Is Diversification a Suitable Option to Reduce Drought-Induced Risk of Forest Dieback? An Economic Approach Focused on Carbon Accounting

Environmental Modeling & Assessment - Extreme or recurrent drought events are the principal source of stress on forests, impairing their overall health. They result in financial losses for...     

Soil sensitivity to acidification in Asia: status and prospects

Exceedance of steady-state critical loads for soil acidification is consistently found in southern China and parts of SE Asia, but there is no evidence of impacts outside of China. This study describes a methodology for calculating the time to effects for soils sensitive to acidic deposition in Asia under potential future sulfur (S), nitrogen (N), and calcium (Ca) emission scenarios. The calculations are matched to data availability in Asia to produce regional-scale maps that provide estimates of the time (y) it will take for soil base saturation to reach a critical limit of 20% in response to acidic inputs. The results show that sensitive soil types in areas of South, Southeast, and East Asia, including parts of southern China, Burma, Hainan, Laos, Thailand, Vietnam, and the Western Ghats of India, may acidify to a significant degree on a 0-50 y timescale, depending on individual site management and abiotic and biotic characteristics. To make a clearer assessment of risk, site-specific data are required for soil chemistry and deposition (especially base cation deposition); S and N retention in soils and ecosystems; and biomass harvesting and weathering rates from sites across Asia representative of different soil and vegetation types and management regimes. National and regional assessments of soils using the simple methods described in this paper can provide an appreciation of the time dimension of soil acidification-related impacts and should be useful in planning further studies and, possibly, implementing measures to reduce risks of acidification.     

Growth kinetics and competition between Methanosarcina and Methanosaeta in mesophilic anaerobic digestion.

Methanosarcina species with a high maximum specific growth rate (mumax) and high half-saturation coefficient (KS) and Methanosaeta species with a low mumax and low KS are the only known aceticlastic methanogens. Because of Methanosaeta's low KS, the low acetate concentrations in conventional, mesophilic anaerobic digestion yield Methanosaeta dominance. However, Methanosarcina absorbs increases in acetate more efficiently and thus promotes more stable digestion. This paper tests the hypothesis that decreasing digester feeding frequencies can increase Methanosarcina predominance. Two acetate-fed reactors were established at a 17-day solids retention time. One reactor was fed hourly, and one was fed once daily. Microscopic and molecular methods were used to verify that the hourly fed reactor enriched for Methanosaeta, while the daily fed reactor enriched for Methanosarcina. Growth and substrate-use kinetics were measured for each reactor. A digester overload condition was simulated, and the Methanosarcina-enriched reactor was found to perform better than the Methanosaeta-enriched reactor. These findings indicate that Methanosarcina dominance can be achieved with infrequent feedings, leading to more stable digestion.     

Assessing Landscape Condition Relative to Water Resources in the Western United States: A Strategic Approach

The Environmental Monitoring and Assessment Program (EMAP) is proposing an ambitious agenda to assess the status of streams and estuaries in a 12-State area of the western United States by the end of 2003. Additionally, EMAP is proposing to access landscape conditions as they relate to stream and estuary conditions across the west. The goal of this landscape project is to develop a landscape model that can be used to identify the relative risks of streams and estuaries to potential declines due to watershed-scale, landscape conditions across the west. To do so, requires an understanding of quantitative relationships between landscape composition and pattern metrics and parameters of stream and estuary conditions. This paper describes a strategic approach for evaluating the degree to which landscape composition and pattern influence stream and estuary condition, and the development and implementation of a spatially-distributed, landscape analysis approach.     

