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Johannes Ranke - One of the best experts on this subject based on the ideXlab platform.

  • risk assessment of biocides in roof paint part 1 experimental determination and modelling of biocide Leaching from roof paint
    Environmental Science and Pollution Research, 2008
    Co-Authors: Christian Jungnickel, Frauke Stock, Thomas Brandsch, Johannes Ranke
    Abstract:

    BACKGROUND, AIM AND SCOPE Many surface coatings, including roof paints, contain biocides. It is generally not known to what extent roof paint biocides leach from the paint, and consequently, what concentration the biocide may attain in a rainwater collection system. To this end the Leaching of specific biocides from a variety of German roof paints was investigated and the resulting concentrations in collected rain water were estimated. MATERIALS AND METHODS A laboratory simulation was used to determine the time dependant Leaching rate of the biocide from the paint into synthetic rainwater. The concentrations of biocide in the leachate were quantified using HPLC. The course of the leachate concentrations over time was fitted using a simple mathematical model. This was then used to estimate concentrations of biocides in a typical household rainwater collection system over time. RESULTS Surprisingly, the biocides found in the paints did not always concur with the declared biocides. Concerning the modelling of runoff concentrations, it was found that--under the model assumptions--the rain intensity and cumulative raining time after application are the dominant factors influencing the concentration of the biocide. At the highest modelled rain intensity of 40 mm/hour it only takes about 2 hours to reach peak concentrations lower than 0.1 mg/L, at 0.3 mm/hour it takes about 10 hours to reach peak concentrations of 1.3, 0.9, 5.2 and 1.1 mg/L for terbutryn from Emalux paint, terbutryn from Sudwest paint, carbendazim from Emalux paint, and carbendazim from MIPA paint, respectively. DISCUSSION The results confirm that biocides leached from roof paint will be present in roof runoff. The highest estimated peak concentrations are close to the water solubility of the respective biocides. This indicates that the model assumption of a concentration independent Leaching rate will tendentially lead to an overestimation of the leached concentrations under these circumstances. However, under most circumstances such as higher rain intensities, and longer time after peak concentrations have been reached, the runoff concentrations are far from the solubility limit, and therefore it is proposed that the model assumptions are tenable. CONCLUSIONS The Leaching of biocides from roof paints can be roughly assessed using a relatively simple approach. The declaration of biocidal ingredients in roof paints should be improved and information on their biocide Leaching behaviour should be made available. Furthermore, the estimations should be evaluated by a field Study. RECOMMENDATIONS AND PERSPECTIVES The Leaching Study indicated that the concentrations of selected biocides can reach significant levels, especially after low intensity rainfall. Taking into account the inherent biological activity of the substances under scrutiny, it can already be concluded that it is not advisable to use runoff water from roofs freshly painted with biocide containing roof paints. These results have been complemented by a literature search of biological effects of the investigated biocides, ecotoxicological tests with several species and a risk analysis for organisms exposed to runoff water. This will be presented in Part 2 of this contribution.

Yuangen Yang - One of the best experts on this subject based on the ideXlab platform.

  • acidic Leaching of potentially toxic metals cadmium cobalt chromium copper nickel lead and zinc from two zn smelting slag materials incubated in an acidic soil
    Environmental Pollution, 2018
    Co-Authors: Feili Li, Yuangen Yang
    Abstract:

