Study On The Environmental Impact Of Exploitation And Application Of Geothermal Resources In Guanzhong Basin

Geothermal resources are a new kind of source minerals with green environmental protection, and it become more important in the development of economy. Nevertheless the main environmental issues may be caused by exploitation and application of geothermal resources: heat pollution, noise pollution, air pollution, chemical pollution, ground subsidence, et al. There are rich geothermal resources in the Guanzhong Basin. Geothermal has been widely used in washing, litter used in heating, fish breeding, planting and cultivation. At present time, the direct use of geothermal resources is at the primary grade, and the tail water was discharged directly after the use without geothermal reinjection. The environmental impact of geothermal impact is of more concern. So the study of environmental impact of exploitation and application of geothermal resources, making a full use of geothermal resources in Guanzhong Basin has important practical and theoretic significance.This paper gives the examples of the spring water in Baoji, Mei town, Chang'an town, Dongwang town in the Guangzhong Basin. The environmental impact of geothermal resources on water, soil, crop and fish was analyzed. The results are as follows:(1)Fluoride in geothermal water is the most important factor to the environmental impact. After the field investigation, about 99 pieces of samples on surface water, ground water, soil, crop (corn, rice) and fish were collected, and 3474 datas were gained by analysied. The elements which are exceeded the national standards are not coming from the geothermal water. There is little impact on surface water and ground water brought about by the exploitation and application of geothermal resources.(2)In the center use area of the geothermal resources, the contents of arsenic and chromium are higher with higher pH in the surface soil, the contents of copper, lead, and zinc are higher in the deep soil. The toxic metallic element may be enriched caused by the irrigation of geothermal water. And it may cause ground water pollution.(3)The contents of fluoride and arsenic, chromium, cadmium, lead are higher in crop which is irrigated by geothermal water. There are more elements and compents in the corn than that of rice. The highest contents fluoride and arsenic, chromium cadmium, lead are in the root of crop, then the contents from highness to the low lever are the base, leaf, fruit. It shows that the crop has been impacted by the irrigation of geothermal water.(4)Fluoride is exceeded the national standard in the geothermal in Guanzhong Basin. The content of fluoride in the geothermal water is 1.87～17.9 mg/L. And fluoride is absorbed by fish which is cultured by geothermal water. The higher content of fluoride is in the varied fish meat is Oreochromis niloticus, lower in grass carp, lowest in Cyprinus carpio. The content order of fluoride is fin>gill>meat of the fish. It is founded that plenty of heavy metal is also accumulated in fish. The contents of some metal are exceeded the standard of"safety requirements for non-environmental pollution aquatic products". The enrichment of fluoride and heavy metal in fish may do harm to the human health.