maintain safe and healthy water resources, carry out and implement water security plans including correct risk assessment and risk management methods, especially considering the protection of groundwater resources. To this end, 265,438+0 countries in Europe adopted an agreement on water resources and public health, while focusing on setting targets and monitoring the progress of targets, including the protection of aquatic resources, especially in cross-border areas.
(Written by Li Caiwu Tian)