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Reuse of Stormwater for Watering Gardens and Plants Using Green Gully: A New Stormwater Quality Improvement Device (SQID)
2009
Begum, Sharmina | Rasul, M. G
This paper introduces a new stormwater quality improvement device, called the "Green Gully" that collects, purifies, and reuses stormwater throughout an automated system. The working principal of the Green Gully is divided into two parts. Firstly, diverting stormwater from roadways to the diverter channel by filtering litter and secondly, watering the gardens and roadside plants with the stormwater that is collected from diverter channel. Stormwater treatment is an important step before reusing the water for gardening purpose. Different treatment levels (primary, secondary, and tertiary) are applied depending on the application to make water suitable for long-term storage and watering purposes. In this study, stormwater samples from three sites of Rockhampton City have been tested and analyzed to determine the quality of water for reuse. The parameters tested were electrical conductivity, pH, salinity, concentration of oil and grease, total suspended solid, turbidity, alkalinity, sodium, and chloride. The results of on-site stormwater quality tests are compared with the Australian and New Zealand Environment Conservation Council (ANZECC) standards and quality data available in the literature for each parameter suitable for irrigating roadside plants and gardening. Although, the results of this study is comparable with the literature data, a significantly different quality data are found compared to ANZECC standards. However, the samples collected for this study gave a basic understanding of stormwater quality issues for potential inflows to the Green Gully. Further study is recommended in order to establish mathematical link between raw stormwater quality and water quality required for gardening and irrigating roadside plants and for adopting required level of treatment facility with Green Gully for purifying and reusing water through an automated network system.
Show more [+] Less [-]Seasonal differences in mercury accumulation in Trichiurus lepturus (Cutlassfish) in relation to length and weight in a Northeast Brazilian estuary
2009
Costa, Monica Ferreira | Barbosa, Scheyla C. T. | Barletta, Mario | Dantas, David V. | Kehrig, Helena A. | Seixas, Tércia G. | Malm, Olaf
Background, aim, and scope At tropical latitudes, and especially on the semi-arid coasts of the Brazilian Northeast, the rainfall regime governs the water quality of estuaries due to the pronounced difference between the rainy and dry seasons. These changes may be responsible for seasonal changes in bioavailability of mercury (Hg) and other pollutants to the estuarine and coastal biota. Mercury bioaccumulates along estuarine-marine food chains usually result in higher concentrations in tissues of top predators and posing a risk to both marine mammals and humans alike. The Goiana River Estuary (7.5° S) is a typical estuary of the semi-arid tropical regions and supports traditional communities with fisheries (mollusks, fish, and crustacean). It is also responsible for an important part of the biological production of the adjacent coastal waters. Materials and methods Trichiurus lepturus (Actinopterygii: Perciformes) is a pscivorous marine straggler. Fish from this species (n = 104) were captured in a trapping barrier used by the local traditional population and using an otter trawl net along the main channel of the low estuary during two dry seasons (D1 = November, December 2005, January 2006; D2 = November, December 2006, January 2007) and the end of a rainy season (R = August, September, October 2006). Fish muscle samples were preserved cold and then freeze-dried prior to analysis of its total mercury (Hg-T) contents. Total mercury was determined by cold vapor atomic absorption spectrometry (CV-AAS) with sodium borohydride as a reducing agent. Results The studied individuals (n = 104) were sub-adult (30-70 cm, 71 ind.) and adult fish (>70 cm, 33 ind.). Weight (W) (204.1 ± 97.9 g, total biomass = 21,229.7 g) and