Toxicologie environnementale et analytique

Recovering of heavy metal ions Zn(II), Cu(II) and Mn(II) in aqueous solution has been investigated using a novel nano silica modified by hemtaprophyrin. Nano sorbent was prepared by sol gel method. Transmission electron microscope and EDAX analysis showed the nano scale with porosity of a new sorbent. The proposed structure of modified silica with HP was predicted according to FTIR and elemental analysis. The new sorbent have good thermal stability. The phenomena of the sorbent sorption included the static studies such as pH and the Langmuir and Freundlish models were applied at equilibrium state. The linear regression analysis was Langmuir isotherm according to the values of relation coefficient (R2). The limit of detection (LOD) for Zn, Cu and Mn were 0.01, 0.12 and 0.03 μg L-1 respectively, within the analytical range 0.1-10 μgL-1. This method achieved highly precision for the samples of environmental and pharmaceutical formulations of % RSD less than 10%.

Eutrophication has become a major water quality problem in most urban landscape waters of the world. Despite extensive research over the last four to five decades, many of the key issues in eutrophication science remain unsolved. In this paper, based on Support Vector Machine (SVM) a new method was proposed to monitor and evaluate the water trophic state of Qujiang South Lake. SVM is suitable for a limited number of samples because of strong nonlinear mapping ability. Model parameters can be automatically chosen by Genetic Algorithm (GA) which contributes to advantages of the Genetic Algorithm- Support Vector Machine (GA-SVM) which has high precision in solving regression problems. Enhanced Thematic Mapper (ETM) data can be used to estimate the chlorophyll-a (Chl-a) concentration of the water body. The characteristic band ratio and SVM method are used to establish a model of Chl-a concentration through remote sensing. The comprehensive eutrophication condition can be evaluated by the remote sensing (RS) results. Results show that the prediction accuracy of the GA-SVM method is better than the retrieval results of the traditional statistical regression method and a neural network. Besides, RS retrieval results corresponded with the in situ measured values, indicating that the GA-SVM is effective. Furthermore, RS data can be free downloaded, so it is also economical than in situ measuring methods. The GA-SVM can also be used to assessment larger lake eutrophication.

Ibeno, the operational base of Mobil Producing Nigeria Unlimited, a subsidiary of ExxonMobil, Nigeria remains one of the most impacted communities by oil and gas activities in the Niger Delta region of Nigeria. Lotic and lentic systems in the region which residents rely on, receive petroleum hydrocarbon inputs almost daily due to oil spills and oily wastes discharges from operators and bunkering activities. This research was carried out to determine the prokaryotic diversity in a remote aviation fuel-polluted lentic ecosystem after 16 years of pollution using metagenomic approaches. DNA extraction from the water samples was carried out using MoBio DNA extraction Kits following the manufacturer’s instructions. Extracted DNA fragments were quantified using picogreen and by recording their UV absorption spectra using NanoDrop spectrophotometer. 16S rDNA sequencing was carried out on a Miseq Illumina sequencing platform and Quantitative Insight Into Microbial Ecology (QIIME) bioinformatics pipeline. Analyses revealed the dominance of bacterial and archaeal communities in both polluted and unpolluted water samples. The polluted sample had 93.83% bacterial and 3.43% archaeal population while the control sample revealed 58.05% bacterial and 39.69% archaeal population. Dominant bacterial phyla from the polluted samples were Proteobacteria, Firmicutes, Actinobacteria, Cyanobacteria, and Chloroflexi while dominant phyla in the unpolluted samples were Proteobacteria, Firmicutes and Actinobacteria. Dominant archaeal phyla from both polluted and unpolluted waters were Euryarchaeota and Crenarchaeota. The use of 16S rDNA metagenomic approach revealed a wide variety of bacterial and archaeal diversity from both polluted and control sites, thus revealing the true ecological status of both sites.

