Biosorption properties of Morus alba L. for Cd (II) ions removal from aqueous solutions

The abundantly available industrial waste product Morus alba L. pomace (MAP) is one of the cost-effective biosorbent for removal of metal ions from aqueous solutions. Hence, in the present study, we aimed to test the ability of MAP to remove Cd(II) ions through batch biosorption process. Firstly, MAP was characterized using several techniques, and then the influence of various experimental parameters such as initial pH of the aqueous solution, initial Cd(II) concentration, contact time, MAP concentration, and temperature were evaluated upon the biosorption process. It was found that the maximum uptake of Cd(II) ions occurred at initial pH 6.0 and optimum contact time was observed as 60 min. Cd(II) ions adsorption on MAP analyzed by the Langmuir and Freundlich isotherm models and the maximum monolayer biosorption capacity of MAP was found to be 21.69 mg?g^?1 by using the Langmuir isotherm model. The pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models were employed to describe the biosorption kinetics. In order to investigate the thermodynamic properties of the biosorption process, the changes in the Gibbs free energy (?G), enthalpy (?H), and entropy (?S) were also evaluated and it has been concluded that the process was feasible, spontaneous, and endothermic in the temperature range of 5–40 °C.     

Nickel(II) biosorption from aqueous solutions by shrimp head biomass

The present study evaluates the capacity of shrimp (Farfantepenaeus aztecus) head to remove toxic Ni(II) ions from aqueous solutions. Relevant parameters that could affect the biosorption process, such as shrimp head pretreatment, solution pH level, contact time and initial Ni(II) concentration, were studied in batch systems. An increase in Ni(II) biosorption capacity and a reduction in the time required to reach Ni(II) biosorption equilibrium was manifested by shrimp head biomass pretreated by boiling in 0.5 N NaOH for 15 min; this biomass was thereafter denominated APSH. The optimum biosorption level of Ni(II) ions onto APSH was observed at pH 7.0. Biosorption increased significantly with rising initial Ni(II) concentration. In terms of biosorption dynamics, the pseudo-second-order kinetic model described Ni(II) biosorption onto APSH best. The equilibrium data adequately fitted the Langmuir isotherm model within the studied Ni(II) ion concentration range. According to this isotherm model, the maximum Ni(II) biosorption capacity of APSH was 104.22 mg/g. Results indicate that APSH could be used as a low-cost, environmentally friendly, and promising biosorbent with high biosorption capacity to remove Ni(II) from aqueous solutions.     

Metal pollution and ecological risk assessment in marine sediments of Karachi Coast, Pakistan

Concentrations of 12 metals (Fe, Mn, Cr, Mo, Ni, Pb, Se, Sr, U, V, Zn, and Zr) in surface sediments of Karachi Coast, Pakistan were determined to evaluate their distribution and pollution assessment. The measured metals in the sediments were found to be in the range of Fe, 0.84–6.96 %; Mn, 300–1,300 μg/g; Cr, 12.0–319.84 μg/g; Mo, 0.49–2.03 μg/g; Ni, 1.53–58.86 μg/g; Pb, 9.0–49.46 μg/g; Se, 0.25–.86 μg/g; Sr, 192–1185 μg/g; U, 0.19–1.66 μg/g; V, 15.80–118.20 μg/g; Zn, 15.60–666.28 μg/g; and Zr, 44.02–175.26 μg/g. The mean contents of the metal studied were: Fe, 3.07 %, Mn, 0.05 %; Cr, 96.75 μg/g; Mo, 1.34 μg/g; Ni, 31.39 μg/g; Pb, 23.24 μg/g; Se, 0.61 μg/g; Sr, 374.83 μg/g; U, 0.64 μg/g; V, 61.75 μg/g; Zn, 204.75 μg/g; and Zr:76.27 μg/g, and arrangement of the metals from higher to lower mean content in this area is: Fe?>?Zn?>?Mn?>?Sr?>?Zn?>?Cr?>?Zr?>?V?>?Ni?>?Pb?>?Mo?>?U?>?Se. There is no significant correlation among most of these metals, indicating different anthropogenic and natural sources. To assess ecotoxic potential of marine sediments, Numerical Sediment Quality Guidelines were also applied. The concentration of Pb in all the sediments except one was lower than the threshold effect concentration (TECs) showing that there are no harmful effects to marine life from Pb. On the other hand, the concentrations of Cr, Ni, and Zn exceeded TEC in three stations, indicating their potential risk. The degree of pollution in sediments for metals was assessed by calculating enrichment factor (EF) and pollution load index (PLI). The results indicated that sediments of Layari River Mouth Area, Fish Harbour, and KPT Boat Building Area are highly enriched with Cr and Zn (EF?>?5). Sediments of Layari River Outfall Zone were moderately enriched with Ni and Pb (EF?>?2). The pollution load index was found in the range of 0.98 to 1.34. Lower values of PLI (≤1) at most of sampling locations imply no appreciable input from anthropogenic sources. However, relatively higher PLI values (>1) at Layari River Mouth Area, Fish Harbour, and KPT Boat Building Area are attributed to increased human activity in the area.     

