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31.
32.
The solubility and potential mobility of heavy metals (Cd, Cu,Hg, Pb and Zn) in two urban soils were studied by sequential andleaching extractions (rainwater). Compared to rural (arable) soils on similar parent material, the urban soils were highlycontaminated with Hg and Pb and to a lesser extent also with Cd,Cu and Zn. Metal concentrations in rainwater leachates were related to sequential extractions and metal levels reported fromStockholm groundwater. Cadmium and Zn in the soils were mainly recovered in easily extractable fractions, whereas Cu and Pb were complex bound. Concentrations of Pb in the residual fractionwere between two- and eightfold those in arable soils, indicatingthat the sequential extraction scheme did not reflect the solidphases affected by anthropogenic inputs. Cadmium and Zn conc. inthe rainwater leachates were within the range detected in Stockholm groundwater, while Cu and Pb conc. were higher, whichsuggests that Cu and Pb released from the surface soil were immobilised in deeper soil layers. In a soil highly contaminatedwith Hg, the Hg conc. in the leachate was above the median concentration, but still 50 times lower than the max concentration found in groundwater, indicating the possibilityof other sources. In conclusion, it proved difficult to quantitatively predict the mobility of metals in soils by sequential extractions. 相似文献
33.
Jennifer Jungerstam Johan Erlandsson Christopher D. McQuaid Francesca Porri Mats Westerbom Patrik Kraufvelin 《Marine Biology》2014,161(7):1507-1519
Habitat-forming species on rocky shores are often subject to high levels of exploitation, but the effects of subsequent habitat loss and fragmentation on associated species and the ecosystem as a whole are poorly understood. In this study, the effects of habitat amount on the fauna associated with mussel beds were investigated, testing for the existence of threshold effects at small landscape scales. Specifically, the relationships between mussel or algal habitat amount and: associated biodiversity, associated macrofaunal abundance and density of mussel recruits were studied at three sites (Kidd’s Beach, Kayser’s Beach and Kini Bay) on the southern and south-eastern coasts of South Africa. Samples, including mussel-associated macrofauna, of 10 × 10 cm were taken from areas with 100 % mussel cover (Perna perna or a combination of P. perna and Mytilus galloprovincialis) at each site. The amount of habitat provided by mussels and algae surrounding the sampled areas was thereafter determined at the 4.0 m2 scale. A number of significant positive relationships were found between the amount of surrounding mussel habitat and the abundances of several taxa (Anthozoa, Malacostraca and Nemertea). Likewise, there were positive relationships between the amount of surrounding algal habitat and total animal abundance as well as abundance of mussel recruits at one site, Kini Bay. In contrast, abundance of mussel recruits showed a significant negative relationship with the amount of mussel habitat at Kayser’s Beach. Significant negative relationships were also detected between the amount of mussel habitat and species richness and total abundance at Kidd’s Beach, and between amount of mussel habitat and the abundance of many taxa (Bivalvia, Gastropoda, Maxillopoda, Ophiuroidea, Polychaeta and Pycnogonida) at all three sites. No threshold effects were found, nor were significant relationships consistent across the investigated sites. The results indicate that the surrounding landscape is important in shaping the structure of communities associated with these mussel beds, with significant effects of the amount of surrounding habitat per se. The strength and the direction of habitat effects vary, however, between shores and probably with the scale of observation as well as with the studied dependent variables (e.g. diversity, abundance, mussel recruitment, species identity), indicating the complexity of the processes structuring macrofaunal communities on these shores. 相似文献
34.
Physical and biological disturbances are ecological processes affecting patterns in biodiversity at a range of scales in a variety of terrestrial and aquatic systems. Theoretical and empirical evidence suggest that effects of disturbance on diversity differ qualitatively and quantitatively, depending on levels of productivity (e.g., the dynamic equilibrium model). In this study we contrasted the interactive effects between physical disturbance and productivity to those between biological disturbance and productivity. Furthermore, to evaluate how these effects varied among different components of marine hard-substratum assemblages, analyses were done separately on algal and invertebrate richness, as well as richness of the whole assemblage. Physical disturbance (wave action) was simulated at five distinct frequencies, while biological disturbance (grazing periwinkles) was manipulated as present or absent, and productivity was manipulated as high or ambient. Uni- and multivariate analyses both showed significant effects of physical disturbance and interactive effects between biological disturbance and productivity on the composition of assemblages and total species richness. Algal richness was significantly affected by productivity and biological disturbance, whereas invertebrate richness was affected by physical disturbance only. Thus, we show, for the first time, that biological disturbance and physical disturbance interact differently with productivity, because these two types of disturbances affect different components of assemblages. These patterns might be explained by differences in the distribution (i.e., press vs. pulse) and degree of selectivity between disturbances. Because different types of disturbance can affect different components of assemblages, general ecological models will benefit from using natural diverse communities, and studies concerned with particular subsets of assemblages may be misleading. In conclusion, this study shows that the outcome of experiments on effects of disturbance and productivity on diversity is greatly influenced by the composition of the assemblage under study, as well as on the type of disturbance that is used as an experimental treatment. 相似文献
35.
