Estimation of industrial and commercial asset values for hazard risk assessment

For risk analyses not only knowledge about the impact of different types of hazards, but also information about the elements and values at risk is necessary. This article introduces a methodology for a countrywide estimation of asset values for commercial and industrial properties using Germany as an example. It consists of a financial appraisal of asset values on the municipal level and a further disaggregation by means of land use data. Novelties are the distinction of 60 economic activities, the consideration of production site sizes and the application of a dasymetric mapping technique for a sector-specific estimation and disaggregation of asset values. A validation with empirical data confirms the feasibility of the calculation. The resulting maps can be used for loss estimations e.g. in the framework of cost–benefit analyses that aim to evaluate hazard mitigation measures or for portfolio analyses by banks and insurance companies. The approach can be used for other countries if the necessary data is available (mainly in industrialized countries). In any case, it reveals the critical points when estimating commercial and industrial asset values.     

How effective are plant macrofossils as a proxy for macrophyte presence? The case of <Emphasis Type="Italic">Najas flexilis</Emphasis> in Scotland

Preventing biodiversity loss is a key aim of modern conservation, and paleolimnology can inform conservation strategies for target species and habitats where other data are unavailable. Care must be taken to fully understand the possibilities and limits of such techniques, particularly where they concern single species. This study uses plant and seed distribution data to inform macrofossil reconstructions of the rare macrophyte Najas flexilis (Slender Naiad) in Scotland, UK. It answers three questions: (a) How does the location of N. flexilis seeds in the surface sediments relate to the distribution of N. flexilis plants? (b) How do the numbers of seeds in surface sediments correlate with % cover of N. flexilis plants across lakes with differing N. flexilis abundances? (c) What are the implications of these findings for paleolimnology? Percentage N. flexilis cover and number of N. flexilis seeds in surface sediments were recorded at ~100 sample points at each of three sites; one where the species was abundant, one where it was occasional and one where it was extinct. At all sites, N. flexilis seeds were present in surface sediments across the entire lake. No correlation between % cover N. flexilis and the number of seeds in surface sediments was found within individual sites. The distribution of seeds in these lakes appeared to be related to multiple environmental and ecological variables including latitude and longitude (proxies for water currents). This is attributed to the ability of seed-bearing N. flexilis plants to fragment and float large distances on water. Between sites, there was a significant difference in the mean seed counts, with higher mean seed counts corresponding to higher abundances of N. flexilis plants. It is concluded that N. flexilis is likely to be well represented in sediment cores taken from any location within a basin, but that care should be taken when inferring changes in N. flexilis abundance from changes in the numbers of seeds in sediment samples. This work demonstrates that the reproductive ecology (number of seeds produced and dispersal mechanisms) is an important factor to consider when attempting reconstructions of single aquatic plant populations from macrofossil records.     

Productivity and nutrient cycling in salt marshes: Contribution to ecosystem health

This study aimed to assess the contribution of different salt marsh halophytes (Spartina maritima, Scirpus maritimus, Halimione portulacoides, Sarcocornia fruticosa, and Sarcocornia perennis) to nutrient cycling and sequestration in warm-temperate salt marshes. Carbon, nitrogen and phosphorus concentration in plant organs and rhizosediment, as well as plant biomass were monitored every two months during one year. Results show that the C retained in the rhizosediment does not seem to be species or site specific. However, some halophytes seem to have a higher contribution to retain C from external sources, namely S. perennis and S. maritima. Regarding N, halophytes colonizing the upper and middle marsh areas had the highest NBPP (net belowground primary production) as well as the retention of N in the rhizosediment. Yet, excluding S. maritimus, all halophytes seem to contribute to the retention of N from external sources. The P retained in the rhizosediment does not seem to be species or site specific. Still, only S. maritima colonizing the lower marsh areas, which also had comparatively lower NBPP, seem to have a higher contribution to retain P from external sources. Additionally, it seems that there is no relation between plants sequestration capacity for nutrients and plant photosynthetic pathway. This work shows that nutrient cycling and accumulation processes by salt marsh halophytes contribute to reduce eutrophication (N and P retention) and also to reduce atmospheric CO₂ (C retention), highlighting salt marsh ecosystems services and the crucial role of halophytes in maintaining ecosystem functions and health.     

Variation in transparent exopolymer particles in relation to biological and chemical factors in two contrasting lake districts

In inland waters, transparent exopolymer particles (TEP) can affect carbon export and sequestration in sediments with consequences for lake C budgets. We measured TEP concentration in 32 lakes from two contrasting lake districts covering wide ranges in biological and chemical characteristics. North temperate lakes, located in a wet region, have low to moderate ionic strength and low to high dissolved organic carbon with corresponding variation in color (light absorbance). Mediterranean lakes located in a semiarid region were characterized by high ionic strength and high concentrations of dissolved organic carbon but low color. TEP concentrations were large relative to the living portion of the particulate organic carbon pool in both Mediterranean (36%) and north temperate (33%) lakes. TEP concentrations ranged from 36 to 1,462 μg [as Gum Xanthan equivalents (GX eq)] L⁻¹ in north temperate lakes. In the Mediterranean lakes, concentrations were higher that previously reported for other systems and ranged from 66 to 9,038 μg GX eq L⁻¹. TEP concentration was positive and significantly related to chlorophyll a (chl a) in north temperate lakes and in the entire data set. Although a significant and positive relationship between TEP and chl a was also detected in the Mediterranean lakes, bacterial abundance was most strongly related to TEP. In contrast with the positive influence of phytoplankton and bacteria on TEP, there were weaker relationships between TEP and the chemical variables tested. We observed a significant and positive relationship between pH and TEP (for all lakes) but this relationship was indirectly driven by a co-variation of pH with phytoplankton biomass based on multiple regression analysis. For the Mediterranean lakes, the negative (but not significant) trends between TEP and both conductivity and divalent cations suggest thresholds above which TEP will likely be destabilized. Under these conditions, TEP may flocculate or disperse in the water column.     

