Evaluation of a real-time monitoring system for river quality — a trade-off between risk attitudes,costs, and uncertainty

Uncertainty is definitely one of the key topics in environmental assessment and management. Typically, attempts to reduce uncertainty are subject to expenses. But how to compare and trade-off expenses and the reduced uncertainty? They only seldom allow the use of a single unit. Instead, the whole analysis and decision procedure is very subjective. This paper presents one approach to handle such problems, namely the combined use of Bayesian influence diagrams, and probabilistic risk attitude analysis. The approach was used in the evaluation of three alternatives for a real time river water quality forecasting system. A trade-off analysis of risk attitudes, costs and uncertainty indicated the levels of socioeconomic utility required for investments in the respective systems, and accordingly illuminated the impact of the uncertainties involved on inference and decision-making with various risk attitudes and discount rates.     

Uptake of some selected aquatic pollutants in semipermeable membrane devices (SPMDs) and the polar organic chemical integrative sampler (POCIS)

The uptake characteristics of semipermeable membrane devices (SPMDs) and polar organic chemical integrative samplers (POCISs) were examined for mono, di and tributyltin, triphenyltin, pyrene, benzo[a]pyrene, 4-tert-butylphenol, 4-n-nonylphenol, PCBs 77 and 153, PBDE 47, lindane, triclosan and DDT. Exposure in a flow through system continued for 28 days with samplers removed every 7 days in order to study the relevant uptake kinetics. Uptake remained linear for POCISs with sampling rates (Rs) of up to 0.2 L d(-1). For SPMDs uptake varied from linear to approaching equilibrium with Rs values of up to 14 L d(-1). 7 out of 9 results for SPMDs could be explained by an empirical model (nonylphenol and lindane were exceptions). None of the four organo-tin compounds studied were detected in POCISs and only tributyltin was accumulated significantly by SPMDs. The establishment of these sampling rates allows the calculation of time weighted water concentrations for several important contaminants. Using presented methods, sampling rates and exposure conditions, theoretical detection limits for selected compounds by SPMDs were between 11-68 pg L(-1), which is well below the environment quality standard proposed for those compounds that are included in the European Water Framework Directive.     

Speciation of arsenic in plants by HPLC-HG-AFS: extraction optimisation on CRM materials and application to cultivated samples

A recently developed method for the determination of arsenic species (arsenite, arsenate, monomethylarsonate, MMAA, and dimethylarsinate, DMAA) has been applied to the study of arsenic speciation in plants. This method uses ion-exchange liquid chromatography coupled on-line to atomic fluorescence spectrometry through continuous hydride generation. Various extraction procedures have been studied in detail using three plant certified reference materials. None of the procedures tested revealed fully satisfying results with all kinds of plant samples; microwave assisted extraction with 0.3 mol dm-3 orthophosphoric acid was found to be the most convenient for dealing with terrestrial plants. Species stability appears good. This method was applied to real world cultivated plant parts. Arsenate appears to predominate in soils, roots and leaves; unidentified species (probably arsenosugars) play an important role (60%) in rice fruits. Carrot was found to be the most contaminated edible plant part, containing 1 mg kg-1 essentially as arsenate species. MMAA was detected in all soils and some plant parts especially shallots at low levels, whereas DMAA was found only in one soil sample and in hot pepper leaves. Arsenite is a minor component of all soils; it is also present in some plant parts at low levels. However, no evident relationships were found between As speciation in the various plant parts and much more detailed studies will be necessary to elucidate As behaviour in plants.     

