Evaluating Impact of Micro and Toxic Elements on Soil and Natural and Cultivated Plants in Rabigh Industrial City

The present work was carried out to investigate the impact of micro and toxic elements in soil and water quality and growth of natural and some cultivated plants. Soil, water and plant samples were collected from three sites, Kiliya village, Rabigh city and Masturah village in Rabigh Governorate. All analysis were carried out in the lab of soil science, Department of Arid Land Agriculture, King Abdulaziz University. The results revealed significant differences between the three sites concerning accumulation of micro and toxic elements in soil, water and plants. Significant differences were observed between analyzed soil, water and plant samples in Fe, Zn, Mn, Cd, Ni, Ph, Cr contents. The concentrations of Fe, Zn, Mn, Cd, Ni, Ph, Cr in plants, and soil samples were below the standards WHO/ FAO 2007 for plant and EU.(2002) for soil. The concentrations of Fe, Zn, Mn, Cd, Ni, Ph, Cr in well water below the standards of (MEWA 2005) and FAO (1985), except water electrical conductivity (EC) and chromium (Cr) contents. The results illustrated that natural plants were characterized by higher concentrations of micro and toxic elements in Rabigh city experimental site than Musturah site and Keliya site. The experimental site of Kiliya showed the highest content of micro elements (Fe, Zn, Mn, Cu, Cd, Ni, Pb and Cr) with averages (271,2, 1.47) , 10,67, 1,17, 0.023, 1,55, 4,92, 2.09 mg / L) as compared to experimental sites of Rabigh city and Msturah. Regarding water and soil Ph the results showed no significant differences between the three experimental sites. The electric conductivity (EC) of water and soil was higher in Masturah village site as compared to experimental sites of Rabigh city and Kiliya village. The highest concentrations of micro and toxic elements were observed for water, soil and plant samples of Rabigh city as compared to Mastura village and the village of Kiliya. The pollution levels at Rabigh city were lower than local and international standards.


I. INTRODUCTION
Pollution affects the atmosphere, vegetation and soil, which is a serious problem in many regions of the world. Pollution is particularly problematic in the vicinity of sources of pollution. The effect of pollution can be physical on the plant through the deposition of particles on the surface of leaves with a detrimental effect on the growth of plants and changes in the activities of stomata (opening and closing mechanisms). The effect can be chemically so by nutrient uptake of the soil and modifications in the ways of recycling the nutrients needed for the plant and their availability for absorption by 2 plants. Industrial cities are normally subjected to pollution as regards its water sources, its soil and its plants. This is because different types of factories and different types of industrial activities represent the main sources of pollution with heavy and toxic metals. On the other hand, many studies have studied the physical effect and chemical effect of pollution on plants, particularly with regard to the accumulation of plant elements (Santelmann and Gorham 1988) and the effect of pollution on the physiological activities of plants (Roser et al., 1992;Hong-Xia et al., 2006) ; Mandre et al. (2008). Most of these studies have shown a decrease in photosynthesis, changes in pigments and plant growth due to exposure of plants to pollution (Brandt and Rhoades 1973;Arianoutsou et al., 1993; Mandre and Tuulmets 1997; Lepedus et al., 2003). For example, "cement dust" in particular, may release calcium hydroxide, which can dissolve or decompose leaf proteins (Czaja 1960(Czaja , 1961(Czaja , 1962Guderian 1986). Hemlata (1991) observed that the activities of three enzymes in plants increased with the increased concentration of cement dust. Soil dust contamination may also lead to a significant reduction in soil microbial biomass (Semhi et al 2009). The composition and concentration of toxic and microbial elements in the plant is directly related to the surrounding environmental conditions of temperature, precipitation and the like,and as the season is hot, weathering and rock decomposition (Nagajyoti et al., 2010, . Alghabari et al., 2015. In the summer season, dust is high in the wind, and this dust is saturated with heavy metals and dust from desert areas contains high levels of iron and fewer manganese, zinc, chromium, nickel and lead (Ross, 1994). A field study was conducted near Jeddah Industrial Zone to assess the potential for accumulation of air pollutants in Ziziphus trees, and the concentration of iron, copper, zinc, and manganese increased by 89, 37, 60 and 93% respectively, compared to trees away from this site (El-Nakhlawi, et al. 2014). The present work focused on evaluating impacts of heavy and toxic elements on soil, water and plants (naturally grown and cultivated plants) at three different sites of Rabigh governorate. .

