Assessing regional trends in groundwater quality can be a difficult task. Data are often scattered in space and time, and the inertia of groundwater systems can create natural, seemingly persistent changes in concentration that are difficult to separate from anthropogenic trends. Here, we show how statistical methods and software for joint analysis of multiple time series can be integrated into a roadmap for trend analysis and critical examination of data quality. Ordinary and partial Mann–Kendall (MK) tests for monotonic trends and semiparametric smoothers for multiple time series constitute the cornerstones of our procedure. The MK tests include a simple and easily implemented method to correct for serial dependence, and the associated software is designed to enable convenient handling of numerous data series and to accommodate covariates and nondetects. The semiparametric smoothers are intended to facilitate detection of synchronous changes in a network of stations. A study of Swedish groundwater quality data revealed true upward trends in acid-neutralizing capacity and downward trends in sulfate but also a misleading shift in alkalinity level that would have been difficult to detect if the time series had been analyzed separately. 相似文献
Energy use is of great concern within fisheries, due to both associated environmental effects and the cost of fuel to fishermen. This article explores the scale of energy consumed by most segments of the Norwegian fishing fleet for gadoid fish and for parts of the pelagic fleet for the period 1980–2005. Fuel use is assigned to the different species caught and different fishing gears using economic and mass-based allocation, where data permit. Correlations between variations in energy use and changing catch rates, quotas and oil prices are found. Inverse correlations are found between fuel consumption per kilogram of fish and catch rates on a yearly basis and between fuel consumption and oil prices on a longer term basis. A long term trend towards increased fuel consumption and reduced real prices is observed from the mid 1980s until 2000. This may indicate that low fuel prices do not motivate the development of energy efficient technology in the long run. Increased fuel use may further be used as an indication of over fishing as the correlation between low catch rates and increased fuel consumption is rather strong. Possible means of reducing energy use and emissions are discussed including changing operational strategies, hull forms and the use of alternative energy carriers. A comparison with measures taken in connection with the previous oil crisis around 1980 is done. 相似文献
Driver celeration (speed change) behavior of bus drivers measured a number of times was used to predict their culpable accidents over increasing time periods. It was found that predictive power was considerable (>.30 correlation) over 5 years of time with aggregated celeration (mean of repeated measurements) as independent variables, and there were also indications that power reached even further, although too low Ns made these results unreliable. Similarly, there were indications of even stronger correlations with increased aggregation of celeration values. The results were discussed in terms of the methodology needed to bring out such results, and the stability of accident-causing behavior over time. 相似文献
Successful transitions to a sustainable bioeconomy require novel technologies, processes, and practices as well as a general agreement about the overarching normative direction of innovation. Both requirements necessarily involve collective action by those individuals who purchase, use, and co-produce novelties: the consumers. Based on theoretical considerations borrowed from evolutionary innovation economics and consumer social responsibility, we explore to what extent consumers’ scope of action is addressed in the scientific bioeconomy literature. We do so by systematically reviewing bioeconomy-related publications according to (i) the extent to which consumers are regarded as passive vs. active, and (ii) different domains of consumer responsibility (depending on their power to influence economic processes). We find all aspects of active consumption considered to varying degrees but observe little interconnection between domains. In sum, our paper contributes to the bioeconomy literature by developing a novel coding scheme that allows us to pinpoint different aspects of consumer activity, which have been considered in a rather isolated and undifferentiated manner. Combined with our theoretical considerations, the results of our review reveal a central research gap which should be taken up in future empirical and conceptual bioeconomy research. The system-spanning nature of a sustainable bioeconomy demands an equally holistic exploration of the consumers’ prospective and shared responsibility for contributing to its coming of age, ranging from the procurement of information on bio-based products and services to their disposal.
