Interrelationships of pollution load index, transfer factor, and concentration factor under the effect of sludge.

A greenhouse experiment was conducted during 2010-2011. A complete randomized blocks design was used including seven treatment levels of sludge(tons per hectare), i.e., 0, 6, 12, 18, 24, 30, and "30+ treated wastewater", in four replications. Lettuce (Lactuca sativa L var longifolia) was chosen as a test plant. The purpose of the experiment was to study the relationships between soil Pollution Load Index, heavy metal transfer factor, and concentration factor and to determine optimum concentration factor values. The following were found: several mathematical relationships were established between the above parameters that could be used for the study of heavy metal accumulation in soils and plants under the effect of the applied sludge. They can be also used for the calculation of one of the above parameters as a function of the others. Based on the experimental data, the optimum concentration factor for several heavy metals were determined by multiple linear regression analysis, expressing the concentration factor as a function of the maximum dry lettuce matter yield, and of optimum/minimum heavy metal content of plant dry matter. The mean value of the calculated concentration factor obtained for each separate metal was: Zn, 2.93; Cd, 0.39; Co, 1.47; and Ni, 0.52.

Soil pollution under the effect of treated municipal wastewater.

Soil heavy metal pollution due to wastewater reuse was assessed by means of the concentration factor (CF) and/or pollution load index (PLI).In this respect, a greenhouse pot experiment was conducted, using a completely randomized block design, including five treatments of treated municipal wastewater (0%, 25%, 50%, 75%, and 100%), in four replications. Brassica oleracea var. Capitata was used as a test crop. The optimum CFs were expressed as a function of maximum dry matter of cabbage plant parts yield, and the values obtained per plant part were as follows: stems-Zn-CF 2.96, Co-CF 0.85, Ni-CF 0.92; whole plant-Cu-CF 3.90, Ni-CF 0.87, and Pb-CF 11.52; and leaves-Pb-CF 11.78. The PLI was calculated as the geometric mean of the CF of each metal, and was related to the maximum dry mater yield of cabbage stems and heads. The optimum values found were: stems PLI 1.99-2.55 and heads 2.25.