Functional mouthpart morphology of the squat lobster Munida sarsi, with comparison to other anomurans

 The mouthparts of Munida sarsi Huus, 1935, including the labrum and paragnaths, are described using LM and SEM, with special attention to the setal composition and its function. We also used high-resolution macrovideo equipment to record the feeding processes and monitor setae in action. This combination of morphological and preliminary behavioral data enabled us to arrive at a more comprehensive understanding of the functional morphology. M. sarsi was found to be an opportunist and capable of handling and eating most kinds of animal tissue. The species can also be a selective deposit feeder, sorting the sediment by quality and not by size. This sorting is performed by the setae on the medial rim of the bases of maxilla 1, maxilla 2 and maxilliped 1. Many of the other mouthpart functions ranging from food detection to ingestion are mapped with comparison to what has been found for other anomurans. Grooming was shown to be a significant function of many mouthparts, especially the endopod of maxilliped 3. In general the mouthparts closest to the mouth have the least complex movements and functional scheme, with the mandibles being able to perform only one movement, i.e. cutting or crunching food objects. Some functions are attributed to the paragnath, the endopod of maxilla 2 and the epipod of maxilliped 1. Received: 3 October 1999 / Accepted: 22 March 2000     

Factors influencing cannibalism in the wolf spider Pardosa agrestis (Araneae, Lycosidae)

Cannibalistic tendencies are well known in spiders and may be a significant factor influencing population size. The wolf spider, Pardosa agrestis, is the dominant non-web-building spider in a wide range of central European agricultural habitats. Preliminary field observations indicated an extended reproductive period, which results in a very wide size distribution of juvenile instars. We hypothesised that if cannibalism is enhanced by differences in size, especially during periods when prey is scarce, these populations might be susceptible to cannibalism in an ecologically significant way. Laboratory studies were conducted on juvenile P. agrestis in arenas. We analysed the following specific aspects of cannibalism: (1) the effect of the weight ratio between the opponents; (2) the effect of weight per se, and (3) the role of hunger level in determining cannibalistic tendencies of spiders. The role of weight and hunger were analysed in separate experiments, in both cases by controlling for the other variable. The results showed that cannibalism was strongly positively correlated with both weight ratio and hunger, but absolute size/age of an individual could not predict the occurrence of a cannibalistic event. These experiments generated the plausible hypothesis that cannibalism might be an important phenomenon in the regulation of real populations, which should be tested specifically in future field experiments. Received: 15 December 1997 / Accepted after revision: 10 October 1998     

Preferential allocation of food by magpies Pica pica to great spotted cuckoo Clamator glandarius chicks

Adult magpies Pica pica provide parasitic great spotted cuckoo Clamator glandarius nestlings with a diet very similar to that fed to their own chicks. In both naturally and experimentally parasitized nests, great spotted cuckoo chicks were fed at a higher rate than magpie chicks in the same nest. This preferential allocation of food by magpie parents to great spotted cuckoo chicks is consistent with the supernormal stimulus hypothesis, because this result implies that cuckoo chicks provide stronger stimuli for parental care than host chicks. Great spotted cuckoo chicks receive most of the food brought to the nest by the foster parents, because they exploit a series of stimuli which jointly (or sometimes individually) operate as a supernormal stimulus. This hypothesis predicts that if any stimulus is masked, the efficiency of the cuckoo in eliciting parental care will decrease. Here, we analyze experimentally the effects of two of these stimuli, preferential feeding of large nestlings and of nestlings with conspicuous palatal papillae. Firstly, when we experimentally introduced one medium-sized (7–9 days) cuckoo chick into an unparasitized magpie nest where the largest magpie chick was 12–15 days old, the cuckoo did not receive significantly more food than the average or the largest magpie chick. Secondly, when unparasitized nests were experimentally parasitized with a cuckoo chick that had its gape painted to mimic that of magpie chicks, the parasitic cuckoo received less food than the average magpie chick.     

