Contamination of coastal water is a persistent threat to ecosystems around the world. In this study, a novel model for describing the dispersion, dilution, terminal layer formation and influence area from a point source discharge into a water body is presented and compared with field measured data. The model is a Combined Integral and Particle model (CIPMO). In the initial stage, the motion, dispersion and dilution of a buoyant jet are calculated. The output from the buoyant jet model is then coupled with a Lagrangian Advection and Diffusion model describing the far-field. CIPMO ensures that both the near- and far-field processes are adequately resolved. The model either uses empirical data or collects environmental forcing data from open source hydrodynamic models with high spatial and temporal resolution. The method for coupling the near-field buoyant jet and the particle tracking model is described and the output is discussed. The model shows good results when compared with measurements from a field study.
Phylogenetic comparative studies rely on species-specific data that often contain missing values and/or differ in sample size among species. These phenomena may violate statistical assumptions about the non-random variance component in sampling effort. A major reason why this assumption is often not fulfilled is because the probability of being sampled (i.e., being captured or observed) may depend on species-specific characteristics. Here, we test this assumption by using information on within-species sample sizes and missing data from five independent comparative datasets of European birds. First, we show that the two estimates of data availability (missing values and within-species sample size) are positively correlated and are associated with research effort in general (the number of papers published). Second, we demonstrate biologically meaningful relationships between data availability and phenotypic traits. For example, population size, risk-taking, and habitat specialization independently predicted within-species sample size. The key determinants of missing data were population size and distribution range. However, data availability was not structured by phylogenetic relationships. These results indicate that the accuracy of sampling is repeatable and distributed non-randomly among species, as several species-specific attributes determined the probability of observation. Therefore, data availability seems to be a species-specific trait that can be shaped by ecology, life history, and behavior. Such relationships raise issues about non-random sampling, which requires attention in comparative studies. 相似文献
Summary The outermost tail feathers of barn swallows Hirundo rustica apparently reliably signal the quality of males, because individuals with the longest tails have the lowest degree of fluctuating asymmetry (random deviations from symmetry in the otherwise symmetrical tail trait) despite the size of their secondary sexual character. I experimentally tested whether females preferred males with symmetrical tails without altering the aerodynamic properties of birds by painting the tips of the outermost tail feathers with white or black correction fluid. Unmated males were randomly assigned to one of four treatments: (i) asymmetrical tails, where the outermost 20 mm of one tail feather was painted white and the other black; (ii) symmetrical tails where the outermost 10 mm of both tail feathers was painted white (symmetric I); (iii) symmetrical tails where the outermost 20 mm of both tail feathers was painted white (symmetric II); or (iv) controls where the outermost 20 mm of both tail feathers was painted black. The experimental treatment affected the duration of the premating period since it took longer for asymmetrical males to acquire a mate than for either group of symmetrical males or control males. This gave rise to a delayed start of laying among males with apparently asymmetrical tails. The seasonal production of fledglings therefore decreased from control males through males with either symmetrical treatment to males with the asymmetrical treatment. Females therefore pay direct attention to the level of fluctuating asymmetry in secondary sexual characters even when the asymmetry does not affect the aerodynamic properties of males. 相似文献
Background, aim, and scope The primary aim of this study was to explore the variations in PCDD/F levels and homologue profiles of Baltic surface sediments
by comprehensively analyzing polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in samples from a large number of sites, encompassing not only previously
known hotspot areas, but also sites near other potential PCDD/F sources, in pristine reference areas (in which there was no
industrial activity) and offshore sites.
Materials and methods Surface sediment samples (146 in total) were collected at various points along the Swedish coast and offshore areas. In addition,
bulk deposition was sampled, monthly, at a single site in northern Sweden during 1 year. The concentrations of tetra- through octa-substituted CDD/Fs were determined in both matrices.
Results Highly elevated concentrations of PCDD/Fs were found at many sites in coastal areas and concentrations were also slightly
elevated in some offshore areas. Homologue profiles varied substantially amongst samples from coastal sites, while those from
offshore and other pristine sediments were relatively similar. The offshore sediments showed different profiles from those
observed in the deposition samples. Sediment levels of PCDD/Fs were not generally significantly correlated to organic carbon
levels, except in some pristine areas. Comparison of data obtained in this and previous studies suggest that both their levels
and profiles are similar today to those observed 20 years ago in coastal and offshore areas. The only detected trend is that
their levels appear to have decreased slightly in the offshore area of the Bothnian Sea.
Discussion The localization of hotspot areas along the coast, the lack of consensus between PCDD/F profiles of sediments and general
background, and their weak correlations with organic carbon suggest that PCDD/Fs in the study area largely originate from
local/regional emissions. However, due to complicating factors such as sediment dynamics and land upheaval, it is not possible
to conclude whether these pollutants derive from recent emissions or from a combination of recent emissions and re-distribution
of previous inputs.
Conclusions The results show that: elevated levels of PCDD/Fs are present in both coastal and offshore areas of the Baltic Sea, the major
hotspots are close to the shore, and there are large variations in profiles, indicating that local emissions are (or have
been) the major causes of pollution.
