Irrigation copper

Bartley, T.R. 1967. Progress report on evaluation of copper for aquatic weed control and herbicide residues on irrigation systems. U.S. Bur. Reclam. Rep. No. WC-32. 58 pp. 

As an example, we will consider the formation of nitrate biogeochemical provinces in the Desert region of biosphere in Zerafshan river watershed that occupies most of the Samarkand administrative region of Uzbekistan. This is an agricultural area with irrigation production of cotton and some other crops like cereals, vegetables and fruits. The natural biogeochemical provinces are characterized by iodine, copper, and zinc deficiency and lithium excess. 

The content of mobile copper form (extracted by acetate-ammonium buffer with pH 4.8) in all soil types varies from 0.05 to 0.41 ppm, being less than 1% from total content. However, it increases sharply in polluted soils of orchards and vineyards until 2.4-12.5 ppm. Some increase occurs also in rice soils, up to 0.26-0.94 ppm. It is clear that this increase is connected with application of irrigation and fungicides. The comparison of Cu content with maximum permissible levels for soils (55 ppm for total and 5 ppm for mobile forms) allowed the researchers to conclude that about 5% of agroecosystem soils are polluted by copper. 

Deposits were formed in dilute cupric sulfate to avoid rapid attak of the substrate by cupric ion. The basic solution was 0.01 M CuSO j 1.0 M H SO. O.lmM or 2.0 mM chloride as HCl was added to two of the solutions. Two solutions without added chloride were prepared, one with reagent grade materials and another with Aesar Puratronic cupric sulfate and sulfuric acid. All of the solutions were made with demineralized water which was doubly distilled and passed through a Nanopivre II filtration system. Copper single crystal disks of orientation 100 and 110 were obtained from Monocrystals Incorporated. They were polished with 0.05 nm alumina on an irrigated wheel and then electropolished in orthophosphoric acid. After polishing, the samples were rinsed sequentially in 10 % nitric acid, 10 % sulfuric acid and water. 

The total concentrations of copper, cadmium and lead in the soil sample used in the study were measured as 125.8, 2.24 and 139.7 mg kg respectively (the mean of three measurements with corresponding standard deviations of 6.15, 0.18 and 10.02 mg kg respectively). The background values of the three metals in uncontaminated soil (same series) in the area were only 29.0 9.0, 0.090 0.023 and 21.0 5.33 mg kg on average, respectively (China Environmental Monitoring Center, 1990). Accordingly, the sample was considered to represent a typical heavy-metal-contaminated soil in the wastewater-irrigated area. 

Fig. 2. Distribution of the five fractions of copper, cadmium and lead in the soil from a waste-water irrigated area in Tianjin.

Eyes. Irrigate copiously and attempt to remove all copper from the surface perform a careful slit-lamp exam and refer the case to an ophthalmologist urgently if any residual material remains. 

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