【摘要】 提出了城市河道湿地——一种新湿地类型的概念,论述了辽宁省葫芦岛市市区五里河城市河道湿地的生态特征,研究了五里河城市河道湿地沉积物和植被中汞的分布特征,采用生态风险指数法评价了该城市河道湿地沉积物中汞污染程度及其生态风险。五里河属季节性河流,葫芦岛市市区段的五里河河道不同的生态位生长着不同类型的植被,具有典型的湿地特征。河道湿地表层沉积物的总汞质量比为0.037～16.07mg/kg,平均质量比为9.241mg/kg。在该城市河道湿地龙湾大桥采样点,比较3种植物的总汞含量发现,三棱草(Rhizomacy-peri)的总汞含量高于稗草(Echinochloa crusgalli),稗草的总汞含量高于芦苇(Phragmites australis)。3种植物都存在根的总汞含量大于叶,叶的总汞含量大于茎的现象。由于水文和地域等条件的差异,五里河城市河道湿地与三江平原的碟形沼泽湿地汞的分布特征明显不同。评价结果显示,五里河城市河道湿地有重度的汞污染且具有严重的潜在生态危害。更多还原

【Abstract】 The Wuli River is a large river that flows through urban area of Huludao,Liaoning province from northwest and ultimately into the Jinzhou Bay.The study area of this paper has continental temperate monsoon climate and mean annual temperature is 9.0 ℃,the annual precipitation is 563-643 mm mainly concentrated in the summer.In recent years,exposure to environmental toxins has been paid attention to as the public adverse effect caused by their toxicity.Mercury is one of the most toxic metals in the world.The Chlor-alkali Plant of Jinxi Chemical Factory,which adopted mercury cathode in its production produce before 1992,had poured a large amount of mercury to the Wuli River in history.Though the Chlor-alkali Plant has adopted the technique without mercury for about 14 years,the mercury discharged to the Wuli River has not been eliminated.After the great effort made by the government of Huludao city,the ecological environment of the Wuli River have been greatly improved.There are various plants along the watercourse of the Wuli River at sampling sites and there are different preferential plants.The watercourse of the Wuli River in Huludao city has wetland’s characteristics so the urban riverine fringe is forming,where various plants developed in the corresponding ecological habitat.Urban riverine fringe,a new concept of wetland type,was brought forward in the paper.In the paper,the ecological characteristics of urban riverine fringe of the Wuli River and the mercury concentrations of sediments and plants were studied.The theory of ecological risk index was used to estimate the mercury contamination of the sediments of study area.It is believed that this paper will give necessary support to future study of urban environment protection and environment assessment.Samples were collected in September 2006,and 9 sampling sites in urban riverine fringe of the Wuli River were setup from upstream to downstream of the river.At each sampling site,the sediments were collected and at some typical sites its preferential plants were also collected.At Longwan Bridge site,3 vertical profiles were taken to invest the variety of mercury concentration with different depth.Sediments and plants were natural dried and then sieved by 80 mesh.The plant and sediment samples were digested using the method of HNO3-H2SO4-V2O5.CVAFS Technique was used to determine the concentration of total mercury.The process of the experiment was controlled by the certified standard reference materials of GBW-07604 and GBW-07405,and the results were accepted.The results showed that the concentrations of total mercury sediments form vertical profile were 0.037～160.68 mg/kg,and the average value was 9.24 mg/kg.The total mercury concentrations of surface sediments of the 9 sites ranged from 0.039 mg/kg to 16.07 mg/kg,average was 9.241 mg/kg.There is nearly no mercury pollutant and the historical mercury contaminant had not been emitted absolutely in the upstream of the river since toll station site.The total mercury concentration of Rhizoma cyperi was the largest,the one of Echinochloa crusgalliv was larger,then was Phragmites australis,and the total mercury concentrations of the tissues of all plants decreased in the order of root,leaf and stem.As the different hydrology dynamics,it was contrary to the mercury distribution of sediments,plants and its organs of the low wetland in the Sanjing Plain.Using Hakanson’s ecological risk index to evaluate it ecological risk of study area,the results indicated that mercury contamination and ecological risk of the sediments of urban riverine fringe of the Wuli River were seriously and suggested to take some ecological measures to renew environment of urban riverine fringe of the Wuli River.更多还原