Chick recognition and acceptance: a weakness in magpies exploited by the parasitic great spotted cuckoo

Hosts of brood parasites have evolved the ability to discriminate non-mimetic and even mimetic eggs, but not non-mimetic chicks. Here we demonstrate that the great spotted cuckoo Clamator glandarius does not provide its magpie Pica pica host with a super-normal stimulus that helps to avoid recognition, because single cuckoo chicks introduced into otherwise unparasitized magpie nests are not fed at a higher frequency than single magpie chicks introduced to parasitized magpie nests. Another series of experiments demonstrated that magpies have the ability to discriminate cuckoo chicks, mainly when these are introduced at the end of the nestling period, and especially when the cuckoo chick together with a magpie chick is presented to adult magpies outside the nest. This supports the idea that cuckoos exploit the obligatory reaction of magpies to feed all young that have been hatched in their nests and whose signatures they have learnt. Furthermore, the experimental cuckoo chicks in parasitized magpie nests were more likely to be accepted than they were in non-parasitized nests. This supports the hypothesis that magpies may learn to recognise their own nestlings as those present in the nest and may indicate that a comparison between cuckoo and magpie nestlings is the basis of discrimination.     

Preface

Water, Air, &; Soil Pollution: Focus -     

A Baumol–Oates approach to solid waste taxation

A national Baumol–Oates tax on waste in Denmark helped achieve a reduction of 26% in net solid waste from 1987 to 1998. The tax, which is levied per ton of waste, was particularly effective as regards the heavier waste streams such as construction waste and garden waste. When it comes to industrial and commercial waste, there are indications that the waste tax is not sufficiently significant to induce changes in behavior, and that except for very waste-intensive enterprises, companies do not seem to be very price sensitive. For household waste, the impact of the tax can be improved where tariffs for garbage collection are weight based, rather than per unit. However, the waste sector is an area in which the price signals are modified and filtered by institutionalized practices in municipal administration, and in which true-cost pricing is not easy to achieve. Hence, the rational choice assumption of environmental economics needs to be supplemented by an institutional dimension to interpret responses to environmental taxes correctly. Received: July 13, 2001 / Accepted: October 2, 2001     

Fluxes of NO3-, NH4+, NO,NO2, and N2O in an Old Danish Beech Forest

The fluxes of the major nitrogen compounds havebeen investigated in many ecosystem studies over the world.However, only in few studies has attention been drawn to theimportance of the fluxes of minor gaseous nitrogen compoundsto complete the nitrogen cycle. In Denmark a detailed study onthe nitrogen cycle in an old beech forest has been implementedin 1997 at Gyrstinge near Sorø, Zealand. The study includesthe fluxes of the gases NO, N₂O and water mediatedtransport of NO₃ ^- and NH₄ ⁺. Measurementsof the fluxes of the gaseous compounds are performed withmicro-meteorological methods (eddy-correlation and gradient)and with chambers. Water mediated fluxes encompass rain,throughfall, stem-flow and leaching from the root zone. Thehydrological model is verified by TDR measurements. The findings show that the total water mediated N input tothe forest floor with throughfall and stemflow was 25.6 kg Nha^-1 yr ^-1, and open field wet deposition withprecipitation was 19.0 kg N ha^-1 yr ^-1. The internalcycling of N in the ecosystem measured as turnover oflitterfall and plant uptake was 100 kg N ha^-1 yr ^-1and 14 kg N ha^-1 yr ^-1, respectively. The fluxes ofthe gaseous N compounds NO and N₂O were of minorimportance for the total N turnover in the forest, NO_xemission being <1 kg N ha^-1 yr ^-1 and N₂Oemission from the soil being 0.5 kg N ha^-1 yr ^-1 withno significant difference between wet and dry soils.Concentrations of NO₃ ^- and NH₄ ⁺ in thesoil solution beneath the rooting zone are very small andconsequently the N leaching is almost negligible. It isconcluded that the nitrogen mass balance of this old beechforest ecosystem mainly is controlled by the input by dry andwet deposition and a large internal N cycle with a fast litterturnover. The nitrogen input tothe forest ecosystem which currently exceeds the critical loadby 5 kg N ha^-1 yr ^-1is mainly accumulated in the soil and no significant nitrateleaching is occurring.