Supply of safe drinking-water is world-wide considered to be an important issue for public health safety and must be the key objective of water supply systems. The aim of this research is to analyze the supply water quality in urban water supply system of Bangladesh. This research was conducted in two Pourashava water supply systems namely Barguna Pourashava and Faridpur Pourashava of Bangladesh. Some concerned chemical, biological and physical parameters were tested for an initial assessment of the water quality of the source water. A total of ten ground water based production well's water samples were examined in those two Pourashava. A total of nine samples, one from each ward were collected form the entry point of the supply water to the user's house were analyzed for E. coli which represented the quality of the piped water. A total of three water samples were collected from each of the ward for microbiological (FC) quality analysis. Millipore microbiological field testing kits was used for E. coli testing, DR 2800 HACH spectrophotometer was used for determination of manganese, iron, and nitrate and Wegtech Digital Arsenator was used for arsenic determination. Physical parameters were tested by HACH potable instruments. The light brown yellowish color created an aesthetic problem among the water users of Barguna Pourashava. In addition, the fecal contamination rate was very high. The findings of E. coli analysis of Barguna Pourashava supply water indicated that 11% have intermediate risk, 37% have high risk and 52% have very high risk considering the health. The water of the production wells of Faridpur Pourashava has high concentration of the arsenic, iron and E. coli. The household's storage water sample analysis result indicated that 48%, 44% and 7% have very high risk, high risk and intermediate risk from the health point of view.

Precipitation forecasts from four Numerical Weather Prediction (NWP) models are evaluated for a case of widespread rainfall event over Central and Southern Nigeria on the 21st of March 2015. The four models evaluated are the European Centre for Medium Range Weather Forecast (ECMWF) with a resolution of 25 km, The UKMET model 20 km, NCEP Global Forecast System (GFS) 50 km and the Weather Research and Forecast Model (WRF) with 10 km resolution. Precipitation forecasts are compared with observed precipitation at station and gridded observation points for different rainfall amount thresholds using the Method of Objective-based Diagnostic Evaluation (MODE), Grid statistics and Point Statistics. The global models ECMWF, UKMET and GFS underestimated the rainfall amount when compared to the WRF regional model. The global models recorded a critical success index (CSI) of less than 10% while the regional WRF model recorded a critical success index of 40% for rainfall amount greater than 25 mm. MODE analysis showed that the WRF model also recorded a 93% relationship between observed and forecast precipitation events of 21st March 2015 over Nigeria when compared with the ECMWF, UKMET and GFS models which showed 88%, 88% and 87% relationship respectively. Our findings suggest that dynamically downscaling a global model using the WRF model added value and gave a better skill of precipitation forecast for the event under study.

The core sample from well QZ-4 is an important climate archive for the central Tibetan Plateau in the middle-late Pleistocene. In this work, a detailed pollen analysis of it is carried out to provide a preliminary insight into the paleoclimate and paleo-altimetry change in the central Tibetan Plateau. It can be concluded that the pollen assemblage can be obviously divided into two pollen zones, Pollen zone I (251.1-314 m in depth, 120.0-345.8 ka BP) and Pollen zone II (200-251.1 m in depth, 105.4-120 ka BP). The paleo-climate during pollen zone I deposition period was comparatively colder and wetter than it was during the pollen zone II deposition period. After Gonghe movement, the center of Tibetan Plateau was uplifted about 300 m (from 3500-3700 m to 3800-4000 m in elevation). The wind was changed from horizontal or downward direction to upward direction, in the study area. In the central of Tibetan Plateau, the climate change seems to be mainly driven by global climate change, and that tectonic uplift may have been a subordinate influence at the middle-late Pleistocene.

The study was conducted to analyze pesticide residues in country bean collected from different areas of Dhaka city from January 2016 to September 2016. A simple and efficient multiple pesticide residue analytical method using Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) extraction technique and Gas Chromatography (GC) coupled with Flame Thermionized Detector (FTD) were used for the determination of pesticide residues in 50 country bean samples. Among the 50 analyzed samples of country bean, 10 samples (20%) contained residues of Dimethoate and Quinalphos, of which 5 samples were above the maximum residue limits (MRLs). Most of the contaminated samples (8 samples) contain residue of Dimethoate. This study reflects the overall scenario of pesticide contamination in vegetables, especially in country bean collected from the local markets of Dhaka city, which will help the consumer to be aware of their health and safety.

