Kinetics of radionuclides and heavy metals behaviour in soils: Implications for plant growth

The extent of metal and radionuclide contamination in the world is immense. In soils, metals and radionuclide can be dissolved in solution, or ion exchanged in reaction, complexed with soil organics or precipitate as pure or mixed solids. Soluble contaminants are subject to migration with soil  water, uptake by plants or aquatic organisms or loss due to volatilization. Lead, chromium, zinc, arsenic and cadmium are the most frequently identified inorganic contaminants in soil and ground water. Unlike degradable organic contaminants and ever short-lived radionuclides that can become less toxic over time, metals can be considered conservative. However, many metals, especially radio-sensitive elements such as arsenic and chromium can undergo transformation or sorption reaction that alter both mobility and relative toxicity. This paper therefore, makes a review of these behaviours of radionuclides and heavy metals in soils, in connection to soil contamination and their effects on plant growth

Detoxification of copper fungicide using EDTA-modified cellulosic material

Pesticides are poisons and can be particularly dangerous when misused or carelessly disposed. The detoxification of a copper fungicide (KOCIDE 101) using maize cob, a cellulosic material, was studied. Based on copper as the active agent (after a sorption period of 1 h), the concentration of the fungicide reduced from an initial value of 2000 to 206.25 ppm for the unmodified maize cob and to 24.31 ppm for the modified maize cob. The pseudo-first and second order rate equations were used to model thedetoxification process. The intraparticle diffusivity and mechanism of the sorption was proposed. Also, equilibrium sorption isotherms were evaluated using the Freundlich, Langmuir and Dubinin-Radushkevich isotherm models. This results show that maize cob is an effective adsorbent for copper fungicide deactivation and detoxification

Organophosphate induced chronic neurotoxicity: Health, environmental and risk exposure issues in developing nations of the world

Organophosphate insecticides account for about half of all the insecticides used in the world and have found very wide applications in agriculture and in household vector control. Exposures of human populations to a wide variety of organophosphates have generated profound concerns about theirneurotoxic consequences. Among these concerns are their potential impacts on children and exposures to the neurodegenerative diseases associated with advancing age. This paper therefore tends to make a review of the health, environmental and other risk exposure issues of organophosphates especially in Africa and other developing nations of the world where data abound toshow that many agents considered toxic and banned in many parts of the industrialized world are still in use. This paper also makes recommendations on the way out of this menace

Change in the usual environment and health condition - is there a connection?

Department of patients car

Designing Durable Vapor-Deposited Surfaces for Reduced Hydrate Adhesion

The formation and accumulation of clathrate hydrates inside oil and gas pipelines cause severe problems in deep-sea oil/gas operations. In the present work, durable and mechanically robust bilayer poly-divinyl benzene/poly(perfluorodecylacrylate) coatings are developed using initiated chemical vapor deposition (iCVD) to reduce the adhesion strength of hydrates to underlying substrates (silicon and steel). Tetrahydrofuran (THF) dissolved in water with a wt% concentration of 0–70 is used to study the formation of hydrates and their adhesion strength. Goniometric measurements of the THF–water droplets on the substrates exhibit a reduction in advancing and receding contact angles with an increase in the THF concentration. The strength of hydrate adhesion experiences a tenfold reduction when substrates are coated with these iCVD polymers: from 1050 ± 250 kPa on bare silicon to 128 ± 100 kPa on coated silicon and from 1130 ± 185 kPa on bare steel to 153 ± 86 kPa on coated steel. The impact of subcooling temperature and time on the adhesion strength of hydrate on substrates is also studied. The results of this work suggest that the THF–water mixture repellency of a given substrate can be utilized to assess its hydrate-phobic behavior; hence, it opens a pathway for studying hydrate-phobicity.Chevron Corporation (MIT-Chevron University Partnership Program

Ecotoxicology of arsenic in the hydrosphere: Implications for public health

Arsenic is a naturally occurring metalloid element that is found in soil, air and water. Environmental arsenic exists in both organic and inorganic states. Organic arsenicals are generally considered nontoxic, whereas inorganic forms are toxic. The most acutely toxic form is arsine gas. Inorganic arsenic exists predominantly in trivalent (As3+) and pentavalent (As5+) forms, where trivalent compounds aremore toxic than pentavalent ones. Human activities have also intensified arsenic accumulation in the environment. Organs most susceptible to arsenic toxicity are those involved with absorption,accumulation or excretion, including the skin, circulatory system, gastrointestinal tract, liver and kidney. Arsenic is associated with multiple health effects, including Blackfoot diseases, diabetes,hypertension, peripheral neuropathy and multiple vascular diseases. Other effects include anemia, liver damage, portal cirrhosis, hematopoietic depression, anhydremia, sensory disturbance and weight loss. In addition to acute toxicity, long-term exposure to inorganic arsenic is associated with certain forms of cancer of the skin, lung, colon, bladder, liver and breast. Understanding the ecotoxicological effects of arsenic in the environment is paramount to mitigating its deleterious effects on ecological and human health. This paper is therefore a review of the ecotoxicological effects of arsenic on human and ecological health

Bioaccumulation of heavy metals in some fauna and flora

Bioaccumulation of heavy metals in fauna and flora in the Ijaw area of the Niger Delta of Nigeria were investigated. The fauna-molluscs and crustacea, and flora Hibiscus esculentus and vernonia amygdalina were selected for this study. Results show that Molluscs and crustacea accumulate considerable amounts of heavy metals. Higher levels of all the metals determined Hg, Pb, Cr, Cu, Ni, and Zn were observed in the shells than in the fleshly tissues. Hibiscus esculentus and vernonia amygdalina also accumulated these heavy metals. The mercury levels in the roots of Hibiscus esculentus and vernonia amygdalina is 0.010 μg/g ± 0.00, while the stem 0.17 ± 0.03 μg/g and leaves 0.25 ±0.02μg/g was recorded for the v. amygdalina. The H. esculenta fruit has lead levels of 0.22 ± 0.03 μg/g. The levels of Cu, Ni, and Zn are generally higher than those of Hg, Pb and Cr in all the samples analyzed. There is a growing concern about the physiological and behavioral effects of environmental trace metals in human population. The toxicity of lead at high levels of exposure is well known but of a major concern is the possibility that continual exposure to relatively low levels of these heavy metals through the consumption of these fauna and flora may entail adverse health effects