Dynamics Of Waterbirds Community And Their Exposure Risk Of Heavy Metal Exposure In Caohai Wetland,Guizhou Province,China

Heavy metal pollution is one of the main environmental hazards facing wild animals and their habitats.Waterbirds communities are extremely vulnerable to environmental heavy metal pollutants due to their high clusters and fixed utilization habits of wetlands.Therefore,prevent,control and reduce this The harm is extremely important.The Caohai Wetland in Guizhou is one of the main wintering habitats and resting places for migratory birds in the southwest.There are many birds,rich species,and many rare and endangered species.However,Caohai is adjacent to Weining city,and heavy metal pollutants generated by human activities seriously threaten the survival of waterbirds communities and the ecological security of their habitats.This paper uses an optimized and targeted comprehensive evaluation model to evaluate the degree of heavy metal pollution of the most relevant environmental factors in the Caohai Wetland and the habitat of waterbirds and reveal its distribution rules;combined with the understanding of the composition and distribution of waterbirds communities,analysis of waterbirds's presence in heavy metals Exposure risks under the pollution pattern to guide the conservation and habitat improvement management of waterbirds.The research results are as follows:?1?During the study period?December 2018-January 2020?,a total of 45 species of waterbirds in the Caohai Wetland were recorded,belonging to 8 orders and 13 families.Anseriformes and Charadriiformes are the main populations that make up the Caohai waterbird community.Feeding habits are mainly omnivorous?20 species?and carnivorous?20 species?waterbirds species;winter migratory bird species?31 species?are the most;black-necked cranes?Grus nigricollis?,gray cranes?Grus grus?,and Tundra Swan?Cygnus columbianus?have been recorded in rare protected animals 3species,waterbird community composition does not change significantly,but we need to continue to pay attention to the change trend of some water bird populations.?2?Whether it is winter or summer,the survey areas of Huyelin,Wangjiayuanzi,and Liujiaxiang have high diversity and rich species of waterbirds,and other areas have greater human disturbance to the habitat of wetland waterbirds.In the Huyelin area in winter,the number of species of waterbirds is the largest?31 species?and the abundance of waterbirds is the highest(D_Ma=3.72);the diversity and uniformity of Wangjiayuanzi are the highest?H'=1.97,J'=0.60?.In summer,Huyelin has the highest diversity and uniformity.Waterbirds especially wading birds prefer shallow swamp?33 species?and meadow?30 species?habitats.In the Caohai Wetland,except for Jiangjiawan,the abundance,diversity and uniformity of waterbirds increased or changed little in winter between 2014and 2018;while in summer,the abundance,diversity and uniformity of waterbird communities It decreases in most areas of Caohai.The Jaccard similarity index?0.69?of the Caohai waterbird community in winter was greater than that of the summer waterbird community?0.58?.?3?The soil heavy metals in the Caohai waterbirds habitat are generally slightly polluted?2.00<CF=2.86?3.00?,The Cd pollution level the highest,reached the moderate pollution level(?3.00?CF?4.00?.and the soil heavy metal pollution index from high to low is Cd?CF=3.85?>Pb?CF=1.44?=Zn?CF=1.44?>As?CF=1.23?>Ni?CF=1.20?>Cr?CF=1.02?>Cu?CF=0.94?.The content of As,Cd,Cr,Pb,Zn in waterbirds edible plants,As content in fish samples and As and Pb content in shrimp samples all exceed the National Food Safety Standard-Limits of Contaminants in Food?GB 2762-The limit value of food contaminants specified in 2017?.The effect of soil on heavy metal content enrichment in different habitats is not significant,but it has a certain effect on plant enrichment,and there is pollution.Certainly affect.The spatial distribution of soil and plant heavy metal pollution in waterbirds habitat has no significant impact on the spatial distribution pattern of waterbirds communities.The higher the concentration of heavy metals in soil and plants,the greater the potential threat to the waterbirds community in the region.Except for the relatively low soil heavy metal pollution in Liujiaxiang,Miaojiayuanzi,and Jiangjiawan areas in the waterbirds survey areas,the soil heavy metal pollution in the other survey areas is relatively serious;The degree of concentration is relatively high,and other regions are relatively low.?4?Different heavy metal elements have different levels of heavy metal exposure in different waterbirds.Cr,Pb,and Zn have different effects on Northern Pintail?Anas acuta?and Little Egret?Egretta garzetta?.Bar-headed geese?Anser indicus?,black-necked cranes all present different levels of exposure risk?HQ>1.00?;other elements have no exposure risk in all waterbirds?HQ?1.00?.Among the potential hazards of heavy metals in waterbird's foods,egrets and pintail ducks are high risk?HQ>3.00?;black-necked cranes and bar-headed geese are medium risk?2.00<HQ?3.00?.Among the soil intake pathways,black-necked cranes have the highest potential risk of heavy metals in cultivated land?HI=2.02>2.00?,and shallow swamps,meadows,and gutterways are all at low risk levels?1.00<HI?2.00?.In the way of edible plants,only meadows has a low risk?1.00<HI?2.00?,and other habitats are at a risk-free level?HI?1.00?.?5?The black-necked cranes mainly inhabit the foraging area and the high risk of potential heavy metal hazards in food are mainly concentrated in the southern,southwest and western areas of the Caohai wetland area,near the nearby urban areas of Wangjiayuanzi,Huyelin,Zhujiawan and Liujiaxiang and The soil heavy metals in the cultivated area near Shuanghe are at a low risk level.Cr,Pb,and Zn elements pose the highest threat to the health of waterbirds in the Caohai Wetland and the ecological security of their habitats,and they are heavy metal pollutants that need priority prevention and control.The soil in the cultivated land and the waterbirds edible plants in the meadow in different habitats in Caohai need to be paid attention to.For the prevention and control of heavy metal pollution in the Caohai environment,attention should be paid to the control of pollution sources such as indigenous zinc smelting relics,factory activities,transportation,agricultural and animal husbandry activities,and garbage incineration.Shuanghe,Huyelin,Louluoshan,Wangjiayuanzi,Gujiadixia,and Liujiaxiang should be priority areas for the prevention and control of heavy metals.