Refine search
Results 1-3 of 3
Ash Leaching of Forest Species Treated with Phosphate Fire Retardants
2009
Liodakis, Stylianos | Tsoukala, Magdalini
The chemical, mineralogical, and leaching behavior of three dominant Greek forest species ashes (Pinus halepensis, Pistacia lentiscus, and Olea europaea), before and after treating forest species with diammonium phosphate (DAP) 5% and 10% weight to weight, have been studied using a new five-step shake leaching method at pH = 6. For the analysis of ashes (prior and after leaching) and leachants, the following analytical techniques were used: atomic absorption spectroscopy, X-ray diffraction, and scanning electron microscopy with energy dispersive X-ray fluorescence analysis. The presence of DAP obstructs the extraction process of some metal ions (i.e., Na, K) contained in ashes by converting the soluble carbonate salts to the less soluble phosphates (i.e., Na₂CO₃ [rightward arrow] Na₃PO₄). On the contrary, DAP enhances the mobility of some other metals (i.e., Ca) by forming more soluble compounds [i.e., CaCO₃ [rightward arrow] Ca₃(PO₄)₂]. In addition, the presence of DAP lowers the pH of leachates, causing dissolution of some toxic elements (i.e., Mn, Pb, Zn). Unexpectedly, DAP prevents the leachability of Cr from ash. The above study concerns the environmental effects (soil and ground and underground water streams) caused by the use of chemical retardants on forest fires.
Show more [+] Less [-]Quantitative Comparison of Heavy Metals and As Accumulation in Agricultural and Forest Soils near Bowling Green, Ohio
2009
Neupane, Ghanashyam | Roberts, Sheila J.
Soil samples from agricultural and adjacent forest soils in Northwest Ohio were collected and analyzed for As, Cr, Cu, Ni, Pb, and Zn. pH, Eh, electrical conductivity, and moisture content were also measured. Selected samples were also evaluated for grain size and X-rayed to identify clay minerals. In this region, soils contain a large proportion of fines (~32% clay and ~37% silt) with illite, dickite, and chlorite as the main clay minerals. Surface soils in the arable land are slightly acidic (pH ~5.6) while forest soils are near-neutral to slightly basic. All soils become more basic with depth. Soil Eh and electrical conductivity range from 300 to 450 mV and 100 to 375 μS, respectively. In the soil profiles, between 0 and 50 cm depth, As increases from 4.6 to 11 mg/kg, Cr increases from19 to 23 mg/kg and Ni increases 21 to 29 mg/kg. In contrast, Cu decreases from 23 to 17 mg/kg and Pb decreases from17 to 10 mg/kg. Surface enrichment of Cu and Pb can be the result of aerosol deposition, while the downward increase in As, Cr and Ni is related to pedogenic variation. The average concentration of Zn in the samples is 64 mg/kg and does not change with land-use or depth. With the exception of As, the concentration of metals in the agricultural soil is not significantly different from the concentration in forest soil. The concentration of As in the near-surface arable soil (5.6 mg/kg) is significantly different from the concentration of As in the near-surface forest soil (4.3 mg/kg). In both cases, deeper soils have similar As contents. The relative enrichment of As in the surface arable soil could indicate input from herbicides or pesticides. The upward increase in electrical conductivity is interpreted to show that the exchangeable fraction of each metal is higher in the surface soils. However, the near neutral pH and organic, clay-rich soils may limit the mobility. The concentration of these heavy metals and As in the soils are much lower than the limits set by the United States Environmental Protection Agency.
Show more [+] Less [-]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 [-]