Levels and tissue-dependent distribution of dioxin in Japanese domestic leafy vegetables--from the 1999 national investigation

In 1999, Japanese domestic leafy vegetables were successively investigated for levels of dioxins, including 17 dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), four non-ortho co-planar PCBs (co-PCBs) and eight mono-ortho co-PCBs, all of which had been assigned toxic equivalency factors (TEFs) by WHO in 1997. The mean levels of dioxins in the edible portions were 0.07 (0.09) pg TEQ/g in spinach, 0.13 (0.14) pgTEQ/g in garland chrysanthemum, 0.01 (0.04) pg TEQ/g in mitsuba (marsh parsley) and 0.01 (0.03) pg TEQ/g in chingentsuai (Brassica Campestris var. chinesis), when non-detects were set to zero (and set to half the limit of detection). In order to understand the dioxin pollution of leafy vegetables in detail, a further investigation of dioxin levels in the tissues of spinach was conducted. As a result, the dioxin levels in the leaves were found to be higher than those in the stem and red collar, but they were much lower than those found in the primary and secondary roots, which are considerably affected by the soil, which is recognized as a sink of airborne dioxins. The dioxin levels in edible portions (leaves, stem and red collar) were obviously lower than those in non-edible portions (primary and secondary roots). In addition, from the finding that several lower-chlorinated PCDD/Fs and co-PCBs, namely 2,3,7,8-TCDD/F, 1,2,3,7,8-PeCDD, 1,2,3,7,8/2,3,4,7,8-PeCDFs, 1,2,3,7,8,9-HxCDD, 1,2,3,4,7,8-/1,2,3,6,7,8-HxCDFs, 3,3',4,4'-TCB, 2,3,3',4,4'-/2,3',4,4',5-PeCBs, and 2,3',4,4',5,5'-HxCB, were more highly represented in the dioxins in the leaves than in those in the secondary roots, it was suggested that in leafy vegetables the deposition of gaseous, presumably moderately volatile dioxins in leaf wax is another pollution pathway in addition to the adhesion of dioxin-contaminated particles including soil.     

Development and calibration of epiphytic lichens as saltfall biomonitors--dry-deposition modelling

Blubber collected from beluga whales and ringed seals during subsistence hunts in the southern Baffin Island region of the Canadian Arctic were analysed for polychlorinated naphthalenes and eight planar PCB congeners (mono-ortho PCBs: 105, 114, 118 and 156; non-ortho PCBs: 77, 81, 126, 169). SigmaPCN (3-7 Cl) concentrations in blubber ranged from 35.9-383 pg/g (lipid weight; lw) in beluga and 35.4-71.3 pg/g (lw) in ringed seal. These represent the first measurements of PCNs in marine mammals in the Canadian Arctic, mammals which are an important part of the traditional diet of the indigenous population. SigmaCoplPCB concentrations were much higher, ranging from 15.5-317 ng/g (lw) in beluga whale blubber and 16.5-40.9 ng/g (lw) in ringed seal blubber. PCNs and coplanar PCBs both exhibit dioxin-like toxicity. Although average sigmaPCN concentrations were less than 1% of sigmaCoplPCBs, PCNs contribute up to 11% of TEQ relative to the coplanar PCBs based on TEFs determined by H4IIE enzyme assays.     

Transfer and effects of cadmium in an experimental food chain involving the snail Helix aspersa and the predatory carabid beetle Chrysocarabus splendens

