Copper and zinc content in soil and their accumulation in some agricultural products in Ha Mo Co operative, Dan Phuong district, Hanoi

Copper and zinc are also toxic to humans when high levels are ingested and an excess of copper and zinc interferes with plant growth. It is important to monitor copper and zinc content in soil to avoid marketing food products which contain dangerous amounts of these heavy metals. This article presents the results of a study done to determine the copper and zinc content of soil and four agricultural products grown in Tan Lap Co-operative, Dan Phuong District, Hanoi.
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Copper and zinc content in soil and their accumulation in some agricultural products in Ha Mo Co operative, Dan Phuong district, Hanoi JOURNAL OF SCIENCE OF HNUE Chemical and Biological Sci., 2012, Vol. 57, No. 8, pp. 66-71 This paper is available online at http://stdb.hnue.edu.vn COPPER AND ZINC CONTENT IN SOIL AND THEIR ACCUMULATION IN SOME AGRICULTURAL PRODUCTS IN HA MO CO-OPERATIVE, DAN PHUONG DISTRICT, HANOI Vu Van Hien Faculty of Biology, Hanoi National University of Education Abstract. Analytical results of Cu and Zn content in 20 soil and 20 pricipal agricultural products samples collected in Ha Mo Co-operative, Dan Phuong District, Hanoi, in 2009 and 2010 indicate that the average total Cu content in the examined soil is 32.12 mg/kg−1 and average available Cu content is 12.84 mg/kg−1 . The average total Zn content is 90.18 mg/kg−1 and average available Zn content is 13.01 mg/kg−1 . The Cu and Zn content in the soil samples is within permissible limits of heavy metal in agricultural soils by Vietnamese standards. The amount of Cu in rice grain, cabbage leaves and tomato and cucumber fruit was found to be 2.81 mg/kg−1 and respectively 0.75 mg/kg−1 , 1.13 mg/kg−1 and 0.79 mg/kg−1 fresh weight. The amount of Zn in rice grain, cabbage leaves and tomato and cucumber fruits was found to be 20.22 mg/kg−1 and respectively 1.29 mg/kg−1 , 3.60 mg/kg−1 and 1.81 mg/kg−1 fresh weight. The Cu and Zn content in these four agricultural products was found to be below the limit set by FAO/WHO. Keywords: Copper, zinc, soil, rice grain, cabbage, tomato, cucumber.1. Introduction In areas which experience a tropical climate with torrential rains and hightemperatures, agricultural soils have a low organic matter content due to increasedmineralization of organic matter after cultivation, tillage methods which physically disruptthe soil surface and erosion of top soil. Consequently, these soils benefit from anapplication of organic matter to improve their quality and fertility. Organic fertilizers, organic residues, municipal refuse, sewage sludge, animal wasteare organic materials which are commonly applied to improve the soil’s physical, chemicaland biochemical properties. However, repeated applications of organic residues can resultin an accumulation of heavy metals in the soil [7, 8].Received August 16, 2012. Accepted September 17, 2012.Contact Vu Van Hien, e-mail address: hienvv@hnue.edu.vn66 Copper and zinc content in soil and their accumulation in some agricultural products... Copper and zinc are two essential trace elements that are required for plant growth,functioning as an activator of enzymes such as carboxy peptidase, carbonic anhydrase,aldolase, phosphatase, xytocromoxydase and DNA polymerase. Copper and zinc are also toxic to humans when high levels are ingested and anexcess of copper and zinc interferes with plant growth. It is important to monitor copperand zinc content in soil to avoid marketing food products which contain dangerousamounts of these heavy metals [10]. This article presents the results of a study done to determine the copper and zinccontent of soil and four agricultural products grown in Tan Lap Co-operative, Dan PhuongDistrict, Hanoi.2. Content2.1. Materials and methods * Sampling and preparation of soil Soil samples were obtained from four fields, each used to grow exclusively rice,cabbage, tomatoes and cucumbers. The soil samples were taken at five randomly selectedsites within each field. Soil samples (0 - 20 cm in depth) were taken using an auger 5 cmin diameter, placed in polyethylene bags, packed in a insulated box and transported to thelaboratory where they were air dried, ground and passed through a 2 mm mesh sieve tobe used for analyses. Five agricultural product samples were collected from each field. * Analytical methods [5] Particle size was determined using the pipette method. Organic carbon in the soilwas determined using the Walkley - Black method. This involved a wet combustion of theorganic matter with a mixture of potassium dichromate and sulphuric acid. After reactionthe residual dichromate was titrated against ferrous sulphate with barium diphenylaminesulphonate. Soil pH was potentiometrically measured in a water:soil solution ratio of 1:2.5using a glass electrode. Total nitrogen was measured using the Kjeldalh method. The soil samples weredigested in sulphuric acid and organic nitrogen was converted to ammonium sulphate. Thesolution was then made alkaline and NH3 distilled. The evolved ammonia was trapped inboric acid and titrated with standard acid. Total phosphorus was determined using thespectrophotometer me ...