An assessment of heavy metal pollution in the East London and Port Elizabeth harbours

The distribution of heavy metals (zinc, cadmium, copper, iron, manganese and lead) was investigated in seawater and in sediment samples from the East London and Port Elizabeth harbours. Both are ports of major importance to the area. The aim was to assess the impact of potential pollution sources, mainly from the cities' formal disposal to the sea, from industry and from dockyard and shipping activities around the harbour. At the East London harbour, metal concentrations in sea water range from 0.2 to 72.0 mg·ℓ-1 for Cd, from 0.6 to 42.6 mg·ℓ-1 for Cu, from 2.4 to 183.0 mg·ℓ-1 for Fe, from 0.6 to 16.3 mg·ℓ-1 for Pb, from 0.9 to 23.9 mg·ℓ-1 for Mn and from 0.5 to 27.6 mg·ℓ-1 for Zn. In sediments, metal concentrations using the total digestion method range from 0.12 to 1.63 mg·g-1 (dry weight) for Cd, 12.7 to 183.0 mg·g-1 (dry weight) for Cu, 1046.0 to 18 114.0 mg·g-1 (dry weight) for Fe, 3.2 to 84.2 mg·g-1 (dry weight) for Pb, 87.4 to5 49.0 mg·g-1 (dry weight) for Mn, 26.1 to 332.0 mg·g-1 (dry weight) for Zn. In the Port Elizabeth harbour, the concentration of metals in seawaters varied between 0.3 mg·ℓ-1 and 4.0 mg·ℓ-1 for Cd, between 0.5 mg·ℓ-1 and 11.3 mg·ℓ-1 for Cu, between 3.7 mg·ℓ-1 and 21.9 mg·ℓ-1 for Fe, between 0.6 mg·ℓ-1 and 4.2 mg·ℓ-1 for Pb, between 0.7 mg·ℓ-1 and 16.8 mg·ℓ-1 for Mn and between 0.7 mg·ℓ-1 and 16.2 mg·ℓ-1 for Zn. In sediments, values of metals also using the total digestion method ranged from 0.1 to 1.4 mg·g-1 (dry weight) for Cd, from 8.6 to 82.3 mg·g-1 (dry weight) for Cu, from 4219.0 to 15 182.0 mg·g-1 (dry weight) for Fe, from 9.0 to 61.9 mg·g-1 (dry weight) for Pb, from 103.0 to 499.0 mg·g-1 (dry weight) for Mn and from 18.8 to 126 mg·g-1 (dry weight) for Zn. The results are indicative of the contribution of heavy metal pollution from storm water drains and streams which carry runoff from industrial, urban and residential sources. Ship repair activities are also suspected to be responsible for elevated concentrations in the upper reaches of the harbour. WaterSA Vol.27(2) 2001: 233-24

Dynamics of zinc sorption from aqueous matrices using plantain (Musa sp.) peel biomass

The influence of climate change on freshwater resources has undoubtedly affected the availability and quality of freshwater resources. However, the demand for water for agricultural, domestic, industrial and recreational purposes increases by the day globally. The need for remediation and reuse of large volumes of industrial wastewaters being generated globally therefore cannot be over-emphasized. The potential ability of plantain peel (Musa sp.) biomass to remove metal ions (Zn2+) from aqueous matrices was studied. Influence of contact time, adsorbent weight, pH, metal concentration, temperature and shaking speed were investigated. Physico-chemical characterization (proximate and infra-red spectroscopic analyses) of the biomass was carried out to elucidate information on adsorption mechanisms. Desorption studies were also performed to determine possible recovery potential of Zn2+ and the re-usability of the biomass. Zn2+ adsorption increased with increasing metal concentration in solution, adsorbent weight and contact period. Optimal pH value for adsorption was 3 after which Zn2+ uptake decreased. Corresponding values for contact time, biomass weight and Zn2+ concentration were 150 min, 24 g/L and 600 mg/L, respectively. Experimental data fitted into Freundlich’s isotherm. Carboxylic and hydroxyl groups were among the prominent functional groups on the surface of the biomass. Desorption of Zn2+ from the biomass was less than 10%. Alternative compounds may be further investigated to improve on metal desorption from plantain peel biomass. This cannot be over-emphasized if the several advantages of this biomass (lesser cost than for synthetic resins, abundance and biodegradability) will be utilized for industrial applicability especially in emerging economies like Africa.Key words: Adsorption, zinc, isotherms, waste utilization, wastewaters

Determination and distribution of polycyclic aromatic hydrocarbons in rivers, surface runoff, and sediments in and around Thohoyandou, Limpopo Province, South Africa