Effects of irrigation with wastewater on the physiological properties and heavy metal content in Lepidium sativum L. and Eruca sativa (Mill.)

The purpose of this study was to determine the physiological properties of and heavy metal content in Lepidium sativum L. and Eruca sativa (Mill.) irrigated with municipal wastewater for 20 days. Wastewater was taken from a section where all wastewater of Adiyaman is collected. We analysed the soil for physicochemical properties, heavy metals and nutrient content and the plants for photosynthetic pigment content, dry weight and length. Irrigation wastewater increased the electrical conductivity and organic matter content in plant soil. In both plant soils, Cd and Ni content significantly increased with respect to control. Dry matter content decreased significantly in the edible parts, and the length of the edible parts increased significantly in E. sativa. Photosynthetic pigment content increased in L. sativum and decreased in E. sativa. Nutrient content changed significantly in both plants. In the edible parts of L. sativum, Cd and Ni content increased significantly compared to Pb and Cr. The edible parts of E. sativa also showed a higher Cd level than the control plant. The enrichment factor of the heavy metals in the edible parts of L. sativum followed this order: Cu?>?Pb?>?Cd?>?Ni?>?Cr and of E. sativa: Pb?>?Cd?>?Cu?>?Cr?>?Ni. The edible parts of both plants showed a high transfer factor (TF?>?1) for Cd, which points to high mobility of Cd from soil to plant. In conclusion, the use of wastewater for irrigation increased heavy metal content in both plants and affected their physiological and morphological properties.     

Uptake of heavy metals by some edible vegetables irrigated using wastewater: a preliminary study in Accra, Ghana

The heavy metals (Fe, Zn, Pb, Ni, Cr, Co, and Cd) burden in wastewater, soil, and vegetable samples from a wastewater irrigated farm located at KorleBu, Accra has been investigated. Flame atomic absorption spectrometry after microwave digestion using a combination of HNO₃, HCl, and H₂O₂ (for water), and HNO₃ and HCl (for soil and vegetables). The mean concentrations (in milligrams per kilogram) of heavy metals in the soil samples were in the order of Fe (171?±?5.22)?>?Zn (36.06?±?4.54)?>?Pb (33.35?±?35.62)?>?Ni (6.31?±?8.15)?>?Cr (3.40?±?3.63)?>?Co (1.36?±?0.31)?>?Cd (0.43?±?0.24), while the vegetables were in the order of Fe (183.11?±?161.2)?>?Zn (5.38?±?3.50)?>?Ni (3.52?±?1.27)?>?Pb (2.49?±?1.81)?>?Cr (1.46?±?0.51)?>?Co (0.66?±?0.25)?>?Cd (0.36?±?0.15). The bioconcentration factors suggest environmental monitoring for the heavy metals as follows: Cd (0.828), Cr (0.431), Ni (0.558), Co (0.485), and Fe (1.067). Estimated daily intakes were very low for both children and adults except Fe (0.767 mg/kg/day) in children. The population that consume vegetables from the study area were, however, estimated to be safe based on the results obtained from the health risk index, which were all?<?<1. The sodium absorption ratio according to FAO (1985) classifications indicate that the wastewater in the study area is unsuitable for irrigation purposes.     