Recommendations and perspectives In order to identify other hotspot areas and trace sources, comprehensive analysis of PCDD/Fs in surface sediments is needed
in all areas of the Baltic Sea that have not been previously investigated. The high levels of PCDD/Fs observed in surface
sediments also indicate a need to elucidate whether they are due mainly to current emissions or a combination of recent pollution
and re-distribution of historically deposited pollutants. To do so, better understanding of sediment dynamics and present-day
inputs, such as riverine inputs, industrial effluents, and leakage from contaminated soil is required. There are indications
that contaminated sediments have a regional impact on fish contamination levels. However, as yet there is no statistically
robust evidence linking contaminated sediments with elevated levels in Baltic biota. It should also be noted that the Baltic
Sea is being massively invaded by the deep-burrowing polychaete Marenzielleria ssp., whose presence in sediments has been shown to increase water concentrations of hydrophobic pollutants. In awareness
of this, it is clear that high levels in sediments cannot be ignored in risk assessments. In order to investigate the emission
trends more thoroughly, analysis of PCDD/Fs in offshore sediment cores throughout the Baltic Sea is also recommended.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
The purpose of the current study was to investigate spatial and seasonal variation of dioxin and dioxin-like PCB (dl-PCB) content in herring sampled along the northern Baltic Sea coast and map out risk zones for dioxins and dl-PCBs. We further aimed to investigate relationships between congener distribution (pattern) and sampling location and season. The results showed that there were distinct geographical differences in concentrations of dioxins, dibenzofurans and dl-PCBs along the Swedish coast, from the Bothnian Bay to north Baltic Proper, with the highest levels detected in the southern Bothnian Sea. The majority of the locations showed concentrations above the prescribed maximum for dioxin residues (4 TEQ pg g(-1) wet weight [w.w.]). If all the edible parts of the fish (muscle, subcutaneous fat and skin) are considered, the estimated concentrations exceeded the prescribed maximum level in the whole study area for herring collected during spring-summer. Concentrations in herring caught during spring-summer compared to concentrations in herring sampled in the autumn indicated seasonal variation. The pattern analysis showed a variation in relative congener concentration at the different sampling locations (spring-summer). Pattern differences were also noticed between seasons. 相似文献
River fisheries are extremely important for food-security among the rural poor in many tropical countries. The growing populations and rapid industrialisation of these countries require that appropriate action should be taken to sustain the resources for future generations. However, an incomplete understanding of river fisheries biology, at the managerial level, often hampers proper planning and management. This is partly due to the difficult access to large parts of such river basins, the complex nature of the fisheries, and in many cases a severe lack of research funds. In contrast, the thousands, or often millions of people who live along the shores of the rivers and rely on the fishery for their daily survival, have a very intimate knowledge of the behaviour and biology of the fish. In this situation, gathering the knowledge of the fishers may provide politicians or planners with baseline knowledge in a relatively quick and cheap way.This paper discusses two years of research using local knowledge in the study of fish migration and spawning in the Lower Mekong Basin. The study involves semi-structured interviews with 355 expert fishermen in four countries along 2,400 km of the Mekong mainstream. By piecing together information from fishermen in different areas, we were able to construct migration maps, and provide rough estimates of the spawning period for 50 fish species. We conclude that river fisheries research can benefit significantly from local knowledge as the basis for future research. 相似文献
The focus of this article was to explore the translocation of 109Cd, 57Co, 65Zn, 63Ni, and 134Cs via xylem and phloem in the newly found hyperaccumulator Solanum nigrum L. Two experiments with the uptake via the roots and transport of 109Cd, 57Co, and 65Zn labeled by roots, and the redistribution of 109Cd, 65Zn, 57Co, 63Ni, and 134Cs using flap label in S. nigrum in a hydroponic culture with a standard nutrient solution were conducted. The results showed that 109Cd added for 24 h to the nutrient medium of young plants was rapidly taken up, transferred to the shoot, and accumulated in the cotyledons and the oldest leaves but was not efficiently redistributed within the shoot afterward leading to a rather low content in the fruits. In contrast, 57Co was more slowly taken up and released to the shoot, but afterward, this element was redistributed from older leaves to younger leaves and maturing fruits. 65Zn was rapidly taken up and transferred to the shoot (mainly to the youngest leaves and not to the cotyledons). Afterward, this radionuclide was redistributed within the shoot to the youngest organs and finally accumulated in the maturing fruits. After flap labeling, all five heavy metals tested (109Cd, 57Co, 65Zn, 63Ni, 134Cs) were exported from the labeled leaf and redistributed within the plant. The accumulation in the fruits was most pronounced for 63Ni and 65Zn, while a relatively high percentage of 57Co was finally found in the roots. 134Cs was roughly in the middle of them. The transport of 109Cd differed from that previously reported for wheat or lupin and might be important for the potential of S. nigrum to hyperaccumulate cadmium. 相似文献
This paper describes a field study of the correlation between annoyance and occupational exposure to noise. Measurements of noise and annoyance were made in different types of working environments with noise dominated by low-frequency, middle-frequency or high-frequency components. The noise was described in terms of dB(A), dB(B), dB(C), dB(D), and dB(lin). Annoyance ratings of the occupational noise and of two verbally described reference noises were collected, using a rating scale. As a result of calibration, a better correlation between noise level and rated annoyance was obtained. The A-weighting procedure did not produce a better prediction of annoyance than any of the other weighting methods. 相似文献