Coupling field observations, soil modeling, and air dispersion algorithms to estimate 1,3-dichloropropene and chloropicrin flux and exposure

Soil fumigants are volatile compounds applied to agricultural land to control nematode populations, weeds, and crop diseases. Field trials used for measuring fumigant loss from soil to the atmosphere encompass only a small proportion of the near semi-infinite parameter combinations of environmental, agronomic, and meteorological conditions. One approach to supplement field observations uses a soil physics model for fumigant emission predictions. A model is first validated against existing field study observations and then used to extrapolate results to a wider range of edaphic and climatic conditions. This work compares field observations of 1,3-dichloropropene and chloropicrin emissions to predictions from the USDA soil model CHAIN_2D. Comparison between model predictions and field observations for a Florida and California study had values between 0.62 to 0.81 and 0.99 to 1.0 for discrete and cumulative emission flux, respectively. CHAIN_2D emission rates were then coupled to several USEPA air dispersion models (ISCST3, CALPUFF6) to extend emission estimates to near field air concentrations. CALPUFF6 predicted slightly higher 1-h maximum air concentrations than ISCST3 for the same source strength (26.2-36.0% for setbacks between 1 and 250 m from the field edge, respectively). A sensitivity analysis for the CHAIN_2D/ISCST3 coupled numerical system is provided, with several soil and irrigation parameters consistently the most sensitive. Changes in the depth of incorporation, tarp material, and initial soil water content illustrate the predicted impact to emission strength and resulting near-field air concentrations with reductions of cumulative emission loss from 8.1 to 71% and average 1-h maximum air concentration reductions between 6.2 and 41% depending on the mitigation strategy chosen. Additionally, a stochastic framework based on the published SOFEA system that couples variability in experiment, model sensitivity, and site specific attributes is outlined should regional air concentration estimates resulting from fumigant use be sought.     

Policy, personal dispositions and the evaluation of aircraft noise

In this paper, we hypothesize and test the ideas that (1) people’s subjectivity in relation to aircraft noise is shaped by the policy discourse, (2) this results in a limited number of frames towards aircraft noise, (3) the frames inform people how to think and feel about aircraft noise and (4) the distribution of the frames in the population is dependent on structural variables related to the individual. To reveal subjects’ frames of aircraft noise a latent class model is estimated based on survey data gathered among a sample of 250 residents living near Amsterdam Airport Schiphol, a major international airport in the Netherlands. In line with expectations, the results show that there are four evaluative frames of aircraft noise, three of which are strongly linked to the policy discourse. The frames are associated with fitting levels of annoyance response. In turn, frame membership is influenced by two structural variables, namely aircraft noise exposure and noise sensitivity. The results indicate that social factors operate discursively in the explanation of subjective reaction to noise, while psychological factors operate within a traditional cause-and-effect model. The paper concludes with several policy implications.     

Science-Policy Interactions in MPA Site Selection in the Dutch Part of the North Sea

At the 7th conference of the parties to the Convention on Biological Diversity (CBD-COP7, Kuala Lumpur, 2004) it was agreed to establish a global network of marine and coastal protected areas by 2012. The defined objectives of this MPA-network are based on the ecosystem approach: to protect biodiversity and other ecological values, and to ensure sustainable use. The (inter)national policy guidelines state that the selection of MPAs should be based on scientific information and ecological criteria only. As a signatory to the Convention, the Netherlands is now faced with meeting this obligation, and the process of designating the first Marine Protected Areas (MPAs) in the Dutch part of the North Sea is currently in progress. We focus on the science–policy interactions that are part of this Dutch MPA selection process. By taking a closer look at the contemporary site selection process as well as its historical background, we show that ecological, socio-economic and political considerations cannot always be easily separated. Uncertainty is high and the ultimate selection and delimitation of candidate sites rather seems to be the result of a balancing act between ecological, socio-economic and political interests, in which scientific and policy guiding procedures blend with ad-hoc political decision making, and with expert judgment in cases where data is lacking. As such, this paper presents an example of present-day environmental policy making in action.     

The Use of Atmospheric Dispersion Models in Risk Assessment Decision Support Systems for Pesticides

In the evaluation of potentially adverse effects oforganic chemicals such as pesticides on theenvironment the atmosphere may play an important role.After its release to the atmosphere the chemical willbe transported/dispersed in the atmosphere and finallyit will be removed either by atmospheric-chemicaldestruction or by deposition to the underlying soil orsurface water. In a risk assessment decision supportsystem both ambient concentrations and depositionfluxes must be known to evaluate the risk of directexposure (inhalation) or the risk of soil and watercontamination caused by deposition. This paperdiscusses the use of atmospheric dispersion models insuch risk assessment decision support systems.     