Geothermal energy is a green and renewable energy source. There are abundant geothermal resources in Gedong area of Guizhou Province, China. The Geothermal resources are controlled by regional structure. The shape of heat storage is zonal distribution. Inorder to know more about the characteristics of banded thermal reservoirs and provide reference for the development and utilization of banded thermal reservoirs in Qiandongnan area of Guizhou, on the basis of fully understanding the geothermal geological conditions in the Gedong area of Guizhou, the samples of geothermal fluid were collected and the hydrochemistry, hydrogen and oxygen isotopes of regional geothermal water were analyzed. The result shows that regional geothermal water circulation is very deep. The circulation depth of geothermal water is at least 1330 m. Ground water is heated continuously by large geothermal flow during circulation and finally becomes geothermal water. The source of geothermal water supply is meteoric water and its lower limit of recharge height is 926 m. The characteristics of hydrogen and oxygen isotopes of geothermal water in different geothermal wells (Springs) are different, and the main factor is elevation. The chemical composition of geothermal water is controlled by the surrounding rock of geothermal water, the dissolved specific mineral of geothermal water and the circulation of geothermal water are difference. Geothermal water in different geothermal wells (Springs) can be divided into two groups. The division is based on whether geothermal water reaches mineral equilibrium and whether it is mixed with shallow ground water.

Heavy metals may affect human health in diverse ways ranging from cancer, reduced growth and development of nervous system damage, organ damage and in extreme cases, death. This study assessed the hazards of heavy metal based on target hazard quotient (THQ), derived from concentrations of heavy metals in water. Eighty-eight (88) water samples were collected from five sources and analyzed for lead (Pb), chromium (Cr), cadmium (Cd), iron (Fe), manganese (Mn), copper (Cu) and zinc (Zn) using inductively couple plasma and mass spectrometer (ICP-MS). Their health risks were assessed for oral ingestion and dermal absorption. The non-carcinogenic effects of these metals due to ingestion were found to be in a decreasing order: stream water>effluent water>Indian Ocean>Mzingazi river>Esikhawini tap water. Whereas via dermal absorption, the effects decrease in the order: effluent water>stream water>Mzingazi river>Esikhawini tap water>Indian Ocean. Additionally, carcinogenic risks were found to range from 1.03×10-10-6.56×10-7 in effluent water, 1.14×10-8-2.22×10-7 in stream, 55.15×10-11-2.61×10-7 in Indian ocean, 4.07×10-9-1.41×10-7 in Esikhawini tap water and 5.15×10-11-2.71×10-7 in Mzingazi river. The Hazard indexes of these selected metals in effluent water, river, Indian ocean and Esikhawini tap water were found to be less than a unity, indicating an unlikely health risk to the population using water from these sources.

The concentrations of Iron (Fe), Copper (Cu), Zinc (Zn), Lead (Pb), Cadmium (Cd), Chromium (Cr) and Manganese (Mn) in water, sediment and selected fish samples from Ureje water reservoir, Ado Ekiti, were determined using Atomic Absorption Spectrophotometer (AAS). A total of three samples each of water, sediment, fishes (Hemichromis fasciatus and Hepsetus odoe) were collected and analyzed for heavy metals. Data obtained were subjected to analysis of variance (ANOVA) test at 0.05%. The results showed higher levels of Zn (13.08 ± 0.45 mg/g) and Fe (2.10 ± 0.56 mg/g) in fish in comparison with other heavy metals examined. Chromium has exceeded the toxicity threshold in the muscle of the fishes in line with W.H.O standards in food. Cadmium was not detected in soil, while other elements detected were in trace amount below the Environmental Protection Agency allowable limits in soil. In water, except for Fe (1.25 ± 0.02) mg/l, other metals were below allowable limit in water with reference to the World Health Organization’s recommendation. This finding indicates that the water is safe for both aquatic life and man.

