Walking in “wild” and “tended” urban forests: The impact on psychological well-being

The positive effect of natural compared to urban environment on human restoration and well-being has been proved in various studies. To go one step further in analyzing the influence of physical environments, we question if this positive effect is consistent in different natural conditions namely wild and tended urban forests. In an experimental field setting, participants were randomly assigned to either a walk through wild or tended forests for 30 min. Multidimensional scales in a pre-post-treatment-setting measured well-being. Results indicate a stronger change in “positive affect” and “negative affect” in the tended forest condition. Well-being factors “activation” and “arousal” changed after solitary walks, too. However, there were no differences between the treatment conditions, indicating a stronger influence of physical activity than the forest condition wild and tended on these well-being factors. Perceived attractiveness of the natural area did not effect the change in well-being, thus questioning the close relation between perceived attractiveness and the effect on well-being suggested in prior research. Furthermore, more and less fatigued persons did not profit differently concerning well-being changes. The results give important advice to design natural areas serving restoration and public health, especially for people living in urban environments.     

Improving the Integration of Recreation Management with Management of Other Natural Resources by Applying Concepts of Scale from Ecology

In this article, we examine how issues of scale affect the integration of recreation management with the management of other natural resources on public lands. We present two theories used to address scale issues in ecology and explore how they can improve the two most widely applied recreation-planning frameworks. The theory of patch dynamics and hierarchy theory are applied to the recreation opportunity spectrum (ROS) and the limits of acceptable change (LAC) recreation-planning frameworks. These frameworks have been widely adopted internationally, and improving their ability to integrate with other aspects of natural resource management has significant social and conservation implications. We propose that incorporating ecologic criteria and scale concepts into these recreation-planning frameworks will improve the foundation for integrated land management by resolving issues of incongruent boundaries, mismatched scales, and multiple-scale analysis. Specifically, we argue that whereas the spatially explicit process of the ROS facilitates integrated decision making, its lack of ecologic criteria, broad extent, and large patch size decrease its usefulness for integration at finer scales. The LAC provides explicit considerations for weighing competing values, but measurement of recreation disturbances within an LAC analysis is often done at too fine a grain and at too narrow an extent for integration with other recreation and resource concerns. We suggest that planners should perform analysis at multiple scales when making management decisions that involve trade-offs among competing values. The United States Forest Service is used as an example to discuss how resource-management agencies can improve this integration.     

The significance of metal hyperaccumulation for biotic interactions

Metal hyperaccumulating plants contain very high metal contents. Because of the general toxicity of metals, chemically-mediated biotic interactions involving hyperaccumulating plants may differ greatly from those of non-hyperaccumulators. Recent research has demonstrated a defensive function for hyperaccumulated metals against herbivores and pathogens. We predict that some herbivore/pathogen species have evolved metal tolerance, and suggest that resulting high metal levels in herbivores/pathogens may defend them against their own predators. Little is known regarding interference and commensal interactions involving hyperaccumulating plants. Decreased competition may occur through an interference interaction similar to allelopathy, in which enrichment of metal in the soil under a hyperaccumulator plant's canopy may inhibit another plant species, thus resulting in “elemental allelopathy”. Metal enrichment of soil under hyperaccumulators also may result in commensalism if another plant species (possibly another hyperaccumulator) derives a benefit from growing in the metal-enriched soil under the canopy of a hyperaccumulating overstory plant. It seems likely that high-metal plant litter will host a specialized microflora of decomposers and may affect nutrient cycling rates. Mutualist biotic interactions also may be affected by the elevated metal contents of hyperaccumulating species. Mycorrhizal fungi may form mutualisms with hyperaccumulators, but the phenomenon is poorly-explored. The few cases investigated to date have not detected mycorrhizae. Pollination and seed dispersal mechanisms may require biotic vectors that might be affected by plant metal content. Hyperaccumulating plants may have solved this dilemma in three ways. First, some may rely on abiotic vectors for pollen or seed dispersal. Second, biotic vectors used by these species may have varied diets and thus dilute metal intake to non-toxic levels. Finally, biotic vectors may have evolved tolerance of elevated dietary levels of metals, and perhaps have become specialists on hyperaccumulator species. Received 7 November 1997; accepted 28 December 1997.     

Development of a hybrid pollution index for heavy metals in marine and estuarine sediments

Heavy metal pollution of sediments is a growing concern in most parts of the world, and numerous studies focussed on identifying contaminated sediments by using a range of digestion methods and pollution indices to estimate sediment contamination have been described in the literature. The current work provides a critical review of the more commonly used sediment digestion methods and identifies that weak acid digestion is more likely to provide guidance on elements that are likely to be bioavailable than other traditional methods of digestion. This work also reviews common pollution indices and identifies the Nemerow Pollution Index as the most appropriate method for establishing overall sediment quality. Consequently, a modified Pollution Index that can lead to a more reliable understanding of whole sediment quality is proposed. This modified pollution index is then tested against a number of existing studies and demonstrated to give a reliable and rapid estimate of sediment contamination and quality.     