    Abstract A column Leaching Study, coupled with acid deposition simulation, was conducted to investigate the Leaching of potentially toxic metals (PTM) from zinc smelting slag materials (SSM) after being incubated in an acid Alfisol for 120 days at room temperature. Two SSMs (SSM-A: acidic, 10 yrs exposure with moderate high PTM concentrations versus SSM-B: alkaline, 2 yrs exposure with extremely high PTM concentrations), were used for the incubation at 0.5, 1, 2.5, 5 wt% amendment ratios in triplicate. Five Leaching events were conducted at day 1, 3, 7, 14, and 28, and the Leaching of PTMs mainly occurred in the first three Leaching events, with the highest PTM concentrations in leachate measured from 5 wt% SSM amendments. After Leaching, 2.5, 12, 5.5, 14, 11, and 9 wt% of M3 extractable Pb, Zn, Cd, Co, Cr, and Ni could be released from 5 wt% SSM-A amended soils, being respectively 25, 12, 4, 2, 2, and 2 times more than those from 5 wt% SSM-B amended soils. In the leachates, the concentrations of PTMs were mostly affected by leachant pH and were closely correlated to the concentrations of Fe, Al, Ca, Mg and P with Cd, Pb, and Zn showing the most environmental concern. Visual MINTEQ 3.1 modeling suggested metallic ions and sulfate forms as the common chemical species of PTMs in the leachates; whereas, organic bound species showed importance for Cd, Pb, Cu, and Ni, and CdCl+ was observed for Cd. Aluminum hydroxy, phosphate, and sulfate minerals prevailed as the saturated minerals, followed by chloropyromorphite (Pb5(PO4)3Cl) and plumbogummite (PbAl3(PO4)2(OH)5·H2O) in the leachates. This Study suggested that incubation of SSMs in acidic soil for a long term can enhance the release of PTMs as the forms of metallic ions and sulfate when subjected to acid deposition Leaching.

  • Leaching of cadmium chromium copper lead and zinc from two slag dumps with different environmental exposure periods under dynamic acidic condition
    Ecotoxicology and Environmental Safety, 2014
    Co-Authors: Zhisheng Jin, Yuangen Yang, Taoze Liu, Daniel Jackson
    Abstract:

    Abstract Over the past few decades, zinc smelting activities in Guizhou, China have produced numerous slag dumps, which are often dispersed on roadsides and hill slopes throughout the region. During periods of acid rain, these exposed slags release heavy metals into surface water bodies. A column Leaching Study was designed to test the potential release of the heavy metals cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), and zinc (Zn) under simulated acid rain events. Two slags with varying environmental exposure periods were packed in columns and subjected to Leaching solutions of pH 3.5, 5.5, or DI H2O at intervals of 1, 7, 14, 28, 56 d. Pulse concentrations of Cd in leachate were found above 5 μg/L, Cr, Pb, and Zn >10 μg/L, whereas, Cu reached 10 μg/L. After five Leaching events, the leachability (percentage of cumulative heavy metal leached after five Leaching events as in its respective total concentration in slags) of Cd was 0.05 percent and 0.035 percent from the old and young slag, respectively. Cr (0.035 percent and 0.05 percent) was greater than Cu (0.002 percent and 0.005 percent) and Zn (0.006 percent and 0.003 percent), while the lowest leachability was observed for Pb (0.0005 percent and 0.0002 percent) from the old and young slags, respectively. Reaction rates (release amount of heavy metals in certain period of Leaching) of heavy metals in the leachates demonstrated the sequence of Zn>Cr>Cd, Cu>Pb. Leaching release of heavy metals was jointly affected by the pH of Leaching solution and mineral composition of slags (including chemical forms of Cd, Cr, Cu, Pb, and Zn). Environmental exposure period of slags, resulting in the alteration of minerals, could affect the release process of heavy metals in Leaching as well.

  • Dolomite phosphate rock (DPR) application in acidic sandy soil in reducing Leaching of phosphorus and heavy metals—a column Leaching Study
    Environmental science and pollution research international, 2012
    Co-Authors: Yuangen Yang, Xiaoe Yang, Peter J. Stoffella
    Abstract:

    A column Leaching Study was designed to investi- gatetheLeachingpotentialofphosphorus(P)andheavymetals from acidic sandy soils applied with dolomite phosphate rock (DPR) fertilizers containing varying amounts of DPR material and N-Viro soils. DPR fertilizers were made from DPR mate- rials mixing with N-Viro soils at the ratios of 30, 40, 50, 60, and 70 %, and applied in acidic sandy soils at the level of 100 mg available P per kilogram soil. A control and a soluble P chemical fertilizer were also included. The amended soils were incubated at room temperature with 70 % field water holding capacity for 21 days before packed into a soil column and subjected to Leaching. Seven Leaching events were con- ducted at days 1, 3, 7, 14, 28, 56, and 70, respectively, and 258.9 mL of deionized water was applied at each Leaching events. The leachate was collected for the analyses of pH, electrical conductivity (EC), dissolved organic carbon (DOC), major elements, and heavy metals. DPR fertilizer application resultedinelevationsupto1unitinpH,7-10timesinEC,and 20-40 times in K and Ca concentrations, but 3-10 times reduction in P concentration in the leachate as compared with the chemical fertilizer or the control. After seven Leaching events, DPR fertilizers with adequate DPR materials signifi- cantly reduced cumulative Leaching losses of Fe, P, Mn, Cu, and Zn by 20, 55, 3.7, 2.7, and 2.5 times than chemical fertilizer or control. Even though higher cumulative losses of Pb, Co, and Ni were observed after DPR fertilizer application, the loss of Pb, Co, and Ni in leachate was

