Search

Heavy metal contamination of soil may pose risks to human health and ecosystem environment. Phytoremediation is a low-cost and ecologically sustainable way to remediate heavy metal contaminated soils. As most of the heavy metal accumulator plants are low biomass producers, we selected maize as our experimental phytoremediation plant, which can both produce large useful biomass and remediate heavy metal contaminated soils. The effect of humic acid and bacterial manure on heavy metal accumulation in different organs of maize was studied in this paper, in order to investigate whether the fertilizer application has an effect on phytoremediation efficiency. The results showed that Cu, Pb and Zn contents in the organs of maize generally followed the order root>stem≈leaf>grain. Application of humic acid and bacterial manure improved the contents of Cu, Zn and Pb in different organs compared with those without fertilizer application. Maize with humic acid application generally had higher contents of Cu, Zn and Pb in the organs than that with bacterial manure application. This study indicated that fertilizer application was possibly one of the efficient ways to enhance the efficiency of soil phytoremediation.

要 旨 2011年11月2~6日に関東地方で高濃度のPM2.5が観測された。この期間は全般に弱風により大気が滞留し、3~4日は接 地逆転層形成による安定、5~6日は中立となっていたことが高濃度を招いたと考えられる。PM2.5の成分は、NO3-とOCが顕著 に高いのが特徴であった。NO3-は特に5~6日に高く、夜間の高湿度の影響でNOからHNO3への生成過程が顕著に起こった ことが要因であると考えられる。また、3~4日にもNO3-は比較的高濃度になったが、NOの時空間的挙動から、農作物残渣(バ イオマス)の燃焼が影響していた可能性が考えられる。NO3-と同様にOCも高く、加えてK+やchar-EC、レボグルコサンなど、バ イオマス燃焼の寄与を示す成分も高かったことから、全般的にこの時期に盛んになる農作物残渣燃焼の影響が大きかったと推 測される。ただし、SO42-やVなどの挙動から、南部を中心に化石燃料燃焼の影響も一定程度あったと考えられる。

MSWI fly ashes sampled from 15 large-scale commercial municipal solid waste incineration plants in China were analyzed for seventeen polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDFs) as well as twelve dioxin-like polychlorinated biphenyls (dl-PCBs). The concentration of PCDD/PCDFs and dl-PCBs in fly ash samples ranged from 2.8 to 190 ng g−1, and 59.6 ng g−1 on average. The toxic equivalent (TEQ) ranged from 34 to 2500 ng WHO(2005)-PCDD/PCDF-PCB-TEQ kg−1, and 790 ng WHO(2005)-PCDD/PCDF-PCB-TEQ kg−1 on average. For PCDDs, hexa-chlorinated homolog was the dominant compound except two fly ash samples. Tetra-chlorinated homolog was dominant for PCDFs except one sample. The ratio of PCDDs/PCDFs ranged from 0.32 to 2.44 (average 0.97). The contribution of dl-PCBs to total concentration and TEQ was relatively minimal. Correlation between the concentration of three congeners and total TEQ values of fly ashes was also established. The findings obtained in this work provided overview information on the PCDD/PCDF-PCB content characterization of MSWI fly ash in China, which can be available for MSWI fly ash management in the environment.

In Japan, Ayase River is one of the most polluted rivers by PCDDs, PCDFs and dioxin-like PCBs, which are referred to as dioxins in this paper. The water samples of the river were collected once per month for a year, and dioxins were analyzed to examine the dioxin sources and their contributions to toxic equivalent (TEQ). The WHO-2006 TEQs ranged from 0.26 to 7.0 pg-TEQ L−1 and the average was 2.7 pg-TEQ L−1; eight of 12 samples exceeded the environmental quality standard in Japan (1.0 pg-TEQ L−1). The TEQ value was high during the irrigation period from May to August. The most part of the dioxins in the river water existed in suspended solids (SS) and it seemed that the river received water with highly-dioxin-contaminated SS in the irrigation period. The homologue profiles of the water samples suggested that the dioxins were influenced by pentachlorophenol (PCP) and chlornitrofen (CNP) formulations which were widely used as herbicides for the paddy fields in Japan. According to TEQ apportionment estimated by using indicative congeners, the TEQ was mainly contributed by PCP. Moreover, it was also shown that the TEQ contributions of PCP and CNP formulations increased along with the increase of the total TEQ and the TEQ contribution was dominated by these herbicides during the irrigation period. Therefore, it was concluded that the herbicides-originated dioxins run off from the paddy fields into the river during the irrigation period and increased the dioxins level in the river water. The result from the principal component analysis was consistent with these conclusions.

