| Fluorine is an essential chemical composition to people, of which almost all of the organs need fluorid, and the most part of fluorine is distributed in hard tissues such as bones and teeth, account for about90%of the total fluoride in human body. But the best intake of fluoride ranges in a very narrow scope. When the fluorine concentration is much too high, pathological phenomena as excessive mineralization or ectopic mineralization will happen, and this will cause fluorosis, called endemic fluorine poisoning (endemic fluorosis for short, EFD). EFD is widely distributed in more than50countries and regions all over the world. In our country, the fluorine endemic area distribute throughout29provinces, autonomous regions and municipalities, we have1226sick districts and counties and more than150,000sick villages, the population of the endemic area is more than100million people.To reduce the morbidity and improve people’s health level, state and the local governments invested a lot of manpower and material resources and discussed the causes of EFD, a variety of methods decreasing fluorine has been taken, but the effect is not ideal so far. The reason is the lack of the deep and scientific understanding the migration and enrichment of the fluorine in groundwater which is the main source of our body.We take the high incidence area-the eastern plain in Henan province as an example in this paper. On the basis of field investigation, sampling test and analysis, guided by the scientific outlook on development and the earth system science theory, using the hierarchy theory and the groundwater system theory, three different spatial scales-the regional geological environment background, the local groundwater flow systems and the water chemical environment of the sampling points-were linked closely and the migration and accumulation process and characteristics of F in groundwater were expounded. Using the open nonlinear system synergy theory, discussed the aggregation effect of fluorine in groundwater and the formation mechanism of high fluoride water in natural conditions of multi-chemical components. Hydrochemistry phase diagram analytical method is put forward, which can further reveal the chemical mechanism of the formation of high fluoride water. From the perspective of ecological geology, the feasibility of building the artificial plant root group dam which is help to reduce the superficial environmental fluoride background value was discussed. We get the following conclusions in this study:1. The different water chemistry components are divided into different combinations of system elements, called the configuration. Steady state formed by the system ultimately comes down to the result of the synergy between different configurations. According to the improved Brodsky classification, chemistry components were divided into98kinds of hydrated state. Among which, the configuration type of CaMgNa-HSCIN, CaMgNa-HCISN, CaNaMg-HSCIN, NaMgCa-HSCI, CaNaMg-HCISN, NaMgCa-HCIS seem to be more, account for12.64%、7.09%、6.29%、5.89%、4.41%、4.01%of the total respectively. Among the98kinds of hydrochemistry configurations,62configurations show high fluoride water, the other36configurations are not high fluoride water, high fluoride water configuration type account for63.3%, an average high fluoride rate is0.25.2. If combine from the angle of the type of hydrochemical, every point is a different configuration and each sample point represents a configuration, namely the high fluoride water concentrate or disperse regularly, this characteristic means the phase. Configuration is made up of status values, such as calcium mg equivalent concentration, sodium mg equivalent concentration, salinity, pH values. When the status values of all the samles are put into a picture, the water chemical phase diagram formed.3.The distribution regularity of the high-F groundwater in various phase spaces(1) The two phase spaces outside the envelope line don’t appear high-F groundwater, high fluoride water appears in the phase spaces inside envelope line. High fluoride water appears in the six phase spaces inside the envelope line, but the probability is not equal.(2) In the inside of the envelope, the probability of high fluoride water of the three phase spaces above(⑥⑦⑧) is larger than the phase spaces below(③④⑤).(3) From phase space③to⑤and from⑥to⑧hase space, the frequency of high fluoride water shows an increasing trend, and as well, salinity is also shows a trend of increase.4.Chemical mechanism of the distribution of high fluoride water(1) The phase space①and space②outside of the envelope do not appear high fluoride water, but things are different. In the phase space②, the water has the feature of high calcium and low fluorine, the phase space has the reaction that the fluoride in water given priority to simple fluorine ion have come into the CaF2precipitation. In phase space①, the water can be high calcium and low sodium or high sodium and low calcium or of about the same calcium and sodium, there is no dominant chemical reaction causes the low fluorine. Some of the fluoride may be exist as simple fluoride ion and the rest may be complex fluorine ion.