Water quality in rural areas is affected adversely by build-up of traffic-generated organic compounds on road surfaces, leading to their presence in water runoff and sediments. Characterising these compounds is a first step in developing measures for the removal of such pollutants from water courses. In this study, liquid-liquid extraction of water samples from several rivers and surface run-off enabled quantification of major PAHs. Soxhlet extraction of sediment samples was followed by clean-up of samples using column chromatography. The PAHs were quantified by gas chromatography. In water and sediment samples, 6 PAHs were identified and quantified. In river water samples, individual PAH levels ranged between 0.1 µg/. and 137 µg/., while in sediment samples levels ranged between 17.9 µg/kg and 9870 µg/kg. For surface run-off, levels ranged between 0.6 µg/. and 2 500 µg/. for water samples and between 112 µg/kg and 34 400 µg/kg for sediment samples. Total levels of PAHs in sediment samples were relatively high (111.6 to 61 764 µg/kg) compared to those in water from both river and surface run-off (29.2 to 3 064.8 µg/.), and PAH levels in surface runoff were much higher than in river waters, implicating tarred roads and parking lots as main point sources of PAHs. PAH ratios also indicate that the PAH content of runoff and sediment is more likely due to pyrogenic sources, i.e. vehicle emissions, although petrogenic sources (mainly oil spills) also play an important role. Toxic Equivalence Quotient (TEQ) values in river and runoff waters ranged from 0.10 to 4.03 µg/. and for sediments the TEQ ranged from 0.50 to 272.23 µg/kg. These results are of concern, as the calculated TEQ is likely to be an underestimate of the actual TEQ, since only 6 PAHs with relatively low toxicities were analysed. Long droughts and low rainfall, and washing of automobiles in and near the rivers are important factors which may have contributed to the observed levels of PAHs in both river water and sediments.Keywords: Polycyclic aromatic hydrocarbon, river water, runoff, sedimen

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

An assessment of the levels of phthalate esters and metals in the Muledane open dump, Thohoyandou, Limpopo Province, South Africa

<p>Abstract</p> <p>Background</p> <p>This work reports the determination of the levels of phthalate esters (dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), diethyl hexyl phthalate (DEHP)) and metals (lead, cadmium, manganese, zinc, iron, calcium) in composite soil samples. The soil samples were collected randomly within the Muledane open dump, Thohoyandou, Limpopo province, South Africa. Control samples were collected about 200 m away from the open dump. The phthalate esters were separated and determined by capillary gas chromatography with a flame ionization detector, whilst the metals were determined by atomic absorption spectrophotometry.</p> <p>Results</p> <p>Open dump values for the phthalate esters and metals to be generally higher in comparison to control samples for DMP, DEP, DBP and DEHP – the mean values calculated were 0.31 ± 0.12, 0.21 ± 0.05, 0.30 ± 0.07, and 0.03 ± 0.01 mg/kg, respectively, for the open dump soil samples. Nonetheless, the mean open dump values for lead, cadmium, manganese, zinc, iron and calcium were 0.07 ± 0.04, 0.003 ± 0.001, 5.02 ± 1.92, 0.31 ± 0.02, 11.62 ± 9.48 and 0.12 ± 0.13 mg/kg, respectively. The results were compared statistically.</p> <p>Conclusion</p> <p>Our results revealed that the discarding of wastes into the open dump is a potential source of soil contamination in the immediate vicinity and beyond, <it>via </it>dispersal. Increased levels of phthalate esters and metals in the soil pose a risk to public health, plants and animals. Sustained monitoring of these contaminants is recommended, in addition to upgrading the facility to a landfill.</p

Determination of Phthalate Esters in the Aquatic Environment

The use of solid phase extraction and capillary GLC provides the basis for selective determination of phthalate ester plasticizers in rivers and marine water samples. Of the several solvent ratios (methanol in dichloromethane) that were tried for selective elution of phthalate esters from the C18 solid phase glass catridge, the 50/50 ratio, CH3OH in CH2Cl2 (v/v) gave the best result. The method was tested on river and marine water samples that receive effluent from industries that use phthalate esters. The rivers and marine water samples are grossly polluted as several phthalate esters, for example, dimethyl(DMP), diethyl(DEP), dibutyl(DBP) and diethylhexyl(DEHP) were found present at 0.03 – 2 306 ± 9.4 m gl-1. A study on uncontaminated water was done to establish bank levels. South African Journal of Chemistry Vol.54 2001: 69-8

Assessment of the phytoremediation potential of Panicum maximum (guinea grass) for selected heavy metal removal from contaminated soils

