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Heavy metal pollution significantly reduces the quality of the environment and threatens human health especially in industrial cities. This study investigated toxic metals concentrations, pollution levels and human health risks assessment of urban soils in Yazd city, as an industrial city in center of Iran. Soil surface samples (0-10 cm) were collected from 30 points in the area for geochemical analysis. The concentrations of heavy metals were determined using an inductively coupled plasma mass spectrometry (ICP-MS).The values of the mean concentrations of toxic metals (mg kg-1) in the urban soils decrease in the order of Zn (83.9) > Pb (34.5) > Cr (32.6) > Cu (23.5) > Ni (23.4) > As (5.86) > Co (4.86) > Cd (0.27). The mean concentration of Zn, Pb, As and Cd elements were higher than the background and the crust values. A pollution assessment by Geo-accumulation Index (I geo), Pollution Index (PI), Contamination Degree (C D),

Urban soil pollution with heavy metals is one of the environmental problems in recent years, especially in industrial cities. The aim of this study is to evaluate the role of geogenic and anthropogenic sources in the urban soil pollution in Yazd, Iran. For this purpose, 30 top-soil (0–10 cm) samples from Yazd within an area of 136.37 Km2 and population of nearly 656 thousand are collected, and the concentration of heavy elements is measured. To evaluate factors affecting the concentration of heavy elements in urban soils and determine their possible sources, Multivariate statistical analysis, including correlation coefficient, principal components analysis (PCA) and cluster analysis (CA) are performed. Enrichment Factor (EF), Geo-accumulation index (Igeo), and Modified potential ecological Risk Index (MRI) are used to assess the level and extension of contamination. Results of this study suggest that As, Cd, Pb and Zn are affected by anthropogenic source, while the concentrations of Fe, Mn, Ni, Cr, Co, Cu and Cs have come from mostly natural geologic sources. As, Cd and Pb are considerably enriched in the area, provided moderately enriched for the elements Mn, Zn and Cu. However, the other heavy elements show minimal enrichment. Igeo reveal that Co, Cr, Cs, Cu, Fe, Mn, Zn and Ni with negative values are unpolluted, Pb posed unpolluted to moderately polluted, and As and Cd represent high polluted. Based on the results of the ecological risk factor, the heavy metals of Mn, Ni, Cr, Zn and Cu have a low ecological risk level. More specifically, we find that Pb shows a moderated ecological risk in 39% of the urban soil in the studied area. As and Cd with respectively 100 and 72% contribution have considerable and very high ecological risk. According to the results of MRI, the area is in a very high ecological risk level, and appropriate management practice is essential to reduce the pollution of heavy elements in this area.

Effect of PRD (partial rootzone drying) on yield and yield components of canola (Brassica napus L.) was investigated in greenhouse conditions. The treatments were: T 1 , full watering of both sides of roots; T 2 , alternate irrigation on both sides; T 3 , half of irrigation water in T 1 was given to one side; T 4 , same as T 3 but without plate; T 5 , same as T 2 but without plate. In T 1 , T 2 , and T 3 treatments, the boxes were evenly separated into two compartments with thin plates. The results showed that grain yield of T 1 to T 5 treatments was 18.11, 16.38, 12.44, 9.29, and 8.66 g plant -1 . T 2 treatment increased plant height by 46.9% and 1000-seed weight by 17.8%, but reduced lateral branches by 16.7% and number of pods by 24%, over T 1 treatment. T 2 treatment was the most efficient (irrigation water use efficiency = 0.679 kg m -3 ) and treatment T 5 was the least efficient (0.359 kg m -3 ). The difference between irrigation water use efficiency (IWUE) of T 2 and T 5 , and T 3 and T 4 treatments, was significant (p \ 0.05). Therefore, halving the amount of applied irrigation water and applying this water alternatively on both sides of the root zone will produce the highest IWUE. This study showed that PRD irrigation management has high influence on rooting system of canola. This phenomenon could affect nutrients uptake and consequently all aspects of plant growth and development.

This work was carried out in collaboration between all authors. The author SSG designed the study, conducted literature review, performed the statistical analysis, wrote the protocol, and wrote the first draft of the manuscript. Authors HA, YMC and JG managed the analyses of the study, read, edit, and approved the final manuscript.