Evaluation of potentially toxic metals pollution in the sediments of the Kor river, southwest Iran

This study is carried out to evaluate potentially toxic metal concentrations (As, Cd, Cr, Cu, Hg, Mo, Ni, Pb, and Zn) together with their spatial distribution, degree of pollution, and potential ecological risk in Kor river sediments (southwest Iran) using sediment quality guidelines, geoaccumulation index (I _geo), Hakanson potential ecological risk index (RI), and standard methods of statistical analysis. The study area stretches some 140 km from the Drodzan Dam to Bakhtegan Lake, a stretch of river where different industrial and domestic activities (e.g., petrochemical complex, oil refinery, industrial meat processing complex, Marvdasht city sewage) and ecological value overlap with each other. Calculated geoaccumulation index indicate that 50 % of the stations are moderately to very extremely polluted. The potential ecological risk for nine investigated metals in Kor river is Hg (948)?>?Mo (51.9)?>?Ni (37.8)?>?Cd (29.8)?>?As (22)?>?Cu (16.6)?>?Pb (13.3)?>?Zn (3.3)?>?Cr (1). Results show that sediments in parts of Kor river sediments are heavily affected by effluents discharged from industrial plants and other parts are affected by agriculture and urban runoff from nearby lands. These phenomena may cause a risk of secondary water pollution under sediment disturbance and/or changes in the physical–chemical characteristics of the aquatic system.     

Spatial and temporal variability of metals in inter-tidal beach sediment of Mumbai, India

Nine metals were monitored in the beach sediment in Mumbai from May 2011 to March 2012 to evaluate the spatial and temporal distributions. The average heavy metal concentrations exhibited the following order: Fe > Mn > Cr > Co > Ni > Pb > Zn > Cu > Cd for the four sampling sites. The mean concentrations (± SD) of Fe, Mn, Cr, Co, Ni, Pb, Zn, Cu and Cd were estimated to be 31.15?±?10.02 g kg^?1, 535.04?±?76.42, 151.98?±?97.90, 92.76?±?14.18, 67.52?±?11.32, 59.57?±?15.19, 54.65?±?15.01, 32.24?±?8.07 and 18.75?±?1.76 mg kg^?1, respectively. The results indicated that the sediments were polluted with Cd, Cr, Co and Pb due to high anthropogenic influences. Spatial variation of metals revealed that most of the metals were high in Dadar beach and low in Aksa beach. Cd was the highest contaminant metal studied with a mean contamination factor of 93.75. The pollution load indices of the studied beaches ranged from 1.63 (Aksa) to 1.91 (Dadar) and indicated that the beach sediments were polluted with heavy metals. The heavy metal contents increased in relation to monsoon, and most of the heavy metals showed significantly high concentrations in November during the post-monsoon. The statistical analysis revealed significant effect of study site on all the metals studied. Further, there was a significant difference on metal accumulation on bimonthly basis in relation to weather pattern in Mumbai beaches.     

Heavy metal in surface sediments of the Liaodong Bay, Bohai Sea: distribution, contamination, and sources

In an effort to assess the potential contamination and determine the environmental risks associated with heavy metals, the surface sediments in Liaodong Bay, northeast China, were systematically sampled and analyzed for the concentrations of Cu, Pb, Zn, Cr, Ni, As, and Hg. The metal enrichment factor (EF) and geoaccumulation index (I _geo) were calculated to assess the anthropogenic contamination in the region. Results showed that heavy metal concentrations in the sediments generally met the criteria of China Marine Sediment Quality (GB18668-2002); however, both EF and I _geo values suggested the elevation of Pb concentration in the region. Based on the effect-range classification (TEL-PEL SQGs), Cu, Pb, Ni, and As were likely to pose environment risks, and the toxic units decreased in the order: Ni?>?Pb?>?Cr?>?Zn?>?As?>?Cu?>?Hg. The spatial distribution of ecotoxicological index (mean-ERM-quotient) suggested that most of the surface sediments were “low–medium” priority zone. Multivariate analysis indicated that the sources of Cr, Ni, Zn, Cu, and Hg resulted primarily from parent rocks, and Pb or As were mainly attributed to anthropogenic sources. The results of this study would provide a useful aid for sustainable marine management in the region.     

Effects of northeast monsoon on trace metal distribution in the South China Sea off Peninsular Malaysia

Concentrations of trace metals in the South China Sea (SCS) were determined off the coast of Terengganu during the months of May and November 2007. The concentrations of dissolved and particulate metals were in the range of 0.019–0.194 μg/L and 50–365 μg/g, respectively, for cadmium (Cd), 0.05–0.45 μg/L and 38–3,570 μg/g for chromium (Cr), 0.05–3.54 μg/L and 21–1,947 μg/g for manganese (Mn), and 0.03–0.49 μg/L and 2–56,982 μg/g for lead (Pb). The order of mean log K _D found was Cd?>?Cr?>?Pb?>?Mn. The study suggests that the primary sources of these metals are discharges from the rivers which drain into the SCS, in particular the Dungun River, which flows in close proximity to agricultural areas and petrochemical industries. During the northeast monsoon, levels of particulate metals in the bottom water samples near the shore were found to be much higher than during the dry season, the probable result of re-suspension of the metals from the bottom sediments.     