Effects of mariculture on macrobenthic assemblages in a western mediterranean site

The effects of solid organic wastes from a marine fish farm on sediment was tested using macrobenthic fauna as biological indicators. Impact on benthic fauna was evaluated in the vicinity of a fish farm in the Tyrrhenian Sea (Western Mediterranean) between July 2001 and October 2002. Changes in benthic community structure were investigated using multivariate, distributional and univariate analyses (diversity indices, AMBI and M-AMBI). The results showed sharp disturbance of assemblages under the cages and no effects in the area more than 25 m from the cages. Sediment alterations were related to an increase in farmed biomass and its wastes, as well as to low current speed that allowed accumulation of organic matter on the sea floor. It was possible to follow the ecological succession from slightly altered assemblages to heavily polluted ones in the very short period of a single fish fattening cycle (15 months).     

L-moments for automatic threshold selection in extreme value analysis

In extreme value analysis, sensitivity of inference to the definition of extreme event is a paramount issue. Under the peaks-over-threshold approach, this translates directly into the need of fitting a Generalized Pareto distribution to observations above a suitable level that balances bias versus variance of estimates. Selection methodologies established in the literature face recurrent challenges such as an inherent subjectivity or high computational intensity. We suggest a truly automated method for threshold detection, aiming at time efficiency and elimination of subjective judgment. Based on the well-established theory of L-moments, this versatile data-driven technique can handle batch processing of large collections of extremes data, while also presenting good performance on small samples. The technique’s performance is evaluated in a large simulation study and illustrated with significant wave height data sets from the literature. We find that it compares favorably to other state-of-the-art methods regarding the choice of threshold, associated parameter estimation and the ultimate goal of computationally efficient return level estimation.     

Finding meaningful participation in volunteer geographic information and citizen science: a case comparison in environmental application

ABSTRACT

Volunteer geographic information (VGI) and citizen science (CS) have been used as a way to promote a form of democratization of knowledge. Crowdsourcing facilitates the massive collection of data through nonexpert volunteers. This study compares 57 VGI and CS projects through a cross-case comparison method to explore the level of involvement of participants, based on three main analytic dimensions (project rationale, actor interaction, and data flow) and 12 sub-variables. The primary goal of this research is to analyze the purpose and the role of technology in VGI and CS projects, using three matrices to explore emerging trade-offs. Finally, we synthesized the workflow of VGI and CS project and compared based on project purposes. At the end of this study, five main purposes were found among the selected projects, uncovering that data collection is the most common purpose. A general workflow can be conceptualized, but detail implementation will involve various trade-offs, especially between local involvement and large-area expert-oriented protocol implementations. By exploring diverse relationships among selected variables of analysis in VGI and CS projects, this study pretends to build a foundation for larger, global meta-analysis that can bring some transparency in the epistemic interactions between experts and nonexperts.     

Quantifying deforestation and secondary forest determinants for different spatial extents in an Amazonian colonization frontier (Rondonia)

Spatial patterns of deforested areas and secondary forest are analyzed in terms of the spatial variation in location factors at different spatial extents. The spatial extents considered are old and new agrarian colonization projects and the administrative units of two different municipalities in Rondonia: Vale do Anari and Machadinho d'Oeste. A grid database was constructed including land cover and potential location factors based on biophysical, accessibility, socioeconomic and policy data. Results of the spatial analyses confirmed the hypothesis that different extents yield different relationships between land use/cover patterns and their location factors, particularly between old and new agrarian colonization projects. It emphasizes that current patterns of forest, secondary forest and pasture/agriculture can only be understood with a combination of policy, accessibility, biophysical and socioeconomic factors while accounting for the historical pathways of change. Because we are dealing with different trajectories of land use/cover change, static analysis of the spatial pattern without acknowledging these trajectories will lead to erroneous interpretations of the current and future land use/cover dynamics.     

Microzooplankton feeding impact in a coastal upwelling system on the NW Iberian margin: The Ría de Vigo

The dilution technique, combined with identification and enumeration of pico-, nano- and micro-plankton by microscopy, was used to estimate microzooplankton impact on the microbial community in surface waters of a coastal embayment on the NW Iberian upwelling system. Microzooplankton were important consumers of autotrophic and heterotrophic plankton in this system, feeding up to 93% of standing stock and more than 100% of production of several groups. Heterotrophic bacteria and heterotrophic picoflagellates experienced the highest and constant impact, with 75–84% of their standing stocks and 85–102% of their production being channelled through the microbial food web. Pico- and nano-phytoplankton were also consumed, although maximum grazing occurred on diatoms during upwelling events, coinciding with highest primary production. Predation on pico-nano-heterotrophs was especially relevant under downwelling conditions, when consumption of total carbon and particularly autotrophic carbon was considerably lower than during upwelling. The results suggest that the existence of a multivorous food web, extending from the microbial loop to the herbivorous food web, could be a major feature in this coastal upwelling system. The microbial loop, which occurs as a permanent background in the system, would contribute to sustain the microbial food web during downwelling, whereas the herbivorous food web could coexist with a microbial food web based on large diatoms during upwelling. The multivorous food web would partially divert diatoms from sinking and hence favour the retention of organic matter in the water column. This could enhance the energy transfer to higher pelagic trophic levels in coastal upwelling systems.