| Duolong ore concentration area is located in Wuma Township,Gaize County,Ali District,Tibet.It is the largest porphyry copper-gold deposit in Bangonghu-Nujiang metallogenic belt.By the end of 2018,more than 20 million tons of copper metals have been identified and tens of millions of tons of copper ore have not yet been found.At present,the whole mineral concentration area is in the pre-development stage.The predecessors'research results in Duolong ore concentration area mainly focused on mineral exploration,chronology,mineralization and other aspects,but the environmental research achievement are very few.In order to provide references for the green exploration and development of Duolong mineral concentration area in the future,this paper assesses the background of water and soil environment in Duolong mineral concentration area and puts forward countermeasures.The main understandings are as follows:?1?The average contents of Cu,Pb,Zn,Cd,Cr,Hg and As were 46.69,36.06,100.23,0.27,324.4,0.03 and 34.71 mg/kg,respectively,and the average pH value was 8.5.Among them,the average contents of Cr and As exceeded the GB15618-2018 national standard,while other five heavy metals were lower than the national standard.pH was positively correlated with Cr and Hg,and negatively correlated with Cu,Pb,Zn,Cd and As.?2?The high value area of Cu is widely distributed in Gaerqin Copper Mine-Gaerqin Copper Mine,Tiegelong,Rongna-Naruo-Saijao,and many areas are not miscellaneous,while the low value area is widely distributed in the eastern part of the north of the study area;the distribution regularity of Pb,Zn,As and Cd is almost the same,while the high value area is widely distributed in Naro-Saikao-Sana and Gaerqin Copper Mines.To the east of Mine-Gaerqin Gold Mine,the low value area is located in the northeast corner of the study area;the high value area of Cr element is located in the northeast of the study area,and its content is decreasing from northeast to southwest;and the Hg content has almost no spatial variation characteristics.?3?The over-standard degree of heavy metals in soil was Cr>As>Cd>Cu>Zn>Pb>Hg.Adults'intake of heavy metals such as Cu,Pb,Zn and Hg in soil orally does not pose a non-carcinogenic risk to human body,while Cr does;As is more carcinogenic than the maximum acceptable level of EPA;children's intake of heavy metals in soil orally is affected by As carcinogenic risk,and Pb and Cr are not.Percutaneous skin contact in adults and children is affected by the non-carcinogenic risk of Cr intake.?4?Bensong Village,Zaduonari Village and Samalong Village?except the tributary of the Rongna River?have good water quality.The contents of Cu and Zn in the tributaries of Rongna River exceed the national surface water standards by 2.1 and 1.4 times respectively,showing strong acidity.The carcinogenic risk of Cu,Pb,Zn,Hg and As is negligible.The average annual total risk of carcinogenesis is 10 times higher than the acceptable level of EPA.?5?Average contents of available potassium,available nitrogen,available phosphorus,total nitrogen and organic matter were 163.86,79.61,7.13,1075.69 mg/kg and 1.16×10-2,respectively.Compared with grassland in Naqu mining area,the average contents of available potassium and available phosphorus in grassland soil were relatively high,but the average contents of available nitrogen,available phosphorus and total nitrogen were relatively low.They are 1/2,1/19 and 1/3 of the grassland in Naqu mining area.?6?The study area is suitable for developing mining industry,not for developing animal husbandry;the tributaries of Rongna River and the areas where heavy metals in soil exceed the standard should be prevented and cured;and the green exploration and development of green mines should be adhered to in the follow-up mining activities. |
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