Report on the levels of cadmium, lead, and mercury in imported rice grain samples

In an attempt to know whether highly consumed food might contribute to metal exposure, we analyzed cadmium, lead, and mercury in 27 rice grain samples commonly consumed in Saudi Arabia by atomic absorption spectrometry after acid digestion. The mean concentrations and ranges of cadmium, lead, and mercury in tested rice samples were 20.261 (range <DL-178.026 μg/kg), 134.819 (range 23.1–1529.0 μg/kg), and 3.186 (range <DL-43.573 μg/kg), respectively. The results showed high concentrations of metals and in some cases exceeded the Provisional Tolerance Weekly Intake (PTWI) recommended by FAO/WHO. It was also noted that different rice grain samples had varying concentrations of these metals. Because the bulk of literature warns against the cumulative effects of prolonged heavy metal exposure, regular consumption of rice by local populations might pose potential health problems.     

Assessment of heavy metal contamination of rice grains (Oryza sativa) and soil from Ada field,Enugu, Nigeria: Estimating the human healtrisk

The concentrations of heavy metals in rice grains and soils from Ada cultivated fields were investigated. Rice and soil samples were digested and the heavy metal concentrations determined using atomic absorption spectrophotometer. The results showed the following concentrations of metals (mg/kg): soil—Pb (4.64 ± 2.18), Cd (0.83 ± 0.83), Zn (20.26 ± 18.60), Mn (68.90 ± 19.91), Ni (3.46 ± 2.42), and Cr (21.41 ± 14.6); rice—Pb (3.99 ± 1.43), Cd (1.10 ± 0.53), Zn (65.37 ± 58.09), Mn (37.81 ± 5.82), Ni (3.12 ± 1.49), and Cr (10.87 ± 6.47). The Canadian, Nigerian and Chinese maximum allowable concentration for cadmium in soil were exceeded by 15%, 30%, and 85% of the soil samples, respectively. Heavy metals in all the rice samples evaluated were found to be above the World Health Organization (WHO) maximum permissible limit for lead, cadmium, and chromium. Strong positive and significant correlations were observed between some metal pairs in soil and rice indicating the similarity in origin. The estimated daily intakes of Pb and Cd from rice grown on the fields were higher than the safety levels established by WHO and the Joint FAO/WHO Expert Committee Food Additive, respectively. Hazard quotients and total hazard index for Pb and Cd were greater than 1. This indicates that consumption of rice from these fields will likely induce adverse health effects arising largely from Pb and Cd exposure.     

Heavy metal concentrations in the breast milk of Saudi women

Lead, cadmium, and mercury concentrations were determined in breast milk of Saudi lactating mothers from Riyadh and Al-Ehssa regions in Saudi Arabia who were not occupationally exposed. The mean levels for cadmium, lead, and mercury were 1.732 μg/L, 31.671 μg/L, and 3.100 μg/L, respectively. In contrast to mercury, mothers living in the Al-Ehssa region had significantly higher cadmium and lead concentrations in their breast milk than those in the Riyadh region. The estimated weekly intakes of cadmium, lead, and mercury of breast-fed infants in this study were in some cases higher than the Provisional Tolerance Weekly Intake (PTWI) recommended by FAO/WHO, which pose a threat to their health. This necessitates the urgent need to undertake a comprehensive study to determine the sources of exposure to these heavy metals. Breast-feeding is of great benefical value for the infant’s development; therefore, efforts should be made to prevent its contamination with environmental pollutants.     

