Validation of modeling approach to evaluate congener-specific concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans in air and soil near a solid waste incinerator

A concise modeling approach using long-term averaged meteorological data was developed to estimate site-specific concentrations of congeners of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) near a solid waste incinerator. This approach consists of calculation of atmospheric dispersion, dry and wet deposition of gaseous and particle-bound congeners, and non-steady-state concentrations in soil. The predictability of this approach was evaluated by comparison of calculated concentrations of congeners in soil with those measured at eight locations near a municipal solid waste incinerator (MSWI). The variation of these concentrations due to variability of meteorological parameters is small. A considerable number of mean values show good agreement with measured concentrations within a factor of three. The reasonable agreement between calculated and measured concentrations indicates that algorithms for the calculation of vapor-phase deposition and non-steady-state concentrations in soil must be included in the modeling approach for an accurate estimation of the concentrations of congeners of PCDD/Fs emitted from MSWIs to the atmosphere. For a detailed estimation of site-specific concentrations, it is important to specify the bulk density of soil in the evaluated area, together with meteorological parameters.     

Ion chromatographic determination of anions in rainwater

High acidity rainwater has recently become an issue in environmental pollution because of its great influence on ecological systems with special reference to the human environment. To solve this problem, the chemical behaviors of various pollutants in the air, particularly in the wet atmosphere must be studied. Ion chromatography was used for rapid analysis of trace amounts of anions.As a result, it was found that a combination of 2mM Na₂CO₃ and 5mM NaOH as an eluent was suitable for the separation of various anions. The reproducibility of determination of anions in standard solutions was found to be satisfactory with a coefficient of variation (CV) of 2–4% for F^?, Br^?, NO^?₃, SO^2?₃, SO^2?₄, and PO^3?₄, but not for NO^?₂. The determination of NO^?₂ was accomplished by preparing an eluent having almost the same composition and cencentration as that of the standard and sample solutions. The precision of the method with rainwater samples was less than 10%, and was considered to be usable for data analysis.In addition, a considerable number of ions in rainwater samples could be determined by using 1–3 ml of the sample without pretreatment. It was found that ion chromatography was one of the best means to obtain information on the chemical behaviors of trace amounts of anions in rainwater.     

Estimation of dioxin risk to Japanese from the past to the future

The transport processes of seventeen 2,3,7,8-chlorinated congeners of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from their major sources to humans were modeled to estimate the time course, from the past to the future, of the human health risk to the Japanese population. The comparison between measured and estimated values showed that the present modeling approach represented the background levels of congeners in the environment, daily intake, and body burden reasonably well, except for in the case of 2,3,7,8-TCDF. Although PCDD/Fs in herbicides have contributed greatly to the daily intake and body burden to the Japanese population in the past, the main sources of the present intake and burden of PCDD/Fs is estimated to be incinerators. The margin of exposure (MOE) for the risk of morphological reproductive alteration in female offspring exposed prenatally was calculated based on the estimated maternal body burden. The results indicated that the MOE values were in the single digits, implying that these values may not be sufficiently large to guarantee the safety of female offspring of mothers born in the 1950s, whereas the MOE values for female offspring born in and after the latter half of the 1990s may be sufficiently large to guarantee safety.     

Improved quartz furnace method for chlorine and sulfur determination in municipal solid waste

 A method of determining the chlorine (Cl) and sulfur (S) in municipal solid waste (MSW) was studied. The quartz furnace method was improved in two ways: recovery from ash by hot extraction with dilute nitric acid, and avoidance of the volatilization of alkali (earth) metal chlorides by setting the sample combustion temperature at 600°C. In a comparison with the bomb method, using nine sets of kitchen garbage and waste plastics, the bomb method yielded a 15%–25% lower value than the improved quartz furnace method. Combustion in the bomb was frequently incomplete, resulting in recovery losses of Cl and S. The average kitchen garbage involved 5.2 mg Cl/g, of which at least 24.1% would be converted to HCl. Plastics contained 23 mg Cl/g generating 88.1% HCl on average. In the same way, kitchen garbage contained 3.0 mg S/g, generating 52.3% SO _x , whereas plastics contained 1.1 mg S/g with 55.1% SO _x formation. Received: March 20, 2002 / Accepted: October 13, 2002     

