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981.
铜、砷单一及复合污染对黑藻的毒性效应 总被引:2,自引:0,他引:2
通过室内模拟试验,研究了铜(Cu)、五价砷〔As(Ⅴ)〕单一及复合污染对黑藻〔Hydrilla verticillata (L.f.) Royle〕生长、富集Cu和As的能力以及对超氧化物歧化酶(SOD)活性的影响.毒性测试结果表明,Cu和As(Ⅴ)对黑藻的4 d-EC50分别为2和12 μmol/L,单一Cu对黑藻的毒性远高于As(Ⅴ). 复合污染试验结果表明,对于5 μmol/L As(Ⅴ)处理组,低浓度Cu〔c(Cu)<2 μmol/L〕的加入,促进了植物生长,降低了植物体内的As总量〔w(As)〕,同时降低了植物体中占主要部分的三价砷的含量(w〔As(Ⅲ)〕). 对于Cu处理组,As(Ⅴ)的加入同样抑制了黑藻对Cu的富集,SOD活性也高于单一Cu处理,可见在低浓度Cu处理下,Cu和As(Ⅴ)之间存在拮抗作用;而高浓度Cu〔c(Cu)≥2 μmol/L〕的加入,虽然植物对Cu和As(Ⅴ)的富集与单一Cu和As(Ⅴ)处理相比均显著降低,但植物生长受到抑制,SOD活性与单一处理相比也显著降低(P<0.05),因此高浓度Cu处理下,二者对黑藻毒性起协同作用. 总之,黑藻具有应用于处理低浓度Cu和As(Ⅴ)单一及复合污染水体的潜力. 相似文献
982.
In general, contamination levels tend to be highest close to sources of a chemical and decline with increasing distance as
a result of dilution, dispersion and degradation. However, contrary to this, circumstances have been described when contamination
levels are higher further away from sources than at the sources themselves. Examples are elevated levels of persistent, hydrophobic,
organic chemicals in the Arctic, in mountain regions and in forest soils. In order to address the questions of why and when
such an inversion of environmental levels is occurring, this paper seeks to identify, name and categorise principles of general
validity leading to such behaviour. By compiling and analysing various causes of elevated contamination levels in the environment,
three main categories became apparent, 1. equilibrium partitioning effects, 2. effects resulting from changes in phase composition,
volume or temperature, and 3. dynamic or kinetic effects. These principles are illustrated with several examples. The case
can be made that understanding, quantifying and predicting these causes could provide a general conceptual framework for studying
the fate of chemicals in the environment. 相似文献
983.
984.
Rebecca J. Safran Kevin M. Pilz Kevin J. McGraw Stephanie M. Correa Hubert Schwabl 《Behavioral ecology and sociobiology》2008,62(3):427-438
Recently, evidence is mounting that females can adaptively engineer the quality of their offspring via the deposition of yolk
compounds, including carotenoids and androgens. In this study, we simultaneously consider how both carotenoids and androgens
in egg yolk relate to parental quality in barn swallows (Hirundo rustica erythrogaster). First, we found no relationship between concentrations or amounts of yolk androgens and carotenoids. Yolk carotenoids decreased
with laying order, whereas we found no relationship between yolk androgens and laying order. Second, we tested the Investment
Hypothesis, which predicts that high-quality females or females paired to high quality mates, allocate differentially more
of these yolk compounds to their offspring. For carotenoids, we mostly found evidence to counter predictions of the Investment
hypothesis: (1) Carotenoid concentrations varied among females, (2) heavier eggs contained lower carotenoid concentrations,
although heavier yolks contained greater amounts of carotenoids, (3) eggs of earlier-laying females had lower concentrations
in their eggs, and (4) yolk carotenoids were not correlated with clutch size or male plumage ornamentation. For androgens,
we found weak support for the Investment Hypothesis: (1) Yolk androgens varied among females, (2) heavier eggs and yolks contained
greater amounts, although not concentrations of androgens, (3) females paired to more colorful males laid eggs with greater
concentrations of androgens, and (4) no effects of laying date or morphological correlates of female quality on androgen concentrations
in egg yolks. Overall, these findings suggest that each yolk compound may have different functions and therefore may be regulated
by different mechanisms. 相似文献
985.
A community is stable, and resilient, if the levels of all community variables can return to the original steady state following a perturbation. The stability properties of a community depend on its structure, which is the network of direct effects (interactions) among the variables within the community. These direct effects form feedback cycles (loops) that determine community stability. Although feedback cycles have an intuitive interpretation, identifying how they form the feedback properties of a particular community can be intractable. Furthermore, determining the role that any specific direct effect plays in the stability of a system is even more daunting. Such information, however, would identify important direct effects for targeted experimental and management manipulation even in complex communities for which quantitative information is lacking. We therefore provide a method that determines the sensitivity of community stability to model structure, and identifies the relative role of particular direct effects, indirect effects, and feedback cycles in determining stability. Structural sensitivities summarize the degree to which each direct effect contributes to stabilizing feedback or destabilizing feedback or both. Structural sensitivities prove useful in identifying ecologically important feedback cycles within the community structure and for detecting direct effects that have strong, or weak, influences on community stability. The approach may guide the development of management intervention and research design. We demonstrate its value with two theoretical models and two empirical examples of different levels of complexity. 相似文献
986.
