Abstract—A greenhouse experiment was carried out to determine heavy metal loading capacity, metal mobility, bioavailability, metal-bound forms and pollution effects in the greenhouse soil and uptake of metals by tomato plant following three cultivation years of sewage sludge (SS) application. The effects of SS application on soil metals were compared with the same amount of manure application. Additional to routine soil analysis, several environmental pollution indexes were used to assess the size of possible environmental pollution risks. Successive applications of SS increased both total and available (DTPA, EDTA and HCL extractable) concentrations of Zn, Cu, Ni, Pb and Cd in the greenhouse soil when compared with the manure application. However, the concentration of heavy metals in soil treated with SS were found below the referenced limits. Correlation values between soil metals and plant metal contents in SS and manure applications were considerebly recorded higher in EDTA- extractable metals. Relative increases of total and bioavailable metal concentration were recorded higher in SS application than in manure application, and more than that, relative increases of bioavailable metals in SS application were more marked than those of manure application.The most mobile metal fraction in control soil was detected in Zn and the most immobile metal fractions were detected in Ni. Manure and SS incorporation into the greenhouse soil significantly increased the sum of metal concentrations in the mobile fractions. Manure and SS applications increased mobility factor values for all metals. SS application to greenhouse soil caused higher mobility factor values for all metals with the exception of Ni. Lead was detected as the most mobile metal in SS application. ‘Single-factor pollution index’ and ‘composite pollution coefficient’ of heavy metals in grennhouse soil were not exceeded critical value by the applications. Thus, all of soil samples may be considered as less contaminated by applications and may be acceptable clean. The average ‘single-ecological risk index’ and ‘potential-ecological risk index’ values for heavy metals were found below the limits that indicate all metals posed low risk to surrounding ecosystem in short or medium-term. SS application increased ‘risk assassion code’ values of metals except Ni and, SS has a medium size risk to ecosystem due to their higher toxicity and percentage in the exchangeable and carbonate fraction. Heavy metal concentrations of tomato leaves in SS application were higher than that of manure application, and Pb and Cd contents of tomato fruits in SS application were excessed the limit values for edible vegetables. But no phytotoxicity or no phytotoxic levels of metals were recorded by the application. SS application led to greater transfers of Ni, Pb and Cd metals in plant. However, ‘target hazard quato’ and ‘hazard index’ values representing health risks of tomato fruit in all applications were found below the critical value. Manuscript received October 6, 2016. Bülent Topcuoğlu is with the Akdeniz University, Vocational School of Technical Sciences, Antalya TURKEY. Index Terms— Sewage sludge; Metals; Mobility, Bioavailability; Pollution risks I. INTRODUCTION Sewage sludge compost contain valuable plant nutrients and organic matter that can improve soil fertility. The phytonutritive capacity of sludge has often been demonstrated to be analogous to that of manure [1]. However, there is a rising concern over SS often contains potentially toxic elements,that can cause soil contamination, phytotoxicity and undesirable residues in plant and animal products [2]. As a matter of fact, pollution problems may arise if toxic metals are mobilized into the soil solution and are either taken up by plants or transported in drainage waters. Risk for human health may then occur through consumption of such crops and intake of contaminated waters. This is particularly the case for heavy metals in SS due to their ubiquity and toxicity. Nevertheless, the main risks associated with the use of organic wastes in agriculture cannot be evaluated directly through determination of the total contents of metals in those materials, since the chemical or physicochemical forms of metals strongly affect their mobility, reactivity and availability to plants [3]. In the long term, the use of SS can also cause a significant accumulation of Zn, Cu, Pb, Ni and Cd in the soil and plants [4]. The maximum permissible concentrations of heavy metals in surface soils amended with sewage sludge or SS are normally based on total concentration, although it is the bioavailable metal fraction that posses environmental concern [5]. Nevertheless, these criteria are insufficient since mobility, environmental diffusion and bioavailability largely depend on soil physico-chemical characteristics and, likewise, on trace metal chemical forms [6]. From an environmental point of view, the evaluation and forecast of food contamination is related to the bioavailable fraction of heavy metals in soil. Information on the fertilizing value of SS and their effects on the heavy metal loading potentials, metal mobility of greenhouse soil and environmental effects are scarce. The aim of this study was to determine successive applications of SS on the total and bioavailable contents of Zn, Cu, Ni, Pb and Cd, metal mobility in the greenhouse soil, and heavy metal accumulation in tomato plant and to assess environmental pollution risks. II. MATERIAL AND METHODS The experiment was conducted from 2011 to 2013 on the greenhouse representative of the major greenhouse vegetable growing area of Turkey Antalya Aksu. The site studied is The Effect of Long-Term Sludge Applications on Soil Metal Characteristics and Pollution Risks Bülent Topcuoğlu International Conference on Advances in Science, Engineering, Technology and Natural Resources (ICASETNR-16) Nov. 24-25, 2016 Parys (South Africa) http://doi.org/10.15242/IAE.IAE1116467 193