Vertical distribution of heavy metals in soil profile in a seasonally waterlogging agriculture field in Eastern Ganges Basin

The accumulation of heavy metals in soil and water is a serious concern due to their persistence and toxicity. This study investigated the vertical distribution of heavy metals, possible sources and their relation with soil texture in a soil profile from seasonally waterlogged agriculture fields of Eastern Ganges basin. Fifteen samples were collected at ～0.90-m interval during drilling of 13.11 mbgl and analysed for physical parameters (moisture content and grain size parameters: sand, silt, clay ratio) and heavy metals (Fe, Mn, Cr, Cu, Pb, Zn, Co, Ni and Cd). The average metal content was in the decreasing order of Fe?>?Mn?>?Cr?>?Zn?>?Ni?>?Cu?>?Co?>?Pb?>?Cd. Vertical distribution of Fe, Mn, Zn and Ni shows more or less similar trends, and clay zone records high concentration of heavy metals. The enrichment of heavy metals in clay zone with alkaline pH strongly implies that the heavy metal distributions in the study site are effectively regulated by soil texture and reductive dissolution of Fe and Mn oxy-hydroxides. Correlation coefficient analysis indicates that most of the metals correlate with Fe, Mn and soil texture (clay and silt). Soil quality assessment was carried out using geoaccumulation index (I _geo), enrichment factor (EF) and contamination factor (CF). The enrichment factor values were ranged between 0.66 (Mn) and 2.34 (Co) for the studied metals, and the contamination factor values varied between 0.79 (Mn) and 2.55 (Co). Results suggest that the elements such as Cu and Co are categorized as moderate to moderately severe contamination, which are further confirmed by I _geo values (0.69 for Cu and 0.78 for Co). The concentration of Ni exceeded the effects-range median values, and the biological adverse effect of this metal is 87 %. The average concentration of heavy metals was compared with published data such as concentration of heavy metals in Ganga River sediments, Ganga Delta sediments and upper continental crust (UCC), which apparently revealed that heavy metals such as Fe, Mn, Cr, Pb, Zn and Cd are influenced by the dynamic nature of flood plain deposits. Agricultural practice and domestic sewage are also influenced on the heavy metal content in the study area.     

Accumulation of heavy metals in Spinacia oleracea irrigated with paper mill effluent and sewage

The present study on heavy metal contamination in soil and their accumulation in edible part (leaves) and roots of Spinacia oleracea (Spinach) on irrigation with paper mill effluent (PME)/sewage revealed that there was significant increase in the nickel (Ni, +227.17 %) content of the soil irrigated with PME, whereas in the soil irrigated with sewage chromium (Cr, +274.84 %), iron (Fe, +149.56 %), and cadmium (Cd, +133.39 %), contents were increased appreciably. The value of enrichment factor (EF) for Ni (3.27) indicated moderate enrichment in PME-irrigated soil. The EF of Fe, zinc (Zn), Cd, and Cr were <2 in PME effluent-irrigated soil which showed deficiency of minimal enrichment. In sewage irrigated soil, EF value for Cr, Fe, and Cd indicated moderate enrichment, while the values for Zn and Ni indicated deficiency of minimal enrichment. Among various metallic concentrations, the maximum concentration of Fe was observed in leaves (400.12?±?11.47 mg/kg) and root (301.41?±?13.14 mg/kg) of S. oleracea after irrigation with PME, whereas the maximum concentrations of Fe was found in leaves (400.49?±?5.97 mg/kg) and root (363.94?±?11.37 mg/kg) of S. oleracea after irrigation with sewage for 60 days. The bioaccumulation factor value was found maximum for Cd (2.23) in the plants irrigated with PME while that of Fe (0.90) in the plants irrigated with sewage. The undiluted use of PME/sewage for irrigation increased the concentration of Cr, Cd, Zn, Ni, and Fe metals which were accumulated in S. oleracea, posing a potential threat to human health from this practice of irrigation.     