Molecular characterization of Escherichia coli O157:H7 recovered from meat and meat products relevant to human health in Riyadh,Saudi Arabia

Raw meat can harbor pathogenic bacteria, potentially harmful to humans such as Escherichia coli O157:H7 causing diarrhea and hemolytic-uremic syndrome (HS). Therefore, the current study was carried out to evaluate the prevalence and the molecular detection characterization of E. coli serotype O157:H7 recovered from raw meat and meat products collected from Saudi Arabia. During the period of 25th January 2013 to 25th March 2014, 370 meat samples were collected from abattoirs and markets located in Riyadh, Saudi Arabia “200 raw meat samples and 170 meat products”. Bacteriological analysis of the meat samples and serotyping of the isolated E. coli revealed the isolation of 11 (2.97%) strains of E. coli O157:H7. Isolation of E. coli O157:H7 in raw beef, chicken and mutton were 2%, 2.5%, and 2.5%, respectively, however, there was no occurrence in raw turkey. The incidences of E. coli O157:H7 in ground beef, beef burgers, beef sausage, ground chicken and chicken burgers were 5%, 10%, 0.0%, 5% and 0.0%, respectively. The multiplex PCR assay revealed that 3 (27.27%) out of 11 E. coli O157:H7 isolates from raw beef, chicken and mutton had stx1, stx2, and eae while 5 (45.45%) E. coli O157:H7 isolates from ground beef, ground chicken, and raw beef had both stx1 and stx2. However, from beef burgers, only one E. coli O157:H7 isolate had stx1 while two were positive for hlyA gene. These results call for urgent attention toward appropriate controls and good hygienic practices in dealing with raw meat.     

Levels of Heavy Metals in Canned Bonito,Sardines, and Mackerel Produced in Turkey

Concentrations of selected metals were determined using ICP-MS in canned bonito, sardines and mackerel commercialized in Turkey. Thirty samples and two different brands were sampled for each fish species. The minimum and maximum concentrations of trace metals in canned bonito, sardines and mackerel were found as 0.000–34.742, 0.000–89.015, 0.000–28.725 mg/kg for iron, 2.388–26.620, 10.930–41.340, 4.778–29.270 mg/kg for zinc, 0.331–1.548, 0.599–2.242, 0.336–2.884 mg/kg for copper, 0.000–0.065, 0.000–0.113, 0.000–0.115 mg/kg for cadmium, 0.000–0.190, 0.000–0.158, 0.000–0.385 mg/kg for tin, 0.000–0.111, 0.000–0.223, 0.000–0.208 mg/kg for mercury and 0.000–3.046, 0.000–2.875, 0.000–3.529 mg/kg for lead, respectively. These levels are similar those found in other studies. Although the samples have concentrations within permissible limits for Zn, Cu, Sn and Hg, some of them contained Fe, Cd and Pb above these limits. Periodical controls of metals in canned fish are essential both to protect human health and to provide data on this subject.     

Effectiveness of naturally occurring Aphis gossypii on tomato plants as a bio-indicator for heavy metals in Riyadh and Hafar Al-Batin,Saudi Arabia

Although certain pollutants can be biologically degraded by microorganisms, rendering their impact short-term, others can not be impaired, such that their effect persists. The present study evaluates the effectiveness of using a field-collected aphid, Aphis gossypii, as a bio-indicator for heavy metals in tomato farms in Riyadh and Hafar Al-Batin, Saudi Arabia. Heavy metals were selected (Cd, Cu, Zn, and Pb) and measured for comparative screening in field-collected plants, soil, and aphids using inductively coupled plasma-mass spectrometry (ICP-MS). Field-collected aphids from both studied regions were identified as Aphis gossypii. In Riyadh, there was no significant difference observed for Cd, Cu, and Zn for all experimental samples, while, Pb was showed differences among samples especially tomato leaves None of the studied samples in Hafar Al-Batin were showed statistically significant differences in Cd, in reverse to significant differences in the other heavy metals. Comparing concentrations of selected heavy metals between the two studied regions was showed that neither region showed a significant difference in heavy metals except for Cu. This study demonstrates that tomato leaf samples showed the highest concentrations of most studied heavy metals, followed by soil, then aphids. Aphids were utilized as a bio-indicator of heavy metals in the studied regions.     

