Short Communication: Conductivity as an indicator of surface water quality in the proximity of ferrochrome smelters in South Africa

South Africa is one of the leading ferrochrome (FeCr) producing countries. One of the main environmental and healthrelated issues associated with FeCr production is the possible generation of Cr(VI). However,  Cr(VI) is not the only potential pollutant that has to be considered during FeCr production. Various water- soluble species are present in FeCr waste materials and in process water. Considering the size of the  South African FeCr industry and its global importance, it is essential to assess the extent of potential surface water pollution in the proximity of FeCr smelters by such watersoluble species. In this study  water conductivity was measured as a proxy of general water quality. Although deposition was not  measured, comparison of surface water results indicated that atmospheric deposition of pollutants  originating from FeCr smelting did not significantly impact surface water quality, but that surface run-off  and/or groundwater leaching were the main contributors. At two FeCr smelters it was observed that these smelters did not impact surface water quality negatively. In contrast, surface water pollution originating from at least four FeCr smelters was apparent. However, only at one smelter did pollution result in surface water conductivity that indicated a water quality not fit for human consumption. No correlations could be made between potable water quality and possible pollution from FeCr smelters.  Not with standing this limitation, it was found that potable water sampled at all sites complied with the conductivity criteria for human consumption.Keywords: surface water, ferrochromium, South Africa, conductivity, elemental composition of total dissolved solids (TDS), potable wate

A survey of Cr(VI) contamination of surface water in the proximity of ferrochromium smelters in South Africa

South Africa holds approximately three-quarters of the world’s viable chromite ore reserves and is one of the largest ferrochrome producers. It is impossible to completely exclude oxygen from all high-temperature ferrochrome production steps, which results in the unintentional possibility of generating small amounts of Cr(VI) species that are generally considered as carcinogenic. In this study, Cr(VI) levels present in surface water within the vicinity of ferrochrome smelters located in the Bushveld Igneous Complex were monitored for a period of 1 year. The results indicated that surface water in the proximity of ferrochrome smelters was mostly unaffected by Cr(VI) pollution. Two surface water sampling sites were consistently impacted by relatively low level Cr(VI) pollution (annual mean values of 4.4 and 6.3 μg/ℓ, respectively), with no values in excess of the 50 μg/ℓ drinking water limit recorded. However, at two other surface water sampling sites, maximum Cr(VI) concentrations of 198 and 220 μg/ℓ were measured. The median Cr(VI) concentrations for these two sites were 1.8 and 1.9 μg/ℓ, respectively, indicating that Cr(VI) pollution of the surface water at these sites was erratic and most likely due to surface run-off. Although drinking water pollution was not the main focus of this paper, results indicated that drinking water in the proximity of most FeCr smelters was not polluted by Cr(VI). However, the annual mean Cr(VI) concentration of drinking water that originated from a borehole at one drinking water sampling site was 45.3 μg/ℓ, with several months exceeding the 50 μg/ℓ limit. Significant steps have, however, already been taken to remedy the situation.Keywords: Cr(VI); hexavalent chromium; surface water; drinking water; South Africa; ferrochromium industr

Cr(VI) formation during ozonation of Cr-containing materials in aqueous suspension – implications for water treatment

Ozonation, or advanced oxidation processes (utilising ozone decomposition products as oxidants) are widely used in industrial wastewater and drinking water treatment plants. In these applications the use of ozone is based on ozone and its decomposition by-products being strong oxidants. In this paper, the possible oxidation of non-Cr(VI) Cr-containing materials suspended in water during ozonation, is presented. This study is of particular interest within the South African context, considering that South Africa holds the majority of global chromium ore resources and has the largest Cr-related industry in the world. Chromium also occurs commonly in other industrial waste materials and is a naturally-occurring element in the crust of the earth. Results indicated that in situ formation of Cr(VI) is possible during aqueous ozonation. pH had a significant influence, since the decomposition products of aqueous O3, i.e. hydroxyl radicals formed at higher pH levels, were found to be predominantly responsible for Cr(VI) formation. Increased ozonation contact time, water temperature and solid loading also resulted in higher Cr(VI) concentrations being formed