Closely related species may occupy very similar niches but are often found to diverge by one or more traits when they share
the same habitat. Five indigenous and sympatric Gammarus species are characteristic for the Baltic rocky littoral ecosystem. Yet, the species-specific distribution of these sympatric
gammarids has not been well studied in the northern Baltic Sea. This study was undertaken to assess the spatial distribution
of gammarid amphipods along wave exposure and depth gradients to study whether they show segregation in their microhabitat
use. We sampled 12 rocky sublittoral shores along a wave exposure gradient over a period of 5 years. Samples differed with
respect to depth and macroalgal type. Three of the five gammarid species occurred mainly in different depth zones and among
different macroalgae at the exposed shores. In contrast, on protected shores, where algal zonation is weaker, a link to zonation
and macroalgal type was almost absent. Moreover, the microhabitat use was strongest during the reproductive seasons of the
species. The observed microhabitats of the three gammarid species fit well to their species-specific mean body sizes. 相似文献
36.
Local authorities in Sweden are responsible for the management of sewage treatment and municipal solid waste. Due to this, they handle large flows and stocks of materials and substances that may be harmful for the environment. However, knowledge about these flows is sometimes deficient. In addition, the capacity to influence the composition of these flows is mainly beyond the jurisdiction of the local authorities. Flow-oriented studies, such as substance flow analysis (SFA), have proven to be a useful tool in order to understand and quantify these flows. Furthermore, SFA is sometimes claimed to be beneficial to the process of decision making, since it generates comprehensive overviews of the substance in focus. However, quantification of stocks and flows of a certain substance does not necessarily provide sufficient information for environmental management on the local level. Hence, for SFA to further contribute to the environmental management process, there is also a need for development in the interpretation of the results. The main objective of this paper is to contribute to the discussion about (1) how to interpret the results from SFA and (2) how the results from an SFA can be used in environmental management by local authorities. A tentative framework for interpretation is discussed in the paper, focusing on five aspects: total material quantities, exposure to humans and the environment, resource economy, function and capacity to influence the substance flows. Furthermore, the paper discusses the suggested framework applied to results of a regional cadmium inventory. 相似文献
37.
Sperm number is often a good predictor of success in sperm competition; however, it has become increasingly clear that, for
some species, variation in probability of paternity cannot be explained by sperm number alone. Intraspecific variation in
ejaculate characteristics, such as the number of viable sperm and sperm longevity, may play an equally important role in determining
fertilization success. Here, we assess variation among ejaculates in three factors that may contribute to fertilization success
(number of sperm per ejaculate, viability, and longevity), in a population of Peron’s tree frog (Litoria peronii). We detected large variation among males in the number of sperm per ejaculate and the proportion of viable sperm within
ejaculates, which could not be explained by variation in either male size or body condition. However, the proportion of viable
sperm released by males increased over the season. Finally, we assessed sperm longevity (proportion viable sperm determined
using a dual-fluorochrome vital dye) at two different temperatures. At 23°C, on average, 75% of sperm remained viable after
2 h, but there were significant differences amongst males with the percentage of viable sperm ranging from 43% to 95%. For
sperm incubated at 4°C, ejaculates varied fivefold in sperm longevity with some males having 50% viable sperm after 5 days.
Our data suggest that ejaculate characteristics (sperm number, viability, and longevity) vary widely in Peron’s tree frog
and may therefore play an important role in determining siring success both in the presence and absence of sperm competition.
We discuss the results in relation to selection on ejaculate traits via natural and sexual selection in this and other amphibians. 相似文献
38.
Physical and biological processes interact to produce pattern in nature. Pattern is scale dependent as processes generating
pattern are heterogeneous in time and space. We tested some causes of variation in abundance and distribution of three marginal
populations of sublittoral blue mussels, Mytilus edulis, in the non-tidal northeastern Baltic Sea. We studied the role of substrate inclination, perennial algae and siltation along
local wave exposure gradients on mussel distribution over a regional salinity gradient. We found marked differences on regional
scales (p < 0.001) with lower densities and biomasses of mussels with declining salinity. Along local gradients, mussel densities increased
with increasing exposure (p < 0.001) and declining slope and sedimentation (p < 0.01). Site specifically, densities of blue mussels and the perennial red algae, Furcellaria lumbricalis, were positively related, results supported by a colonisation experiment. Also, young post-recruits showed significant relations
to adult biomass, wave exposure, algal biomass, bottom slope and sediment cover. Findings showed that the relative importance
of the determinants affecting blue mussels at the edge of their range vary with scale and are affected by the density and
size structure of mussel populations. The study provides an indication of the types of factors that may be invoked as causes
of spatial variation in marginal blue mussel populations and reinforces the need to consider multiple aspects when distributional
patterns are assessed. 相似文献
39.