Isolation and molecular characterization of mycotoxigenic fungi in agarwood

Agarwood (Oudh), is often used by people in the Kingdom of Saudi Arabia. The Oudh has been mentioned in the Hadith and is traditionally used for its aroma (perfuming smell) and potential medicinal applications. The aim of the study was to isolate mycotoxigenic fungi that grow on agarwood and the factors and storage conditions that enhance their growth potential. In addition to the detection of associated mycotoxins like: Aflatoxin B1 (AFB₁) and ochratoxin A (OTA) from agarwood. Agarwood samples were collected from local markets of Jeddah governorate, Kingdom of Saudi Arabia. Standard dilution plate method was used for the isolation of fungi. Isolated fungi were identified based on morphological characteristics and confirmed using molecular biology techniques. AFB₁ and OTA were detected by High Performance Liquid Chromatography (HLPC). The results indicated that the most commonly isolated fungal genera were in the following descending order: Aspergillus, Penicillium, Fusarium and Rhizopus. Among Aspergillus genera, A. flavus and A. ochraceus were detected based on their morphology and confirmed by PCR using specific primers. It was also noted that AFB₁ was released by 15.3 and 55.0% of A. flavus and A. parasiticus isolates respectively with levels reaching up to 14.60 µg/L. The moisture content in the samples ranged from 3% to 10% affected fungal growth. AFB₁ was detected in 22 out of 50 of the samples. The maximum level of AFB₁ (50.7 µg/kg) was detected in samples with higher moisture content (12%) stored at a temperature of 32 °C. Aspergillus fungi were found to be the most predominant fungal genera found on agarwood. Moisture content (9–10%) and storage temperature (32 °C) stimulated fungal growth and their ability to produce mycotoxins. For this reason, storage conditions at the marketing place should be adequate in order not to provide a conducive environment for fungal growth which is associated with the mycotoxin production. In order to prevent fungal growth and mycotoxin production, it would be recommended to store agarwood at temperatures not exceeding 25 °C and moisture content of up to a maximum of 5–6%.     

Heavy metals in Antarctic organisms

 To evaluate levels of essential (zinc and copper) and non-essential (mercury and cadmium) heavy metals, 34 species of organisms from different areas close to the Antarctic Peninsula were analysed. These included algae, filter-feeders, omnivorous invertebrates and vertebrates. Mercury was not detected, while cadmium was found in the majority of organisms analysed (detection limit was 0.05 ppm for both metals). The highest cadmium concentration was observed in the starfish Odontaster validus. Anthozoans, sipunculids and nudibranchs showed maximum levels of zinc, while the highest copper level was found in the gastropod Trophon brevispira. Mercury and cadmium levels in fishes were below the detection limit. Concentrations of essential and non-essential metals in birds were highest in liver followed by muscle and eggs. Cadmium and mercury levels in muscle of southern elephant seals were above the detection limit, whereas in Antarctic fur seals they were below it. The objective of the study was to gather baseline information for metals in Antarctic Ocean biota that may be needed to detect, measure and monitor future environmental changes. Received: 17 July 1995/Accepted: 11 April 1996     

Concentrations of Lead,Cadmium, and Mercury in Halfbeaks (Hyporhampus affinis) from the East Java Coast,Indonesia and Human Health Hazard

The objectives of this study were to measure the levels of lead, cadmium, and mercury in the muscle tissues of halfbeaks (Hyporhampus affinis) captured at five stations along the East Java coast, Indonesia. This fish is one of the important species and consumed by local people as a cheap source of protein. We evaluated the hazard level posed by the metals in relation to the maximum residual limit for human consumption and to estimate the weekly intake and compare it with the provisional tolerable weekly intake (PTWI). The Pb, Cd, and Hg concentrations in fish at all stations ranged from 0.006 to 0.023 mg/kg, 0.007 to 0.024 mg/kg, and 0.047 to 0.055 mg/kg wet weight, respectively. All samples of halfbeaks collected from this area appear to be safe for human consumption because their metals’ levels are below the permissible limit for human consumption and the maximum weekly intakes are below the recommended values of PTWI.     