The pollution of metals and metalloids in soils caused by industrial activities is a major issue and invests the whole planet earth. The area we investigated is present in the Petrochemical of Porto Torres (Sardinia-Italy), which has an extension of about 1100 ha, is located along the northwest coast of Sardinia, about 1.8 km west of the town and with a surface contamination (0-50 cm depth) from As, Tl and V. The aim of this study is the investigation of spontaneous species present in the areas and the possibility to find some species among those useful to the phytoremediation. We also evaluate (mesocosm) some species that spontaneously live in the Porto Torres area but not on the area under consideration such as Dittrichia viscosa and Piptatherum miliaceum which, according to literature data, showed a good attitude towards phytoremediation. In conclusion, Dittrichia viscosa, Piptatherum miliaceum and Bromus madritensis are good candidates to build a phytoremediation design.

The coal was sampled from No.15 coal seam in coalfield of southeast Shanxi. The Hg, As, Se, Cr and Pb occurrence in coal seam and environmental features of the heavy metal elements of coal were studied by X-ray fluorescence spectrometry (ARL Quant 'X), X-ray diffraction (XRD) and inductively couple-plasma mass spectrometry (ICP-MS). Environmental features, such as heavy metal element concentration, distribution and occurrence mode, etc., were studied by systematic determination of element concentration, inorganic element and mineral composition in coal. The results showed that the coal from No.15 coal seam had the mercury (Hg) concentration between 0.44 and 0.268 μg/g, and average Hg concentration of 0.11 μg/g; arsenic (As) concentration between 0.31 and 0.91 μg/g, 0.61 μg/g on average; selenium (Se) concentration between 0.94 and 3.56 μg/g, 2.45 μg/g on average; chromium (Cr) concentration between 9.54 and 24.58 μg/g, 17.06 μg/g on average; lead (Pb) concentration between 10.23 and 23.56 μg/g, 18.13 μg/g on average. The comparison with the Clark value showed Se was significantly enriched, As and Cr were lost, and Hg and Pb were normal. Compared with the coal from other counties and regions both at home and abroad, as was lost and other elements were normal. The elements irregularly distributed vertically. In spite of different element concentrations in adjacent coal seams, no significant enrichment occurred. The target elements mainly occurred in the form of inorganic matters except As. Hg was mainly concentrated in pyrite and clay minerals. Se, Cr and Pb were mainly concentrated in kaolinite, and Se was mainly concentrated in illite. Because of different occurrences or different forms in one mineral, the Hg, As, Se, Cr, and Pb loss rates were 99.43%, 85.91%, 77.89%, 73.81%, and 68.85% at 815°C, respectively.

This present work investigated surface response modeling and optimization of corrosion inhibition of water hyacinth on mild steel surface in an acidic medium. This was achieved using the central composite design (CCD) experimental design. Response Surface Methodology was used to assess the effects of experimental process variables that influenced rate of corrosion, and for searching of optimum combinations of factors. The rate of corrosion on mild steel surface was study using weight loss method. The optimum process variables obtained from the quadratic model developed were 1.50 g/l inhibitor’s concentration, 8 hours exposure time, and temperature of 60°C with a predicted inhibitor’s efficiency value of 82.89%. The experimental result obtained from optimum value validation was 81.5% and the predicted optimum value was adequately represented. The mild steel corrosion inhibition was achieved through the double bond adsorption of carbonyl group existing in the inhibitor phytochemical constituent.