Dioxins,chlorophenols and other chlorinated organic pollutants in colloidal and water fractions of groundwater from a contaminated sawmill site 总被引:1,自引:1,他引:0
Persson Y Shchukarev A Oberg L Tysklind M 《Environmental science and pollution research international》2008,15(6):463-471
BACKGROUND, AIM, AND SCOPE: The distribution of chlorinated organic contaminants in groundwater and the importance of colloids were studied in groundwater from a sawmill site contaminated by chlorophenol preservatives. MATERIALS AND METHODS: The groundwater was fractionated into three different size ranges: (1) >0.7 mum, (2) 0.4-0.7 mum and (3) 0.2-0.4 mum and the filtered water phase. The concentrations of chlorophenols (CP), chlorinated phenoxy phenols (PCPP), chlorinated diphenyl ethers (PCDE), chlorinated dibenzofurans (PCDF) and chlorinated dibenzo-p-dioxins (PCDD) were determined in each fraction. The colloids were characterised regarding the chemical composition using X-ray photoelectron spectroscopy (XPS). RESULTS: Chlorophenols were mostly found in the water fraction and PCDD/Fs were found almost exclusively in the particulate fractions. For example, the filtered water phase contained 2,100 mug l(-1) and 0.72 ng l(-1) for CPs and PCDD/Fs, respectively, and the particulate fractions contained 27 mug l(-1) and 32 ng l(-1) for CPs and PCDD/Fs, respectively. XPS evaluation of the particulate phases showed no correlation between the surface chemistry of the particle properties and the distribution of chlorinated compounds. DISCUSSION: The results suggest that groundwater transport of CPs, PCPPs, PCDEs and PCDD/Fs may occur from contaminated sawmill sites and that the colloid-facilitated transport, especially of PCDD/Fs, is substantial. The results correlated well with previous studies of compounds sorbed to dissolved organic carbon, which indicate that dissolved and colloidal organic carbon facilitated the transport of PCDEs, PCDFs and PCDDs particularly. CONCLUSIONS: Several classes of chlorinated compounds were readily detected in the groundwater samples. Due to the differences in their physicochemical properties, CPs, PCPPs, PCDEs and PCDD/Fs vary in their partitioning between colloidal fractions and the filtered groundwater. The proportion of the bound fraction increased with an increasing hydrophobicity of the chlorinated compounds. The groundwater transport of colloid-associated pollutants from the site may be significant. RECOMMENDATIONS AND PERSPECTIVES: The results imply that colloidal particles <0.7 mum are freely mobile in groundwater from this site. The groundwater transport of colloid-associated pollutants may be significant. However, the extent of the problem is not yet known and, thus, further research is needed to evaluate the impact of colloidal transport of hydrophobic organic contaminants. In Sweden alone, 400 to 500 sawmill sites are estimated to be contaminated with PCDD/Fs as a result of the former use of CP-based wood preservatives. The widespread use of CP mixtures for a variety of applications, including wood preservation, indicates that potential colloidal transport will be an issue of concern in many countries. 相似文献
40.
Patrik L. Andersson Peter Haglund Mats Tysklind 《Environmental science and pollution research international》1997,4(2):75-81
The internal barrier of rotation (Erot) was calculated for all 209 polychlorinated biphenyls (PCBs) by using a semi-empirical
method, viz. the Austin Model 1 (AMI) Hamiltonian. The difference in total energy between a forced planar state and an optimised
twisted structure was defined as Erot. The Erot values were in the range of 8.33 to 483 kj/mol, and were significantly influenced
by the number of chlorine atoms inortho position. An additional structural characteristic of the PCBs influencing Erot ofortho substituted congeners was substitution by chlorine atoms in vicinalmeta positions, which is assumed to prevent outward bending ofortho substituents. This so-called buttressing effect contributed with 4 to 31 kj/mol per added chlorine atom. In conclusion, the
internal barrier of rotation, calculated for all 209 PCBs, provides an important structure dependent physico-chemical parameter
for multivariate modelling of future quantitative structure-activity and structure-property relationships (QSARs/QSPRs). 相似文献