The occurrence and distribution of metals (Al, Cd, Cr, Cu, Pb, Zn), organochlorine residues (HCH, DDT and metabolites, PCBs) and EOC1 (extractable organic bound chlorine) were monitored in 1993 and 1996 in sediment, water and fish in the catchment area of Lake Baiyangdian, China. The levels of the metals, especially Cd and Zn, were significantly higher in the sediment than those in non‐polluted areas. PCBs and chlorinated pesticides constituted only a minor part (< 8.4%) of the extractable organic bound chlorine, indicating the presence of additional, unknown, organochlorine residues. Among the pesticides, DDT was widely distributed and high levels occurred in fish despite a ban of its production and use in 1983. The low quotient of pp‐DDT/pp‐DDE in sediment and fish indicated that the input of DDT to the catchment area was not of recent origin. 相似文献
The last several decades of research in behavioral ecology have resulted in a deeper appreciation of post-mating processes
and sexual conflict in sexual selection. One of the most controversial aspects of sexual selection is cryptic mate choice.
Here, we take advantage of male pregnancy in a sex-role-reversed pipefish (Syngnathus typhle) to quantify cryptic choice based on perceived parasite load and other sources of variance in female fitness. Studies have
shown that S. typhle males preferentially mate with females with lower parasite loads and that a male’s perception of female parasite load can
be altered by tattooing females. We manipulated the apparent parasite load of females in controlled mating experiments to
test the hypothesis that post-copulatory sexual selection is dependent on a male’s perception of female parasite load in pipefish.
Our results provided no evidence for cryptic male choice based on perceived female parasite load. However, we found evidence
that eggs from larger females were more likely to result in viable offspring than eggs from smaller females and that the first
female to mate with a male transferred more eggs per copulation on average. Overall, our results show that potential for post-copulatory
sexual selection does exist in pipefish, but the male’s perception of female parasite load does not play a major role in this
process. 相似文献
Non-random distribution patterns of specialized phytophagous insects on their hosts may depend on intraspecific differences
in plant tissue quality, including nutrients and secondary compounds. Secondary compounds are involved in plant resistance,
but are also important for the recognition and acceptability of plants as resources by specialized insects. If individuals
within a plant species vary in their content of such secondary substances, there may also be qualitative differences between
them. In such cases, natural selection will favor insects with the ability to distinguish and prefer the more suitable plants.
In Sweden, the leaf beetle Gonioctena linnaeana Schrank (Coleoptera, Chrysomelidae) is highly specialized on one host, the native willow Salix triandra L (Salicaceae). Field observations reveal that some host plants in a population harbor many feeding larvae, causing severe
defoliation, whereas neighboring plants may have few or no feeding larvae. Our hypothesis is that the distribution pattern
of G. linnaeana larvae in this population results from qualitative differences between individual host plants in combination with the ability
of G. linnaeana females to distinguish between plants that are suitable and not suitable for offspring performance. We examine whether larval
survival differs depending on diet and whether the content of secondary chemical compounds explains female preference. Based
on the higher survival rate of larvae reared on leaves from preferred hosts, we conclude that G. linnaeana females have evolved a behavior that maximizes offspring performance and thus positively affects female fitness. A chemical
survey of the plants indicates that luteolin-7-glucoside and an unidentified flavonoid are important for separating the preferred
from the non-preferred plants. 相似文献
Behaviour on migration was often suggested to be selected for time-minimising strategies. Current optimality models predict
that optimal fuel loads at departure from stopover sites should increase with increasing fuel deposition rates. We modified
such models for the special case of the east Atlantic crossing of the Northern Wheatear (Oenanthe oenanthe). From optimality theory, we predict that optimal time-minimising behaviour in front of such a barrier should result in a
positive correlation between fuel deposition rates and departure fuel loads only above a certain threshold, which is the minimum
fuel load (fmin) required for the barrier crossing. Using a robust range equation, we calculated the minimum fuel loads for different barrier
crossings and predict that time-minimising wheatears should deposit a minimum of 24% fuel in relation to lean body mass (m0) for the sea crossing between Iceland and Scotland. Fuel loads of departing birds in autumn in Iceland reached this value
only marginally but showed positive correlation between fuel deposition rate (FDR) and departure fuel load (DFL). Birds at
Fair Isle (Scotland) in spring, which were heading towards Iceland or Greenland, were significantly heavier and even showed
signs of overloading with fuel loads up to 50% of lean body mass. Departure decisions of Icelandic birds correlated significantly
with favourable wind situations when assuming a migration direction towards Spain; however, the low departure fuel loads contradict
a direct non-stop flight. 相似文献