The transfer and the toxic effects of Cd were studied in an experimental food chain involving the snail Helix aspersa as prey organism and one of its natural predators, the carabid beetle Chrysocarabus splendens. Juvenile snails were fed plant-based food enriched with 0, 10, 50 and 100 microg g(-1) of Cd, then were offered as prey to beetle larvae from egg hatching to pupation stage. Cd concentrations in snail tissues increased with increasing Cd concentration in food and with duration of exposure. Bioaccumulation factors ranged from 1.87 to 3.39, showing that H. aspersa snails, even in their early life stages, belong to macroconcentrator species for Cd. No significant reduction of snail consumption by beetles was found in exposed groups. Cd concentrations in beetle larvae remained very low (lower than 1 microg g(-1) for all groups), demonstrating a very effective regulation capacity in beetle larvae. However, Cd concentrations in highest exposed groups were higher than those found in control groups. Cd contents in adult beetles were lower than in larvae, showing a loss of Cd during metamorphosis. Despite the low Cd concentrations found in beetles, their exposure to Cd contaminated snails led to 31% of mortality, which occurred only during pupation and for the highest exposure level. No clear sublethal effects were found. These results showed that snails inhabiting heavily polluted areas may represent a risk of secondary poisoning for predatory invertebrates and provided quantitative data on the transfer of Cd between two compartments of a terrestrial food chain.     

Cobalt-based alumina pillared zirconium phosphate catalysts for the selective catalytic reduction of NO by propane

A series of cobalt containing alumina pillared zirconium phosphate materials have been prepared by ion exchange or by impregnation, and fully characterised. The catalytic behaviour of these materials in the selective catalytic reduction of NO by propane, in excess of oxygen, at temperatures ranging between 350 and 550 degrees C, has been also evaluated. A maximum NO conversion close to 14% is obtained on Co-impregnated catalysts heated at 600 degrees C. The NO reduction seems to be related to the presence of Co3+, thus the calcination temperature of samples influences the resulting activity much more than the cobalt content.     

A European survey of atmospheric heavy metal deposition in 2000-2001

The background, administration and current status of the monitoring programme "European Survey of Atmospheric Heavy Metal Deposition" is described. All European states are invited to join the survey 2000-2001. The co-ordination and responsibility for the survey will gradually be transferred from the Nordic Council of Ministers to the International Cooperative Programme on Effects of Air Pollution on Natural Vegetation and Crops (ICP Vegetation).     

Summer-time distribution of air pollutants in Sequoia National Park, California

Concentrations of air pollutants were monitored during the May November 1999 period on a network of forested sites in Sequoia National Park, California. Measurements were conducted with: (1) active monitors for nitric oxide (NO), nitrogen dioxide (NO2) and ozone (O3); (2) honeycomb denuder/filter pack systems for nitric acid vapor (HNO3), nitrous acid vapor (HNO2), ammonia (NH3), sulfur dioxide (SO2), particulate nitrate (NO3-), ammonium (NH4+), and sulfate (SO4(2-)); and (3) passive samplers for O3, HNO3 and NO2. Elevated concentrations of O3 (seasonal means 41-71 ppb), HNO3 (seasonal means 0.4-2.9 microg/m3), NH3 (seasonal means 1.6-4.5 microg/m3), NO3 (1.1-2.0 microg/m3) and NH4+ (1.0-1.9 microg/m3) were determined. Concentrations of other pollutants were low. With increasing elevation and distance from the pollution source area of O3, NH3 and HNO3 concentrations decreased. Ammonia and NH4+ were dominant N pollutants indicating strong influence of agricultural emissions on forests and other ecosystems of the Sequoia National Park.     

Polychlorinated dibenzo-p-dioxins and dibenzofurans in River Po sediments

The River Po is the main Italian river draining one of the most populated and industrialised regions in Italy. As part of a monitoring project to assess environmental quality in the River Po, we measured the concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in bottom sediments collected along the whole course of the river, from the spring to the delta, downstream from the confluence of its main tributaries. The aim was to investigate the level of contamination in the main Italian river and the contribution of contaminant loads from the subbasins. Composite sediment samples were collected in summer and winter surveys in low-flow water conditions and analysed by HRGC-HRMS for PCDD and PCDF homologue groups and for the 2,3,7,8-substituted congeners. The spatial trend observed in the Po River for PCDD and PCDF concentrations varied depending on the load of contaminants received from the tributaries and the processes of sedimentation. The sum of PCDD and PCDF concentrations, and the toxic equivalent content, ranged from 121 to 814 and from 1.3 to 13 ng/kg dry weight sediment, respectively. These levels of contamination seem lower than in the sediments of rivers draining highly industrialised areas. The PCDD and PCDF homologue profiles in all the samples were very similar, suggesting a common source of this contamination in the River Po. Principal component analysis suggested that widespread sources, such as urban runoff and domestic wastewaters, are probably the main cause of these levels of PCDDs and PCDFs.     

