| ?Background?1. Water is one of the most indispensable and basic materials in people's daily life. Due to the growing demand for water, water resources crisis first occurs in some water vulnerable areas, while the deterioration of the water does harm to to the survival environment [1]. The safety of drinking water is a major issue related to the national economy and the people's livelihood [2].2. Soil is the foundation of human existence. As a medium for production of green plants, soil is site for processing and purifying various pollutants. But with the rapid economic development and urbanization process acceleration, the problem of contaminated soil is increasing, and China's soil pollution is more serious than any other country in the world. Heavy metals can accumulate in the soil, remain in the object, enter the body through the food chain, accumulate in the body, and thus develop to form a potential hazard to the human body [3]. Therefore, the heavy metal has become a serious environmental pollution, which has attracted the attention of all countries in the world [4-7]. ?Aim?We propose to test the hygiene quality of rural drinkable water, and the basic soil situation of heavy metal pollution in Baoji from 2011-2015. Through five years of collecting samples, monitoring, and laboratory testing, the quality of rural drinkable water and the change of soil conditions will be timely mastered. This study will accumulate of data and provide scientific basis for making the safety development plans of soil and rural drinkable water, as well as provide guarantee of safe water to drink. Therefore, it has an important practical significance in improving production, living and health quality of residents in rural area. ?Methods?We took Random selection of Meixian Qishan, Longxian County of Baoji City as a monitoring point.1. The monitoring of rural drinkable water1.1 The number of monitoring points were 150 in 2011, 140 in 2012, 40 in 2013, 116 in 2014, and 94 in 2015.1.2 Test basis for rural drinkable water: Water samples collection, transport, storage, and inspection were according to "drinkable water standard test methods"(GB / T 5750-2006).1.3 Evaluation criteria for rural drinkable water: According to "drinkable water health standards"(GB5749-2006), if one indicator was unqualified, the whole water sample was determined unqualified.2. Soil monitoring:For each year, soil samples were collected from farmland in five towns(streets), which were randomly selected from each county.2.1 The number of monitoring points were 40 in 2011,40 in 2012, 60 in 2013, 60 in 2014, and 60 in 2015.2.2 Test items: Lead, cadmium, chromium(hexavalent). There were 3 items totally.2.3 Test basis: The tests were according to "Determination of lead, cadmium in soil by graphite furnace atomic absorption spectrophotometry"(GB / T 17141- 1997) and "Determination of total chromium in soil by flame atomic absorption spectrophotometry(HJ491-2009).2.4 Evaluation criteria: The test results were get on environmental quality analysis by "soil environmental quality standards"(GB15618-1995).2.5 Statistical analysis: The count data was statistically analyzed using chi-square test in SPSS17.0, by which p <0.05 was considered statistically significant. ?Results?A total of 1080 samples of rural drinkable water and 260 samples of soil were collected for testing during 5 years. The monitoring results were shown as below:1. During 5 years, a total of 1080 water samples were detected, of which 955 water samples were qualified. The pass rate was 88.42%.1.1 Inspection of water samples in different years1.1.1 Qualified situation: The qualified rate of water samples was the highest in 2011, and the lowest in 2015, by a declining trend. The qualified rate of water samples between different years was with significant difference(?~2 = 7.070, p = 0.029). The qualified rate of water samples from dry season and wet season water were 91.30% and 85.56%, with which the difference was statistically significant(?~2 = 8.69, p <0.01). The qualified rate of water samples from factory water and tap water were 91.11% and 85.94% respectively, with which the difference was statistically significant(?~2 = 8.69, p <0.01).1.1.2 The unqualified situation of indicators:There were unqualified samples in each year with individual indicators exceeding standards. Unqualified projects included mainly thermotolerant coliforms, hexavalent chromium, iron, oxygen consumption and so on. The over-standard rate of microbial was highest by 6.57%, which mainly included heat-resistant and total coliform of 3.89%, followed by total coliforms of 2.31%. The over-standard rate of nitrate and chromium, which were toxicological indicators, were 3.80% and 0.92%.1.2 The situation of water samples in different county1.2.1 Qualified situation: The qualified rate of water samples in Qishan county was the highest by 92.09%, while that in Long county was the lowest by 81.29%. The difference of qualified rate in three counties was statistically significant(?~2 = 22.37, p <0.01). But in three counties, the passing rate of water samples in wet period(?~2 = 1.77, p> 0.05), dry season(?~2 = 0.32, p> 0.05), finished water(?~2 = 0.20, p> 0.05), tap water(?~2 = 0.75, p> 0.05) were not statistically significant.1.2.2 Unqualified indicators: The over-standard rate of microbial indicators in Long county was by 16.13%, while that in Qishan county was the lowest by 1.07%; the overstandard rate of toxicology indicators in Qishan county was the highest by 6.62%.2.The situation of soil testing:Among the 260 soil samples, 69.23% of them met the first and second level of standards, and 30.77% of them met higher than the secondary standards. The level of Pb and Cd in soil samples were all in compliance with the secondary standards. The rate of samples was 69.23% for cadmium content arriving the second level of standards, 26.92% for the third level, and 3.85% for over the third level.2.1 The pollution in farmland soils in different years: The difference of lead, chromium content in soil among each year was statistically significant(?~2 = 21.42, p <0.01). For each year, the difference of cadmium in soil was statistically significant by classification comparison(?~2 = 15.68, p <0.05).2.2 Different county soil test results: The lead and chromium content of soil samples from three counties met the first and second level of standards. There were six samples in Qishan county, and four samples in Mei county, of which soil cadmium content individually exceeded the third level of standards. ?Conclusions?The water was not treated by purification and disinfection in most of engineering points for rural drinkable water in Baoji. The microbial level is relatively serious, and the water from some factory was of excess chromium. In general, the farmland soil has been polluted by heavy metal, but the pollution of that was below the national average level. 3. It is suggested that the rural drinking water and farmland soil in Baoji area should be monitored by the supervision department, that the spotted problems about water resources as well as soil should be timely treated, and that the monitoring of the heavy metals pollution in food should be strengthened in order to ensure the health of rural residents. |
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