Regional Variability of Cd,Hg, Pb and C Concentrations in Different Horizons of Swedish Forest Soils

Contents of cadmium (Cd), mercury (Hg), lead (Pb) and carbon(C) in the O, B and C horizons of podzolized forest soils inSweden were surveyed. Concentrations and storage of Cd, Hg andPb in the O and B horizons were high in southern Sweden and gradually decreased towards the north, though with considerablelocal variability. This pattern reflects the influence of anthropogenic emissions of these metals, as well as the effectsof soil-forming processes. Parent till material, as representedby the C horizon concentration of the respective metal, accountedfor little of the variation in metal concentration in the O horizon. For Cd and Pb, the correlations were not significant orslightly negative (R² = 0.12 and 0.09 respectively) depending on region, while for Hg the correlation was not significant or slightly positive (R² = 0.03 and 0.08). Furthermore, parent till material accounted for more of the variation in metal concentrations in the B horizons in the northern part of Sweden than in the middle and southernmost parts, where the concentration of total carbon had more influence. The correlation between the metal concentrationsin the B and C horizon was strongest for Pb (R² = 0.63 and 0.36 in the two northernmost regions), lower for Cd (R² = 0.19 and 0.16) and not significant for Hg. For allsoil horizons, total C concentration accounted for much of thevariation in Hg concentration in particular (O-horizon R² = 0.15–0.69, B horizon R² = 0.36–0.50, C horizon R² = 0.23–0.50 and ns in one region). Ratios of metal concentrations between the B and C horizons were highest for Hg(maximum value of 30), indicating a relatively larger addition or retention of Hg compared to Cd and Pb (maximum value of 10)in the B horizon. This study indicate that factors other than parent material account for the large scale variation in O horizon concentrationsof metals but patterns correspond well with those of atmosphericdeposition of heavy metals and acidifying substances. Furthermore, the study highlights the importance of soil organicmatter and the intensity of pedogenic processes for the content and distribution of metals throughout the soil horizons.     

Conjoint analysis for environmental evaluation

BACKGROUND, AIM AND SCOPE: Conjoint analysis and the related choice-modelling methods have been used for many years in marketing research to evaluate consumer behaviour and preferences for different kinds of product attributes. Recently, the number of applications in environmental science and management has started to grow. Conjoint analysis is found in many different forms, and the environmental studies evaluated in this review display the same range of methods as in other fields. The key characteristic of all these methods is that trade-offs are evaluated by jointly considering a number of important attributes. MAIN FEATURES: This paper is a review of the literature on environmental applications of conjoint analysis and assesses in which environmental area conjoint analysis has been most successful. The method and the design of the studies are reviewed as well. RESULTS: A total of 84 studies were found, dealing with environmental issues that were evaluated by conjoint analysis. The studies concern agriculture, ecosystem management, energy, environmental evaluation, forestry, land management, pollution, products, recreation, environmental risk analysis and waste management. DISCUSSION: Choice experiments seem to have a comparatively stronger position in environmental studies than elsewhere. Most of the environmental applications are related to natural resource management. This is somewhat surprising, but a number of reports have appeared also on product evaluation, which could be a key application area in the future. CONCLUSIONS: Compared to marketing and transportation, the number of environmental conjoint studies is rather small but increasing, and the method has proven to work effectively in eliciting preferences on environmental issues. In environmental issues, experimenters often use choice experiments, especially concerning ecosystem management and environmental evaluations. When it comes to evaluating preferences concerning agriculture, forestry, energy and products, a more traditional approach of conjoint analysis is favoured. RECOMMENDATIONS AND PERSPECTIVES: Two new areas of application are identified in this review--environmental communication and expert elicitation. Conjoint analysis can thus be developed into a useful instrument for environmental risk analysis and communication, both of which are necessary for an efficient approach to risk governance.     

Distribution of Cd,Ck, Pb and Zn in Soil and Vegetation Compartments in Stands of Five Boreal Tree Species in N.E. Sweden

Concentrations and total quantity of cadmium (Cd), cupper (Cu),lead (Pb) and zink (Zn) were determined in biomass and soil compartments in a replicated tree species experiment with 27-yr-old stands growing on former farmland in N.E. Sweden. Sequentialextractions of soil samples were performed in order to estimate the exchangeable and an organically bound fraction of each element. The tree species included were Picea abies (L.)H. Karst., Pinus sylvestris L., Pinus contorta Dougl., Larix sibirica Ledeb., and Betula pendula Roth.Tree species influenced the rate of removal of Cu, Pb and Zn incase of stemwood harvesting, and of Cd, Cu and Zn in the case ofwhole-tree harvesting. B. pendula and P. abies had higher quantities and average concentrations of Zn in the biomass. For all species, >50% of the Zn in the stems was found in the bark. P. abies and L. sibirica had higher quantities of Cu in the biomass than the other species.P. abies and P. contorta had high quantities of Cd inthe biomass in relation to the other species. Branches and stembark contained high concentrations of Cd and Pb in relation to foliage and stemwood. Dead branches had especially high concentrations of Pb. The high accumulation rate of Zn in thebiomass of B. pendula was related to a low exchangeable amount of Zn in the A horizon. In the superficial centimeters ofthe A horizon, a depletion similar to that found for Zn was detected for Cu, whereas for Cd and Pb, no correlations were found between quantities of elements in the trees and element pools in the soil.     

Comparison of ordinary and lognormal kriging on skewed data of total cadmium in forest soils of Sweden

Spatial statistical analysis of georeferenced data of total cadmium (TCd) in forest soils of Sweden was assumed to providemore advantageous maps than traditional interpolated maps. However, 264 measurements of TCd in O-horizon of forest soils displayed skewed frequency distribution. Since atypicalobservations affect badly the variogram, outliers wereidentified, different data transformations were tested andordinary (OK) and lognormal kriging (LK) scenarios werecompared based on cross-validation. Results were comparedusing overall measures of predictors, e.g. traditionalmean squared prediction error (MSPE), mean of krigingvariances, variance ratio, median of internallystandardised residuals, and assessments of classificationaccuracy, such as percentage of correctly predictedsamples and within-class MSPE.One outlier was identified based on the absolute value of skewness of value differences less or equal to one in data pairs separated at certain lag classes. Mapping categories characterised by percentage of correct classification and within-class MSPE were found to be essential in comparison of kriging results additionally to the overall measures. In comparison of kriging methods, OK predicted high values moreaccurately and LK was more effective to predict low and mediumvalues. Thus, OK was suggested for mapping high concentration of TCd and other pollutants. Percentage of correctly predictedsamples and within-class MSPE were found to be dependent on kriging method, as well as on the number and limits of categories.