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (DL-PCBs) contained in the smoke generated from rice straw burning in post-harvest paddy fields in Japan were analyzed to determine their congener profiles. Both the apportionment of toxic equivalent (TEQ) by using indicative congeners and the comparison of the homolog profiles showed that the PCDDs/PCDFs/DL-PCBs present in the rice-straw smoke were greatly influenced by those present as impurities in pentachlorophenol (PCP) and chlornitrofen (CNP, 4-nitrophenyl-2,4,6-trichlorophenyl ether) formulations that had been widely used as herbicides in paddy fields in Japan. Further, in order to investigate the effects of paddy-field soil on the PCDDs/PCDFs/DL-PCBs present in rice-straw smoke, PCDD/PCDF/DL-PCB homolog profiles of rice straw, rice-straw smoke and paddy-field soil were compared. Rice-straw smoke was generated by burning rice straw on a stainless-steel tray in a laboratory. The results suggested that the herbicides-originated PCDDs/PCDFs/DL-PCBs and the atmospheric PCDDs/PCDFs/DL-PCBs contributed predominantly to the presence of PCDDs/PCDFs/DL-PCBs in the rice-straw smoke while the contribution of PCDDs/PCDFs/DL-PCBs formed during rice straw burning was relatively minimal. The major sources of the PCDDs/PCDFs/DL-PCBs found in the rice-straw smoke were attributed primarily to the paddy-field soil adhered to the rice straw surface and secondarily to the air taken by the rice straw. The principal component analysis supported these conclusions. It is concluded that rice straw burning at paddy fields acts as a driving force in the transfer of PCDDs/PCDFs/DL-PCBs from paddy-field soil to the atmosphere.

The major sources of dioxins (polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (DL-PCBs)) in the environment in Japan have been considered to be combustion by-products, pentachlorophenol (PCP) formulations, chlornitrofen (CNP, 4-nitrophenyl-2,4,6-trichlorophenyl ether) formulations, and PCB products. Data on PCDDs, PCDFs and DL-PCBs from the four sources were analyzed, and indicative congeners whose concentrations were highly correlated with WHO-2006 toxic equivalencies (TEQs) were identified for each source sample. The indicative congeners for combustion by-products, PCP formulations, and CNP formulations were 2,3,4,7,8-pentachlorodibenzofuran, 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin, and 1,2,3,7,8-pentachlorodibenzo-p-dioxin, respectively; for PCB products, the indicative congeners were IUPAC Nos. #126- and #105-pentachlorobiphenyls. Moreover, using the data on PCDDs, PCDFs and DL-PCBs, we developed a set of equations for estimating the apportionment of TEQs from the four sources by using only the concentrations of the above-mentioned five indicative congeners. The equations were used along with the analysis results of different types of environmental samples collected from Japan, to determine the TEQ contributions of the four sources. The obtained values of TEQ contributions seemed to be reasonable. The estimation method was developed by using the data on major dioxin sources in Japan, and therefore, it is generally adaptable to environmental samples from any part of Japan. The method may be usable for regions outside Japan if source identification is carried out and the estimation equations are modified appropriately.

