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11.
Dissolved organic matter (DOM) in soil solution is considered to interact with herbicides enhancing their mobility and promoting
subsequent leaching.
Batch experiments were conducted to test if free and DOM-bound herbicides can be separated by a DOM-flocculation technique
with Cu as a coagulant.
DOM was extracted from the H and A horizons of two soils (Terric Histosol, Cumuli-Calcaric Cambisol) and from the O horizon
of a forest soil (Humic Cambisol). DOM-solutions (100 mL) were fortified with the herbicides terbuthylazine and pendimethalin
(100 μg active ingredient each) and equilibrated for 14 hours. After DOM-flocculation with Cu (addition of 0,5 mM CuCl2) herbicide recovery was determined in the supernatant solutions and in the precipitate of Humic Cambisol-DOM, respectively.
Recovery of the herbicides from pure water was 85–99% and was not influenced by the addition of Cu. At low pH (4,8–5,3) DOM-flocculation
of different DOM-extracts was insufficient and varied in a range of 18 – 90%. Herbicide recovery from DOM-solutions decreased
moderately for terbuthylazine (60–90%) and strongly for pendimethalin (5 – 30%). In general, the addition of Cu caused no
further reduction of herbicide recovery from supernatant solutions, except for Humic Cambisol-DOM. The effects of Cu-addition
were most evident for pendimethalin (strongly reduced concentration in the supernatant solutions) and were considered to be
caused by a flocculation of DOM-bound moieties. Flocculation of Humic Cambisol-DOM increased from 18 – 24% at pH 5 to > 95%
at pH 8. However, at this pH the formation of Cu(OH)2 as a sorbing subcomponent of the flocculated matter lead to an overestimation of DOM-bound pendimethalin. Calculating this
side effect 6% of pendimethalin added was DOM-bound. Only traces of terbuthylazine (< 1%) were found in the solid matter of
flocculated Humic Cambisol-DOM.
To sum up, the new approach to separate freely dissolved herbicides from DOM-bound moieties not fully corresponded to our
expectations. DOM-flocculation was found to depend strongly on pH-environment influencing not only DOM-herbicide interactions
but also the clear separation of DOM-bound herbicides from herbicides in solutions. 相似文献
12.
Numerous analyses of the possible impacts of future climatic changes on tree species composition have been published for
both lowland and high-elevation forests. Most of these studies were based on the application of forest "gap" models, and the
vast majority of them considered only changes in the average of climatic parameters over time. In this study, we use a unique
data set on reconstructed past climatic variations to analyse forest dynamics simulated by the forest gap model ForClim. This
analysis forms the basis for a systematic exploration of the ecological effects of changing means vs. changing variability
of climate on central European forests. A reconstruction of historical climate covering the last 470 years in the Swiss lowlands
(ClimIndex) is extrapolated to a transect across the alpine (cold) treeline and used to simulate the influence of climate
variations on the time scale of decades on forest biomass and tree species composition at both sites. While the simulation
at the low-elevation site shows little sensitivity to climate variations, the results from upper subalpine forests suggest
that two major dieback events would have occurred at elevations above the current but below the climatic tree line, induced
by clusters of exceptionally cold summers. The results are in agreement with available dendrochronological data and with documentary
evidence on massive negative impacts on flora and fauna at high elevations during these periods. We conclude that ForClim
is capable of capturing the effects on tree population dynamics of climate variability at these sites as reconstructed from
the ClimIndex record. A factorial design is used to address the sensitivity of ForClim to changes of the long-term averages
vs. changes of the variability of monthly temperature and precipitation data. To this end, the simulated tree species composition
of near-natural forests is examined along a climate gradient in Europe. The results indicate that there are three types of
forest response: (1) little sensitivity to both kinds of change, (2) strong sensitivity to changes in the means, but little
sensitivity to changing variability, and (3) strong sensitivity to changing variability at least in parts of the examined
climate space. Half of the cases investigated fall under the third category, suggesting that emphasis should be placed on
also assessing the sensitivity of ecosystems to future changes in climate variability rather than on changes of average values
alone.
Electronic Publication 相似文献
13.
Hollert H Dürr M Holtey-Weber R Islinger M Brack W Färber H Erdinger L Braunbeck T 《Environmental science and pollution research international》2005,12(6):347-360
Goal, Scope and Background In order to evaluate the estrogenic activity of sediments and XAD water extracts of selected sites of the catchment area
of the River Neckar, a river system in Southern Germany, an integrative assessment approach was used to assess the ecological
hazard potential of endocrine-disrupting compounds in sediment and water.
Methods The approach is based on estrogen receptor-mediated vitellogenin synthesis induced in isolated hepatocytes of rainbow trout
and quantified in a non-radioactive dot blot/RNAse protection-assay in parallel to comprehensive chemical analyses of estrogenic
substances.