(2) There are six phase spaces inside the parabola. These spaces can be divided into two secondary phase spaces, the one contains the space③to⑤, the other contains the space⑥to⑧. The space⑥to⑧ave better frequency of the occurrence of high floride water than the space③to⑤significantly, and have the characteristic of low calcium and high sodium, the probability of high fluoride water were29.17%,63.18%and75.00%respectively. Fluoride in this secondary phase is given priority to simple fluorine ion and low in complex fluorine ion (via calculating, the chemical reaction of NaF'Na+F+have the preponderance), which lead the dominant chemical reaction of high-F to be NaF'Na+F+.In addition, salinity of the phase space⑥to⑧ncrease gradually and the probabilities of the occurrence of high fluoride water also increase gradually.The probabilities of the occurrence of high fluoride water in the apace③to⑧were6.96%,29.14%and73.53%respectively. In this secondary phase space, the sodium content is not sure, the occurrence of high fluoride water has a great deal of uncertainty, and the content of simple fluorine ion and complex fluorine ion are almost the same. Maybe there is no dominant chemical reaction or the rate of the two dominant chemical reaction above have a large differences under two different locations, which leads to the probability of high fluoride water not as high as three phase spaces discussed above.5. The multi-factor synergism in the causes and distribution of high fluoride groundwater. It is insisted that the formation process of high fluoride groundwater is not affected by a certain one factor but the synergy of many factors. The synergy of these factors and regional flow system control the macroscopic distribution pattern of high fluoride groundwater; the different effects between different factors and local flow systems lead to non-uniformity of high fluoride water distribution; the nested structure between different level flow systems cause vertical differentiation of fluorine distribution.6. Discussed how to reduce the fluoride content of shallow groundwater by vegetation ecosystem.Ecological method is a method based on the isolation mechanism of the system theory and the basic principle of ecological geology, through various levels of "plant root group dam", dicompose the fluoride movement in the study area, and by breaking up the fluoride migration process and intercepting fluoride layer by layer, reduce the distribution area of high fluoride in groundwater and soil, make the human intake of fluoride content in water and food lower than the national standard.7. Characteristics of the storing form and distribution of high fluoride groundwater in the study area:①According to the results of sample testing and simulation of the PHREEQC software, it is confirmed that in the neutral or partial alkaline (PH7-8.3) groundwater in the deep and shallow aquifer of the study area, fluorine exists as F-, HF, CaF+, MgF+, NaF, A1F2+, AIF3, FeF+8modes.②Simple fluoride anion and its complex concentration in shallow groundwater is:F-> MgF+> CaF+> NaF> AlF2+> A1F3> HF and FeF+. Generally, F-accounted for79.55%to96.08%of the total F (total fluorine concentration), followed by MgF+, CaF+and NaF, accounted for2.91%to18.01%,0.16%to2.58%and0.16%to18.01%of the total F respectively;③Arrange the concentrations of simple fluorine ion and its complex compounds in the deep groundwater from big to amall:F-> MgF+> CaF+> NaF> HF> AlF2+> AIF3> FeF+. Generally, F-accounted for84.91%to99.17%of the total F, followed by MgF+, CaF+and NaF, accounted for0.23%to13.28%,0.05to1.75%and0.08%to0.96%of the total F;④The morbidity of EFD is affected by the internal factors significantly, like fluorine content in groundwater and its storing form. As for the area with low fluorine content and high morbidity, its shallow groundwater is mainly affected by simple fluorine ion and fluoride magnesium complex compound, the former range from0.036to3.59mg/L, the later range from0.172to0.258mg/L; Deep groundwater is not only affected and controlled by the simple fluorine ion and fluoride magnesium complex compound, it may also affected by HF. In this condition, the concentration of F-range from0.039to3.19mg/L, fluoride magnesium complex compound range from0.009to0.014mg/L, HF range from0.002to0.003mg/L.The innovation of this paper is:The "configuration analysis" and "water chemical phase diagram method" for the formation mechanism of high fluoride groundwater.In microcosmic scale, using the polymorphic methods and synergetics theory, put forward the "configuration analysis" and "water chemical phase diagram method" for the first time, and have a more clear understanding of the formation mechanism of high fluoride groundwater.Configuration analysis method is proposed based on synergetics theory. The "configuration" refers to the hydrogeochemical environments, all kinds of the chemical components conmbine in a relatively constant proportion, forming the combined state. According to this theory, indicators except F-1were divided into98kinds of water types according to the improved Brodsky classification, drawing the conclusion:①fluorine ion can exist in a variety of groundwater configuration;②the fluoride ion concentration have certain differences in different configurations;③in the different water chemical microenvironment containing the same fluoride ion concentration, the proportions of simple fluorine ion and complex fluorine ion are different;④the fluorine ion concentration and the different ratio between ions of each water chemical microenvironment, can be determined by the dominant chemical reaction, also can be the result of several coupling chemical processes when there’s no dominant chemical reaction, such as the multistage chemical reaction.The essence of water chemical phase diagram analysis method is regarding each sample as a configuration. Configuration is made up of calcium milligram equivalent concentration, sodium milligram equivalent concentration, salinity, pH values and so on. All the samples tested in this study can be put in the8phase spaces in the picture. The following problems have been solved in this study:①the high fluoride water, low fluorine water may occur in what water chemical microenvironment, and the probabilities, and in what chemical background, high fluoride water has obvious randomness;②from non-beryl water and lead to a high incidence of low fluorine water is controlled by dominant chemical reaction, what are the dominant;③for the pH value of6.7-8.4, where fluoride in groundwater given priority to simple ion in microenvironments, in which microenvironment simple fluorine ion coexist with complex fluorine ion. |
PDF Full Text Request