Environmental Pollution And Controlling Suggestion In Petroleum Development Region In Northern Yan'an

Beiluohe Basins have enjoyed the fastest growth of economy due to petroleum development in this region. However, the rapid petroleum developments have resulted in the adverse impacts to its natural environment. For many years, the Beiluohe River has been the recipient of uncontrolled petroleum effluents containing high loads of organic matter, heavy metals and nutrients. Now Beiluohe River is seriously contaminated due to a long history of wastewater drainage from nearby petroleum industries. In this paper, we studied river water quality, hydrocarbon pollution in sediments and soils and heavy metal pollution in soils through data collection, field investigation and laboratory tests. In summary, the dissertation includes the following contents and conclusions.(1) Beiluohe River had a poor water quality on natural background, characteristics of high salinity and high hardness, which was attributed to high saline Cretaceous and Tertiary strata supplying groundwater for upstream of Beiluohe River. At present, wastewater drainage from nearby petroleum industries has resulted in an obvious increase in hardness and salt.(2) The main water quality criteria such as hydrocarbon, ammonia-nitrogen, COD, has exceeded many times from 1980s to 2000s. The concentrations of chloride concentration showed high values ranging from 250-1000 mg/l with some even exceeding 1000 mg/1. Nearly all river waters were not proper to drink and lost the function of irrigation. The level of surface water quality in Beiluohe River belonged to grade V.(3) Results of THC values showed an unpolluted to slightly polluted levels in most sediment samples from the studied areas. Relatively high concentrations of total hydrocarbons were found in those sediments collected from Ningsai River, Zhouhe River and Zhidan reach. Total PAH concentrations (sum of the 16 EPA priority pollutants) for the six analyzed samples ranged from 17.7 to 407.7 ng g^-1 dry wt. The concentration of PAHs hasn't exceeded the level of ERL, which showed that PAHs in sediments in this region had not adverse impact on biology. (4) Hydrocarbon pollution in soils was related to different environment. Most samples in surface soils were unpolluted to slightly polluted levels. Heavily polluted samples were located on oil well sites, road side, oil storage pools. Moderate polluted samples were located on farms near oil wells and sewage-irrigated regions.(5) Total PAH concentrations for the some plant samples ranged from 30.6 to 439.4 ng g^-1 dry wt. The concentrations of PAHs in plants are high by comparison with those observed in foreign countries and are comparative with those in Tianjin. In general, tested samples belonged to green plants according to concentration of benzo[a]pyrene.(6) According to the results obtained from the water quality assessment and hydrocarbon analysis in sediments and soils, some suggests were raised for controlling petroleum pollution in Beiluohe Basins.