The interaction effects of binary mixtures of benzene and toluene on the developing heart of medaka (Oryzias latipes)

The United States Environmental Protection Agency (USEPA) has pursued the estimation of risk of adverse health effects from exposure to chemical mixtures since the early 1980s. Methods used to calculate risk estimates of mixtures were often based on single chemical information that required assumptions of dose-addition or response-addition and did not consider possible changes in response due to interaction effects among chemicals. Full factorial designs for laboratory studies can produce interactions information, but these are expensive to perform and may not provide the information needed to evaluate specific environmentally relevant mixtures. In this research, groups of Japanese medaka (Oryzias latipes) embryos were exposed to binary mixtures of benzene and toluene as well as to each of these chemicals alone. Endpoint specific dose-response models were built for the hydrocarbon mixture under an assumption of dose-additivity, using the single chemical dose-response information on benzene and toluene. The endpoints included heart rate, heart rate progression, and lethality. Results included a synergistic response for heart rate at 72 h of development, and either additivity or antagonism for all other endpoints at 96 h of development. This work uses an established statistical method to evaluate the toxicity of an environmentally relevant mixture to ascertain whether interaction effects are occurring, thus providing additional information on toxicity.     

Avoidance behaviour of Enchytraeus albidus: effects of benomyl, carbendazim, phenmedipham and different soil types

Enchytraeids are typical inhabitants of many soils, contributing to vital processes of this environmental compartment. Indirectly they are involved in regulating the degradation of organic matter, as well as improving the pore structure of the soil. Due to their behaviour, they are able to avoid unfavourable environmental conditions. Avoidance tests with enchytraeids, initially developed with earthworms by several authors, are quick and easy to perform. With these tests a first assessment of the toxicity of a (contaminated or spiked) soil is possible in just 48 h by using the reaction of the enchytraeids as measurement endpoint. In this period of time the organisms can choose between the control soil and the other soil (a contaminated or spiked or another soil with different physico-chemical properties). In the tests reported here, the enchytraeids were exposed to control soils spiked with the fungicides Benomyl and Carbendazim and the herbicide Phenmedipham. Several chemical concentrations were tested in order to evaluate the avoidance behaviour to toxic substances. In fact, often these short-term screening tests gave results showing avoidance at concentrations in a range similar to the acute test results but, higher than in chronic tests. Further tests are needed to decide whether the results gained in this study can be extrapolated to other chemicals. It is proposed to standardize the Enchytraeid Avoidance Test as it is currently done for the Earthworm Avoidance Test by the International Standard Organization (ISO).     

Simultaneous determination of Cd(II), Cu(II), Pb(II) and Zn(II) by derivative stripping chronopotentiometry in Pittosporum tobira leaves: a measurement of local atmospheric pollution in Messina (Sicily, Italy)

The purpose of this study is to investigate the bio-accumulation of Cd(II), Cu(II), Pb(II) and Zn(II) in Pittosporum tobira (Thunb.) Aiton leaves sampled in different zones of Messina, in order to assess the level of atmospheric metal deposition in correlation with the traffic volume. Derivative stripping chronopotentiometry was used as a practical, precise and sensitive technique to determine simultaneously Cd, Cu, Pb and Zn levels in Pittosporum leaves. In the optimised electro-chemical conditions, detection limits lower than 0.05 microg kg(-1) were achieved, whereas the accuracy, expressed as obtained recoveries from certified materials, was in the range 93.5-102.7%. The obtained data provided evidence that Cd and Pb levels significantly decreased from high to low traffic density zones (p < 0.005, ANOVA), whereas Cu and Zn are accumulated by plants particularly from the soil and their contents is not related to the traffic volume.