Triazines in the aquatic systems of the Eastern Chinese Rivers Liao-He and Yangtse

The results of a one-year monitoring program on the two Eastern Chinese River systems, i.e. the Liao-He and the Yangtse, with special emphasis on the presence of triazine herbicides are presented. Sediment, suspended solids and water samples from both rivers were analyzed. Additionally, recovery experiments on the SPE-in-field-enrichment procedure and the extraction methods were performed. The samples were measured by gas chromatography coupled with mass spectrometry, electron capture detection and a newly developed mu-plasma atomic emission detector. A typical result of a one-year monitoring was obtained in case of the Liao-He: During winter, at low water period, low triazine values were found. A similar situation was found in early spring. Highest concentrations of atrazine up to 1600 ng/l were found in late spring in the water samples. Maximum concentrations of atrazine, simazine, propazine, simetryn and prometryn were observed in this season as a result of the actual use of triazines. Finally, after the high water period in autumn the triazine concentrations decreased. Additionally, atrazine adsorbed on sediment (up to 2.8 ng/g) and suspended solids was determined (up to 8 ng/l) during late spring sampling. Therefore, the logarithm of the organic carbon based sorption coefficient of atrazine could be calculated. Low levels of atrazine were measured in the water of Yangtse (up to 18.3 ng/l). The concentrations from all sampling points and sampling stations of a particular sampling date were similar, which indicates a homogeneous distribution of this herbicide. Due to the high discharge rate of up to 79,000 m3/s in case of the Yangtse a considerable mass transport of up to 57.5 kg per day atrazine may take place, even at concentrations below the European drinking water limit of 100 ng/l.     

不同预处理技术提取沉积物中多氯联苯有机物的比较

长期以来 ,人们对多氯联苯类有机物在水 沉积物中的迁移、吸附 解吸及降解等行为进行了广泛的研究 ,但是 ,在分析环境样品中的多氯联苯时难以准确定量 ,特别是从环境介质中准确提取多氯联苯非常困难 ,因此 ,有必要建立快速、精确的提取技术 ,以取得最大的提取效率 .沉积物中多氯联苯类有机物的分析预处理技术 ,一般用经典的索氏提取方法 ,近年来发展了超声波提取、微波辅助提取、超临界提取和加速溶剂提取等技术 ,这些提取方法的测定结果准确灵敏 ,但部分技术也存在消耗大量溶剂、费时且操作繁琐等不足 .本文应用索氏提取、固相流体热萃取…     

Polycyclic aromatic hydrocarbon contamination in coastal sediments of the Izmit Bay (Marmara Sea): case studies before and after the Izmit Earthquake

Izmit Bay and its coastal environment was strongly affected by the August 17th, 1999 Izmit Earthquake. The changes in the Bay ecosystem and its chemical oceanography have been studied in detail previously [Okay, O.S., Tolun, L, Telli-Karako?, F., Tüfek?i, V., Tüfek?i, H. And Morko?, E. 2001. Yzmit Bay ecosystem after Marmara earthquake and subsequent fire: The long-term data. Marine Pollution Bulletin 42, 361-369; Balkys, N. 2003. The effect of Marmara (Izmit ) Earthquake on the chemical oceanography of Izmit Bay, Turkey. Marine Pollution Bulletin 46, 865-878.]. In this study surface sediments collected from the Izmit Bay before and after the earthquake have been analysed for total and individual (14 compounds) polycyclic aromatic hydrocarbons (PAH). Analyses have been performed by high performance liquid chromatography with fluorescence detection (HPLC/FD). Before the earthquake, total PAH concentrations in the Bay sediments ranged from 120 to 8900 ng/g while after the earthquake PAH concentrations varied between 240 and 11,400 ng/g. Molecular indices based on isomeric PAH ratios used to differentiate the pollution sources, clearly indicate the differences in molecular distribution of PAHs before and after the earthquake. Sediment data obtained before the earthquake shows that most of the contamination originated from high temperature pyrolytic inputs while after the earthquake it originated from petrogenic sources. This difference emphasises the environmental impact of uncontrolled discharges from petroleum industries after the earthquake. The LMW/HMW ratio (sum of the low molecular weight PAHs / the sum of higher molecular weight PAHs) predominance also changed after the earthquake as a result of the strong water movements. According to the characteristics of aromatic rings distributed in the bay sediments, the soluble parts of the total PAH were probably transferred to the water column after the earthquake as a result of resuspension process. The TEL/PEL (Threshold Effect Level / Probable Effect Level) analysis suggests that the Izmit Bay sediments were likely contaminated by acutely toxic PAH compounds.