Effect of pH,ionic strength,and background electrolytes on Cr(VI) and total chromium removal by acorn shell of Quercus crassipes Humb. & Bonpl.

The ability of Quercus crassipes acorn shells (QCS) to remove Cr(VI) and total chromium from aqueous solutions was investigated as a function of the solution pH, ionic strength, and background electrolytes. It was found that Cr(VI) and total chromium removal by QCS depended strongly on the pH of the solution. Cr(VI) removal rate increased as the solution pH decreased. The optimum pH for total chromium removal varied depending on contact time. NaCl ionic strengths lower than 200 mM did not affect chromium removal. The presence of 20 mM monovalent cations and anions, and of divalent cations, slightly decreased the removal of Cr(VI) and total chromium by QCS; in contrast, divalent anions (SO₄ ^2?, PO₄ ^2?, CO₃ ^2?) significantly affected the removal of Cr(VI) and total chromium. The biosorption kinetics of chromium ions followed the pseudo-second-order model at all solution pH levels, NaCl ionic strengths and background electrolytes tested. Results suggest that QCS may be a potential low-cost biosorbent for the removal of Cr(VI) and total chromium from aqueous solutions containing various impurities.     

Hazard assessment of metals in invasive fish species of the Yamuna River,India in relation to bioaccumulation factor and exposure concentration for human health implications

Monitoring of heavy metals was conducted in the Yamuna River considering bioaccumulation factor, exposure concentration, and human health implications which showed contamination levels of copper (Cu), lead (Pb), nickel (Ni), and chromium (Cr) and their dispersion patterns along the river. Largest concentration of Pb in river water was 392 μg L^?1; Cu was 392 μg L^?1 at the extreme downstream, Allahabad and Ni was 146 μg L^?1 at midstream, Agra. Largest concentration of Cu was 617 μg kg^?1, Ni 1,621 μg kg^?1 at midstream while Pb was 1,214 μg kg^?1 at Allahabad in surface sediment. The bioconcentration of Cu, Pb, Ni, and Cr was observed where the largest accumulation of Pb was 2.29 μg kg^?1 in Oreochromis niloticus and 1.55 μg kg^?1 in Cyprinus carpio invaded at Allahabad while largest concentration of Ni was 174 μg kg^?1 in O. niloticus and 124 μg kg^?1 in C. carpio in the midstream of the river. The calculated values of hazard index (HI) for Pb was found more than one which indicated human health concern. Carcinogenic risk value for Ni was again high i.e., 17.02?×?10^?4 which was larger than all other metals studied. The results of this study indicated bioconcentration in fish due to their exposures to heavy metals from different routes which had human health risk implications. Thus, regular environmental monitoring of heavy metal contamination in fish is advocated for assessing food safety since health risk may be associated with the consumption of fish contaminated through exposure to a degraded environment.     

Metal speciation in sediment and bioaccumulation in <Emphasis Type="Italic">Meretrix lyrata</Emphasis> in the Tien Estuary in Vietnam

The concentrations of seven toxic metals (cadmium (Cd), nickel (Ni), chromium (Cr), arsenic (As), lead (Pb), copper (Cu), and zinc (Zn)) were determined in sediments and the soft tissues of a bivalve species (Meretrix lyrata) collected from the Tien Estuary in Tien Giang Province, South Vietnam. The total metal concentrations in sediments (mg/kg dry weight) increased as Cd (0.06) < Cu (5.0) < Pb (13.9) < As (16.3) < Ni (24) < Cr (50) < Zn (62). Speciation analysis revealed that these metals existed mainly in the residual fraction (43–94%), followed by the Fe-Mn oxide-bound (5–35%) and organic/sulfide-bound (0.6–9.2%) fractions. The metal concentrations in M. lyrata (mg/kg dry weight) were in the ranges of 1.3–1.9 (Cd), 1.5–2.8 (Ni), 1.8–3.4 (Cr), 11–16 (As), 0.3–0.6 (Pb), 6.9–8.7 (Cu), and 95–128 (Zn), which are safe for human consumption. The order of the mean biota-sediment accumulation factor (BSAF) of the metals in the non-residual fractions of the sediment for M. lyrata was Cd > Cu > As > Zn > Cr > Ni > Pb. The Risk Assessment Codes (RACs) suggest that the highest mobility of Cd (with RAC = 37%) poses greater environmental risk to aquatic biota. Correlation analysis results show that M. lyrata can be used as a biomonitor of Cd and Cu pollution in the exchangeable, acid-soluble, and non-residual sediment fractions.     

