Exposure Risk Assessment Of Qinling Giant Panda Habitat To Heavy Metals And Pollution Source Apportionment

Qinling subspecies(Ailuropoda melanoleuca qinlingensis)is the most north and east population of the giant panda distribution.According to the latest survey data of the 4th national survey report on giant panda in China,the number of Qinling wild pandas is only 345.In recent years,with the advancement of industrialization and urbanization in our country,the environmental pollution problem is becoming more and more serious,heavy metal pollution is spreading in various environmental media and leading to heavy metal pollution has happened frequently,which give a serious threat to human and animal for their health and survival.Previous studies have found that Qinling captive pandas exposed to the poisonous and harmful heavy metals.But the heavy metal pollution degree of the whole giant panda habitat and the exposure risk of Qinling wild panda have not been considered previously.So in this study,we selected the soil,water bamboo in Qinling giant panda habitat and the non-invasive feces samples as the research object to assess the ecological risk of Qingling giant panda habitat and the health risk of Qinling giant panda exposure to the heavy metals and explore the heavy metal pollution sources.The main result was as followed:(1)There is a significant variation in the metal content of soil collected from different population distribution area and the concentration of heavy metal in buffer where has the frequent human activities was significantly higher than that of in core area.The toxic response coefficients of Cd and Hg are bigger to lead to the potential ecological risk of this study area is higher and the sensitivity of RI based on Monte-Carlo analysis also show that the sensitivity of potential hazard index of Cd is higher,accounting for 86% and the second is Hg.The result shows that the high ecological risk of heavy metals in soil is mainly caused by Cd and Hg,Cd mainly comes from transportation and Hg mainly comes from vulgar heating and waste incineration.(2)There is aslo a significant variation in the metal content of water collected from different habitat area and the concentration of heavy metal in buffer where has a larger interference of human activities is significantly higher than that of in core area.But in addition to Hg,other 8 kinds of elements are not exceed the national standard,the comprehensive pollution index of heavy metal in water of Qinling habitat aslo does not exceed the critical limits,which belong to no pollution level.Source analysis suggests that Cd in water mainly comes from road traffic and chemical fertilizers,whereas the sewage is the main source of the Hg.Building the high-speed rail,piling up a larger amount of solid waste and drainaging industrial wastewater and domestic sewage are the main scorces to lead to the nine kinds of metals increase abnormally in the water of Xiongllongling buffer area.(3)There is aslo a significant variation in the metal content of bamboo collected from different habitat area and the concentrations of heavy metal in buffer are significantly higher than that of in core area.There is aslo a significant variation in the metal content of different bamboo species and differernt parts in the same bamboo.The concentration of Cu,Zn and Mn is Bashania fargesii >F.dracocephala > Fargesia qinlingnsis,whereas the concentration of Pb,Cd,Cr,Ni,As and Hg is Fargesia qinlingnsis > F.dracocephala> Bashania fargesii.The concent of nine kinds of metals in leaves are higher than that of in stems of Fargesia qinlingnsis and F.dracocephala.And except the content of Cu and Zn in stems is greater than the bamboo leaves,other 7 kinds of heavy metal content in leaves is greater than that of Bashania fargesii.The results of heavy metal exposure risk show that Pb,Cd,As and Hg in bamboo have a higher potential risk.Therefore the Bashania fargesii with smaller enrichment coefficient,should be selected to control the high risk elements.The sources of Pb,Cd,As,Hg are basically identical with the sources of that in soil.Coal-fired heating and waste incineration are the main source of Hg and As,whereas Cd,Pb are classified as the element coming from the traffic.(4)There is a significant variation of heavy metal in feces samples collected from different giant panda habitatand the spatial variation of heavy metal is affected by comprehensive factors including the heavy metal contamination of feeding thestaple food of bamboo,drinking water,soil and so on.And the variation of heavy metals in these factors is mainly due to the interference of human activity and the type,degree of interference.The result of Hazard Quotient of nine kinds of heavy metal in Qinling giant panda feces indicated that Cd,As,Hg and Cd removing the essential element Mn could pose health risks to the Qinling wild giant panda populations and the results are almost equivalent to the results of health risk assessment via diet way.The multivariate statistical analysis of heavy metals in soil,water,and bamboo and the heavy metals in feces shows that the main way exposed to heavy metal for giant panda is via the diet way especially the contaminated bamboo.The classified result of9 kinds of heavy metals was found Cd and Pb,As and Hg are considered one category in feces.So combining with the heavy metal in environment,the sources of Pb and Cd are mainly derived from traffic pollution and As,Hg mainly comes from Coal-fired,waste incineration and sanitary sewage.The analysis find the giant panda and their habitat is affected by human activities.Soil,water,bamboo of Qinling giant panda habitat has the higher ecological risk and the Qinling giant panda exposured to heavy metals has the higher health risks,which mainly caused by the pollution of Cd,Pb and As,Hg.And the traffic is an important human activity,so we select the 108 th National highway as the object to verify the road traffic really make an impact on the giant panda habitat,especially the Cd.In addition the content of Cr,As and Hg in the soil collected from the residential area in Niuweihe population distribution area is significantly higher than that in the core and buffer area,which determine the source of these elements was the life pollution.Given the exposure risk of heavy metal to lead to adverse effects,it is important to explore the pollution sources of heavy metals and to take some protective measures.(1)Wild giant panda can no choose the food,so to really solve the problem of the giant panda intake of heavy metals,it only to do is control pollution from fountainhead,stop further pollution and ensure the enrichment of heavy metals in natural habitat of giant pandas to reduce.So we should control vehicle flowrate in a certain extent and now efforts may be concentrated upon transplanting some hyperaccumulators along the road to alleviate the influence of Cd and Pbcontamination to protect the giant panda.For As and Hg contamination,the main measure is control the human activities such as coal-fired heating and waste incineration,living sewage in giant panda habitat and the propaganda work giant panda protection should be strengthen and rewards and punishment system should be implemented to protect the rare and endangered wild animals effectively.(2)For captive panda,different staple food bamboos have the different abilities of the enrichment of heavy metals,so captive pandas should be selected Bashania fargesii,which is because the accumulation capacity of this species for Cd,Pb,As,Hg is smallest and ensure to wash using clean water prior to food provisioning.In addition,the daily oral intake of giant panda and the exposure time should be decreased and select some high quality fruits,vegetables,and mixed material to reduce the exposure risk of polluted staple food bamboo in a certain extent.(3)From the perspective of a long-term plan,the giant panda nature reserve should be completely taken in consideration in the road location project and the residents should migrate to other area that is far away from the nature reserve,taking collective heating,collective waste and wastewater treatment to avoid indiscriminate discharge.Of course,controlling heavy metal at source in the living environment of Qinling giant panda habitat would be the most thorough way to protect their health and survival.