Mating skew in Barbary macaque males: the role of female mating synchrony,female behavior,and male–male coalitions

A fundamental question of sexual selection theory concerns the causes and consequences of reproductive skew among males. The priority of access (PoA) model (Altmann, Ann NY Acad Sci 102:338–435, 1962) has been the most influential framework in primates living in permanent, mixed-sex groups, but to date it has only been tested with the appropriate data on female synchrony in a handful of species. In this paper, we used mating data from one large semi-free ranging group of Barbary macaques: (1) to provide the first test of the priority-of-access model in this species, using mating data from 11 sexually active females (including six females that were implanted with a hormonal contraceptive but who showed levels of sexual activity comparable to those of naturally cycling females) and (2) to determine the proximate mechanism(s) underlying male mating skew. Our results show that the fit of the observed distribution of matings with sexually attractive females to predictions of the PoA model was poor, with lower-ranking males mating more than expected. While our work confirms that female mating synchrony sets an upper limit to monopolization by high-ranking individuals, other factors are also important. Coalitionary activity was the main tactic used by males to lower mating skew in the study group. Coalitions were expressed in a strongly age-related fashion and allowed subordinate, post-prime males to increase their mating success by targeting more dominant, prime males. Conversely, females, while mating promiscuously with several males during a given mating cycle, were more likely to initiate their consortships with prime males, thus reducing the overall effectiveness of coalitions. We conclude that high-ranking Barbary macaque males have a limited ability to monopolize mating access, leading to a modest mating skew among them.     

How temperature and habitat quality affect parasitoid lifetime reproductive success—A simulation study

Adult parasitoid females lay their eggs in or on host insects. Most species are incapable of de novo lipogenesis as adults, and lipids accumulated during the larval stage are allocated either to egg production or to adult survival. Lipid consumption increases with distance covered by the parasitoids and thus with the distance between available hosts within a habitat. Temperature should affect parasitoid fitness because it changes the constraint imposed by a limited reserve of lipids and because it influences behaviour. Climate change involves both an increase in average temperature and an increased frequency of extreme weather such as heat waves. We investigated how the predicted increase of temperature will affect parasitoid fitness and how this depends on habitat parameters (spatial distribution of hosts and lipid cost of habitat exploitation). We studied optimal behaviour and calculated fitness at different temperatures and in different habitats using a stochastic dynamic programming model for pro-ovigenic parasitoids (which mature all their eggs before becoming adult). We show that an increase in temperature decreases fitness of parasitoids adapted to lower temperatures. This decrease in fitness depends on habitat quality. In field conditions (assuming small costs of intra-patch foraging), the loss of fitness should be larger in habitats with high inter-patch distance and in habitats with a more aggregated distribution of hosts. The foraging behaviour of parasitoids is also affected; at higher temperature we show that intra-patch foraging becomes less efficient, and patch residence times are longer.     

Extreme genetic diversity and temporal rather than spatial partitioning in a widely distributed coral reef fish

Mitochondrial control region (HVR-1) sequences were used to identify patterns of genetic structure and diversity in Naso vlamingii, a widespread coral reef fish with a long evolutionary history. We examined 113 individuals from eight locations across the Indo-Pacific Ocean. Our aims were to determine the spatial scale at which population partitioning occurred and then to evaluate the extent to which either vicariance and/or dispersal events have shaped the population structure of N. vlamingii. The analysis produced several unexpected findings. Firstly, the genetic structure of this species was temporal rather than spatial. Secondly, there was no evidence of a barrier to dispersal throughout the vast distribution range. Apparently larvae of this species traverse vicariance barriers that inhibit inter-oceanic migration of other widespread reef fish taxa. Thirdly, an unusual life history and long evolutionary history was associated with a population structure that was unique amongst coral reef fishes in terms of the magnitude and pattern of genetic diversity (haplotype diversity, h = 1.0 and nucleotide diversity π = 13.6%). In addition to these unique characteristics, there was no evidence of isolation by distance (r = 0.458, R ² = 0.210, P = 0.078) as has also been shown for some other widespread reef species. However, some reductions in gene flow were observed among and within Ocean basins [Indian–Pacific analysis of molecular variance (AMOVA), Φ _st = 0.0766, P < 0.05; West Indian–East Indian–Pacific AMOVA Φ _st = 0.079, P < 0.05]. These findings are contrasted with recent studies of coral reef fishes that imply a greater degree of spatial structuring in coral reef fish populations than would be expected from the dispersive nature of their life cycles. We conclude that increased taxon sampling of coral reef fishes for phylogeographic analysis will provide an extended view of the ecological and evolutionary processes shaping coral reef fish diversity at both ends of the life history spectrum.     