Irrigational impact of distillery effluent on Abelmoschus esculentus L. Okra with special reference to heavy metals

The present study was performed under natural environment to assess levels of different heavy metals in soil and Abelmoschus esculentus plants along with soil microbial population irrigated with five rates of distillery effluent (DE) viz. 10, 25, 50, 75 and 100 % concentration in comparison with control (Bore well water). Results revealed that among various concentrations of DE, irrigation with 100 % DE significantly (P < 0.001) increased Zn (+63.46 %), Cu (+292.37 %), Zn (+3763.63 %), Cd (+264.29 %), Ni (+48.39 %) and Cr (+815.74 %), while decreased total bacteria (?45.23 %), fungi (?17.77 %) and actinomycetes (?42.57 %) in the soil. Enrichment factor of various heavy metals for soil was in the order Ni > Cr > Cd > Zn > Cu, and for A. esculentus plants, it was in the order Ni > Cr > Cu > Cd > Zn after irrigation with distillery effluent. The enrichment factor value was found maximum for Ni in comparison to other metals at 100 % DE concentration as compared with BWW. However, the values of these metals were below the recommended permissible limit.     

Comparative assessment of essential and heavy metals in fruits from different geographical origins

The aim of this investigation was to estimate and compare essential and heavy metals contents in 98 commercially available fresh fruits from different geographic regions using multivariate techniques. The concentrations of 12 elements (calcium, magnesium, potassium, sodium, phophorus, cobalt (Co), manganese, iron, chromium (Cr), nickel (Ni), zinc and copper) were determined using flame atomic absorption spectrometry with deuterium-background correction. Phosphorus was determined in the form of phosphomolybdate by a spectrophotometric method. Reliability of the procedure was checked by analysis of the certified reference materials tea (NCS DC 73351), cabbage (IAEA-359) and spinach leaves (NIST-1570). Recoveries of the elements analysed varied between 85.5 and 103 %, and precisions for the reference materials were 0.13–6.08 %. Based on recommended dietary allowance and adequate intake estimated for essential elements, it was concluded that accessory fruits such as pineapples, raspberries and strawberries supply organism with the highest amounts of bioelements. Although accessory fruits were also found to be the greatest source of Ni among all the analysed fruits, in all the fruits Ni was more abundant than Cr and Co. Significant correlation coefficients (p?<?0.001, p?<?0.01 and p?<?0.05) were found between concentrations of some metals in fresh fruits. Application of ANOVA Kruskal–Wallis test and multivariate techniques such as factor analysis and cluster analysis enabled us to differentiate particular botanical families and types of fruits.     

Heavy metal concentration in deepwater rose shrimp species (Parapenaeus longirostris,Lucas, 1846) collected from the Marmara Sea Coast in Tekirdağ

Zn, Cd, Cr, Hg, As (total), Cu, Pb, and Ni levels of the deepwater rose shrimp (Parapenaeus longirostris, Lucas 1846), which were collected from the Tekirda? coast of the Marmara Sea, were evaluated. The Marmara Sea is the recipient of discharges from both land-based sources and the Black Sea Bosphorus stream. There are large numbers of anthropogenic activities in the coastal region of the northern Marmara Sea that include urban effluent, discharges from touristic resorts, agricultural runoff, fishing, and transportation. Heavy metal contamination of water resources may cause critical health problems for the people living around these water bodies. In deepwater rose shrimp (P. longirostris), the highest concentration level detected for Zn was 22.4?±?24.4 mg/kg in winter 2012, Cd 0.106?±?0.01 mg/kg in summer 2012, Cr 0.77?±?0.05 mg/kg in winter 2012, Hg 0.18?±?0.04 mg/kg in summer 2011, As 9.93?±?1.4 mg/kg in spring 2012, Cu 25.48?±?0.3 mg/kg in winter 2012, Pb 2.12?±?0.8 mg/kg in spring, and Ni 19.25?±?7.1 mg/kg in spring. The values of heavy metal analysis were compared to both the Turkish Food Codex (TFC) limits and international standards for human consumption. The Pb, As, and Cu levels were found to be higher than the maximum allowable limits.     

