Some Typical Heavy Metal Toxicity and Their Effects on Rice, Vegetables, Sorghum and Super Shrimp

Applying research method of the field assessment, investigating, compensating with method of examination pilot and the field experimenting, the authors have some following results: on the soil of rice fields, are influenced by wastewater from the southern Ho Chi Minh City (HCMC) have potential of contamination by heavy metal toxic. The concentration of Cd is 4.7 – 10.3 ppm, some places it is over than 2 – 3 times of the safe standard. The concentration of Cd is higher in 3 kinds of soil: the yellow-red allusion, the allusion-acid sulphate soil and the actual acid sulphate soil. When the concentration of Cd in soil is over than 25 ppm, effect on the agro-characteristic, on the field parts and disease the rice yield. However, with different rice varieties it has affected differences on the quality of the rice. The results of field, greenhouse and laboratory studies show that the accumulation and influence of heavy metals in the soil environment on accumulation in leaves, roots, and stems are different. Cd2+: 1.0 ppm has no effect on vegetables, but when Cd2+=100 ppm, limits vegetables. Meanwhile, with rice, Cd2+: 0.1ppm, has a stimulating effect on growth, but with Cd2+ 30ppm, it will have a strong effect. With Hg2+ at 0.1ppm stimulates cabbage, 10ppm stimulates rice, but Hg+ at 100ppm will be harmful to rice. The analysis data shows that, in the new alluvion soil of Go Cong District, Tien Giang Province and Grey soil in Cu Chi District, Ho Chi Minh City does not contain many heavy metals and it is safe. Besides, the southern paddy soils area of Ho Chi Minh City belong to the final downstream area of Sai Gon-Dong Nai river watershed before flowing into the sea. It was polluted by domestic, industrial waste waters and sediments of the urban waste water drainage canals from HCMC and neighboring provinces. This land has also been identified as potentially contaminated by Cadmium (Cd). The study Cd accumulated in parts of rice was very important for food safety controls and rice production development for environmental problem areas. The subject studied Cd accumulation of two rice cultivars included one traditional rice variety (Mahsuri) and one high-yielding rice variety (VND95-20). Pots of experimental soils were infected by Cd at nine different levels from 0 to 40 mg Cd kg-1 (cry weight). All pot experiments carried out in the field of southern HCMC. The result showed that Cd concentration of Cd in soils. At accumulated ability of rice plants depends on each part of rice, various varieties and experimental condition, distribution of Cd in roots, straws and brown rice as almost equivalent ratio 1000:100:1, and Cd accumulation of brown rice correlate positive as Cd concentration of soils. Cd accumulated ability in brown rice of Mahsuri traditional rice variety is much lower than VND95-20 high-yielding variety. In the other, influence of heavy metal toxicology on Shrimp shows that: Among the toxic factors affecting directly and indirectly to the organism living, heavy metal are noticeable. It have recently warned that the natural water sources poisoned by heavy metals is likely to cause a break of mass shrimp death in ponds in which shrimp is reared. This research to find out that, when the Water environment polluted by heavy metal agents will cause great harm to the growth of plants Penaeus monodon. Specifically: (1) The 50% lethal concentration (LC50-96h) of As3+ for Penaeus monodon variety is 51.29 g/l; Arsenic concentration limit according to Vietnamese standards in aquaculture water is 10.00 g/l. (2) The 50% lethal concentration (LC50-96h) of Cd2+ for Penaeus monodon seed is 23.39 g/l, cadmium concentration limit according to Vietnamese standards in aquaculture water is 5.00 g/l. (3)The 50% lethal concentration (LC50-96h) of Cu2+ for Penaeus monodon variety is 181.97 g/L ; The limit copper concentration of Vietnamese standards in aquaculture water is 10.00 g/l. (4) The 50% lethal concentration (LC50-96h) of Cr3+ for Penaeus monodon variety is 218.78 g/l; The limit chromium concentration of Vietnamese standards in aquaculture water is 100.00 g/l. (5)The 50% lethal concentration (LC50-96h) of Fe3+ for Penaeus monodon variety is 295.12 g/l; The limit iron concentration of Vietnamese standards in aquaculture water is 100.00 g/l. (6) The 50% lethal concentration (LC50-96h) of Hg+ for Penaeus monodon variety is 19.5 g/l; The limit mercury concentration Vietnamese standards in aquaculture water is 5.0 g/l. And, (7) The 50% lethal concentration (LC50-96h) of Pb2+ for Penaeus monodon variety is 190.55 g/l; The only limit of TCVN in aquaculture water is 10.00 g/l. (8) The 50% lethal concentration (LC50-96h) of Zn2+ for Penaeus monodon variety is 31.63 g/l; The concentration of zinc in Vietnam standard limit in aquaculture water is 10.00 g/l. At the same time, heavy metals, typically Fe2+, Fe3+, in the presence of Al3+, SO42- have strongly influenced rice and sorghum: 1-With rice: For Fe2+: in water, at 600 ppm: start to have a bad effect. But in soil, sometimes Fe2+ at about equal to or greater than 1,000ppm still does not cause significant damage to plants. Particularly with Al 3+ in solution = 135ppm begins to affect. In soil, (actually) = 800pm-900ppm to cause poisoning- Sorghum: lower toxicity than rice: at Al3+< 792ppm, Fe3+<2,500 ppm, SO42-<0.38%. 2-The amount of toxic accumulation in the plant. Depends heavily on the amount of toxic substances in the soil and the characteristics of the plant variety: Al3+ can be from 600-960 ppm in plants and 1-3 times higher in roots than in leaves. Fe is from 600-2,300 ppm in plants and in roots 2-3 times higher than in leaves. SO42- can accumulate from 0.1 to 1.5% in the roots twice as much as in the leaves. Toxicological correlation in plants: Al3+, Fe is proportional, tight. 3- Toxicity resistant varieties has characteristics: a-- Has a high ability to accumulate P, Al3+, Fe. b--The correlation of toxic accumulation in the soil, the positive correlation in the roots and less correlation in the leaves and stems, has the ability to retain toxic substances in the roots. c-- Ability to accumulate toxic substances in roots, than in leaves: much higher than varieties with poor tolerance to alum (Al3+ roots/stems: 4 times, Fe greater than 2.5 times) and 4- Peroxidase enzyme activity in functional leaves (active leaves) has the ability to resist the penetration of toxins in toxic tolerant varieties.