total length (TL) (63.1 ± 10.1 cm, range 29.5-89.0 cm) presented a significant (p < 0.05) correlation. Two-way ANOVA (n = 81) showed that TL and W had significant differences (p < 0.05) among seasons, being higher in D1 than in D2 and R, respectively. Moreover, season vs. month interaction were detected for the variables length and weight. For the variable weight was detected significant difference for the factor month (p < 0.05). It suggests that the fish enter the estuary at the end of the rainy season and increase in length and weight during the time they spend in the estuary. Fish from this estuary are shown to be fit for human consumption (125.3 ± 61.9 μgHg-T kg⁻¹ w.wt.; n = 104). Fish mercury contents increased with size and weight. Correlations between TL and Hg-T (r = 0.37286) and between W and Hg-T (r = 0.38212) were significant (p < 0.05). Dryer months showed higher mercury concentrations in fish (D1 773.4 ± 207.5 μgHg-T kg⁻¹ d.wt., n = 27; D2 370.1 ± 78.8 μgHg-T kg⁻¹ d.wt., n = 27; R 331.2 ± 138.5 μgHg-T kg⁻¹ d.wt., n = 27). The variable mercury concentration showed differences in relation to the factor season (p < 0.05), where fish captured during the first dry season showed the highest concentration of mercury. The correlation between Hg-T and rainfall (Rf) showed a negative correlation (r = -0.56; p < 0.05). Discussion The main likely source of mercury to this estuary is diffuse continental run off, including urban and industrial effluents. Since concentration of mercury in fish tissue is negatively correlated to rainfall, but positively correlated with fish length and weight, it suggests that fish growth in this estuary results in mercury uptake and concentration on the fish tissue. In the dry season of 2005-2006, when rainfall remained below the historic average, fish bioaccumulated significantly more mercury than in the dry season 2006-2007, when rainfall was within the predictable historic average. It is suggested that less rainfall, and consequently less particulate matter and less primary production in the estuary, make mercury more available to the higher levels of the estuarine food chain. In the case of higher rainfall, when river flow increases and water quality in the estuary is reduced, mercury probably is quickly exported associated to the particulate matter to the adjacent coastal waters where it then disperses. This species is a potential routine bioindicator for mercury contamination of the biota, but so far was used only with a limited number of individuals and contexts. Conclusions Fish from the Goiana River estuary can still be safely consumed by the local population. However, any further contamination of this resource might lead to total mercury levels above the recommended limits for pregnant women and small children. The proposed heavy dependency of total mercury levels in fish on water quality indicates that land use and water quality standards must be more closely watched in order to guarantee that best possible practices are in place to prevent bioaccumulation of mercury and its transfer along the food chain. Human interventions and climatic events which affect river water flow are also playing a role in the mercury cycle at tropical semi-arid estuaries. Recommendations and perspectives T. lepturus is largely consumed by coastal populations of tropical and sub-tropical countries all over the world. It is also consumed by a number of marine mammals over which we have a strong conservation interest. This species is also a link among different ecosystems along the estuarine ecocline. Therefore, knowledge of its degree of contamination might contribute to public health issues as well as marine conservation actions. Studies on mercury and other contaminants using this species as bioindicator (cosmopolitan, readily available) could help elucidating mechanisms through which pollutants are being transferred not only through the food chain, but also from estuarine-coastal-open waters. In addition, using the same species in marine pollution studies, especially as part of a mosaic of species, allows for wide range comparisons of marine food chain contamination.