Non-vascular plants have potential for rapid uptake of metals, but are rarely used for phytoremediation because of their short life cycle. This property can however be advantageously used in a number of metal removal cycles within a short time. The selection of promising plants is critical to success of phytoremediation. The potential for heavy metal uptake by Panicum maximum a non-vascular plant was investigated using pot plant experiments. Seventy-two (72) pots of 7 L capacity were each filled with 5 kg of mixed soil collected from the Fadama (fertile soil) and College of Animal Sciences and Livestock Production farms (less fertile) of the University of Agriculture Abeokuta, Ogun State Nigeria. The pots were divided into six groups of twelve pots each. Each of the group of 12 pots was further divided into three groups of four pots each, in which P. maximum were planted. Five of the six groups were treated with 20, 50, 75, 100 and 120 ppm each of Pb2+, Cr3+ and Cd2+ and the sixth served as control. Levels of Pb2+ decreased from 1.40 to 1.05 µg/g and 1.57 to 1.30 µg/g in soils treated with 20 and 120 ppm of Pb2+, respectively. Generally there was increase in Pb2+ uptake by the different tissues of P. maximum ranging between 0.21 to 0.38 µg/g, 0.18 to 0.30 µg/g, and 0.09 to 0.18 µg/g in root, stem and foliage, respectively. Corresponding bioaccumulation factors (BAF) ranged between 0.21 to 0.45, 0.17 to 0.35 and 0.08 to 0.21. Metal uptake followed similar trends for Cr3+ and Cd2+ in plant tissues. The BAF values for Cr3+ ranged between 0.31 to 0.69 in root, 0.17 to 0.52 in stem and 0.07 to 0.34 in foliage. Similar values for Cd2+ were 0.14 to 0.53, 0.10 to 0.44 and 0.05 to 0.37. Accumulation of heavy metals in P. maximum ranged from 13 to 45%, Pb2+; 13 to 65%, Cr3+ and 11 to 52%, Cd2+ of the soil concentration level with tissue abundance decreasing in the order Cr3+ &gt; Pb2+ &gt; Cd2+. Furthermore, the concentration of metals in P. maximum tissues decreased in the order root &gt; stem &gt; foliage. The phytoremediation of Pb2+, Cr3+ and Cd2+contaminated soils with P. maximum seems to be promising under the conditions of the experiment. Obvious signs of phyto-toxicity however appeared in plants exposed to 120 ppm Pb2+ and Cd2+ at day twenty-three, suggesting that P. maximum may be a moderate metal accumulator.Keywords: phytoremediation, heavy metals, uptake, tissues, accumulatorAfrican Journal of Biotechnology, Vol 13(19), 1979-198

Effect of coagulant treatment on the metal composition of raw water

This study reports the results of an investigation on the use of two coagulants, namely Al2 (SO4)3 and Fe2 (SO4)3 which were investigated for their capabilities to reduce the metal levels of raw river water samples when treated. Generally, the percentage removal of the metals from raw water samples increased with mg/l dosage of either coagulant used. Although both coagulants were efficient in removing Cr and Ni, generally Fe2 (SO4)3 was proved to be the more efficient coagulant for the removal of all the metals studied. Fe2 (SO4)3 was 89.58% efficient in removing Cr and 99.73% efficient in removing Ni. It was 68.42% efficient in removing Zn, 40.14% efficient in removing Mn and 35.29% efficient in removing Cd (all at 13 mg/l dosage of coagulant). Judging from these results and taking into consideration the potential health threat to man from the possible Al contamination of treated water from the use of aluminium-based coagulants, the use of Fe2 (SO4)3 as coagulant in water treatment for the removal of suspended matter was preferred and would be highly recommended. WaterSA Vol.28(3) 2002: 293-29

Levels of Cd, Hg and Zn in some surface waters from the Eastern Cape Province, South Africa

Total trace metals levels - Cd, Hg and Zn, which may affect human health and the "health" of the aquatic ecosystem, were determined in the Umtata, Buffalo, Keiskamma and Tyume Rivers and in the Sandile and Umtata Dams. These elements were also determined in sediment samples from some of these surface waters. Normal levels of the metals were detected in water samples from the Umtata River and the Umtata Dam but samples from Buffalo, Keiskamma and Tyume Rivers contained elevated levels of Cd. Generally the levels of Hg and Zn were normal in samples from all the surface waters. The probable sources of the metals in the rivers are diffuse, originating from rural and urban runoff and from agricultural runoff in the catchments although there could be contribution from natural and point sources. Water SA Vol.29(4): 375-38