[Assessment of groundwater quality of different aquifers in Tongzhou area in Beijing Plain and its chemical characteristics analysis].

In order to evaluate the groundwater quality of Tongzhou area in Beijing Plain and to discuss the characteristics of its distribution by the view of hydrochemistry, a total of 151 groundwater samples, collected within study area in the dry period of 2008 according to the geological and hydrogeololgical condition of Tongzhou area, were classified as shallow, middle and deep groundwater, respectively. Based on the data, the groundwater quality was evaluated by the method of F value. The mean and variance of main chemical constituents of groundwater samples were presented. Almost all the quaternary groundwater of Chaobai river pluvial fan belonged to the alkaline water type. The evaluation results based on the analysis results showed that from shallow to deep, the quality of groundwater in Beijing became better. The total areas of groundwater belonging to class IV and V area were 884 km2, 599 km2 and 94 km2 respectively for shallow, middle and deep groundwater. The evaluation results showed that the main exceeding chemical constituents were TDS, hardness, NH4(+), F(-) and total Fe. Most exceeding samples belonged to middle and deep aquifers. The main types of shallow groundwater were HCO2-Ca x Mg- and HCO3 x Cl-Ca x Na x Mg, while the chemical types of mid-deep groundwater were mostly HCO3-Na x Ca- and HCO3 x SO4(2-) -Na x Ca type due to the increased Na(+), SO4(2-) and Cl(-) concentration. Study results showed that the quality of shallow groundwater became worse mainly due to human activities. The deterioration of groundwater quality in mid-deep aquifers was due to both human activities and natural occurrence of poor-quality water.

[Groundwater organic pollution source identification technology system research and application].

Groundwater organic pollutions are found in large amount of locations, and the pollutions are widely spread once onset; which is hard to identify and control. The key process to control and govern groundwater pollution is how to control the sources of pollution and reduce the danger to groundwater. This paper introduced typical contaminated sites as an example; then carried out the source identification studies and established groundwater organic pollution source identification system, finally applied the system to the identification of typical contaminated sites. First, grasp the basis of the contaminated sites of geological and hydrogeological conditions; determine the contaminated sites characteristics of pollutants as carbon tetrachloride, from the large numbers of groundwater analysis and test data; then find the solute transport model of contaminated sites and compound-specific isotope techniques. At last, through groundwater solute transport model and compound-specific isotope technology, determine the distribution of the typical site of organic sources of pollution and pollution status; invest identified potential sources of pollution and sample the soil to analysis. It turns out that the results of two identified historical pollution sources and pollutant concentration distribution are reliable. The results provided the basis for treatment of groundwater pollution.