The objective of this paper is crystallized around the explanation of the energy paradox, that of the non adoption of cost-effective energy-saving investments. The latter is mutually driven by two major factors. Uncertainty future benefits of energy savings, which we assume that they follow a geometric Brownian motion. In this stochastic process, we take into account the lower costs of efficient equipment as a result of learning by doing. To affirm the robustness of the model, we generate simulation results for the case of solar water heaters. The minimum rate of return required by households reached 18.81%. Beyond that, the model allows the simulation of the effects of the instruments of energy policy oriented to the promotion of the adoption of this equipment. We urge policymaker’s ineffectiveness of the policy of subsidy to the purchase of energy-saving equipment and the effectiveness of energy taxation policy. The combination of these two instruments amplifies the adoptions of these devices and generates very positive externalities in terms of energy saving and emission reduction of greenhouse gases.

In the era of increasing environmental pollution, microevolutionary processes occurring in plants inhabiting anthropogenic areas play a special role. With time, these processes may lead to formation of new plant species. A good example of occurrence of microevolutionary processes on anthropogenically altered areas is the metallophyte Biscutella laevigata L. The studies have shown the existence of significant morphological, anatomical and physiological differences between two groups of the B. laevigata populations occurring in Poland – the population of calamine waste heaps in Bolesław near Olkusz (Silesian Upland) and the population inhabiting the Tatra Mountains (Western Carpathians). The demonstrated differences are the adaptation (hereditary characteristics) of the plants to the unfavorable conditions of the calamine waste heap, i. a. high concentration of heavy metals in the soil. The research has also shown theexistence of significant differences between these two groups of populations – both at the genetic and morphological levels (a clonal form of vegetative propagation, removal of heavy metals by the oldest and drying leaves, a zinc tolerant species, trichomes accumulating metals, metal detoxification at the cellular level). The demonstrated differences between the zinc-lead (calamine) waste heap population and the Tatra Mountains population indicate the existence of the new subspecies of Biscutella laevigata subsp. woycickii on the heaps in Boleslaw, in Poland.

Air quality and climatic factors are closely linked through atmospheric chemical reactions and dynamic processes. This work based on a study conducted over an area of industrial plant located in Saudi Arabia during three consecutive weeks with noticeable varying meteorological parameters in the last week of survey with the main objective to examine the role of climatic factors on differences in air pollutant concentration. A systematic analysis of air pollutants including TVOC, CO, SO2, NO2, and O3 and meteorological parameters including temperature, wind speed (WS), and relative humanity (RH) was conducted for a continuous period of 3 weeks from March to mid-April 2015. Acquired results indicate most of observed key air pollutants increase with increase in relative humidity, except NO2, which experiences a decrease in concentrations simultaneous with increasing relative humidity. This survey study suggests that concentrations of TVOC concentrations increase by 201%, CO by 15.2%, SO2 by 21.6% and ozone by 16% as a direct contribution to relative humidity change. While NO2 experiences a decrease by 53.4% as a result of increase in relative humidity. Ozone exhibits only slightly spatial variation due to sudden change of meteorological variables.

Current approaches to risk assessment assume the neurotoxic response for arsenic at the low doses while the mechanism of arsenic-induced developmental neurotoxicity is unknown. Because of this, our previous studies point out that arsenic-induced cholinergic and dopaminergic dysfunctions with associated behavior and also observed the persistent effects were more pronounced in dopaminergic system in early life exposed rats. In continuation of previous studies, rats were exposed to arsenic in drinking water at low doses (2 or 4 mg/kg) during early life. Here, we investigated that alteration in the levels of biogenic amines and their metabolites (norepinephrine (NE), epinephrine (EPN), dopamine (DA), 3, 4-Dihydroxyphenylacetic acid (DOPAC), Homovanillic acid (HVA) and 5-hydroxytryptamine (5-HT) by using reversed phase high performance liquid chromatography in different brain regions of arsenic exposed rats on PD60 as compared to controls and furthermore determine persistent effect of arsenic after withdrawal of exposure. Levels of nitric oxide (NO) were also declines in brain regions of arsenic-treated rats in different brain regions of early life exposed rats. Arsenic has been found to modulate the monoaminergic and nitrergic systems during the critical periods of brain development; however, these modifications get more compromised in corpus striatum than frontal cortex and hippocampus even after withdrawal of exposure on PD90 as compared to controls. Modification at the level of biogenic amines and NO in certain brain regions would provide opportunities for the development of therapeutics tools for minimizing developmental neurotoxicity.

