خيارات البحث
النتائج 1 - 10 من 196
Persistent effects of ozone on needle water loss and wettability in Norway spruce.
1990
Barnes J.D. | Eamus D. | Davison A.W. | Ro Poulsen H. | Mortensen L.
Throughfall and canopy interactions in five different tree species in Denmark
2002
Hansen, K. | Bastrup-Birk, A. | Hovmand, M.F. (Danish Forest and Landscape Research Institute, Hoersholm (Denmark))
Acidification of forest soils is dependent on the tree species for several reasons. One reason is that the deposition to deciduous tree species normally is considered lower than to coniferous tree species. This study therefore considers the differences in deposition to different tree species in Denmark. Canopy throughfall and precipitation were collected during the period 1986 to 1999 at three trial species experimental sites in Denmark. At each site the species Norway spruce, sitka spruce, Douglas fir, beech and oak were studied. The paper presents and discusses the differences in canopy exchange processes and dry deposition in different tree species and at different locations
اظهر المزيد [+] اقل [-]Forms - an integrated forest monitoring system in Denmark
2002
Bastrup-Birk, A. | Johannsen, V.K. (Centre of Forest, Landscape and Planning, Hoersholm (Denmark))
A FORest Monitoring System (FORMS) has been implemented in Denmark in order to gain and deliver knowledge and information for operational and strategic decisions concerning nature and environment. FORMS integrate four national monitoring programmes. Forest condition monitoring is performed on 52 permanent plots distributed on a 16 x 16 km grid. FORMS gives a systematic and representative assessment of the resources in and development of the forests in Denmark, includes the monitoring of important processes in the forest ecosystem and follows the use of forest for recreational purposes
اظهر المزيد [+] اقل [-]Chronic health risk comparison between China and Denmark on dietary exposure to chlorpyrifos
2020
Sang, Chenhui | Sørensen, Peter Borgen | An, Wei | Andersen, Jens Hinge | Yang, Min
Chlorpyrifos is one of the most heavily used pesticides in domestic and agricultural insect prevention globally. Given the potential neurotoxicity of chlorpyrifos and its high detection rates in food and drinking water, health risks attributable to chlorpyrifos residue in Chinese drinking water and food in both China and Denmark were assessed in this study. Mixed left-censored handling models were used to deal with the non-detected values in chlorpyrifos concentrations. Results show that chronic exposure imputed to chlorpyrifos residue is much lower than the reference dose, and will thus not pose appreciable health risk to the consumer. Compared to the total exposure from chlorpyrifos in drinking water and food sources, chronic exposure from drinking water sources in China accounts for 0–4.4%. Health risk owing to chlorpyrifos in food within China is 6-7-fold higher than in Denmark, and this coincides with the fact that all application of chlorpyrifos is banned in Denmark, in contrast to China. However, the Danish consumers are still exposed from imported food items. The main health risk contributors in China are the food groups of Grains and grain-based products and Vegetable and vegetable products, while the main chronic health risk contributor in Denmark is the food group of imported fruit and fruit products.
اظهر المزيد [+] اقل [-]The effect of nitrogen deposition on the species richness of acid grasslands in Denmark: A comparison with a study performed on a European scale
2011
Damgaard, Christian | Jensen, Lennarth | Frohn, Lise Marie | Borchsenius, F. (Finn) | Nielsen, Knud Erik | Ejrnæs, Rasmus | Stevens, Carly J.
The effect of atmospheric nitrogen deposition on the species richness of acid grasslands was investigated by combining data from a large Danish monitoring program with a large European data set, where a significant non-linear negative effect of nitrogen deposition had been demonstrated (Stevens et al., 2010). The nitrogen deposition range in Denmark is relatively small and when only considering the Danish data a non-significant decrease in the species richness with nitrogen deposition was observed. However, when both data sets were combined, then the conclusion of the European survey was further corroborated by the results of the Danish monitoring. Furthermore, by combining the two data sets a more comprehensive picture of the threats to the biodiversity of acid grasslands emerge; i.e., species richness in remnant patches of acid grassland in intensively cultivated agricultural landscapes is under influence not only from nitrogen deposition, but also from current and historical land use.
