Assessing the bioconcentration of heavy metals in Nypa Palm (Nypa fruticans (Wurmb) from selected mangrove forests in Rivers State, Nigeria

The bioconcentration of Pb, Zn, Cd, Cr and Ni in tissues of Nypa palm (Nypa fruticans) was investigated during wet and dry seasons from selected mangrove forests, using the randomized complete block design. Soil and plant samples were randomly collected from plant dominated growth stations and analyzed for heavy metal content using the Perkin Elmer Analysts 200 Atomic Absorption Spectrophotometer (AAS). The results obtained showed the bio-transfer factors of heavy metals at wet season as Pb (1.08mg/kg), Zn (1.42 mg/kg), Cd (6.14 mg/kg), Cr (0.56 mg/kg) Ni (0.90 mg/kg) and dry season as Pb (0.86 mg/kg), Zn (1.15 mg/kg), Cd (5.44 mg/kg), Cr (0.66 mg/kg), Ni (1.12 mg/kg). The result further showed the bio-translocation factors of the metals at wet seasons as Pb (0.59 mg/kg), Zn (0.76 mg/kg), Cd (3.25 mg/kg), Cr (0.22 mg/kg), Ni (0.54 mg/kg) and dry season as Pb (0.64 mg/kg), Zn (1.03 mg/kg) Cd (3.07 mg/kg), Cr (0.24 mg/kg), Ni (0.61 mg/kg) respectively. Findings indicate the study plant as a hyper accumulator of Ni, Cd and Zn, and non-hyper accumulator of Cr and Pb. It is thus recommended that N. fruticans be utilized for phytoremediation of Ni, Cd and Zn in polluted mangrove ecosystem.

Deriving “potential target values” of PCDD/F in animal feed: the role of livestock at the interface between feed and food chain

Linking derivation of potential target values of PCDD/Fs in animal feed with risk assessment for consumer protection is a challenge when tolerable weekly intake (TWI) and transfer factors from feed to food are considered. Generally, maximum values for feed and food are set separately without considering the feed and the food producing animal as an important factor along the food chain from farm to fork. Levels of contaminants in feed can accumulate in animals and their products effect consumers at the end of the food chain. Hence, the process of setting legal maximum levels of contaminants should account for transfer from feed consumed by food producing animals into animal products for human consumption. Here, we calculated potential target values of PCDD/F in feed to ensure that animal products such as milk from dairy cows, eggs from laying hens and pork and pork products from fattening pigs are safe for human consumption. In our approach, we calculated potential target values of PCDD/Fs in animal feed using transfer factors for PCDD/F-TEQs from feed to milk fat, eggs fat, and fat in pork and pork products, taking into account the tolerable weekly intake derived by European Food Safety Authority. We assumed equal proportions of WHO-PCDD/F-TEQ and WHO-PCB-TEQ in feed. Potential target values of PCDD/F in feed are expressed as the quantity of toxicologically evaluated PCDD/Fs, expressed in WHO toxic equivalents (WHO2005-PCDD/F-TEQ) per kg feed with 12% moisture. In the current approach, derived values would be 10–54 times lower than the current legal maximum level of 0.75 ng WHO2005-PCDD/F-TEQ per kg feed (12% moisture), according to Directive 2002/32/EC as amended.

Catalytic Oxidation of Methylene Blue by Attapulgite/TiO2

Methylene blue (MB) is a common pollutant in wastewater of printing and dyeing industry. At present, ozone oxidation is commonly used in the treatment of printing and dyeing wastewater. Ozone is used for oxidation reaction directly and indirectly. However, the reaction rate is not fast enough. In this study, the attapulgite (ATP) was modified by tetrabutyl titanate-ethanol solution. The TiO2/ATP nanocomposite with high catalytic activity was prepared. The synthesized samples were subjected to characterized by X-ray diffraction (XRD) and Fourier Transform infrared spectroscopy (FTIR). The morphology and particle size of the particles were observed by scanning electron microscopy (SEM). The TiO2/ATP nanocomposite was calcined at 300°C for 2 h, and the degradation rate of 80 mg/L methylene blue was 99.8%. The experimental results show that the ozone, temperature and mass transfer factors are excluded, and the effects of temperature, MB concentration and pH on the degradation of methylene blue are investigated. The optimal reaction conditions are as follows: The ozone concentration is 0.067 g/min; the ozone flow rate is 0.15 NL/min; the stirrer rotation speed is 550 r/min; the catalyst is 0.1 g; the temperature is 50°C; Based on the results, the reaction mechanism was derived and the kinetic study of the experiment was carried out.

Variations of some Metallic Elements in Different Parts of Lingonberries (Vaccinium vitis-idaea L.)

