Linking field experiments to long-term simulation of impacts of nitrogen deposition on heathlands and moorlands

The results from three long-term field manipulation studies of the impacts of increased nitrogen deposition (0–120 kg N ha^–1 yr^–1) on lowland and upland heathlands in the UK were compared, to test if common responses are observed. Consistent increases in Calluna foliar N content and decreases in litter C:N ratios were found across all sites, while increases in N leaching were not observed at any site over the range 0–80 kg ha^–1 yr^–1. However, the response of Calluna biomass did vary between sites, possibly reflecting site differences in nutrient status and management histories. Five versions of a simulation model of heathland responses to N were developed, each reflecting different assumptions about the fate and turnover of soil N. Model outputs supported the deduction from mass balance calculations at two of the field sites that N additions have resulted in an increase in immobilisation; the latter was needed to prevent the model overestimating measured N leaching. However, this version of the model significantly underestimated Calluna biomass. Model versions, which included uptake of organic N by Callunaand re-mobilisation of N from the soil organic store provided some improvement in the fit between modelled and field biomass data, but re-mobilisation also led to an overestimation of N leaching. Quantification of these processes and their response to increased N deposition are therefore critical to interpreting experimental data and predicting the long-term impacts of atmospheric deposition on heathlands and moorlands.     

Treatment of phenol wastewater by microwave-induced CIO_2-CuO_x/Al_2O_3 catalytic oxidation process

The catalyst of CuO_x/Al_2O_3 was prepared by the dipping-sedimentation method usingγ-Al_2O_3 as a supporter.CuO and Cu_2O were loaded on the surface of Al_2O_3,characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS).In the presence of CuO_x/Al_2O_3,the microwave-induced chlorine dioxide(ClO_2) catalytic oxidation process was conducted for the treatment of synthetic wastewater containing 100 mg/L phenol.The factors influencing phenol removal were investigated and the results showed that microwave-induced ClO_2-CuO_x/Al_2O_3 process could effectively degrade contaminants in a short reaction time with a low oxidant dosage,extensive pH range.Under a given condition(ClO_2 concentration 80 mg/L,microwave power 50 W,contact time 5 min,catalyst dosage 50 g/L,pH 9),phenol removal percentage approached 92.24%,corresponding to 79.13% of COD_(Cr) removal.The removal of phenol by microwave-induced ClO_2-CuO_x/Al_2O_3 catalytic oxidation process was a complicated non-homogeneous solid/water reaction, which fitted pseudo-first-order by kinetics.Compared with traditional ClO_2 oxidation,ClO_2 catalytic oxidation and microwave-induced ClO_2 oxidation,microwave-induced ClO_2 catalytic oxidation system could significantly enhance the degradation efficiency.It provides an effective technology for the removal of phenol wastewater.     

Ecology of toxicity in marine sponges

An investigation of the ecology of toxicity in marine sponges from different latitudes on the North American continent was made. Results indicated that toxicity in sponges increased with decreasing latitude. Three of the 34 species (9%) of sponges from San Juan Island, Washington, USA (48°N), were toxic to fishes. Nine of the 44 species (20%) of sponges from Santa Catalina Island, California, USA (33°N), were toxic. Seven of the 11 species (64%) of sponges from Zihuatanejo Bay, Guerrero, México (17°N), were toxic. Twenty-seven of the 36 species (75%) of sponges from La Blanquilla, Veracruz, México (19°N), were toxic. Most of these toxic sponges are openly exposed to fishes. The most common exposed sponges proved to be highly toxic to fishes. Force-feeding experiments conducted with wrasses demonstrated the effectiveness of the toxin of sponges. A hypothesis is proposed which explains the relationship between species diversity of fishes and sponge toxicity with latitude.     

Effect of mercury on the survival,respiration, and growth of postlarval white shrimp,Penaeus setiferus

The results of toxicity experiments have shown that a level of 17 ppb ionic mercury is acutely toxic (96-h LC₅₀) to postlarval white shrimp (Penaeus setiferus). In addition, the size of the shrimp, within the range tested (7 to 35 mm) did not significantly alter the toxicity values of mercury to this species. Fifty-seven days pre-exposure to low levels of mercury (0.5 and 1.0 ppb) had no effect on the acute toxicity (96-h LC₅₀) of mercury to the shrimp. The effect of chronic exposure to low levels of mercury on the respiratory rate, growth, and molting rate of postlarval P. setiferus was studied, and the results showed that 60 days exposure to 0.5 and 1.0 ppb mercury did not significantly affect any of these parameters for the postlarvae.     

Garden sharing and garden stealing in fungus-growing ants

 Fungi cultivated by fungus-growing ants (Attini: Formicidae) are passed on between generations by transfer from maternal to offspring nest (vertical transmission within ant species). However, recent phylogenetic analyses revealed that cultivars are occasionally also transferred between attine species. The reasons for such lateral cultivar transfers are unknown. To investigate whether garden loss may induce ants to obtain a replacement cultivar from a neighboring colony (lateral cultivar transfer), pairs of queenright colonies of two Cyphomyrmex species were set up in two conjoined chambers; the garden of one colony was then removed to simulate the total crop loss that occurs naturally when pathogens devastate gardens. Garden-deprived colonies regained cultivars through one of three mechanisms: joining of a neighboring colony and cooperation in a common garden; stealing of a neighbor's garden; or aggressive usurpation of a neighbor's garden. Because pathogens frequently devastate attine gardens under natural conditions, garden joining, stealing and usurpation emerge as critical behavioral adaptations to survive garden catastrophes. Received: 16 June 2000 / Accepted in revised form: 14 September 2000     

Incorporating sustainable development in the design of mineral processing operations – Review and analysis of current approaches

This paper reviews the tools and methodologies used for incorporating sustainability considerations into the design of mineral processing operations. It was found that while there is a range of tools and methodologies that contribute to Design for Sustainability, there is no consistent, integrated approach to support the mineral industry in incorporating a greater level of sustainability into the design process. This paper identifies the required elements in such an approach and discusses the ways in which its development would progress the industry towards sustainability.     

Spatial and temporal variability of greenhouse gas emissions from rural development land use operations

Climate change objectives of mitigation and adaptation are being mainstreamed into many policies and strategies around the world. In Europe, this has included the Rural Development Programme, which aims to tackle multiple social, economic and environmental objectives in rural areas, and the integration of climate change objectives adds another strand of complexity to the decision making process. When formulating policies determining the likely effectiveness of any particular measure can be challenging, especially with respect to the spatial and temporal variability of greenhouse gas emissions. This is a challenge faced by all countries and regions around the world. This study uses Europe as an example to explore this issue. It highlights the variability in emissions from land use operations that may be encountered under different conditions and time horizons and considers this in the context of policy formulation. The Optimal Strategies for Climate change Action in Rural Areas software has been adapted to derive net greenhouse gas emissions for rural development operations for all regions in Europe. Operations have been classified into five categories based on their benefit/burden over different time horizons. The analysis shows that it is important to understand the time period over which benefits or burdens are realised and determine how this fits with policy instruments, such as land management agreements and the permanency of actions. It also shows that in some regions an operation can have benefits, but in other regions it has burdens; thus, location can be critical. Finally, in the context of developing operations to meet multiple social, economic and environmental objectives, it is important to acknowledge that seeking options that only reduce emissions may not always be practical or possible. In some instances, we may have to accept an increase in emissions in order to meet other objectives. It is important that we evaluate the net greenhouse gas emissions of all operations, not just those aimed at climate change mitigation. We can then select those with the least burden in the process of developing optimal solutions to meet multiple objectives.