Major aim of the paper is to determine calibration factor for LR 115 type II detectors used to measure indoor 220Rn . To determine calibration factor, LR 115 detectors were fixed on top and bottom inside urban cup chamber and sent to NIRS, Japan to 220Rn calibration exposure. After detectors have been calibration exposure at NIRS, authors carried out following all steps of procedure, which set up at laboratory in INST, Vietnam. This paper discusses the experimental method that is used in calculating the calibration factor of 220Rn inside the urban cup, calibration factors (CF) were determined by experimental with detectors placed at top and bottom inside urban cup were 0.023 ± 0.004 and 0.038 ± 0.007(tracks.cm-2/Bq.m-3.d), respectively. The curve between integrated 220Rn concentration and tracks density with factor R2=0.96 and 0.97 at top and bottom inside urban cup, respectively. In order to precision evaluation, authors used 20 couple of LR-115 detectors at 8cm detector-source distance with relative standard deviation less than 1.48%.

In all global aquatic ecosystems, species composition of micro and macro organisms, abundance, growth, development and their distribution depend on quantity of contaminants, types of contamination; levels of chemical concentrations; sediment load; electrical conductivity; turbidity; seasonal variations; depth, width, flow rate, number of inlets and outlets with volume of water and also the impacts of anthropogenic activities always reflect on the water quality of a wetland. Physico-chemical parameters and planktonic diatoms species composition were studied at five selected sampling stations (C1-C5) along River Kisat from March to August 2016. There are 26 species of planktonic diatoms belong to 13 genus which are Amphora, Aulacoseira, Cyclotella, Cymbella, Diatoma, Fragillaria, Gomphocymbella, Navicula, Nitzschia, Pinnularia, Stephomodiscus Surillela and Synedra. Out of these 26 species, only eight species (Cymbella cistula; Cymbella sp; Diatoma hiemiale; Navicula granatum; Nitzschia lucastris; Nitzschia palea; Nitzchia recta and Nitzschia sub-acicularis) are present in all the five sampling stations, while Fragillaria longissima and Gomphocymbella beccari are present only once in sampling station C4 and C5 respectively. Only genus Nitzschia has five species followed by the genus Aulacoseira represented by three species. There are seven genus which are Amphora, Cyclotella, Cymbella, Diatoma, Fragillaria, Navicula and Synedra represented by two species each, while rest of the four genus including Pinnularia, Gomphocymbella, Surillella and Stephomodiscus are represented only with one species each. The mean monthly values of selected physico-chemical parameters are: electrical conductivity 657.27 ± 186.78 μS/cm, temperature 24.84 ± 0.65°C, pH 7.87 ± 0.24, dissolved oxygen 4.19 ± 0.7 mg/l, turbidity 89.90 ± 9.76 NTU, flow rate 1.38 ± 0.05 km/h; total alkalinity 150.85 ± 28.23 mg/l, total nitrogen 657.27 ± 227.56 μg/l, total phosphorus 677.18 ± 20.87 μg/l, silicates 4.11 ± 0.52 mg/l and chlorophyll-a 130.54 ± 40.15 mg/l. The study revealed that only pH, dissolved oxygen, alkalinity and silicate show significant difference (p ≤ 0.05) along Kisat river but rest of the physico-chemical levels of conductivity, turbidity, total nitrogen, total phosphorus show higher concentrations in river water. It is concluded that the presence or absence of planktonic species and their frequency should be used as bioindicator( s) to assess the status of water quality of any aquatic ecosystem.