Plume Characterization of a Typical South African Braai

To braai is part of the South African heritage that transcends ethnic barriers and socio-economic groups. In this paper, a comprehensive analysis of atmospheric gaseous and aerosol species within a plume originating from a typical South African braai is presented. Braai experiments were conducted at Welgegund – a comprehensively equipped regional background atmospheric air quality and climate change monitoring station. Five distinct phases were identified during the braai. Sulphur dioxide (SO2), nitrogen oxides(NOx) and carbonmonoxide (CO) increased significantly, while ozone (O3) did not increase notably. Aromatic and alkane volatile organic compounds were determined, with benzene exceeding the 2015 South African one-year ambient air quality limit. A comparison of atmospheric PM10 (particulate matter of an aerodynamic diameter ≤10 μm) concentrations with the 24-hour ambient limit indicated that PM10 is problematic during the meat grilling phase. From a climatic point of view, relatively high single scattering albedo (ωo) indicated a cooling aerosol direct effect, while periods with lowerωo coincided with peak black carbon (BC) emissions. The highest trace metal concentrations were associated with species typically present in ash. The lead (Pb) concentration was higher than the annual ambient air quality limit. Sulphate (SO4 2–), calcium (Ca2+) and magnesium (Mg2+) were the dominant water-soluble species present in the aerosols. The largest number of organic aerosol compounds was in the PM 2.5–1 fraction, which also had the highest semi-quantified concentration. The results indicated that a recreational braai does not pose significant health risks. However, the longer exposure periods that are experienced by occupational vendors, will significantly increase health risks.KEYWORDS Braai (barbeque), atmospheric gaseous species, aerosols, atmospheric organic compounds, optical properties, chemical properties

Internet-based interventions for adults with hearing loss, tinnitus and vestibular disorders: protocol for a systematic review

Background: Internet-based interventions are emerging as an alternative way of delivering accessible healthcare for various conditions including hearing and balance disorders. A comprehensive review regarding the evidence-base of Internet-based interventions for auditory-related conditions is required to determine the existing evidence of their efficacy and effectiveness. The objective of the current protocol is to provide the methodology for a systematic review regarding the effects of Internet-based interventions for adults with hearing loss, tinnitus and vestibular disorders. Method: This protocol was developed according to the Preferred Reporting Items for Systematic reviews and Meta-analyses for Protocols (PRISMA-P) 2015 guidelines. Electronic database searches will include EBSCOhost, PubMed and Cochrane Central Register performed by two researchers. This will be complemented by searching other resources such as the reference lists for included studies to identify studies meeting the eligibility for inclusion with regard to study designs, participants, interventions, comparators and outcomes. The Cochrane risk of bias tool (RoB 2) for randomised trials will be used for the bias assessments in the included studies. Criteria for conducting meta-analyses were defined. Discussion: The result of this systematic review will be of value to establish the effects of Internet-based interventions for hearing loss, tinnitus and vestibular disorders. This will be of importance to guide future planning of auditory intervention research and clinical services by healthcare providers, researchers, consumers and stakeholders

The sensitivity of Afromontane tarns in the Maloti-Drakensberg region of South Africa and Lesotho to acidic deposition

<p>Despite their remoteness from sources of atmospheric pollutant emissions, the Afromontane tarns in the Maloti-Drakensberg region are perfect candidates to study the negative effects of acidifying atmospheric pollution, because mountain lakes are widely recognised as sentinel ecosystems, unimpacted by direct human disturbance within their catchments. Thirty-four tarns were sampled in the Maloti-Drakensberg region and most were found to be extremely sensitive to acidic deposition, as indicated by their low acid neutralising capacity. There are very few studies of freshwater critical loads for any region within South Africa. The steady-state water chemistry model (SSWC) was adapted and used to determine critical loads, whereas exceedance was estimated relative to modelled regional deposition data, in order to understand the risk of harmful effects to aquatic ecosystems. Seventy-six percent of sampled sites across the Maloti-Drakensberg would exceed critical loads even at the lowest modelled deposition levels, but there are no current measured deposition data for the region. The sensitivity of the Maloti-Drakensberg tarns needs to be considered in future policy formulation regarding acceptable levels of acidifying atmospheric pollution from South Africa’s energy sector and indicates the need for assessing aquatic ecosystem impacts in other regions of South Africa.</p

Modelling new particle formation events in the South African savannah

Africa is one of the less studied continents with respect to atmospheric aerosols. Savannahs are complex dynamic systems sensitive to climate and land-use changes, but the interaction of these systems with the atmosphere is not well understood. Atmospheric particles, called aerosols, affect the climate on regional and global scales, and are an important factor in air quality. In this study, measurements from a relatively clean savannah environment in South Africa were used to model new particle formation and growth. There already are some combined long-term measurements of trace gas concentrations together with aerosol and meteorological variables available, but to our knowledge this is the first detailed simulation that includes all the main processes relevant to particle formation. The results show that both of the particle formation mechanisms investigated overestimated the dependency of the formation rates on sulphuric acid. From the two particle formation mechanisms tested in this work, the approach that included low volatile organic compounds to the particle formation process was more accurate in describing the nucleation events than the approach that did not. To obtain a reliable estimate of aerosol concentration in simulations for larger scales, nucleation mechanisms would need to include organic compounds, at least in southern Africa. This work is the first step in developing a more comprehensive new particle formation model applicable to the unique environment in southern Africa. Such a model will assist in better understanding and predicting new particle formation - knowledge which could ultimately be used to mitigate impacts of climate change and air quality. © 2014. The Authors