Mycobiota of Oil-Contaminated Soil Samples and Their Abilities for Dibenzothiophene Desulfurization

High sulfur content of crude oil leads to poor quality of oil products and many other negative consequences such as corrosion, catalyst poisoning and environmental pollution. Saudi Arabia is seeking to reduce sulfur content in diesel and gasoline to 10 ppm and to lower benzene content in gasoline to 1%. Biotechnological processes such as biodesulfurization can be considered an alternative or complement to conventional oil refining technologies. So, the objective of the present project is to isolate and identify endogenous fungal isolates capable of oil biodesulfurization. From 60 oil-contaminated soil samples collected from Saudi Arabia, 15 species belonged to 9 fungal genera were collected and identified morphologically and with ITS sequencing. Members of Aspergillus, Penicillium and Fusarium were the most prevalent in the investigated samples. Among the collected fungal species, only Stachybotrys bisbyiisolates were able to utilize dibenzothiophene (DBT) as the sole sulfur source. Stachybotrys bisbyi TUSb1 could desulfurize 99% of the DBT (0.3 mM) as the sulfur source by a co-metabolism reaction with other carbon sources through the same pathway as 4S (involves sequential oxidation of the sulfur part and cleaving of the C–S bonds), and produced 2-hydroxy biphenyl (2-HBP) during 7 days of incubation at 30°C and 180 rpm. Stachybotrys bisbyi TUSb1 showed broad specificity for removing sulfur in different sulfur-containing compounds.     

Traffic and industrial activities around Riyadh cause the accumulation of heavy metals in legumes: A case study

The objective of this study was to analyse the effect of the continuously increasing anthropogenic activities around Riyadh, Saudi Arabia on the accumulation of heavy metals in leguminous crops. This study determined whether four legume crops, Pisum sativum L., Vicia faba L., Glycine max and Vigna sinensis, could accumulate the heavy metals Cu, Mn, Pb and Zn in their leaves, pods and grains during the summer when grown under conditions with ambient air pollution from heavy traffic and industrial activities in Riyadh, Saudi Arabia. The effect of the air pollution was examined by quantifying the protein and trace element Cu, Mn, Pb and Zn concentrations in the leaves, pods and grains of the four plant species. Analysis of the results indicated that air pollution significantly increased the heavy metal concentrations in the leaves, pods and grains. Toxic concentrations of the heavy metals were found in the plants grown at L3, L4 and L5. In conclusion, the air pollution increases as the traffic, industrial activities and population density increase.     

Seasonal variations in the body composition and bioaccumulation of heavy metals in Nile tilapia collected from drainage canals in Al-Ahsa,Saudi Arabia

The body composition of Nile tilapia (Oreochromis niloticus) collected from drainage canals in Al-Ahsa, Saudi Arabia and the concentration of four heavy metals; zinc (Zn), cadmium (Cd), cobalt (Co) and lead (Pb) in both fish muscles and the water collected from this environment were assessed across the four seasons. The body composition was found to change with the seasons, with the best body composition being recorded in autumn and winter, where higher levels of protein (17.24, 17.65%), and fat (0.58, 0.71%) and lower water content (80.15, 79.86%) respectively were noted. The concentration of heavy metals in both fish muscles and the water body also varied significantly with the seasons. In the fish muscles, the highest content of Zn (0.409 mg/kg dry weight) and Cd (4.140 mg/kg dry weight) was recorded in winter, however, the highest concentration of Co (0.318 mg/kg dry weight) and Pb (1.96 mg/kg dry weight) was observed in spring and summer respectively. On the other hand, the water samples collected in autumn showed the maximum concentration of Cd (1.385 mg/L), Co (0.762 mg/L) and Pb (0.18 mg/L) however, the maximum concentration of Zn (0.0041 mg/L) was recorded in winter. With the exception of Cd, the accumulation of the studied heavy metals in fish muscles was within the safe limits for seafood recommended by various organizations.     