Ambient air pollutant has become a major problem in most town in Nigeria. The study aimed at assessing the spatiotemporal variation of abattoir operation on the ambient air quality in Ogbor-hill Aba. The study was carried out within 3 months with emphasis on seven pollutant that originated from abattoir operation at graded distance. From the result, three of the criteria pollutants monitored, SO2, NO2 and PM10 recorded the mean values of 613.25 µg/m3. 699.05 µg/m3 and 1966.67 µg/m3. these exceeded the national ambient air quality standard (NAAQS) by 13%, 14.31% and 76.27% respectively. With a statistical model, the PSI value for the pollutants were found to be SO2 (588.81 µg/m3), NO2 (878.62 µg/m3) and PM10 (585.91 µg/m3) which signifies elevated concentration of pollutant. Further comparisons were made using WHO and FMENV, the result of the pollutants exceeded their approved standards. On subjection to ANOVA, SO2 and NO2 exerted a significant effect at p = 0.01 and PM10 proved significant at p = 0.05. the entire result indicated a very serious health implication on the public especially those with existing health challenges. The high concentration of these pollutants on the ambient air triggers health alters and every one may experience more serious health effect on continuous exposure. To mitigate this emission, the abattoir operators must adopt a hygienic and modern of effluent before disposal. Excess waste can be used for agricultural purposes. Further abatement measures may require the relocation of the abattoir far from residential areas.

Total air suspended particulates (TSP) samples were collected over glass fiber filter and determined gravimetrically. The contents on the glass filter was digested in HF-HCl-HNO3 mixture and the trace elemental analysis of Al, Fe, Mn, and Pb were performed using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) technique, which offers many advantages such as low detection limits, wide linear calibration range and no matrix interference in addition to simultaneous multi-element determination. The filter with TSP was weighted, dissolved in HF-HCl-HNO3 acid mixture and the trace element such as Al, Fe, Mn and Pb were determined using (ICP-OES) technique.

This work was carried out at four sites around Zawia city. Three sampling location were selected on sites of heavy traffics and industrial activities. These sites were (A1) at the center of Zawia city; (A2) near the power station and the refinery; (A3) nearby the main coastal road and (A4 control) at zone where there are no industrial activities or any obvious source of pollution. These samples were collected during Summer, Autumn, Spring, and Winter. The daily variation of TSP during this period showed the lowest value 70 µg/m3 in January (Winter), and the highest value 587.121 µg/m3. This value is relatively high compared with EU limit values (300 µg/m3), USEPA (150 µg/m3), and WHO (150-230 µg/ m3). The mean monthly variation of TSP showed the lowest measured result of 78.28 ± 0.08 µg/m3 in January and the highest value 306 µg/m3 in May. Seasonal variation of TSP showed high results during Spring season which is 239.44 µg/m3 and all other seasons showed lower values of 131.19 µg/m3, 198.28 µg/m3 and 159.85 µg/m3 for Winter, Autumn, and Summer, respectively compared with Spring season. The trace elements levels in TSP were Al>Fe>Pb>Mn. The concentration of Al, Fe, Mn and Pb are lower in site A4 and Al and higher in sites A3 and A2 due to heavy traffic and industrial activities. The meteorological parameters over the study area showed some factors such as wind speed, humidity and temperature that may affect TSP concentrations.

In view of the geological setup and the long-standing mining history of the Gauteng Province, South Africa, it is expected that the mine dumps around the gold mines could contribute to a significant radium (226Ra) concentration in water in Gauteng Province. Radium decays to its daughter radioisotope radon (222Rn) which is a potential source of radiation exposure to the general public. Radon-222 easily escapes from surface of mineral grains and it becomes dissolved in ground water, rivers and dams which are ultimately used by the public. The research study was carried out to determine the effective dose (mSv) to the general public from radioactive (222Rn) in the water from 25 rivers and tributaries in the surrounding areas of Krugersdorp, Johannesburg, Pretoria and Vaal regions.

Water samples were collected from the rivers and analysed in the laboratory at Necsa in Pretoria. An α - spectrometry analysis using a solid-state alpha detector (RAD-7) was optimized to measure (222Rn) in the water by counting α - particles emitted by 218Po and 214Po in secular equilibrium with their parent, (222Rn).