Very few studies have investigated the effect of genetic diversity on the behavioral and phenotypic traits linked to the competitive
ability of individuals. In this study, we reared juvenile Atlantic salmon (Salmo salar) alone or with the competitive rainbow trout (Oncorhynchus mykiss) in order to: (1) to assess correlations between heterozygosity and traits related to individual competitive ability [i.e.,
heterozygosity–fitness correlations (HFCs)] in Atlantic salmon, and (2) to evaluate the effect of the competitive rainbow
trout on any such HFCs. We also tested whether a few loci had a disproportionately large effect (i.e., the local effect hypothesis)
or, on the contrary, if all loci contributed equally (i.e., the global effect hypothesis) in explaining the observed HFCs.
We found significant HFCs for phenotypic traits related to the competitive ability of juvenile Atlantic salmon, i.e., the
growth rate and the distance to the feeding source. Some HFCs were nonlinear, suggesting that individuals with intermediate
levels of heterozygosity were favored. In addition, we found that the competition exerted by rainbow trout only weakly modified
these HFCs as the relationships were highly consistent across treatments. We demonstrated that the local-effect hypothesis
best explained both linear and nonlinear HFCs. Overall, our results illustrated the importance of genetic diversity in explaining
the behavioral variability observed within populations. Moreover, we provide evidence that, even if a competitive species
can have strong ecological effects, the relationships between genetic diversity and fitness-related traits in juvenile Atlantic
salmon were not influenced by such effects. 相似文献
987.
The main aim of the present work is to discuss the methodological approaches that underpin the “contaminant migration–population effects” models for the evaluation of the detriment to populations of moving organisms in environmental systems with spatial and time dependent pollution levels. A technique to couple the equations controlling the population dynamics and the pollutant dispersion is described and discussed. The domain of application and the limitations of the methodology are analysed and illustrated by some examples. Possible alternative approaches are briefly presented. 相似文献
988.
Maternal yolk androgens in bird eggs represent an important pathway along which offspring phenotype is shaped. Most of the
hormone-mediated maternal effects are highly important in the context of sibling competition. However, there is also increasing
evidence for long-lasting effects far beyond the nestling period, and these effects may have important consequences on the
reproductive success of the offspring. Here, we investigated the effects of experimentally elevated yolk testosterone concentrations
on growth and reproduction in female canaries. Elevated yolk testosterone concentrations enhanced the post-natal growth rate,
but not the asymptotic mass, and reduced the survival probability. The latter may be a consequence of the higher growth rate,
which may have rendered females hatching from testosterone-treated eggs (T-females) more vulnerable to harsh environmental
conditions. Adult T-females made a larger investment in their clutch by laying more but not heavier eggs than females hatching
from control-treated eggs. Our results suggest that the observed long-lasting effect on clutch size relates to changes in
the growth trajectory rather than being a direct consequence of testosterone, since studies manipulating early growth conditions
obtained similar results. Clearly, further studies are now required in order to investigate the intriguing relationship between
yolk testosterone, elevated growth rates, and clutch size. 相似文献
989.
Suiliang HUANG Yafei JIA Sam S. Y. WANG 《Frontiers of Environmental Science & Engineering》2009,3(2):178-185
The effects of chemical spills on aquatic nontarget organisms were evaluated in this study. Based on a review of three types of current eco-toxicological models of chemicals, i.e., ACQUATOX model of the US-EPA, Hudson River Model of PCBs, and critical body residual (CBR) model and dynamic energy budget (DEBtox) model, this paper presents an uncoupled numerical ecotoxicological model. The transport and transformation of spilled chemicals were simulated by a chemical transport model (including flow and sediment transport), and the mortalities of an organism caused by the chemicals were simulated by the extended threshold damage model, separately. Due to extreme scarcity of data, this model was applied to two hypothetical cases of chemical spills happening upstream of a lake. Theoretical analysis and simulated results indicated that this model is capable of reasonably predicting the acute effects of chemical spills on aquatic ecosystems or organism killings. 相似文献
990.
H. Chanson 《Environmental Fluid Mechanics》2009,9(2):125-142
In hydraulic structures, free-surface aeration is commonly observed: i.e., the white waters. The air bubble entrainment may
be localised (hydraulic jumps, plunging jets) or continuous along an interface (water jets, chutes). Despite recent advances,
there are some basic concerns about the extrapolation of laboratory results to large size prototype structures. Herein the
basic air bubble entrainment processes are reviewed and the relevant dynamic similarities are discussed. Traditionally, physical
studies are conducted using a Froude similitude which implies drastically smaller laboratory Reynolds numbers than in the
corresponding prototype flows. Basic dimensional analyses are developed for both singular and interfacial aeration processes.
The results are discussed in the light of systematic investigations and they show that the notion of scale effects is closely
linked with the selection of relevant characteristic air–water flow properties. Recent studies of local air–water flow properties
highlight that turbulence levels, entrained bubble sizes and interfacial areas are improperly scaled based upon a Froude similitude
even in large-size models operating with the so defined Reynolds numbers ρ
w × q
w/μ
w up to 5 E+5. In laboratory models, the dimensionless turbulence levels, air–water interfacial areas and mass transfer rates
are drastically underestimated. 相似文献