An urban river, Kamo River, located at the southern part of Saitama Prefecture had been found to be seriously polluted by nonylphenol (NP). Concentrations of nonylphenolic compounds (NP, nonylphenol ethoxylates, nonylphenoxy acetic acids) in the effluents from and the chemical products used in a dyes production factory, an industrial laundry, four gas stations, two car washing stations and a rubber product manufacturing factory were determined, and their characteristics were evaluated. The concentration of nonylphenolic compounds were ranged from 3.2 to 1,600 μg/L in the effluents. Seven out of 33 chemical products (detergents, dispersants, waxes) used in the factories and the stations contained nonylphenolic compounds of 1.1 μg/g to 0.97g/g. An annual emission load of nonylphenolic compounds in the effluent from the rubber product manufacturing factory, whose nonylphenolic compounds detected was 1,600 μg/L, was estimated to be 105 kg. Whereas the factory was identified to be the major pollution sources of nonylphenolic compounds in the Kamo River, it was also found that gas stations and car washing stations widely distributed in the river basin were pollution sources. Moreover, it was suggested that the oligomer pattern of nonylphenolic compounds in an effluent reflected the situation of wastewater treatment of each business site.

Waste combustion, commercial PCB products, and two agrochemicals, PCP and CNP, are considered as four major sources of dioxins in the environment of Japan. In this study, 2,3,4,7,8-PeCDF, 2,3,3',4,4'-PeCB (#105), 1,2,3,4,6,7,8-HpCDD, and 1,2,3,7,8-PeCDD were selected as respective indicator isomers for the above-mentioned four dioxin sources. Formulas to estimate the respective TEQs originated from the four sources using the concentrations of the four indicator isomers were proposed, and were validated by comparison with the previous reports. The formulas were applied to environmental samples such as ambient air, soil, river sediment, and river water. The estimated total TEQ was approximately equal to the observed total TEQ.

A survey study for estrogens, nonylphenol (NP) and its precursors (nonylphenol ethoxylates and nonylphenol ethoxy acetates) was conducted for water and sediment of the Kamo River and its inflow waterways. 17β-estradiol (β-E2), estrone (E1) and 17α-estradiol were detected in river water and sediment up to the levels near their highest concentrations detected in the nationwide surveys. β-E2 concentration in water at almost all sampling sites was higher in winter and spring and lower in summer and autumn, suggesting more active decomposition of β-E2 by microorganisms at high water temperature. E1 showed the largest contribution to estrogenic activity of water among the examined compounds. However, NP accounted for a large part in estrogenic activity of sediment. The average emission loads of β-E2 and E1 estimated in the Kamo River basin were 12 and 75 nmol/cap/day, respectively. These values corresponded to a comparatively high amount estimated in the effluents from sewage treatment plants.

In this study, we analyzed over 30 types of PFCs, including precursors in both the dissolved phase and particle solid phase, in 50 samples of river water collected from throughout the Tokyo Bay basin. PFCs were detected in suspended solids (SSs) at levels ranging from −1 (0.11–2470 ng g −1 dry weight). The concentrations of PFCs in the SS were one to two order(s) of magnitude lower than those of PFCs in the dissolved phase. Relatively high levels of PFCs (total of 35 PFCs) in SS were observed in urbanized areas. The concentration of PFCAs, including PFOA and PFNA, were significantly correlated with the geographic index as artificial area ( R 2 of the linear regression curve in a double logarithmic plot: 0.09–0.55). Conversely, PFOS and FOSA were significantly correlated with the arterial traffic area ( R 2 in a double logarithmic plot: 0.29–0.55). Those spatial trends were similar to the trends in dissolved PFCs. We estimated the loading amount of PFCs into Tokyo Bay from six main rivers and found that more than 90% of the total PFCs reached Tokyo Bay in the dissolved phase. However, 40.0–83.5% of the long chain PFCAs (C12–C15), were transported as particle sorbed PFCs. Rain runoff events might increase the loading amount of PFCs in SS. Overall, the results presented herein indicate that greater attention should be given to PFCs, especially for longer chain PFCs in SS in addition to dissolved PFCs.