اظهر المزيد [+] اقل [-]Inherent mineralization of 2,6-dichlorobenzamide (BAM) in unsaturated zone and aquifers – Effect of initial concentrations and adaptation
2011
Janniche, Gry Sander | Clausen, Liselotte | Albrechtsen, Hans-Jørgen
The dichlobenil metabolite BAM (2,6-dichlorobenzamide) is frequently detected in aquifers e.g. in Denmark despite the mother compound dichlobenil was banned here since 1997. BAM mineralization was investigated at environmentally relevant concentrations in sediment samples. Undisturbed sediment cores with known dichlobenil application were collected from topsoil to 8.5 m below surface resulting in 57 samples hereof 4 aquifer samples. Mineralization was only substantial (>10%) in the uppermost meter of the unsaturated zone. Microbial adaptation, observed as faster mineralization in pre-exposed than in pristine sediments from the same location, was only evident in sandy sediment where dichlobenil was still present, but not in clayey sediments. Higher initial concentrations (1–5000 μg/kg) did not stimulate mineralization in pristine clayey or sandy sediments, or in pre-exposed sand. However, in pre-exposed clay mineralization was stimulated at high concentrations. Furthermore BAM was for the first time mineralized in aerobic aquifer sediments from different BAM-contaminated groundwater locations.
اظهر المزيد [+] اقل [-]The influence of organic matter on sorption and fate of glyphosate in soil - Comparing different soils and humic substances
2009
Albers, Christian N. | Banta, Gary T. | Hansen, Poul Erik | Jacobsen, Ole S.
Soil organic matter (SOM) is generally believed not to influence the sorption of glyphosate in soil. To get a closer look on the dynamics between glyphosate and SOM, we used three approaches: I. Sorption studies with seven purified soil humic fractions showed that these could sorb glyphosate and that the aromatic content, possibly phenolic groups, seems to aid the sorption. II. Sorption studies with six whole soils and with SOM removed showed that several soil parameters including SOM are responsible for the strong sorption of glyphosate in soils. III. After an 80 day fate experiment, ~40% of the added glyphosate was associated with the humic and fulvic acid fractions in the sandy soils, while this was the case for only ~10% of the added glyphosate in the clayey soils. Glyphosate sorbed to humic substances in the natural soils seemed to be easier desorbed than glyphosate sorbed to amorphous Fe/Al-oxides.
اظهر المزيد [+] اقل [-]Environmental monitoring study of pesticide contamination in Denmark through honey bee colonies using APIStrip-based sampling
2021
Murcia-Morales, María | Díaz-Galiano, Francisco José | Vejsnæs, Flemming | Kilpinen, Ole | Van der Steen, Jozef J.M. | Fernández-Alba, Amadeo R.
Due to their extensive use in both agricultural and non-agricultural applications, pesticides are a major source of environmental contamination. Honey bee colonies are proven sentinels of these and other contaminants, as they come into contact with them during their foraging activities. However, active sampling strategies involve a negative impact on these organisms and, in most cases, the need of analyzing multiple heterogeneous matrices. Conversely, the APIStrip-based passive sampling is innocuous for the bees and allows for long-term monitorings using the same colony. The versatility of the sorbent Tenax, included in the APIStrip composition, ensures that comprehensive information regarding the contaminants inside the beehive will be obtained in one single matrix. In the present study, 180 APIStrips were placed in nine apiaries distributed in Denmark throughout a six-month sampling period (10 subsequent samplings, April to September 2020). Seventy-five pesticide residues were detected (out of a 428-pesticide scope), boscalid and azoxystrobin being the most frequently detected compounds. There were significant variations in the findings of the sampling sites in terms of number of detections, pesticide diversity and average concentration. A relative indicator of the potential risk of pesticide exposure for the honey bees was calculated for each sampling site. The evolution of pesticide detections over the sampling periods, as well as the individual tendencies of selected pesticides, is herein described. The findings of this large-scale monitoring were compared to the ones obtained in a previous Danish, APIStrip-based pilot monitoring program in 2019. Samples of honey and wax were also analyzed and compared to the APIStrip findings.