Experimental sites:
In order to evaluate the pollution level with micro and toxic elements in soil, water and plants (naturally grown and cultivated plants), three different sites of the industrial city at Rabigh Governorate called : Kiliya villages, Rabigh city and Masturah vallage were selected (Fig 1). The longitudes and maps of the three sites were presents in Table (1  device. These elements were estimated after digestion with pyrochloric acid and nitric (Shelton and Harper, 1941). These elements were estimated using the Atomic Absorption Spectro Photometer model 5000 perkin Elmer.

Analysis of plant samples:
Samples of naturally grown and cultivated plants were used. The concentrations of Iron (Fe), Zinc (Zn), Manganese (Mn), Copper (Cu), Lead (Pb), Chromium (Cr), cadmium (Cd) and nickel (Ni) were determined using an atomic absorption device. These elements were estimated after digestion with pyrochloric acid and nitric (Shelton and Harper, 1941). These elements were estimated using the Atomic Absorption Spectro Photometer model 5000 perkin Elmer.

Analysis of Water Samples :
Various chemical analyzes were carried out according to the standard methods used by the American Public Health Organization for Water Analysis (APHA, 1998). The conductivity meter was used to measure the conductivity of Md / cm and the device was calibrated using a standard solution of potassium chloride (KCl). The pH was measured by a glass electrode pH meter and the device was calibrated using Buffer Solutions. The concentrations of Iron (Fe), Zinc (Zn), Manganese (Mn), Copper (Cu), Lead (Pb), Chromium (Cr), cadmium (Cd) and nickel (Ni) were determined using an atomic absorption device. These elements were estimated after digestion with pyrochloric acid and nitric (Shelton and Harper, 1941). These elements were estimated using the Atomic Absorption Spectro Photometer model 5000 perkin Elmer. Statistical Analysis: Statistical analyzes of the results measured in the study were carried out by calculating the analysis of variance for each of the measured traits in the soil, plant and water. The statistical comparisons of the mean of the mean parameters were then carried out by the LSD test at a significant level of 0.05 according to El-Nakhlawy (2010) Statistical Analysis SAS(SAS, 2010).

III. RESULTS: Effect of Experimental site on electric conductivity (EC) and acidity (pH) of irrigation water and soil:
The results showed significant differences between the three experimental sites as regards EC of irrigation water and soil samples, while the results were not significant wit regard soil pH    (Table 5). Table (   The averages followed by the same letters did not differ significantly from each other according to the Lsd test at a significant level of 0.05 *

The effect of the Experimental sites on the contents of micro and toxic elements in the wells irrigation water:
The analysis of variance data in Table (7) showed significant differences (P≤ 0.01) between the three different water sites in Rabigh Governorate with respect to their content of the studied micro and toxic elements (Zn, Cu, Pb, Ni, Cr). There were no significant differences between sites for the contents of cadmium, manganese and iron (Cd, Mn, Fe). Data of means of micro and toxic elements content in water in the three sites (Table 8)     The averages followed by the same letters did not differ significantly from each other according to the Lsd test at a significant level of 0.05 *