Results and Discussion Numerous investigated extracts revealed an estrogen activity comparable to that of the positive control (1 nM 17?-estradiol
corresponding to 270 ng/L in the test medium). Based on a concentration factor of 30 in the extracts and a recovery of XAD
resins of approximately 80 %, 17?-estradiol equivalent concentrations between 20 and 26.7 ng/L could be calculated downstream
of a sewage treatment plant (< 0.1 ng/L for a reference site). A comparison of the bioassay-derived Bio-TEQs (toxicity equivalents)
and the Chem-TEQs revealed a high correlation with a Pearson coefficient of 0.85, indicating that the same ranking of the
samples could be obtained with respect to the endocrine disrupting potential with both chemical and bioanalytical analysis.
However, the TEQ concentrations computed from chemical analyses were significantly lower than the bioassay-derived TEQ concentrations.
In fact, in none of the samples, more than 14 % of the vitellogenin-inducing potency could be attributed to the substances
(steroids, alkylphenols, bisphenol A, diethylstilbestrol) analyzed.
A comparison of the endocrine disrupting potential of sediments extracted by the solvents acetone and methanol revealed lower
biological effects for acetone-extracted samples. Possible reasons may be a masking of endocrine effects in acetone extracts
by cytotoxicity, a low extraction efficiency of the solvent acetone, or anti-estrogen potencies of some extracted sediment
compounds.
Using a mass balance approach, the contribution of the compounds analyzed chemically (Chem-TEQs) to the total endocrine activity
(Bio-TEQs) was calculated. Based on the very low detection limits, particularly of the steroids with their high TEF factors,
results revealed that a calculation of the Chem-TEQs is associated with considerable scale inaccuracy: Whereas only 7-15 %
of the biological effectiveness (Bio-TEQs) could be explained by endocrine substances identified above the detection limits,
the assumption of concentrations slightly below the given detection limits would result in a significant over estimation (137-197
%) of the Bio-TEQs. Even the interassay variation of the dot blot assay with different fish donors for primary hepatocyte
(factor 2 - 2.5) is relatively low, when compared to the large range of the Chem-TEQ concentrations (factor 20) obtained when
applying different modes of calculation.
Conclusions and Outlook Overall, only a minor portion of the endocrine activity detected by bioassays could be linked to compounds identified by
chemical analysis. In vitro assays for assessment of endocrine activities are useful as sensitive integrating methods that
provide quantitative estimates of the total activity of particular receptor-mediated responses. Although discrepancies may
also result from different bioanalytical approaches, it is overall likely that bioanalytical and not chemical analytical approaches
give the correct estimate of endocrine disrupting potencies in environmental samples. As a conclusion, assessment of endocrine
disruption based on chemical analysis alone does not appear sufficient and further research into the spectrum of substances
with potential endocrine activity as well as into additive or even synergistic effects in complex environmental samples is
urgently needed. 相似文献
14.
Harald Schaaf 《Umweltwissenschaften und Schadstoff-Forschung》2007,19(1):63-68
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Brenda Maria Zoderer Paola Sabina Lupo Stanghellini Erich Tasser Janette Walde Harald Wieser Ulrike Tappeiner 《Regional Environmental Change》2016,16(7):2033-2044
The socio-cultural assessment of ecosystem services has been proposed as a promising tool for eliciting people’s preferences towards ecosystem services. Despite an increasing integration of the socio-cultural perspective in ecosystem service research, little knowledge exists about linkages between landscape and the socio-cultural values people assign to ecosystem services. This paper combines a socio-cultural valuation approach with the use of landscape pictures to analyse and compare people’s perceived importance of the provisioning, regulating, and cultural ecosystem service categories across three landscape types (i.e. larch meadows, spruce forests, and hay meadow). A survey with 470 tourists visiting the region of South Tyrol (Italy) was conducted to link people’s perceived importance to their socio-demographic background and to the landscape types explored. The results show that regulating ecosystem services are preferred over provisioning and cultural services, whereby environmental awareness is found to be more influential than formal education levels regarding the perceived importance of regulating services. The results further demonstrate that cultural background is an important driver in determining people’s perceived importance of cultural services. The underlying landscape types, however, exert an even stronger influence on people’s socio-cultural valuation of ecosystem service categories. This finding suggests that the focus of most ecosystem services assessments on the study area as a whole risks mistakenly attributing differences in people’s socio-cultural values to socio-demographic characteristics only. A better knowledge of the spatial integration of socio-cultural values, however, could help with anticipating the consequences of changes in the landscape and provide better guidance for future landscape planning. 相似文献
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