Molecular identification of isolated fungi from stored apples in Riyadh,Saudi Arabia

Fungi causes most plant disease. When fruits are stored at suboptimal conditions, fungi grows, and some produce mycotoxin which can be dangerous for human consumption. Studies have shown that the Penicillium and Monilinia species commonly cause spoilage of fruits, especially apples. Several other genera and species were reported to grow to spoil fruits. This study was conducted to isolate and identify fruit spoilage by fungi on apples collected in Riyadh, Saudi Arabia and conduct a molecular identification of the fungal isolates. Thus, we collected 30 samples of red delicious and Granny Smith apples with obvious spoilage from different supermarkets between February and March of 2012 in Riyadh, Saudi Arabia. Each apple was placed in a sterile plastic bag in room temperature (25–30 °C) for six days or until fungal growth was evident all over the sample. Growth of fungal colonies on PDA was counted and sent for molecular confirmation by PCR. Six fruit spoilage fungi were isolated, including Penicillium chrysogenum, Penicillium adametzii, Penicillium chrysogenum, Penicillium steckii, Penicillium chrysogenum, and Aspergillus oryzae. P. chrysogenum was the most frequent isolate which was seen in 14 of a total of 34 isolates (41.2%), followed by P. adametzii and A. oryzae with seven isolates each (20.6%) and the least was P. steckii with six isolates (17.6%). Penicillium species comprised 27 of the total 34 (79.4%) isolates. Sequence analysis of the ITS regions of the nuclear encoded rDNA showed significant alignments for P. chrysogenum, P. adametzii and A. oryzae. Most of these fungal isolates are useful and are rarely pathogenic; however they can still produce severe illness in immune-compromised individuals, and sometimes otherwise healthy people may also become infected. It is therefore necessary to evaluate the possible production of mycotoxins by these fungi to determine a potential danger and to establish its epidemiology in order to develop adequate methods of control.     

Heavy Metals in Mussels (Mytilus galloprovincialis) from Marmara Sea, Turkey

Marmara Sea is one of the main catching areas of mussels (Mytilus galloprovincialis) in Turkey, and a significant portion of the harvest has been exported mainly to European countries. In this study, Zn, Cu, Cd, Hg, and Pb in mussels from ten catching areas in Marmara Sea were analyzed to investigate health risks associated with consuming mussels. Mercury was not detected (<0.15 ppb) in any of the samples. The highest concentrations of Cu and Cd were 3.473 and 0.740 mg kg^?1 (wet weight, WW), respectively, well below the maximum permissible levels. All samples contained Zn higher than 50 mg kg^?1, while Pb was above the limits in the samples from stations 1, 4, 6, and 8. Mussels from Marmara Sea are safe regarding Cu, Cd, and Hg but may contain Zn and Pb above the permissible limits. However, metal contents of mussels from Marmara Sea are mostly lower than those of the regions in other areas of the world. It was concluded that Marmara Sea has a potential of being a safe source of mussels if industrial inputs somewhat reduced and controlled. Concentrations of heavy metals in mussels must be monitored comprehensively and periodically with respect to the consumer health.     