اظهر المزيد [+] اقل [-]Elevated mercury concentrations in biota despite reduced sediment concentrations in a contaminated coastal area, Harboøre Tange, Denmark
2020
Bjerregaard, Poul | Schmidt, Torben Grau | Mose, Maria Pedersen
Metals sequestered in coastal sediments are normally considered to be stable, but this investigation shows – somewhat surprisingly – that mercury concentrations in a previously contaminated area, Harboøre Tange, Denmark, have decreased since the 1980s. Mercury concentrations were determined in sediment and benthic biota and present values were compared to values in the 1980s and values from areas without known; history of mercury contamination. Concentrations in both the upper 20 cm of the sediments and; biota are considerably lower now compared to latest monitoring (1980s). Sediment.concentrations at most locations have decreased from the 100–300 ng Hg g⁻¹ dry weight (dw) level to levels below the Background Concentration (BC) of 50 ng Hg g⁻¹ dw defined by Oslo-Paris Convention for the Protection of the Marine Environment of the North-East Atlantic; some stations are at the 2–10 ng Hg g⁻¹ dw level characteristic of Danish coastal sediments with no known history of mercury contamination. Concentrations of mercury in the benthic biota along Harboøre Tange have also decreased since the 1980s but despite the lowered mercury concentrations in the sediments, concentrations in most samples of benthic invertebrate fauna still exceed those in uncontaminated coastal areas and also the Environmental Quality Standard (EQS) of 20 ng Hg g⁻¹ wet weight (≈100 ng Hg g⁻¹ dry weight) defined by the European Union’s Water Framework Directive. Concentration ranges in selected organisms are: (Harboøre Tange l980s/Harboøre Tange now/uncontaminated areas - given in ng Hg g⁻¹ dw): Periwinkles Littorina littorea 9000/150–450/55-77, blue mussels Mytilus edulis up to 9000/300–500/40–170, cockles Cerastoderma edule up to 8000/400–1200/200, brown shrimp Crangon crangon 700–2200/150-450/47, eelgrass Zostera marina up to 330/25–70/12. The present results - together with a literature review - show that a simple and straight forward relationship between the concentrations of mercury in sediment and benthic organisms does not necessarily exist.
اظهر المزيد [+] اقل [-]Worldwide human daily intakes of bisphenol A (BPA) estimated from global urinary concentration data (2000–2016) and its risk analysis
2017
Huang, Ri-ping | Liu, Ze-hua | Yuan, Su-fen | Yin, Hua | Dang, Zhi | Wu, Ping-xiao
To evaluate BPA's potential risk to health, it is important to know human daily intake. This study describes a simple but effective method to estimate the levels of human BPA intake among four different populations based on urinary concentration data. Nationally, of the 30 countries examined, the top ten countries for adult intake were Italy, Sweden, Denmark, France, Cyprus, Australia, Israel, Ghana, Jamaica, and Belgium. When the urinary excretion sample size was large enough and over 1000, it was found that the national estimated BPA daily intakes in the child group among countries, showed a good linear relationship with those of their corresponding adult group. Except the infant group with limited data, the global estimated BPA daily intakes for children and pregnant women were 2 and 1.4 times that of the adult group. Although the national and global estimated BPA daily intakes were generally below the temporary tolerable daily intake (tTDI) recommended by the European Food Safety Authority (EFSA), but some normal individuals' daily intakes exceeded the tTDI.
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