The Migration Of Heavy Metals In The Coastal Wetland Ecosystem Of The Yellow River Delta And Its Effect On The Reproductive Effect Of Saunders' S Gull

The migration of heavy metals on the food chain affects the structure and function of the ecosystem and poses a threat to the survival and reproduction of the Saunders' s Gull(Saundersi larus saundersi).Therefore,the scientific understanding of heavy metal migration and its impact on birds is of great significance to the ecological security and wildlife protection in this area.According to the study on the heavy metal content in surface sediments of Saunders' s Gull breeding site in the Yi Qian Er Management of the Yellow River delta in 2018 and 2019,The order of heavy metal content levels in 2018 is as follows: Fe(25.939g/kg)> Mn(528.855mg/kg)>Cr(62.193mg/kg)>Pb(56.430mg/kg)>Ni(31.923mg/kg)>Cu(31.002mg/kg)> Cd(2.156 mg/kg);The order of heavy metal content levels in 2019 is as follows: Fe(13.09g/kg)>Mn(584.76mg/kg)>Cr(81.07mg/kg)>Cu(49.93mg/kg)>Ni(36.32mg/kg)>Pb(35.82mg/kg)> Cd(1.89mg/kg).It was found that Cd,Cr,Ni,Mn,Pb and Cu exceeded the Shandong soil geochemical background value and the national soil geochemical datum to different degrees except Fe,among which the exceeded rate of Cd was the highest.The Enrichment Factor(EF)of each heavy metal was greater than 1.5,indicating that on the whole,the sources of these six heavy metals in the surface sediments of the Yi Qian Er nature reserve were all significantly affected by human pollutant emissions.Igeo results show that the geographic accumulation of heavy metals index 2018 sampling points slightly contaminated by Pb(0 < Igeo < 1),2019 sampling points slightly contaminated by Pb and Cu(0 < Igeo < 1),2018 and 2019 sampling points were heavily polluted by Cd(3 < Igeo < 4).When evaluating the heavy metal pollution of the sampling station in 2018 and 2019 according to the national level 2 standard,the Nemero Comprehensive Pollution Index was 18.453 and 22.905,respectively,which were far beyond the severe pollution level of the Nemero Comprehensive Pollution Index,indicating that the soil pollution in the Yi Qian Er nature reserve was quite serious,mainly Cd pollution.The study of bio-sediment enrichment factor showed that Cu enrichment ability of all the nine biological tissues in the food of Saunders' s Gull was the strongest,while Mn enrichment ability was the weakest.The Residue Index method showed that,except for Cd,the heavy metal RI of Cr,Pb and Cu in the nine biological tissues were all greater than 1,indicating that all the nine organisms were polluted by Cr,Cu and Pb,and the Pb pollution was the highest among the nine biological tissues.Among the chick,egg shell,egg shell membrane and contents of Saunders' s gulls,the egg shell membrane has the strongest ability to enrich heavy metals and is the place where most heavy metals are enriched.The accumulation of heavy metal Cr may negatively affect the hatching of Saunders' s Gull.Pb did not show different sex in the successful or failed eggs.A certain degree of Cu and Fe in egg shell and egg shell membrane is helpful for successful incubation.For Mn,Pb,Cu and Fe,the contents of the hatching failure and the successful hatching nestlings all showed consistency,and there was no difference.Cr enrichment in contents may lead to incubation failure;A degree of Ni may help with incubation.Heavy metal elements on covert hatching success rate are not all negative impact,but the lack of some heavy metals will reduce the covert hatching success rate.In eggs,Cr and Mn may reduce the hatching success rate,and the accumulation of Ni,Pb,Cu and Fe heavy metal elements to a certain extent may contribute to the hatching success rate.In addition to Cd,Cr,Ni,Mn,Pb,Cu and Fe all have a significant impact on the breeding effect of black-billed gulls,among which Ni,Cu and Fe are positive effects,which to some extent are conducive to the breeding success of black-billed gulls.The negative effects of Cr,Mn,Pb may cause breeding failure of Saunders' s Gull.The mean concentration of heavy metals in the diet of young birds was obtained by quantitative analysis of the diet proportion of black-beak gulls.The order of size was Fe(323.777)> Cu(242.009)> Pb(31.637)> Ni(18.438)> Mn(18.157)> Cr(17.373)> Cd(0.091).By analyzing the Biological Amplification Factors of heavy metals between the food of black-headed gulls and the muscle of young black-headed gulls,the BMF of heavy metals such as Cd,Cr,Ni and Cu were less than 1.0,indicating that the heavy metals showed biological dilution between the food and the muscle of young gulls.The BMF values of heavy metals Mn,Pb and Fe were greater than 1.0,showing the biological amplification effect.In the biological enrichment process of young Saunders' s Gull,Mn enrichment rate was the highest,followed by Pb and Fe.The migration characteristics of Cr,Ni,Pb,Cu and Fe on the main food chain(net)of Saunders' s Gull in the Yellow River delta were obvious,in which Cr and Ni showed significant biological dilution,while Pb,Cu and Fe showed significant biological amplification.The transfer characteristics of Cd and Mn on the main food chain(net)of Saunders' s Gull in the Yellow River delta were not obvious,and there was no obvious biological dilution or biological amplification.