Residential indoor,outdoor, and workplace concentrations of carbonyl compounds: relationships with personal exposure concentrations and correlation with sources

Personal 48-hr exposures of 15 randomly selected participants as well as microenvironment concentrations in each participant's residence and workplace were measured for 16 carbonyl compounds during summer-fall 1997 as a part of the Air Pollution Exposure Distributions within Adult Urban Populations in Europe (EXPOLIS) study in Helsinki, Finland. When formaldehyde and acetaldehyde were excluded, geometric mean ambient air concentrations outside each participant's residence were less than 1 ppb for all target compounds. Geometric mean residential indoor concentrations of carbonyls were systematically higher than geometric mean personal exposures and indoor workplace concentrations. Additionally, residential indoor/outdoor ratios indicated substantial indoor sources for most target compounds. Carbonyls in residential indoor air correlated significantly, suggesting similar mechanisms of entry into indoor environments. Overall, this study demonstrated the important role of non-traffic-related emissions in the personal exposures of participants in Helsinki and that comprehensive apportionment of population risk to air toxics should include exposure concentrations derived from product emissions and chemical formation in indoor air.     

Multivariate statistical and GIS-based approach to identify heavy metal sources in soils

The knowledge of the regional variability, the background values and the anthropic vs. natural origin for potentially harmful elements in soils is of critical importance to assess human impact and to fix guide values and quality standards. The present study was undertaken as a preliminary survey on soil contamination on a regional scale in Piemonte (NW Italy). The aims of the study were: (1) to determine average regional concentrations of some heavy metals (Cr, Co, Ni, Cu, Zn, Pb); (2) to find out their large-scale variability; (3) to define their natural or artificial origin; and (4) to identify possible non-point sources of contamination. Multivariate statistic approaches (Principal Component Analysis and Cluster Analysis) were adopted for data treatment, allowing the identification of three main factors controlling the heavy metal variability in cultivated soils. Geostatistics were used to construct regional distribution maps, to be compared with the geographical, geologic and land use regional database using GIS software. This approach, evidencing spatial relationships, proved very useful to the confirmation and refinement of geochemical interpretations of the statistical output. Cr, Co and Ni were associated with and controlled by parent rocks, whereas Cu together with Zn, and Pb alone were controlled by anthropic activities. The study indicates that background values and realistic mandatory guidelines are impossible to fix without an extensive data collection and without a correct geochemical interpretation of the data.     

Nitrate storage by phytoplankton in a coastal upwelling environment

The storage of nitrate by phytoplankton cells during the early phases of upwelling was studied in coastal stations off northern Spain (southern Bay of Biscay) between 1990 and 1994. In this region, a persistent upwelling during summer is characterised by intermittent pulses of variable intensity, and increased nutrient concentrations in the surface layer. The main effect of an upwelling pulse on phytoplankton distribution is the shifting of the chlorophyll a and primary production maxima to near the surface. When the upwelling relaxes, thermal stratification of the water column occurs, and a distinct subsurface chlorophyll maximum develops below the production maximum. An accumulation of intracellular nitrate characterized the early phases of upwelling (mean = 2.73 μmol N m⁻³), maximum concentrations being attained at depths where biomass and production values were moderate. In contrast, phytoplankton cells from non-upwelling situations contained significantly lower concentrations of intracellular nitrate (mean = 0.17 μmol N m⁻³). The variations in the intracellular pool of nitrate may result from the differential allocation of resources within the cell as a result of variations in the energy available, since the uptake and assimilation of nitrate is a relatively expensive process involving several enzymatic systems. We hypothesize that nitrate storage by phytoplankton cells is characteristic of early phases of upwelling and is linked to patterns of carbon fixation. Average nitrogen budgets for upwelling and non-upwelling situations indicate that intracellular nitrate reserves are not responsible for maintaining high phytoplankton growth rates, since they only account for <2% of daily primary production during upwelling events. Received: 28 August 1996 / Accepted 3 December 1996     

High-rate biodegradation of 3- and 4-nitroaniline

A municipal wastewater biosludge was acclimated to the degradation of 4-nitroaniline (4-NA). The acclimation was achieved by using this compound as the sole source of nitrogen during the degradation of succinate as the sole source of carbon and energy. The acclimated bacteria were able to eliminate and mineralize 4-NA as the sole source of carbon and energy. However, in batch tests, the degradation process was somewhat instable and only occurred at comparatively low rates. A continuously operated miniaturized fixed-bed bioreactor was used in order to increase the degradation rates. It was inoculated with the acclimated bacteria and fed with 4-NA as the sole substrate. The system enabled high bioconversion efficiency, due to the development of a high biomass concentration of up to 5.45 g SS L-1. At input concentrations of 4-NA up to 4.5 mM and a hydraulic retention time of 3.5 hours a high degradation rate of 1.1 mmol 4-NA L-1 h-1 and 90 ... 95% DOC removal were achieved. Partial nitrification, also occurred. After gradual adaptation, the bacteria also degraded 3-NA and 4-NA simultaneously in this system. Additional batch tests showed, that 3-NA can serve as the sole source of carbon, nitrogen and energy.     

