Heavy metals speciation in soakaways sediment and evaluation of metal retention properties of surrounding soil.
ABSTRACT Heavy metals speciation analysis was carried out on sediment samples accumulated within soakaways in an old stormwater infiltration facility in Tokyo, Japan and on a soil core sample collected near the facility. Heavy metals content in soakaways sediments were much elevated compared to nearby surface soil with the content for Zn, Pb and Cd reaching about 5 to 10 times the content in surface soil. Speciation results revealed that significant amount of the accumulated heavy metals were present in potential mobile fractions, posing threat of release to underlying soil with changing environmental conditions. Detail analyses of soil characteristics indicated significant heterogeneity with depth, especially between the surface soil and underlying soil at site. Decrease in potential adsorption sites with depth was observed in case of underlying soil. Reduced adsorption capacity for heavy metals was evidenced for underlying soil when compared with surface soil. Furthermore, less capability of the soil organic matter to bind heavy metals was evidenced through speciation analyses, which raises concern over the long-term pollution retention potential of the underlying soil receiving infiltrated runoff.
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ABSTRACT: There are high expectations that stormwater infiltration facilities will be effective nonpoint source control measures in urban areas. However, far less is known about pollutant removal efficiency of infiltration facilities than its water quantity removal effects and in particular, there are few data concerning the efficiency of infiltration facilities obtained through field surveys. This paper presents the pollutant removal efficiency of infiltration facilities which have already been installed in two cities in Japan. The field survey was carried out in two cities, City A and B, and was performed by measuring the flow rate and the water quality of influent, effluent and infiltrated water of infiltration inlets installed beside streets. The water quality constituents that were analyzed were COD, TN, TP, TS and SS. This field survey shows that a stormwater infiltration inlet that has appropriate infiltration capacity is capable of capturing pollution load at a high rate. Furthermore, it suggests that selecting suitable installation sites and appropriately maintaining them are important, in terms of obtaining higher pollutants removal efficiency from urban stormwater.01/2008;
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ABSTRACT: Urban road dusts (URDs, n=10) were collected from arterial, residential, parking area in highway and highway roads in and around Tokyo, Japan, to characterize toxicity of size-fractions by the ostracod Heterocypris incongruens direct contact test. The URDs were collected with vacuum cleaner and highway sweeping vehicles, dried and size-fractionated before conducting toxicity test. The LC20 and LC50 of URDs varied (v/v) from 1.6 to 49%, and 3.8 to 67% respectively. Cluster analysis of URDs based on the concentration of heavy metal and PAHs standardized with the organic matter content was able to differentiate URDs into two groups, one group of higher toxicity and the other group of medium and lower toxicity. Mortality of ostracod decreased for some of the URDs when holding time of URD-water mixture was changed from 1h to 24h prior to the toxicity test. Fraction of fine particles was not always more toxic than the other fractions of coarse and medium particles. Site specific differences in toxicity of size-fractionated URDs indicated the complexity in defining URD toxicity as there could be co-existence of various non-targeted toxicants.Journal of hazardous materials 11/2013; 264C:53-64. · 4.33 Impact Factor
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ABSTRACT: Selective sequential dissolution (SSD) and isotopic dilution are two most commonly applied techniques for the measurement of mobile fraction of heavy metal present in the urban environment. This work examined the compliance between SSD proposed by the Community Bureau of Reference (BCR) and isotopic dilution technique (IDT) for determination of mobile pool of heavy metal contained in soakaway sediment, road dust, and soil sample. Heavy metals (Cu, Zn, Cd and Pb) were fractionated using the three-stage BCR protocol, while isotopically exchangeable metal concentrations (E-value) were investigated through isotopic tracers (¹¹¹Cd, ⁶⁵Cu, ²⁰⁷Pb and ⁶⁶Zn). In general, total contamination level, E-value and BCR exchangeable fractions of different samples followed the similar order of road dust > soakaway sediment > soil. Results revealed that the E-value exceeded the BCR exchangeable fraction in all samples. In addition, the first three fractions of BCR which have potential to become mobile under certain environmental conditions were collectively termed as "potential mobile pool" and compared with E-value. It was concluded that metal extracted by weak acid underestimates the exchangeable fraction while the potential mobile pool extracted by three reagents overestimates the real mobile forms of heavy metals. However, better mobility characteristics of heavy metals can be assessed by coupling information obtained through sequential extraction and isotopic exchange.Water Science & Technology 08/2010; 62(4):920-8. · 1.21 Impact Factor