The Speciation Of Copper In Orchard Soils And Its Biological Effects

Copper distribution, and speciation in orchard soils of east and middle of Shandong was studied in this paper. The correlation of copper speciation with copper biological effects was also studied by both field investigation and pot experiments, with apple, strawberry and ryegrass as the testing materials. The items studied were content and distribution of copper in soil profile and copper speciation, copper distribution in different tissues of apple trees, in the root cells, copper toxicity to plants, copper effects on the ultrastructure of roots, and plant responses to copper toxicity. The copper accumulating status in orchard soil, its chemical activities and their relations with copper bioavailability were studied deeply and the key results are as following:l.The soil copper increased with the orchard age and the annual increase was 2.5-9.0 mg/kg. The differences between orchards with different ages were significant except between orchards with ages of 20 and 10 year. The copper was unevenly distributed vertically in the soil profile, decreasing from top to deeper layers and the difference was significant. Some difference was also noticed with the horizontal distribution, with areas far away from the tree having a lower level, but it was not significant.2. The Shuman fractions bounded with organic matter, Mn oxide and arnorphors Fe oxide and the Tessier fractions bounded with carbonate, Fe, Mn oxide and organic matter were much higher than other forms. Fractions extracted with the two methods all significantly correlated with each other and with the total FTNOa extracted copper. All the fractions also decreased from top to deeper layers, with fractions bounded with organic matter, Mn oxide and amorphous Fe oxide, carbonate, Fe.Mn oxide and organic matter decreasing more rapidly. The Shuman fractions bounded with organic matter, Mn oxide and amorphous Fe oxide in 10-20cm and 20-3 Ocm was 17-30% and 4-15% that of the top layer, while for the other two fractions only 89-92% and 69-86%. The Tessier fractions of carbonate, Fe.Mn oxide and organic matter bounded copper in 10-20cm and 20-30cm was 22-14% and 13-6% that of the top layer respectively, 95-32% and 78-18% for the other two forms. The fraction content increased with the total copper and the content in adjacent layers correlated significantly with each other.3.The water soluble copper was low in the soil, only 1.2-2.8% of the total copper in soil with pH of 6.0. DOCCu was 0.11-0.28% of the total copper and 8-10% of the soluble copper and the figure was 0.0003-0.018% and 0.01-1.4% for the ionic fraction. With the decrease of soil pH all forms increased, with the soluble form 3.1-8.3% of the total copper, DOCCu 0.1-0.3% of the total and 1-9% of soluble and ionic Cu 0.007-0.072% of total and 0.2-8.7% of the soluble. All the forms had significant correlations with the total copper.4.The soil adsorption of copper increased with the equilibrium copper concentration in the solution but with a max value, whose properties could be simulated well with the Frundlich, Langmiur, Temkin and Michaclis Meten models. The adsorption properties varied with soil types and soil environmental conditions, higher for cinnamon soil compared with brown soil and decreasing with decrease in pH and increase in ionic strength and high valence cations.5. There were significant differences between brown soil and cinnamon soil in all fractions except for the exchangeable form, with cinnamon soil having higher contents. With the application of organic materials, T2,S3 fractions decreased significantly, while the Tl,T4,T5,Sl,S2fractions increased significantly, with the increase in organically bounded form more significant. With the decrease in soil pH, the water soluble copper and ionic copper all increased significantly, while DOC decreased and no difference was noticed in DOCCu content. Nitrogen had no significant effects on soil copper speciation and ryegrass absorption.6. The absorption of fruit trees could be simulated with the Frundlich, Langmiur,Temkin and Michacli...