Determination of aldehydes and ketones in air samples using cryotrapping sampling

A cryotrapping sampling technique using glass traps cooled in liquid nitrogen for monitoring carbonyl compounds in air has been developed. Sampling was followed by derivatization by addition of acidified 2,4-dinitrophenyl hydrazine (DNPH) solution to the traps and an aliquot of the sample was analysed with a high performance liquid chromatograph system (HPLC), equipped with a diode array detector. The procedure was optimised concerning derivatization conditions and analytical parameters on formaldehyde, acetaldehyde, propanal, acetone, butanal and benzaldehyde. The technique was applied in monitoring their concentration in the urban atmosphere in Ljubljana.     

Photocatalytic oxidation of triclosan

In the spring of 2003, there was an outbreak of the severe respiratory syndrome (SARS) in Hong Kong. Health concerns have thus triggered an increased and predominant use of various types of household cleansing agents such as triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol). However, it has been reported recently that triclosan could be photochemically converted to toxic 2,8-dichlorodibenzo-p-dioxin (2,8-Cl(2)DD) in the environment. It is therefore necessary to develop environmentally friendly methods for the treatment of triclosan. To this end, photocatalytic degradation of triclosan in aqueous solution was conducted using TiO(2) (Degussa P25) under irradiation of UV light (lambda < 365 nm). It was found that triclosan could be degraded by this approach. Hydrogen peroxide was added to enhance the degradation process, and the optimal initial hydrogen peroxide concentration for triclosan degradation was 0.005% (w/v). Product identification indicated that triclosan oxidation occurred at its phenol moiety and yielded quinone and hydroquinone intermediates. The formation of a dichlorophenol intermediate in triclosan degradation suggested bond-breaking of the ether linkage occurred during the process. Moreover, no chlorinated dibenzo-p-dioxin congener was detected. These findings confirm that the photocatalytic degradation of triclosan is an environmentally friendly process.     

Phosphorus fractionation in lake sediments--lakes Volvi and Koronia, N. Greece

Sediments from two lakes, the meso-to-eutrophic Volvi and the hypertrophic Koronia, located in N. Greece were examined on the basis of P-fractionation. In both lakes, the rank order of P-fractions was HCl-P > NaOH-P > BD-P > NH4Cl-P. The loosely sorbed phosphorus (NH4Cl-P) represented < 1% of the sedimentary inorganic phosphorus, while the reductant phosphorus (BD-P) ranged 5-6%. The calcium bound phosphorus (HCl-P) showed considerable contribution (59-74%) to the sedimentary inorganic P-loads. The metal oxide bound phosphorus (NaOH-P) was higher in the hypertrophic (30-35%) than in the meso-to-eutrophic system (19-28%). Fine-sized sediments exhibited significantly higher concentrations of HCl-P in Volvi and NH4Cl-P in Koronia. Sampling month had significant effect in variance of most P-fractions and other sediment features in both lakes. Use was also made of multivariate statistics to identify the factors which influence the sedimentary phosphorus. NaOH-P was the most reactive fraction in Lake Volvi. Iron compounds and organic matter seem to play a significant role in regulating this labile P-budget. NH4Cl-P was the more reactive fraction in Lake Koronia which was influenced by sedimentation of P-absorbed on clay/silt fine particles.     

Effect of gamma-irradiated sludge on the growth and yield of rice (Oryza sativa L. var. GR-3)

The effects of gamma-irradiated sludge on the growth and yield of rice (Oryza sativa L. var. GR-3) in pot cultures have been studied. Compared to plants grown only in soil, shoot length, root length, fresh weight, dry weight, total proteins, total soluble sugars, starch and chlorophyll content of plants grown in soil supplemented with unirradiated or gamma-irradiated sludge were found to be significantly increased. Irradiation of sludge significantly stimulated the linear growth of shoot and root systems as well as fresh and dry weights of plants, compared to those grown in soil containing unirradiated sludge. There was also an improvement in the grain yield (weight of seed) when plants were grown in soil supplemented with irradiated sludge. The results obtained suggest that the gamma-irradiated sewage sludge can be beneficially recycled for agricultural uses.