Reference values for heavy metals in soils of the Brazilian agricultural frontier in Southwestern Amazônia

Guideline values are used to identify polluted or contaminated areas based on background values. Brazilian law establishes three guideline values for pollutants: a quality reference value (QRV), a prevention value, and an intervention value. Reference values refer to the natural concentration of an element or a substance in soils that have not been modified by anthropogenic impacts. These values inform assessments of soil quality and are used to establish maximum permissible limits. The objective of this study was to determine the natural levels and reference values for Cd, Co, Cr, Cu, Ni, Pb, and Zn in samples from the surface layer (0–20 cm) of 19 representative soils of the states of Mato Grosso and Rondônia, on Brazil’s agricultural frontier. Pseudo-total metal concentrations were obtained following microwave-assisted digestion using the aqua regia and EPA3051 methods. QRVs were calculated for each element as the 75th and 90th percentiles of the frequency distribution of the data. Natural levels of heavy metals in the soil samples followed the order: Cr?>?Zn?>?Cu?>?Co?>?Pb?>?Ni?>?and Cd (aqua regia) and Cr?>?Co?>?Cu?>?Pb?>?Zn?>?Ni?>?Cd (EPA3051). These values are generally lower than those reported in the Brazilian and international literature, which highlights the importance of establishing reference values for each state or for each soil type, taking into account the geomorphological, pedological, and geological diversity of the region under study.     

Preconcentration of metal ions through chelation on a synthesized resin containing O, O donor atoms for quantitative analysis of environmental and biological samples

Nascent Amberlite XAD-4 has been used as the polymeric support for the synthesis of a stable extractor of metal ions, by incorporating phthalic acid through azo bridging. Elemental analyses and infra-red spectral and thermal studies were carried out for its characterization. The water regain value and hydrogen ion capacity were found to be 12.50 and 5.75 mmol g^?1, respectively. The optimum pH range for the maximum sorption of Ni(II), Mn(II), Cu(II), Zn(II), Cd(II), Cr(III), and Co(II) was observed at pH 5.5–8.0 with the corresponding half-loading time (t _1/2) of 9, 5, 9, 9, 3, 9, and 5 min, respectively. The preconcentration factor for Ni(II), Mn(II), Cu(II), Zn(II), Cd(II), Cr(III), and Co(II) are 190, 190, 190, 180, 180, 160, and 160, with the corresponding limit of preconcentration in the range of 5.25–6.25 μg L^?1. The detection limits, for flame atomic absorption spectrophotometry, were found to be 0.62, 0.60, 0.65, 0.75, 0.72, 0.84, and 0.85 μg L^?1, respectively. Method has been successfully applied to the analysis of water samples, multivitamin formulations, infant food substitutes, hydrogenated oil, and fishes.     

Seaweeds as bioindicators of heavy metals off a hot spot area on the Egyptian Mediterranean Coast during 2008–2010

Concentrations of Cu, Zn, Cd, Pb, Ni, Co, Fe, Mn, and Hg were measured successively in water, sediments, and six macroalgal species belonging to three algal classes during 3 years (2008–2010) from Abu Qir Bay, Alexandria, Egypt: Chlorophyceae (Enteromorpha compressa, Ulva fasciata), Phaeophyceae (Padina boryana), and Rhodophyceae (Jania rubens, Hypnea musciformis, Pterocladia capillacea). The study aimed to assess the bioaccumulation potential of the seaweeds, as well as to evaluate the extent of heavy metal contamination in the selected study site. Metals were analyzed using atomic absorption spectrophotometry coupled with MH-10 hydride system. The obtained data showed that the highest mean concentrations of Cu, Zn, Fe, and Mn were recorded in E. compressa; Cd, Ni, and Hg exhibited their highest mean concentrations in P. boryana, while Pb and Co were found in J. rubens. Abundance of the heavy metals in the algal species was as follow: Fe?>?Mn?>?Zn?>?Pb?>?Ni?>?Co?>?Cu?>?Cd?>?Hg. E. compressa showed the maximum metal pollution index (MPI) which was 11.55. Bioconcentration factor (BCF) for the metals in algae was relatively high with a maximum value for Mn. The Tomlinson pollution load index (PLI) values for the recorded algal species were low, which ranged between 1.00 in P. boryana and 2.72 in E. compressa. Enrichment factors for sediments were low fluctuating between 0.43 for Hg to 2.33 for Mn. Accordingly, the green alga E. compressa, brown alga P. boryana, and red alga J. rubens can be nominated as bioindicators. Based on MPI and PLI indices, Abu Qir Bay in the present study is considered as low-contaminated area.