Christian Jungnickel - One of the best experts on this subject based on the ideXlab platform.

  • risk assessment of biocides in roof paint part 1 experimental determination and modelling of biocide Leaching from roof paint
    Environmental Science and Pollution Research, 2008
    Co-Authors: Christian Jungnickel, Frauke Stock, Thomas Brandsch, Johannes Ranke
    Abstract:

    BACKGROUND, AIM AND SCOPE Many surface coatings, including roof paints, contain biocides. It is generally not known to what extent roof paint biocides leach from the paint, and consequently, what concentration the biocide may attain in a rainwater collection system. To this end the Leaching of specific biocides from a variety of German roof paints was investigated and the resulting concentrations in collected rain water were estimated. MATERIALS AND METHODS A laboratory simulation was used to determine the time dependant Leaching rate of the biocide from the paint into synthetic rainwater. The concentrations of biocide in the leachate were quantified using HPLC. The course of the leachate concentrations over time was fitted using a simple mathematical model. This was then used to estimate concentrations of biocides in a typical household rainwater collection system over time. RESULTS Surprisingly, the biocides found in the paints did not always concur with the declared biocides. Concerning the modelling of runoff concentrations, it was found that--under the model assumptions--the rain intensity and cumulative raining time after application are the dominant factors influencing the concentration of the biocide. At the highest modelled rain intensity of 40 mm/hour it only takes about 2 hours to reach peak concentrations lower than 0.1 mg/L, at 0.3 mm/hour it takes about 10 hours to reach peak concentrations of 1.3, 0.9, 5.2 and 1.1 mg/L for terbutryn from Emalux paint, terbutryn from Sudwest paint, carbendazim from Emalux paint, and carbendazim from MIPA paint, respectively. DISCUSSION The results confirm that biocides leached from roof paint will be present in roof runoff. The highest estimated peak concentrations are close to the water solubility of the respective biocides. This indicates that the model assumption of a concentration independent Leaching rate will tendentially lead to an overestimation of the leached concentrations under these circumstances. However, under most circumstances such as higher rain intensities, and longer time after peak concentrations have been reached, the runoff concentrations are far from the solubility limit, and therefore it is proposed that the model assumptions are tenable. CONCLUSIONS The Leaching of biocides from roof paints can be roughly assessed using a relatively simple approach. The declaration of biocidal ingredients in roof paints should be improved and information on their biocide Leaching behaviour should be made available. Furthermore, the estimations should be evaluated by a field Study. RECOMMENDATIONS AND PERSPECTIVES The Leaching Study indicated that the concentrations of selected biocides can reach significant levels, especially after low intensity rainfall. Taking into account the inherent biological activity of the substances under scrutiny, it can already be concluded that it is not advisable to use runoff water from roofs freshly painted with biocide containing roof paints. These results have been complemented by a literature search of biological effects of the investigated biocides, ecotoxicological tests with several species and a risk analysis for organisms exposed to runoff water. This will be presented in Part 2 of this contribution.

D. Kossoff - One of the best experts on this subject based on the ideXlab platform.

  • Mechanisms and Products of the Weathering of Mine Tailings: A Column Leaching Study
    2012
    Co-Authors: K. A. Hudson-edwards, D. Kossoff, William E. Dubbin, M. Alfredsson
    Abstract:

    salts. Arsenic, Ca, Cd, Cu, Fe, Mg, Mn, Na and Zn showed significant cumulative losses of up to 29%, 95%, 100%, 60%, 20%, 30%, 95%, 40% and 60%, respectively, compared to those of Al, K, Pb, Sb, Sr, Sn and Ti, which were up to 3%, 1.5%, 1.1%, 1.9%, 5%, 1% and 0.05%, respectively. The high losses are attributed to the dissolution of relatively soluble minerals such as biotite, and oxidation of pyrite, chalcopyrite and wurtzite, while low losses are attributed to the presence of sparingly soluble minerals such as cassiterite, rutile and svanbertie. A series of secondary minerals, including soluble sulfate salts, Fe oxides and jarosite, formed during the weathering experiments, and were partly responsible for the retention of some of the metals and metalloids (e.g., Pb, Sb). Retention of other metals (e.g., Cu) in the soil-containing columns is postulated to be due to complexation with low molecular weight organic ligands. The results demonstrate the influence of mine tailings on the mobility of potentially toxic metals and metals from tailings and soils, and strongly suggest that these materials should be isolated from fluvial environments.

  • incongruent weathering of cd and zn from mine tailings a column Leaching Study
    Chemical Geology, 2011
    Co-Authors: D. Kossoff, William E. Dubbin, Karen A Hudsonedwards, M. Alfredsson
    Abstract:

    The weathering of discharged mine tailings can contaminate groundwaters, rivers and floodplains with potentially toxic Cd and Zn, depending on tailings mineralogy, storage, dispersal and climatic conditions. The mechanisms of long-term tailings weathering and its influence on waste piles and floodplain environments were assessed by a column Leaching experiment that incorporated tailings and soil from Potosi, Bolivia, and modelled 20 cycles of wet and dry season conditions over three calendar years. Chemical analysis of the leachate and column solids, optical mineralogy, XRD, SEM, EPMA, BCR and water-soluble chemical extractions and speciation modelling were carried out to determine the processes responsible for the Leaching of Cd, Fe, S and Zn. Over this period, approximately 50 to 95% of the original Cd and 50 to 60% of the Zn were leached from the columns. Large amounts of leached Cd and Zn at the beginning of the experiment are attributed to the dissolution of soluble sulphate minerals present in the original tailings and formed after the first wetting of the columns. The Zn/Cd mass ratios of the tailings and soil, initially 429 and 400, respectively, vary considerably over the course of the experiment. Low values (between 220 and 300) in the early cycles are attributed to preferential weathering of Cd-rich wurtzite [Zn,Fe)S] and sequestration of Zn in preference to Cd in secondary Fe phases forming in the columns. In the middle cycles, dissolution of secondary Fe(OH)3 under low pH (< 3) conditions, and of ferroan (Cd-poor) sphalerite [Zn,Fe)S], releases Zn and raises the Zn/Cd ratio to 550–600 in the tailings-only columns and up to 1500 in the mixed tailings-soil columns. The very high ratios in the latter are also ascribed to the formation of low molecular weight organic ligands that have high affinity for Zn over Cd. In the later column-cycles, Zn/Cd ratios return to near-initial values, due to the weathering of Fe-poor sphalerite and secondary Fe phases, and the declining preference of Zn over Cd in the soil organic acids under the strongly acidic conditions prevailing in the columns. The formation and dissolution of secondary soluble sulphate minerals also play a role in Cd and Zn cycling, especially at the beginning of the experiment.

Nicholas M Dickinson - One of the best experts on this subject based on the ideXlab platform.

  • exposure of an anoxic and contaminated canal sediment mobility of metal loid s
    Environmental Pollution, 2010
    Co-Authors: William Hartley, Nicholas M Dickinson
    Abstract:

    A derelict canal contains an estimated 9800 tonnes of anoxic sediment with highly elevated concentrations of trace elements. Lack of maintenance, reduced water levels and vegetation colonization threaten the stability of pollutants by removing existing waterlogged reduced conditions. A column Leaching Study of the sediment under increasingly oxidized conditions showed reductions in As mobility but increased heavy metal concentrations. In a reduced state, As mobility was higher (as a consequence of enhanced Fe and organic carbon solubility) whilst heavy metal concentrations in leachates were lower (due to markedly higher pH). Over 10 contiguous wetting and drying cycles, the consequences were profound; all trace elements were continuously leached with enhanced flushing of Fe, As, Zn and Cu. This raises concern over possible mobilization of pollutants to the wider environment, including groundwater. Options for management to stabilize contaminants are discussed that point to the importance of limiting water flow through the sediment.