Speciation Distribution Of Heavy Metals And Effects Of Disturbance In Typical Wetland Types Soil In Xiaoxing'anling

The research of speciation of heavy metals in wetland soil is significant for evaluating the heavy metals'origin, vary, mobility and biotoxicity, which can provide scientific evidence for the restoration of degraded wetland and exploitation. According to BCR sequential extraction procedure, it analyzed the speciation distribution of Fe,Cu,Zn in typical wetland types soil in Xiaoxing'anling, the results showed that:(1) The average content of weak acid extractable Fe appeared that scrub mire>herb mire>arborous mire(p<0.01); the average content of oxidizable Fe appeared that scrub mire> arborous mire>herb mire(p<0.05); the average content of residual Fe appeared that arborous mire>herb mire>scrub mire(p<0.01); both of the average contents of total Fe and reducible Fe showed no significant differences among the three wetland types(p>0.05).The content of total Fe decreased with the depth of arborous mire and scrub mire, and reduced firstly and increased afterward with the depth of herb mire. The contents of weak acid extractable Fe, reducible Fe and oxidizable Fe decreased with the depth of arborous mire and scrub mire, and increased firstly and reduced afterward with the depth of herb mire. The content of residual Fe reduced firstly and increased afterward with the depth of arborous mire and herb mire, and decreased with the depth of scrub mire.(2) The average content of total Cu appeared that herb mire>scrub mire>arborous mire(p<0.01); the average content of weak acid extractable Cu appeared that herb mire>scrub mire>arborous mire(p<0.05); the average content of reducible Cu appeared that scrub mire> herb mire>arborous mire(p<0.01); both of the average contents of oxidizable Cu and residual Cu showed no significant differences among the three wetland types(p>0.05).Among the three wetland types, the content of total Cu increased firstly and reduced afterward with the depth, the content of weak acid extractable Cu decreased with the depth, the contents of oxidizable Cu and residual Cu increased with the depth. The content of reducible Cu increased firstly and reduced afterward with the depth of arborous mire and decreased with the depth of scrub mire and herb mire.(3) Both of the average contents of weak acid extractable Zn and reducible Zn appeared that herb mire>scrub mire>arborous mire(p<0.01); the average content of residual Zn appeared that arborous mire>herb mire>scrub mire(p<0.01); both of the average contents of total Zn and oxidizable Zn showed no significant differences among the three wetland types(p>0.05).The content of total Zn appeared no significant differences with the depth of arborous mire and decreased with the depth of scrub mire and herb mire. The content of weak acid extractable Zn decreased with the depths of arborous mire and scrub mire,and increased firstly and reduced afterward with the depth of herb mire.Among the three wetland types, both of the contens of reducible Zn and oxidizable Zn decreased with the depth. The content of residual Zn increased with the depth of arborous mire, appeared no significant differences with the depth of herb mire, and increased firstly and reduced afterward with the depth of scrub mire.(4) After the disturbance of harvest, the average contents of total Fe(30-50cm),residual Fe (5-50 cm)increased 25.44% and 47.03% respectively; the average contents of total Fe(0-15 cm),reducible Fe(0-15 cm) and oxidizable Fe(0-50 cm) decreased 28.72%,30.73% and 72.30% respectively. After the disturbance of grazing, the average contents of total Fe(0-50 cm),oxidizable Fe(0-15 cm) and residual Fe(0-50 cm) increased 1.33 times,5.65 times and 2.66 times respectively; the average contents of weak acid extractable Fe(0-50 cm),reducible Fe(0-50 cm) and oxidizable Fe(15-50 cm) decreased 82.92%,49.03% and 56.85% respectively.After the disturbance of harvest, the average contents of total Cu(0-25 cm),weak acid extractable Cu(10-50 cm),reducible Cu(0-50 cm) and residual Cu(0-25 cm) increased 1.28 times,3.59 times,2.86 times and 2.41 times respectively; the average content of oxidizable Cu(15-50 cm) decreased 48.85%. After the disturbance of grazing, the average contents of total Cu(0-15 cm),reducible Cu(15-50 cm) and residual Cu(0-15 cm) increased 87.84%,1.26 times and 3.43 times respectively; the average contents of total Cu(25-50 cm),weak acid extractable Cu(0-15),oxidizable Cu(30-50 cm) and residual Cu(25-50 cm) decreased 40.35%,74.51%,66.21% and 65.80% respectively.After the disturbance of harvest, the average content of reducible Zn(0-50 cm) increased 97.47%; the average contents of total Zn(0-20 cm),oxidizable Zn(0-50 cm) and residual Zn(0-10 cm) decreased 29.66%,84.84% and 60.10% respectively. After the disturbance of grazing, the average contents of total Zn(0-50 cm),reducible Zn(20-50 cm),oxidizable Zn(0-50 cm) and residual Zn(0-50 cm) increased 60.85%,56.70%,2.35 times and 85.23% respectively; the average content of weak acid extractable Zn(0-50 cm) decreased 84.43%.(5) The average content of pH appeared that arborous mire>herb mire>scrub mire(p<0.01), which increased with the depth. The average content of organic matter appeared that scrub mire>arborous mire>herb mire(p<0.01), which decreased with the depth except the herb mire. The pH and organic matter are active factors in the study area.The correlation analysis of the speciation appeared that Fe>Zn>Cu.Most of the wetland types, the residual fraction is the most; the weak acid extractable fraction is the fewest. It is more scientific to study the pollution of soil by speciation of heavy metal.