Safety and quality of some chicken meat products in Al-Ahsa markets-Saudi Arabia

One hundred samples of 10 poultry meat products were collected from AL-Ahsa markets (Kingdom of Saudi Arabia). The samples were ranked from carcass cuts (chilled, frozen, fillet and thigh) to minced meat or further processed products as burger, nuggets, frankfurter and meat paste loaf. Samples were collected in triplicate for sensory, chemical and microbiological analysis to assure their quality and safety.The obtained results revealed variation in chemical composition; some products with high fat percentage had a high thiobarbituric acid value, which resulted in the appearance of an unacceptable flavor.Bacteriological analysis revealed that the mean total bacterial count was ranged from 2.7 × 10⁴ cfu/g for nuggets^A to 3.3 × 10⁷ cfu/g for burger^B and the other products in the range of 10⁵–10⁶ cfu/g. While Staphylococcus aureus mean count ranged from less than 10² cfu/g for all samples, accept 10⁴ and 10⁶ cfu/g for mince^B and frankfurter samples, respectively. Escherichia coli isolated from 70% of the samples and Salmonella arizona was isolated at once from thigh samples. Thirty percentages of samples not comply with Saudi Standards due to sensory unacceptability and 21% of samples nonconforming with bacteriological specifications.     

Field accumulation risks of heavy metals in soil and vegetable crop irrigated with sewage water in western region of Saudi Arabia

Wastewater irrigated fields can cause potential contamination with heavy metals to soil and groundwater, thus pose a threat to human beings . The current study was designed to investigate the potential human health risks associated with the consumption of okra vegetable crop contaminated with toxic heavy metals. The crop was grown on a soil irrigated with treated wastewater in the western region of Saudi Arabia during 2010 and 2011. The monitored heavy metals included Cd, Cr, Cu, Pb and Zn for their bioaccumulation factors to provide baseline data regarding environmental safety and the suitability of sewage irrigation in the future. The pollution load index (PLI), enrichment factor (EF) and contamination factor (CF) of these metals were calculated. The pollution load index of the studied soils indicated their level of metal contamination. The concentrations of Ni, Pb, Cd and Cr in the edible portions were above the safe limit in 90%, 28%, 83% and 63% of the samples, respectively. The heavy metals in the edible portions were as follows: Cr > Zn > Ni > Cd > Mn > Pb > Cu > Fe. The Health Risk Index (HRI) was >1 indicating a potential health risk. The EF values designated an enhanced bio-contamination compared to other reports from Saudi Arabia and other countries around the world. The results indicated a potential pathway of human exposure to slow poisoning by heavy metals due to the indirect utilization of vegetables grown on heavy metal-contaminated soil that was irrigated by contaminated water sources. The okra tested was not safe for human use, especially for direct consumption by human beings. The irrigation source was identified as the source of the soil pollution in this study.     

Implications of fungal infections and mycotoxins in camel diseases in Saudi Arabia

Natural feed ingredients (corn, barley and wheat bran) and compound feed (manufactured pellet) are two types of fodder used for animal feeding, especially camel in Saudi Arabia. Twenty samples of each type of fodder were collected from seven different regions and screened for the presence of fungi, aflatoxins, ochratoxin and zearalenone. Fungal isolation of natural feed ingredients yielded 10 genera and 38 species of different fungi. Compound fodder samples were contaminated with 16 genera and 32 species of fungi. Total counts of Aspergillus, Penicillium and Fusarium in the animal feed samples were ranged from 54 to 223 × 10³, 31.9 to 60 × 10³ and 18 to 29 × 10³ CFU/g, respectively. These isolates when tested for aflatoxin, ochratoxin and zearalenone producing ability, revealed this property in only four isolate, identified as Aspergillus flavus, A. parasiticus, A. ochraceus and Fusarium graminaerum. The percentage of toxigenic fungi was ranged from 5.5% to 30% for natural feed ingredients and from 4.5% to 20% for compound feed. The incidence of aflatoxins (AFT) in samples of natural feed ingredients was found to be ranged from 1 to 24.8 ppb, ochratoxin A (OTA) ranged from 1 to 44 ppb and zearalenone (ZON) ranged from 1 to 23 ppb. Contamination of compound feed with aflatoxin and ochratoxin A was ranged from 1 to 6.4 ppb and 1 to 4.7 ppb, respectively. All samples collected were found contaminated with fungi or their toxins and natural feed samples were more contaminated compared to compound feed samples. The concentrations detected were in the allowed limit (<20 ppb) except four samples of natural feed ingredients which were above the allowed limit of the tested mycotoxins. In conclusion, feed samples were contaminated with fungi and some toxigenic isolates which were responsible about mycotoxin production. Some samples had exceeded amount of AFT, OTA and ZON and may be contaminated with other mycotoxins which mean implication of fungi in camel health problems and death in Saudi Arabia.     