Show more [+] Less [-]Risk assessment of boron in glass wool insulation
2009
Jensen, Allan Astrup
Background, aim and scope Glass wools are man-made vitreous fibres, which consist principally of sodium, calcium and magnesium silicates, but may contain smaller amounts of other elements, including boron. The boron contents originate from the use of borates in the glass melting process as a glass former and a flux agent. During the production and application of glass wool insulation products, workers may legally be exposed to glass fibre up to the occupational limit value, commonly of 1 fibre/cm³. However, in practice, the fibre exposure will be at least ten times lower. Boron is a non-metallic element widely distributed in nature, where it occurs as boric acid, borates and borosilicates. Humans are mainly exposed to boron via vegetarian food and drinking water, mineral supplements and various consumer products. Boron is an essential element for plant growth, but the essentiality for humans is not proven, although intakes of trace amounts of the element seem to be useful for bone health and proper brain function; higher concentrations of boron, however, may be toxic. In relation to the European Union legislation on dangerous substances, an EU Expert Group has recommended classifying boric acid and borates with risk phrases for reproductive toxicity. The aim of this paper is to assess whether the new EU hazard classification of boron compounds should imply that glass wool products used for building insulation in the future should be labelled, “may impair fertility and cause harm to the unborn child”, because of the low boron content. Materials and methods Boron intakes are estimated in a worst-case occupational situation with human exposure to glass wool fibres at the occupational limit of 1 fibre/cm³ by calculation of the mass of the amount of fibres inhaled during an 8-h work day. Fibres are supposed to be cylinders of glass with a length of 30 μm, an average diameter of 1.5-2 μm and containing either 1.5% or 3.5% boron. As a worst-case scenario, the density of the fibres is set to 2,700 kg/m³. The inhalation rate of the individuals at moderate work load was set to 2 m³/h. A worst-case scenario also corresponds to 100% retention and to 100% solubility of the retained fibres in the lungs. Results With the normal boron content of 1.5% in glass wool fibres for building insulation, the extra daily occupational boron intake/uptake will be 0.03-0.06 mg B for 5 days a week. For more uncommon glass wool with maximum boron content of 3.5%, the worst-case daily boron intake/uptake will be 0.08-0.16 mg B. The main boron exposure in the general population is from vegetarian food, and the average daily dietary intake with food is estimated to 1.2-1.5 mg B/day. In addition, significant intakes may come with drinking water, especially from mineral water. In some instances, exposure from mineral supplements, cosmetics and other consumer products may be significant. For example, individuals taking mineral supplements, e.g. for bodybuilding, may have an additional intake to that of 1-10 mg/day. During the years, various organisations have recommended safe intake values for boron. Recently, the Scientific Panel on Dietetic Products, Nutrition and Allergies of the European Food Safety Authority (EFSA) has established the 'Tolerable Upper Intake Level' (UL) for the intake of boron (boric acid and borates) at 0.16 mg B/kg body weight per day or about 10 mg B/day for an adult. Discussion The calculated, worst-case exposure scenario during an 8-h work day will result in an extra daily boron intake that only corresponds to about 10% of the average daily adult boron intakes through food and drinks of about 1.5 mg. The inter-individual variations in boron intakes from foods, water and supplements will be much greater than an eventual, very worst-case, additional intake of boron from inhalation of glass wool fibres. In addition, the combined intakes are far lower than the 'Tolerable Upper Intake Level' of 10 mg B/day for a person weighing 60 kg, as recommended by the European Food Safety Agency. The potential boron intake from inhalation of glass wool fibres is also much lower than boron intakes by workers in the boron industry, who at the present occupational limit value will be exposed to 50 mg of boron 5 days a week, or 100 times more than the worst case for glass wool fibres. Furthermore, in practice, exposure levels will mostly be ten to 100 times lower than the occupational limit used here as a worst case. Conclusions The estimated boron intake from inhalation of glass wool fibres in occupational settings will be insignificant and without any health risks, even in the case of non-compliance with the occupational limit value. Any proposal requiring hazard labels on commercial glass wool products for building insulation, because of the boron content, is not supported by the present scientific knowledge. Recommendations and perspectives The European Commission should ensure that the new EU hazard classification of boron compounds is not applied to commercial glass wool products for building insulation having a low content of boron.