A comparison of taxon co-occurrence patterns for macro- and microorganisms

We examine co-occurrence patterns of microorganisms to evaluate community assembly "rules". We use methods previously applied to macroorganisms, both to evaluate their applicability to microorganisms and to allow comparison of co-occurrence patterns observed in microorganisms to those found in macroorganisms. We use a null model analysis of 124 incidence matrices from microbial communities, including bacteria, archaea, fungi, and algae, and we compare these results to previously published findings from a meta-analysis of almost 100 macroorganism data sets. We show that assemblages of microorganisms demonstrate nonrandom patterns of co-occurrence that are broadly similar to those found in assemblages of macroorganisms. These results suggest that some taxon co-occurrence patterns may be general characteristics of communities of organisms from all domains of life. We also find that co-occurrence in microbial communities does not vary among taxonomic groups or habitat types. However, we find that the degree of co-occurrence does vary among studies that use different methods to survey microbial communities. Finally, we discuss the potential effects of the undersampling of microbial communities on our results, as well as processes that may contribute to nonrandom patterns of co-occurrence in both macrobial and microbial communities such as competition, habitat filtering, historical effects, and neutral processes.     

Induced defenses in herbivores and plants differentially modulate a trophic cascade

Inducible defenses are dynamic traits that modulate the strength of both plant-herbivore and herbivore-carnivore interactions. Surprisingly few studies have considered the relative contributions of induced plant and herbivore defenses to the overall balance of bottom-up and top-down control. Here we compare trophic cascade strengths using replicated two-level and three-level plankton communities in which we systematically varied the presence or absence of induced defenses at the plant and/or herbivore levels. Our results show that a trophic cascade, i.e., significantly higher plant biomass in three-level than in two-level food chains, occurred whenever herbivores were undefended against carnivores. Trophic cascades did not occur when herbivores exhibited an induced defense. This pattern was obtained irrespective of the presence or absence of induced defenses at the plant level. We thus found that herbivore defenses, not plant defenses, had an overriding effect on cascade strength. We discuss these results in relation to variation in cascade strengths in natural communities.     

Schwermetalle in Regenwürmern Baden-Württembergs

Goal and Scope

The heavy metal burden of the soil and of earthworms from representative long-term forest observation plots has been measured since 1984 as one component of the media-embracing environmental monitoring network of the State of Baden-Wuerttemberg. These investigations are aimed at elucidating and assessing adverse effects of pollutants on the soil biocenosis

Methods

So-called characteristic curves for the metals Cd, Cu, Ni, Pb, and Zn were developed for the assessment. Earthworm toxicity data and background values in soil served as criteria. This procedure facilitates a comparative assessment of different pollutants. The mobility of the metals, which greatly influences their bioavailability and toxicity, was taken into account for the effects assessment.

Results and Conclusion

Besides inventorying the heavy metals (Part 1), the question of threshold values for toxic reactions as well as for accumulation was raised. The metal concentrations were assessed in the soil with regard to its habitat function. The ecotoxicological assessment revealed that the heavy metal burden of the investigated plots lies within the background- or precautionary range, well below the screening value established here to indicate the effect threshold in earthworms. This result means that a pollution of the forest observation plots with the metals cadmium, copper, lead, nickel, and zinc is low or absent. Only the distribution of the lead content is centered slightly above background (but clearly below the toxicity threshold). This slight lead burden of the soil of the observation plots can be explained by emissions from motor vehicles. Investigations at sites that are contaminated with either chromium or copper or cadmium showed that an accumulation of these metals in the body of the worms can be observed only above a threshold concentration of several hundred micrograms of mobile metal per kilogram in the upper layer of the soil.

Recommendations and Perspectives

The hitherto unknown threshold values for the accumulation in the body of the earthworm should be statistically validated and extended to other elements. Further research is needed in order to build a well founded basis for the ecotoxicological assessment of soil pollution. Acute and chronic earthworm effect thresholds are neither available yet for arsenic, cobalt, and mercury nor for some other elements occurring less frequently as soil pollutants. Background values depending on the kind of rock have been measured so far for total chromium only. They are lacking for the more toxic chromium (VI) which is a frequent soil pollutant but naturally occurs in traces only.