The aim of the research was to evaluate the content of metallic elements in different parts of lingonberries (Vaccinium vitis-idaea L.) depending on their place of growth and evaluate the transfer factor values from between different parts of plants (fine roots, leaves, berries). Obtained results show that there are no significant differences between the content of Fe, Cu, Zn and K, and there are similar element transfer factors between different parts of lingonberries independent from which site the samples are taken.

Soil to Cassava Transfer Factors of Natural Radionuclides in Farms in Ini Local Government Area, Akwa Ibom State, Nigeria

Knowledge of activity concentration of radionuclides in soil of our farmlands and the consequent transfer factors of the radionuclide to plants are necessary to estimate the contamination level of the soil, plants and food. The activity concentration of 40K, 238U and 232Th in soils and cassava in Ini Local Government Area, Akwa Ibom State, Nigeria were measured using gamma spectrometry. Activity concentrations of radionuclides in soils in the locations ranged from BDL (below detectable limit) to 298.76 ± 21.40 Bq/Kg for 40K; BDL to 7.95 ± 1.88 Bq/Kg for 238U and 2.59 ± 0.25 to 16.56 ± 1.61 Bq/Kg for 232Th. Activity concentration of the radionuclides in cassava in all locations ranged from 213.96 ± 15.38 Bq/kg to 520.58 ± 37.25 Bq//Kg for 40K; BDL to 33.02 ± 8.91 Bg/Kg for 238U and BDL to 16.34 ± 1.59 Bq/kg for 232Th. The activity concentrations of all the radionuclides were lower than the world standard. Transfer factors obtained ranged between 3.21 to 4.18 for 40K; 0.93 to 12.64 for 238U and 0.75 to 1.01 for 232Th. Effective ingestion dose due to the consumption of cassava from the studied area obtained ranged between 1.31 to 1.74 mSv/yr and 3.52 to 4.69 mSv/yr for children and adult respectively. These values are above the 1.0 mSv/yr recommended dose limit for general public, therefore the consumption of this food stuff could pose a radiological health effect on humans. However the risk could be minimized when the cassava is cooked.

Nanoscale Zero-Valent Iron Modified by Bentonite with Enhanced Cr(VI) Removal Efficiency, Improved Mobility, and Reduced Toxicity

The aggregation of nanoscale zero-valent iron (nZVI) particles and their limited transport ability in environmental media hinder their application in environmental remediation. In this study, the Cr(VI) removal efficiency, transport performance, and toxicity of nZVI and bentonite-modified nZVI (B-nZVI) were investigated. Compared with nZVI, B-nZVI improved the removal efficiency of Cr(VI) by 10%, and also significantly increased the transport in quartz sand and soil. Increasing the flow rate can enhance the transport of nZVI and B-nZVI in the quartz sand columns. The transport of the two materials in different soils was negatively correlated with the clay composition. Besides, modification of nZVI by bentonite could reduce toxicity to luminous bacteria (Photobacterium phosphereum T3) and ryegrass (Lolium perenne L.). Compared with Fe-EDTA, the transfer factors of nZVI and B-nZVI were 65.0% and 66.4% lower, respectively. This indicated that although iron nanoparticles accumulated in the roots of ryegrass, they were difficult to be transported to the shoots. The results of this study indicate that B-nZVI has a strong application potential in in situ environmental remediation.

Steroidogenic electron-transfer factors and their diseases

Most steroidogenesis disorders are caused by mutations in genes encoding the steroidogenic enzymes, but work in the past 20 years has identified related disorders caused by mutations in the genes encoding the cofactors that transport electrons from NADPH to P450 enzymes. Most P450s are microsomal and require electron donation by P450 oxidoreductase (POR); by contrast, mitochondrial P450s require electron donation via ferredoxin reductase (FdxR) and ferredoxin (Fdx). POR deficiency is the most common and best-described of these new forms of congenital adrenal hyperplasia. Severe POR deficiency is characterized by the Antley-Bixler skeletal malformation syndrome and genital ambiguity in both sexes, and hence is easily recognized, but mild forms may present only with infertility and subtle disorders of steroidogenesis. The common POR polymorphism A503V reduces catalysis by P450c17 (17-hydroxylase/17,20-lyase) and the principal drugmetabolizing P450 enzymes. The 17,20-lyase activity of P450c17 requires the allosteric action of cytochrome b5, which promotes interaction of P450c17 with POR, with consequent electron transfer. Rare b5 mutations are one of several causes of 17,20-lyase deficiency. In addition to their roles with steroidogenic mitochondrial P450s, Fdx and FdxR participate in the synthesis of iron-sulfur clusters used by many enzymes. Disruptions in the assembly of Fe-S clusters is associated with Friedreich ataxia and Parkinson disease. Recent work has identified mutations in FdxR in patients with neuropathic hearing loss and visual impairment, somewhat resembling the global neurologic disorders seen with mitochondrial diseases. Impaired steroidogenesis is to be expected in such individuals, but this has not yet been studied.