Heavy metals contamination of Chrysichthys nigrodigitatus and Lates niloticus in Ikere Gorge, Oyo state, Nigeria

This study investigates the presence of heavy metal contamination of Chrysichthys nigrodigitatus and Lates niloticus. Adult C. nigrodigitatus and L. niloticus were obtained from fishermen in Ikere Gorge, Oyo state, Nigeria. Water samples were also collected during the wet and dry seasons of the year in the same locality. The presence of five metals were analyzed in both fish and water. Iron, copper, zinc, lead and manganese were investigated by atomic absorption spectrosocopy (AAS) in two separate experiments. In each case, four tissues; gills, bone, intestine and muscle were compared with the level of metals in the water. Lower concentrations of metals were recorded in water than in fish. Lower concentration of the metals found in fish and water was less than that recommended by the World Health Organisation (WHO) guideline for maximum concentration recorded in the tissue of the two samples. Iron was found to be dominant in the intestine of C. nigrodigitatus, while manganese was found to be highest in the bone of L. niloticus, copper recorded the least of all the metals. There is significant difference (P < 0.05) in heavy metals concentration in the gill of C. niloticus and water, as well as the concentration in the intestine of L. niloticus and water. It was concluded that though the heavy metals of interest were present in measurable quantities, they were still within safe limits for consumption.Key words: Heavy metals, fish, gorge, contamination

Variation in levels and removal efficiency of heavy and trace metals from wastewater treatment plant effluents in Cape Town and Stellenbosch, South Africa

This study focused on one year monitoring campaign to monitor the occurrence and removal of Endocrine Disruptive Metals (EDMs) and trace metals from selected wastewater treatment plants (WWTPs) in Stellenbosch and Cape Town. Composite water samples were collected from the WWTPs from January 2010 to December 2010 on a quarterly basis and concentrations determined using inductively coupled plasma-mass spectrometry (ICP-MS) after open beaker digestion. A total of 432 water samples consisting of raw, primary effluent, secondary effluent and final effluents were collected and analyzed. The general abundance distribution pattern for metals was Zn > Cu > Pb > Cr > Ni > As > Co > Cd > Hg. The removal efficiency ranged from 1.5% for Hg at Zandvliet WWTP plant during winter to 98.27% for Cu at Athlone WWTP treatment plant during summer. The final effluent concentration for most of the metals were within South African water quality guidelines while As, Hg, Cd and Pb concentration were higher than maximum limits set by the Canadian Council of Ministers of the Environment. Potsdam WWTP showed to be the most effective at heavy metals removal as compared with the other five treatment plants investigated in this study. The effluent metal concentration over time could pose health risk if used for agricultural irrigation.Keywords: Seasonal variation, endocrine disrupting metals, wastewater treatment plants, effluents, coupled plasma-mass spectrometry (ICP-MS), Cape Tow

Method development for simultaneous determination of phthalate and eleven priority phenols as tert-butyldimethylsilyl derivatives in grab samples from wastewater treatment plants using GC-MS in Cape Town, South Africa

Method was developed for the simultaneous determination of 17 classified and suspected endocrine-disrupting compounds (EDCs). Phenol, 2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, 4-chlorophenol, 2,4-dimethylphenol, 2- methyl 4,6-dinitro-phenol, 2-chlorophenol, 2,4-dichlorophenol, 4-chloro-3-methylphenol, pentachlorophenol, dimethyl phthalate, diethyl phthalate, benzylbutyl phthalate, dioctyl phthalate, diethylhexylphthalate and dibutyl phthalate. Qualitative and quantitative analyses were performed by gas chromatography–mass spectrometry (GC–MS) using DB-5MS column. These compounds were evaluated using solid-phase extraction for raw and treated wastewater from a municipal treatment plant. Phenols were derivatized with N-(t-butyldimethylsilyl)-N-methyl-trifluoroacetamide (MTBSTFA) to form their respective t-butyldimethylsilyl derivatives. The extraction recovery range from 73.21 to 101.32% for 2,4,6-TCP and DEHP respectively. The occurrence pattern of phenol is in the order of PCP > 2CP > POH > 2NP > 2M- 4,6 DNP (old plant) and PCP > 2M- 4,6 DNP > POH ≥ 2CP ≥ 2NP for old and new plants respectively. Phthalates ranked as DEP > DBP > DEHP with corresponding values of 2473 ± 991; 2000 ± 236; and 192 ± 127 µgL-1 in the new plant. The average percent removal of analytes range from 54.77 to 89.34% in the two plants investigated

Solid-phase extraction method for the analysis of eleven phenolic pollutants in water samples

An analytical protocol for the determination of priority phenolic compounds: phenol, 2-methyl 4,6-dinitrophenol, 2-chlorophenol, 2,4- dichlorophenol, 2,4,6-trichlorophenol, pentachloro-phenol, 2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, 4-chloro-3-methylphenol, 2,4,6-tribromophenol and 2,4-dimethylphenol, in water samples using strata C18 cartridge is presented. Different parameters affecting extraction and peak separation were optimized. Recoveries using spiking of the test compounds varied in the ranged between 69.43 ± 1.76 % and 101.87 ± 0.45 %. The high recoveries obtained validated the method. Detection limits obtained ranged from 4 µg L-1 for 2,4- dimethylphenol to 166 µg L-1 for 4-nitrophenol, using LC-UV. The results obtained by applying the developed method to real environmental water sample containing 2,4-dichlorophenol, 2-methyl, 4,6-dinitrophenol, pentachlorophenol and 2,4,6-tribromophenol indicated the following concentration levels: 5.129, 0.561, 4.788 and 0.868 ng µL-1 , respectively.Cape Peninsula University of Technolog

Assessment of selected polybrominated diphenyl ethers and 2,2’, 4,4’, 5,5’- hexabromobiphenyl (BB-153) in bottom sediments of the Kuils River, Cape Town

An assessment of the concentrations of selected polybrominated diphenyl ether (PBDE) congeners as well as BB 153 in leachate samples collected from three landfill sites within the city of Cape Town was conducted. A liquid–liquid extraction technique was employed for the isolation of all the target compounds from the leachate samples. Extracts obtained were further subjected to multi-layer column chromatography employing different forms of silica gel. The prepared samples were analysed using a high capillary gas chromatograph equipped with a micro-electron capture detector (GC-μECD). The overall mean concentrations of the total PBDEs, including BDE 209 ranged between 5.65 and 2,240, 0.28–20.5 and 1.66–1,170 ng/l for Bellville, Coastal Park, and Vissershok landfill sites, respectively. The mean concentrations of BB 153, which were generally low in most of the samples analysed, were 70.4, 7.14 and 8.16 ng/l for Bellville, Coastal Park and Vissershok sites, respectively. The influence of precipitation on the characteristics and quantity of leachate produced from the landfill sites investigated was most pronounced during the August/September sampling regime

Arsenic contamination: Africa the missing gap

Arsenic (As) is becoming a major challenge around the world due to its effect on human health. The World Health Organisation set the standard for As as 10 µg/L but most country do not adhere to this but rather still work with old standard of 50 µg/L. A lot of research has been carried out in different part of the world to determine the level of contamination. Europe has been able to reduce the effect of As to the extent that it is almost non existence. Other continents are also trying to reduce the effect of As and this can be seen from the number of research that has been reported. However, Africa is behind in this regard and not much data can be obtained on As pollution or contamination. There is therefore a need for a thorough monitoring of As in Africa so as to have a true picture of the level of As contamination in Africa