Show more [+] Less [-]Do heavy metals and metalloids influence the detoxification of organic xenobiotics in plants
2009
Schröder, Peter | Lyubenova, Lyudmila | Huber, Christian
Background, aim and scope Mixed pollution with trace elements and organic industrial compounds is characteristic for many spill areas and dumping sites. The danger for the environment and human health from such sites is large, and sustainable remediation strategies are urgently needed. Phytoremediation seems to be a cheap and environmentally sound option for the removal of unwanted compounds, and the hyperaccumulation of trace elements and toxic metals is seemingly independent from the metabolism of organic xenobiotics. However, stress reactions, ROS formation and depletion of antioxidants will also cause alterations in xenobiotic detoxification. Here, we investigate the capability of plants to detoxify chlorophenols via glutathione conjugation in a mixed pollution situation. Materials and methods Typha latifolia and Phragmites australis plants for the present study were grown under greenhouse conditions in experimental ponds. A Picea abies L. suspension culture was grown in a growth chamber. Cadmium sulphate, sodium arsenate and lead chloride in concentrations from 10 to 500 µM were administered to plants. Enzymes of interest for the present study were: glutathione transferase (GST), glutathione reductase, ascorbate peroxidase and peroxidase. Measurements were performed according to published methods. GST spectrophotometric assays included the model substrates CDNB, DCNB, NBC, NBoC and the herbicide Fluorodifen. Results Heavy metals lead to visible stress symptoms in higher plants. Besides one long-term experiment of 72 days duration, the present study shows time and concentration-dependent plant alterations already after 24 and 72 h Cd incubation. P. abies spruce cell cultures react to CdSO₄ and Na₂HAsO₄ with an oxidative burst, similar to that observed after pathogen attack or elicitor treatment. Cd application resulted in a reduction in GSH and GSSG contents. When a heavy metal mixture containing Na₂HAsO₄, CdSO₄ and PbCl₂ was applied to cultures, both GSH and GSSG levels declined. Incubation with 80 µM arsenic alone doubled GSSG values. Based on these results, further experiments were performed in whole plants of cattail and reed, using cadmium in Phragmites and cadmium and arsenic in Typha as inducers of stress. In Phragmites australis, GST activities for CDNB and DCNB were significantly reduced after short-term Cd exposure (24 h). In the same samples, all antioxidant enzymes increased with rising heavy metal concentrations. Typha latifolia rhizome incubation with Cd and As leads to an increase in glutathione reductase and total peroxidase activity and to a decrease in ascorbate peroxidase activity. Measurements of the same enzymes in leaves of the same plants show increased GR activities, but no change in peroxidases. GST conjugation for CDNB was depressed in both cattail rhizomes and leaves treated with Cd. After As application increased, DCNB enzyme activities were detected. Discussion T. latifolia and P. australis are powerful species for phytoremediation because they penetrate a large volume of soil with their extensive root and rhizome systems. However, an effective remediation process will depend on active detoxifying enzymes, and also on the availability of conjugation partners, e.g. glutathione and its analogues. Species-specific differences seem to exist between the regulations of primary defence enzymes like SOD, catalase, peroxidases, whereas others prefer to induce the glutathione-dependent enzymes. As long as the pollutant mix encountered is simple and dominated by heavy metals, plant defence might be sufficient. When pollution plumes contain heavy metals and organic xenobiotics at the same time, this means that part of the detoxification capacity, at least of glutathione-conjugating reactions, is withdrawn from the heavy metal front to serve other purposes. In fact, glutathione S-transferases show strong reactions in stressed plants or in the presence of heavy metals. The spruce cell culture was a perfect model system to study short-term responses on heavy metal impact. Overall, and on the canopy level, this inhibitory effect might result in a lower detoxification capacity for organic pollutants and thus interfere with phytoremediation. Conclusions We present evidence that pollution with heavy metals will interfere with both the oxidative stress defence in plants, and with their ability to conjugate organic xenobiotics. Despite plant-species-dependent differences, the general reactions seem to include oxidative stress and an induction of antioxidative enzymes. Several processes seem to depend on direct binding of heavy metals to enzyme proteins, but effects on transcription are also observed. Induction of xenobiotic metabolism will be obtained at high heavy metal concentrations, when plant stress is elevated. Recommendations and perspectives Plants for phytoremediation of complex pollution mixtures have to be selected according to three major issues: uptake/accumulation capacity, antioxidative stress management, and detoxification/binding properties for both the trace elements and the organic xenobiotics. By way of this, it might be possible to speed up the desired remediation process and/or to obtain the desired end products. And, amongst the end products, emphasis should be laid on industrial building materials, biomass for insulation or biogas production, but not for feed and fodder. Each of these attempts would increase the chances for publicly accepted use of phytoremediation and help to cure the environment.
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