Effect of experimental sites on soil content of micro and toxic elements
The data for analysis of variance in table (9) indicate that there are high significant differences (P≤ 0.01) between the sites in the three different regions of Rabigh Governorate with respect to their soil composition of the studied micro and toxic elements (Zn, Cu, Pb, Ni, Cr Cd, Mn, Fe) ,). The data of averages of soil content of micro and toxic elements in the three sites (Table 10)   The averages followed by the same letters did not differ significantly from each other according to the Lsd test at a significant level of 0.05 * IV. DISCUSSION Heavy metals means any chemical element with relatively high density or toxicity at low concentrations. The danger is that if it enters the body does not go out and accumulate over time, unlike other chemicals. The results of the study showed a significant variation between the plants developing in those sites with regard to their contents of micro and toxic Pb, Cr) than those growing in Masturah city, suggesting that these plants are exposed to a higher pollution rate because Rabigh is an industrialized city and Masturah is a city with no factories. The results of these tests indicate that the plants that grow at Rabigh city contain the highest rates of micro and toxic elements compared to those plants growing in the city of Mastura and Kiliya villages and their contents of these elements were lower. This is because the smoke and dust of factories in Rabigh city are airborne and are placed on the leaves of growing plants near the city and are absorbed into the plant, as well as through the roots that absorb these elements falling on the soil. In general, it can not be said that these plants are accumulater plants for micro and toxic elements because their contents are less than international and local standards. El-Nakhlawy et al., (2015) studied the effect of three industrial activities on concentrations of toxic metals (Pb, Ni, Cr, Cd) and micro elements (Fe, Cu, Zn and Mn) in Azadirachta indica leaves and found that the highest concentrations of Pb, Ni, Cr, Cd, Fe, Cu, Zn, Mn , were in the tree leaves located near the areas of paint factories, chemical and paper industries and in the areas of mineralization, plastic and building materials compared to the trees growing away from these sites. There are significant differences between plants in their ability to accumulate heavy and toxic elements within their tissues. The plants absorb heavy and poisonous elements not only by leaves but also by roots. The roots absorb these elements if the soil is exposed to pollution by any of the different pollution methods, including the accumulation of these elements after their transport by air from the surrounding factories and industries Minerals, and mines, or through the tainted fog of oceans, acid rain, etc. (Brooks, 1998, Zhao, et al., 2000, and Whiting et al., 2002, and McGrath et al., 2002 and from roots elements move to stem then to leaves.

Micro and toxic elements in the irrigation water of wells in Rabigh Governorate:
The micro and toxic elements contents of the wells water used for irrigation varied in the three regions. That the water of Rabigh contained the highest concentrations of iron (Fe), zinc (Zn), manganese (Mn), copper (Cu) and lead (Pb) compared to the content of water of both Masturah city and Kiliya villages. The highest water content of nickel(Ni) and chromium (Cr) was in Masturah water (0,075 and 0,260 mg / L respectively) and the highest metal content of water of the villages of Kiliya site was Pb, shared with Rabigh. All elements concentrations in these three sites well water were below the standards of the World Food and Agriculture Organization (FAO,1985) and the Ministry of Water and Agriculture (MEWA,2005) of Saudi Arabia except Fe in the water of Rabigh wells, Cd and Cr in the wells water at all sites. The increase in micro and toxic elements in well water of the city of Rabigh compared to the content of these elements in wells water of of Masturah city is because the city of Rabigh is an industrial city with various industries as well as densely populated and traffic density is high compared to the city of Masturah and Kiliya, and the sewage from the factories as well as domestic wastewater of this city permeates and seeps into the soil around the city and dips and reaches the groundwater which is the source of this water. In a similar study carried out by Oyekul and Eludoyin (2010) in urban areas of Nigeria, it was found that their groundwater contains high levels of micro and toxic elements, especially Fe Cu, Pb, Co) above WHO standards although this groundwater is 2 km from the landfill. The results of this study differ from those found by (Zaki, 2012) who found that most well water contaminated with micro and toxic elements (Fe, Cu, Zu, AL, Mn, Ba Ni, Pl, Cd, Cr, AG, Mo, Co, Be, V , Av, Sb, Ti, U) are the wells of the Masturah area followed by Rabigh region, then the wells water of Kiliya region, and therefore not suitable for drinking or use for agricultural purposes, but all these wells are located in valleys flowing in the waters of the Red Sea in the western region of the Kingdom, and these valleys may also carry sewage water. The results showed that salinity of well water used in irrigation in these three sites is below the standard of FAO (1985), but less than the standard set by Saudi Ministry of Environment, Water and Agriculture (MEWA, 2005). According to these results the well waters in the three sites can safely be used for irrigation.