Drinking water quality and human health risk evaluations in rural and urban areas of Ibeju-Lekki and Epe local government areas,Lagos, Nigeria

Abstract

This study evaluated the drinking water quality and associated human health risks in three (3) rural and urban areas each in Ibeju-Lekki and Epe local government areas of Lagos, Nigeria. Two hundred structured questionnaires were administered to stakeholders, and samples were obtained from prevailing drinking water sources in the study areas using standard methods for microbiological, physicochemical, heavy metals and human health risk evaluations. Wells and boreholes were the major sources of drinking water in the rural and urban areas, respectively. Drinking water samples from the study areas contained more than one pathogenic bacterium. The physicochemical parameters except total organic carbon (TOC) were within permissible limits of the Nigerian Standard for Drinking Water Quality (NSDWQ). The mean values of Cd and As exceeded the maximum permissible limit of NSDWQ. The hazard quotient of cadmium and arsenic was greater than 1 indicating potential health risks if the water is not treated. In order to achieve the UN Sustainable Development Goal 6 on clean water and sanitation by the next decade (2030), we recommend that frequent monitoring, treatment and stakeholders education on drinking water treatment techniques should be actively conducted particularly in rural areas in the state, country, region and continent.     

Survey of the mycoflora of desert soils in Saudi Arabia

Thirty-four genera and 80 species in addition to one variety of A. nidulans were identified from 40 soil samples colleted from different places in desert of Saudi Arabia. More than forty-two species are new records from Saudi Arabian soils. Aspergillus and Penicillium contributed the greatest number of species (15 species + 1 variety and 13 species respectively).The most frequent genera were Aspergillus, Penicillium, Botryotrichum, and Ulocladium followed by Macrophomina, Rhizopus, Fusarium, Alternaria and Cladosporium from which A. fumigatus, A. terreus, A. niger, A. flavus, P. citrinum, P. corylophilum, B. atrogriseum, U. botrytis, M. phaseoli, R. stolnifer, F. moniliforme, A. alternata and C. herbarum were the most common.Comparison between the present results and those of the other studies showed that there is no fungal flora characteristic of desert soils of Saudi Arabia.     

Effects of different sewage sludge applications on heavy metal accumulation,growth and yield of spinach (Spinacia oleracea L.)

In this study, we present the response of spinach to different amendment rates of sewage sludge (0, 10, 20, 30, 40 and 50 g kg^?1) in a greenhouse pot experiment, where plant growth, biomass and heavy metal uptake were measured. The results showed that sewage sludge application increased soil electric conductivity (EC), organic matter, chromium and zinc concentrations and decreased soil pH. All heavy metal concentrations of the sewage sludge were below the permissible limits for land application of sewage sludge recommended by the Council of the European Communities. Biomass and all growth parameters (except the shoot/root ratio) of spinach showed a positive response to sewage sludge applications up to 40 g kg^?1 compared to the control soil. Increasing the sewage sludge amendment rate caused an increase in all heavy metal concentrations (except lead) in spinach root and shoot. However, all heavy metal concentrations (except chromium and iron) were in the normal range and did not reach the phytotoxic levels. The spinach was characterized by a bioaccumulation factor <1.0 for all heavy metals. The translocation factor (TF) varied among the heavy metals as well as among the sewage sludge amendment rates. Spinach translocation mechanisms clearly restricted heavy metal transport to the edible parts (shoot) because the TFs for all heavy metals (except zinc) were <1.0. In conclusion, sewage sludge used in the present study can be considered for use as a fertilizer in spinach production systems in Saudi Arabia, and the results can serve as a management method for sewage sludge.