Effects of Acid Rain on Competitive Releases of Cd, Cu, and Zn from Two Natural Soils and Two Contaminated Soils in Hunan, China

Leaching experiments of rebuilt soil columns with two simulated acid rain solutions (pH 4.6–3.8) were conducted for two natural soils and two artificial contaminated soils from Hunan, south-central China, to study effects of acid rain on competitive releases of soil Cd, Cu, and Zn. Distilled water was used in comparison. The results showed that the total releases were Zn>Cu>Cd for the natural soils and Cd>Zn≫Cu for the contaminated soils, which reflected sensitivity of these metals to acid rain. Leached with different acid rain, about 26–76% of external Cd and 11–68% external Zn were released, but more than 99% of external Cu was adsorbed by the soils, and therefore Cu had a different sorption and desorption pattern from Cd and Zn. Metal releases were obviously correlated with releases of TOC in the leachates, which could be described as an exponential equation. Compared with the natural soils, acid rain not only led to changes in total metal contents, but also in metal fraction distributions in the contaminated soils. More acidified soils had a lower sorption capacity to metals, mostly related to soil properties such as pH, organic matter, soil particles, adsorbed SO₄ ²⁻, exchangeable Al³⁺ and H⁺, and contents of Fe₂O₃ and Al₂O₃.     

Enhanced photocatalytic activity of electrospun TiO2/polyacrylonitrile membranes in a crossflow reactor using dual lights

Photocatalytic membranes reactors have become one of the most efficient technologies to treat polluted waters. However, a major drawback is the unilateral irradiation of the membrane, where only one side of the membrane is exploited. To overcome this issue, we developed a reactor where the membrane can be irradiated on both sides. Polyacrylonitrile membranes containing different amounts of TiO₂ nanoparticles up to 60% were first prepared by electrospinning. These membranes were used in a 3D-printed crossflow photocatalytic membrane reactor for the degradation of methylene blue under different combinations of lights. The use of both sides of the photocatalytic membrane significantly enhanced the photocatalytic activity for the decolorization of methylene blue in water. The prepared membranes showed the best decolorization rate for a loading of 60% of TiO₂ and the use of dual ultraviolet lights, where the methylene blue solution was completely discolored after 90 min. This is the first report of a such system configuration, and this new irradiation concept is promising for photocatalytic membrane reactions and water cleaning.

     

Social relationships in a cooperatively polyandrous group of tamarins (Saguinus fuscicollis)

Summary This paper presents detailed data on the social relationships among the adults, and between the adults and young, of a cooperatively polyandrous saddle-back tamarin (Saguinus fusciollis; Callitrichidae) group studied for one year. Some data are also presented from groups studied in other years. Adult males in the study groups gave more grooming than they received, while the opposite was true for females (e.g. Fig. 1). The two polyandrous males in the main study group were very rarely aggressive to each other, rarely tried to disrupt each others' copulations, groomed each other, and occasionally shared food, suggesting that their relationship was more affiliative than agonistic. Data on grooming (Fig. 2), spatial relationships, and the initiation of copulations suggest that the males of this group, may have been somewhat more responsible than the female for the maintenance of male-female relationships. Both males and females performed all forms of parental care except lactation. In the main study group each of the males groomed the offspring and remained in close proximity to them more than did the female (Figs.3 and 4). These data are compared with existing data on social relationships in bird species that exhibit cooperative polyandry.     

Beyond the Requirements: Improving Public Participation in EIA

Virtually every environmental planner at some time deals with environmental impact assessment (EIA). Public participation is required in most environmental impact assessment programmesaround the world. However, citizen involvement is often reduced to a procedural exercise instead of a substantive process to include the public in environmental decision making. This paper examines public participation in EIA and provides ways to improve its effectiveness. We first examine the rationales for public involvement and its institutionalization through EIA. Next, we analyse the shortcomings and strengths of common approaches to public involvement. Our analysis, supported by two case studies, suggests that going beyond the minimum requirements can benefit the public, the project proponent and the final plan. We conclude with practical steps to improve public participation programmes in environmental planning and decision making.     

The outcomes of downward managerial mobility

Research examining the effects of unemployment among white collar workers has produced patterns of findings different to those for lower socio-economic groups. The present longitudinal questionnaire study examines the psychological impact of managerial job moves which are downward in status, and considers the effects of periods of unemployment between job changes. The results indicate that among managers the negative impact of downward status moves on psychological adjustment is greater than that of temporary role loss. These effects are associated with decrements in preceived growth and development opportunities at work. The relationship between work and non-work life for our understanding of psychological adjustment is considered.