Screening-Level Risk Assessment of Di(2-ethylhexyl)phthalate for Aquatic Organisms Using Monitoring Data in Japan

Screening-level ecological risk assessments of di(2-ethylhexyl)phthalate (DEHP) for aquatic organisms in Japan were conducted using estimated statistical values based on surface water and sediment monitoring data and effect threshold values based on a large aquatic toxicity database. An alternative method is proposed to handle monitoring data that contain nondetects including multiple detection limits and to determine the statistical values of DEHP concentrations in Japanese surface waters. The No-Observed-Effect-Concentration (NOEC_water) of DEHP for aquatic life of 77 μ g/L was determined giving equal importance to both physical effects probably caused by undissolved DEHP and to the intrinsic toxicity potentially caused by DEHP. The NOEC_sediment of 615,000 μg/kg was determined by the Equilibrium Partitioning (EqP) theory, conservatively assuming a threshold effect level in the water column as the water solubility of 3 μ g/L. The potential risks of DEHP in Japanese water environments were characterized simply by comparing the margin of exposure (MOE) with a specified uncertainty multiplier (UM). The MOE is expressed as the ratio of NOEC_water or NOEC_sediment to the expected environmental concentrations such as the 95th percentiles of the estimated DEHP concentration distributions for surface water or sediment. The results of risk characterization show that all MOE values calculated using the statistical values of DEHP concentrations in Japanese surface waters and sediments are above 10, indicating minimal risk. Although the DEHP concentrations of some surface water samples showed MOE values of less than 10, considering environmental chemistry such as bioavailable fractions and the form of existence of DEHP in a water environment, we conclude that the current levels of DEHP are of little concern to aquatic life in the majority of Japanese surface waters and sediments.     

Clonal structure affects the assembling behavior in the Japanese queenless ant <Emphasis Type="Italic">Pristomyrmex punctatus</Emphasis>

The queenless ant Pristomyrmex punctatus (Hymenoptera: Myrmicinae) has a unique society that differs from those of other typical ants. This species does not have a queen, and the workers lay eggs and produce their clones parthenogenetically. However, a colony of these ants does not always comprise members derived from a single clonal line. In this study, we examined whether P. punctatus changes its “assembling behavior” based on colony genetic structure. We prepared two subcolonies—a larger one comprising 200 individuals and a smaller one comprising 100 individuals; these subcolonies were established from a single stock colony. We investigated whether these subcolonies assemble into a single nest. The genetically monomorphic subcolonies (single clonal line) always fused into a single nest; however, the genetically polymorphic subcolonies (multiple clonal lines) did not tend to form a single colony. The present study is the first to demonstrate that the colony genetic structure significantly affects social viscosity in social insects.     

Plutonium concentration and 240Pu/239Pu atomic ratio in liver of squid collected in the coastal sea areas of Japan

Plutonium isotopes, 239Pu and 240Pu, were measured in liver samples from Surume squid using a sector-field high resolution ICP-MS after radiochemical purification. Surume squid samples were obtained from nine landing ports in Japanese inshore during fishery season from September to December 2002. Concentrations of 239Pu and 240Pu ranged from 1.5 to 28 mBq kg(-1) and 1.1 to 24 mBq kg(-1), respectively. Plutonium (239,240Pu) concentrations in liver were several thousand times higher than levels found in seawater. The concentration factor (CF) compared to seawater for 239,240Pu and 13 other elements ranged from 10(0) to 10(7). The CF values for 239,240Pu, V and Th were 10(2)-10(4). Pu had an intermediate CF between conservative and scavenged elements. 240Pu/239Pu atomic ratios in the squid liver ranged from 0.177 to 0.237 which were slightly higher than 0.178+/-0.014 for global fallout. The variations of 240Pu/239Pu atomic ratios in ocean currents with different source functions are important for interpreting high 240Pu/239Pu atomic ratios in Surume squid liver. It seems likely that Pu with high 240Pu/239Pu atomic ratio is continuously transported through the solubilization and seawater transport from the North Equatorial Current to Kuroshio and its branch, Tsushima Current. By assuming that Pu found in Surume squid liver is a mixture of global fallout Pu (0.178) and close-in fallout Pu with high 240Pu/239Pu atomic ratio (0.30-0.36) around Bikini Atoll, Pu contribution from Bikini close-in fallout Pu accounts for close to 35% of the whole plutonium in Surume squid liver. These results highlight that Surume squid is a useful organism for evaluating environmental Pu levels of larger sea area and facilitate the development of models to understand oceanic transport of close-in fallout Pu from Bikini Atoll.     

