a survey of heavy metals accumulation in foraging plants irrigated by sewage in south of tehran, case study: "maize & alfalfa

alfalfa and maize are important agricultural plants for animal consumption. in this survey, accumulation quantity of heavy metals (fe,zn,mn,cd,pb,ni,cr) in plants irrigated by sewage and well water were compared statistically together and with normal or standard(permeable) limits in plants or foraging, during 2005. the results were as following 1-maize: the value of accumulation in maize irrigated by sewage is nearly 1.5 times of the maize crop irrigated by well water. apart from mn and zn, the accumulated quantities of heavy metal were more than normal and standard limits of maize crop. in the corn and maize grains ni, cr, pb, and zn were less than permeable limits and mn and cd were more than permeable limits. in the maize crop irrigated by sewage cadmium accumulation in upper organs at dehkhair & salehabad and in the seed and corn at the all of the three regions and lead accumulation in the upper organ in salehabad and talebabad, and in the root in dehkhair & salehabad and iron in the root at the all of the regions were more than permeable foraging limits. transition coefficients to upper maize organs at the three regions were more than standard limits, and pb had the maximum value.2- alfalfa: accumulated amounts of heavy metals in the first mowing were more than those amounts in the second mowing totally. accumulated amounts (apart from ni,cr and pb in talebabad and pb and zn in dehkhair ) in the first harvest of alfalfa irrigated by sewage were more than of these amounts in alfalfa irrigated by the well water. accumulated limits of fe in salehabad and dehkhair, cd in dehkhair, cr and pb in the all of these regions at the first mowing were more than permeable limits of plant growth. the heavy metals accumulation reduced in the second mowing but the amounts of cd and pb in dehkhair and pb in the all of the surveyed regions were more than permeable limits of plant growth. in the alfalfa irrigated by sewage, cd accumulations in all of the surveyed regions were more than permeable foraging limits. in survey aboat amounts of transition coefficient pb had minimum amount of transition from soil to upper organs. heavy metal transition, especially for cd and fe, reduced in the second mowing.