The measured (222Rn) concentrations ranged from 1.4 × 10-1 to 3.56 Bq.l-1 with an average of 1.43 ± 4.3 × 10-1 Bq.l- 1. The average annual effective dose was found to be 4 × 10-3 μSv. The study showed that 222Ra concentration in river water from Gauteng is lower than international acceptable limits cited in the United States Environmental Protection Agency and the World Health Organisation of 1.11 × 10-1 Bq.l-1 and 1.0 × 10-2 Bq.l-1 respectively. The average effective dose is negligible (about 0.32%) as compared to the worldwide average annual effective dose from inhaled 222Rn of 1.26 mSv. Hence, the effective dose of 4 × 10-3 μSv does not pose any health threat to the general public that use water from Gauteng Rivers.

We have described the development of electrochemical nano sensor for the detection of mercury ions from aqueous solutions based on the formation of polyaniline nanoparticle films. Screen printed carbon electrodes were modified with polyaniline nanoparticles. Electropolymerization of polyaniline nanoparticles was performed by the pulsed potentiostatic method. The sample of polyaniline nanoparticles was prepared by repeating the potential step process three times. Structural and morploigcal characterization of polyaniline nanoparticles modified screen printed carbon electrode was performed using Fourier Transmission infrared (FTIR), X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). PANI nanoparticles were spherical shaped having an apparent dimeter varying from 20 to 45 nm. Square wave anodic stripping voltammetry was used for the detection of Hg(II) on PANI NPs modified screen printed carbon electrode under optimized conditions. Hg(II) was deposited for 60 seconds by the reduction of Hg(II) in buffer solution:(citric acid and sodium chloride pH 2.30), followed by Hg stripping between 0.3 and 0.8 V at the following parameters: Scan rate: 100 mV s-1, frequency: 60 Hz, amplitude: 0.025 V and increment: 4.0 mV. it was found that the PANI NPs modified screen printed carbon electrode had a highest anodic stripping peak current in solution of pH 2.30. The limit of detection value for Hg(II) was found to be 2.50 ± 0.03 ppb. The limits of detections determined are below the corresponding guideline value from the World Health Organization (WHO). In addition, the modified nano electrode exhibited excellent reproducibility and high stability. The developed method was successfully applied to determine Hg(II) in real water samples with satisfactory results.

Cereal crops grown under irrigation in a semi-arid ecological habitat can be used to assess food quality and safety of agricultural systems at proximity to highways in the Sudan savannah of Northern Nigeria. This study focussed on the risk assessments of Pb transfer, translocation and uptake at selected growth stages (15-, 30-, 45-, 60-, 75- and 90-days representing seedling or germination, tillering, shooting/booting, earing, flowering and ripening stages respectively of two cultivars of Triticum aestivum L. The experimental (SU 1) and control (SU 2) sites were selected based on distances (345 m and 1936 m) from the Kano-Zaria Highway. Pb levels in soils and the two cultivars of Triticum aestivum L. was measured using the double-beam AAS and plant uptake factors (PUF), soil-plant transfer coefficients (TC) and translocation factors (TF) were worked out. Result reveals differences in metal levels of the cultivars of wheat according to growth stages and plant parts. Pb levels was highly significant (P=0.05 and 0.01) in the stems of Siettecerros at the control site indicating selective ability of cultivar to Pb. Pb levels were highest in both cultivars at the 30-days growth stage indicating sensitivity of tillering stage to Pb uptake. A greater than unity value indicate anthropogenic source of Pb. Siettecerros had the highest TF indicating incorporation of higher levels of Pb in the edible plant parts. A higher PUF (45), TC (6.32) and TF (7.66) for Pb in Pavon-76 and Siettecerros respectively, indicates their suitability for bioremediation particularly, phytoextraction of polluted soils from atmospheric pollutants.