Mercury pollution and childhood in Amazon riverside villages

Mercury is a hazardous metal responsible for environmental contamination and human intoxication. Methylmercury, a very toxic organic compound, bio-accumulates through food chain, and is responsible for chronic mercury exposure of riverside Amazonian communities with a diet rich in fish. Uncertainties about the reference exposure dose that could have damaging consequences for nervous system development makes necessary the biomonitoring of these Amazonian populations, especially children. In this work, a comparative study was performed in exposed and non-exposed children living in the Amazon. A total of 168 children were analyzed to find possible correlations between gender, age, location, and hair mercury content. For each location, no statistically significant differences (P<0.05) were detected for gender and age versus mercury content. However, mean mercury levels in hair samples may indicate a tendency of boys to average higher hair concentrations. Also, in the community with highest levels of mercury, the limit of 10 micro g/g of mercury was surpassed by 65% of 2-6 years and 50% of 7-12 years children but only by 27% of 0-1 year babies, pointing to a lower bioaccumulation and/or the existence of a protection mechanism in babies. Log normal distributions of mercury concentrations for each location showed that children from populations under influence of gold mining activity contain the highest mercury levels in hair samples, though this intoxication may have decreased when compared to previous studies. Knowledge originated by this monitoring will better assist in the development of prevention strategies and government actions targeting the mercury contamination of Amazonian environment.     

Adsorption,desorption, potential and selective distribution op heavy metals in selected soils of japan

Abstract

Adsorption, desorption, potential and selective distribution of Cu, Zn, Cd, Pb and Ni were investigated in three typical soils of Japan under flooded condition.

The results indicate that the sorption of all heavy metals was linear upto the maximum concentration (500 μg/g soil) employed in the present studies in all the soils. The magnitude of sorption in general was in the order of Pb > Cu > Zn > Cd > Ni. The adsorption coefficients showed wide variations among different soils as well as metal ions. The hysteresis of sorption and desorption by KNO₃ was well pronounced for both the metal ions and the soils. The desorption rate was greater than the fixation rate indicating the predominance of the chemosorption over physical processes. The major portion of sorbed metals were retained in the unextractable form, which over all accounted for more than 50% of the sorbed metals.     

Mercury pollution in the Tapajos River basin, Amazon: mercury level of head hair and health effects.

There is increasing concern about the potential neurotoxic effects of exposure to methylmercury for the 6 million people living in the Amazon, even in regions situated far away from the gold mines (garimpos), considered to be the major source of mercury pollution. In November 1998, a spot investigation on mercury contamination was conducted in three fishing villages (Barreiras, Rainha, and Sao Luiz do Tapajos) on the Tapajos River, an effluent of the Amazon, situated several hundred kilometers downstream from the gold-mining areas. A total of 132 fishermen and their families volunteered for the current study. As was anticipated, the total mercury levels in the head hair collected from the fishing villages were relatively high (14.1-20.8 ppm on the average) and the number of subjects with a high total mercury level over 10 ppm (the least upper bound of a normal value) was 103 (78.0%) in total, along with various symptoms, thereby suggesting wide mercury contamination in the Tapajos River basin. Moreover, in view of the absence of other diseases (e.g., alcoholism or malaria), a high intake of fish containing a methylmercury level, and high hair mercury levels in addition to the various symptoms such as sensory disturbance (especially glove-and-stocking type, which is characteristic of Minamata disease), tremor, failure in two-point discrimination, and slight balancing failure, several subjects examined were diagnosed with mild Minamata disease. The findings obtained suggest, thus, that the mercury pollution in the Amazon should be crucially observed for head hair mercury level and health in a much broader region.