Biota Connect Aquatic Habitats throughout Freshwater Ecosystem Mosaics

Freshwater ecosystems are linked at various spatial and temporal scales by movements of biota adapted to life in water. We review the literature on movements of aquatic organisms that connect different types of freshwater habitats, focusing on linkages from streams and wetlands to downstream waters. Here, streams, wetlands, rivers, lakes, ponds, and other freshwater habitats are viewed as dynamic freshwater ecosystem mosaics (FEMs) that collectively provide the resources needed to sustain aquatic life. Based on existing evidence, it is clear that biotic linkages throughout FEMs have important consequences for biological integrity and biodiversity. All aquatic organisms move within and among FEM components, but differ in the mode, frequency, distance, and timing of their movements. These movements allow biota to recolonize habitats, avoid inbreeding, escape stressors, locate mates, and acquire resources. Cumulatively, these individual movements connect populations within and among FEMs and contribute to local and regional diversity, resilience to disturbance, and persistence of aquatic species in the face of environmental change. Thus, the biological connections established by movement of biota among streams, wetlands, and downstream waters are critical to the ecological integrity of these systems. Future research will help advance our understanding of the movements that link FEMs and their cumulative effects on downstream waters.     

One day is all it takes: circadian modulation of the retrieval of colour memories in honeybees

In this study, we examined how honeybees coped with successive tasks of colour discrimination with conflicting demands. Free-flying honeybees (Apis mellifera) were trained on tasks in which they had to choose one of three colours to obtain a reward of sugar water. In acquisition, the bees learned this task in about four trials of training. Colour memory was retained after 24-h delay in an unrewarded retention test. Integration experiments were then conducted in which the bees had to learn two successive tasks of colour discrimination with conflicting demands, task 1 for 20 trials and task 2 for ten trials. In task 1, one of three colours provided sugar water while the other two provided tap water, while in task 2 a different colour provided the reward. The bees were given unrewarded tests immediately after training on task 2 and then re-tested after 10 min, 22 h (circadian time of the start of task 1 training), or 24 h (circadian time of the end of task 2 training). Bees strongly preferred the rewarded colour for task 2 on immediate testing and after 10-min delay. After 22-h delay, they switched their preference to the rewarded colour for task 1. But after 24-h delay, the bees again strongly preferred the rewarded colour for task 2. Further tests at a number of delays between 0 and 22 h revealed a sigmoidal pattern of rise in the preference for the task 1 colour. We conclude that circadian time modulates the retrieval of colour memories in honeybees, even when all the training took place in a single day.     

Quantifying the availability and the stability of trace cationic elements in fly ash

For adsorption-desorption controlled leaching processes, the total leachable mass and the adsorption constant are parameters representing the availability and the stability of trace elements in solid media. With these parameters, one can predict the leaching behavior of trace elements from solids under various pH and solid-to-liquid ratio conditions. An approach was developed in this paper to determine these parameters for model elements Cu(II), Cd(II), and Ni(II) in fly ash. This approach consists of a batch equilibrium titration, a batch equilibrium leaching with and without target element addition, and mathematical modeling. Results indicated that the adsorption constant of a trace element can be determined by modeling the adsorption ratio of the added element to the system as a function of pH. Results also indicated that the trace element originally present in fly ash had similar adsorption-desorption behavior as that added externally. By modeling the batch leaching data with and without external element addition, the total leachable mass and adsorption constant of the target element can be determined simultaneously. The total leachable mass is in agreement with experimental data from 50mM EDTA extraction.     

Evaluation of the STP model: comparison of modelled and experimental results for ten polycyclic aromatic hydrocarbons (PAHs)

Screening level risk assessment models are used by many countries to assess the treatability of organic chemicals during the sewage treatment process, especially those that are new to commerce. The performance of one such model, the sewage treatment plant model, is evaluated in the current study by comparing model predictions with actual measurement data collected at various stages of a typical full-scale activated sludge type sewage treatment plant. A suite of ten polycyclic aromatic hydrocarbons (PAHs) with widely varying physico–chemical properties were monitored for the comparison. Model predicted removal efficiencies were in very good agreement with those measured for all ten PAHs. Observed chemical concentrations and their trends at various stages of the sewage treatment process were also well simulated by the model. Results also suggest that a reasonable first approximation estimate of a range for the biodegradation half-life needed for the model may be obtained by dividing reported aqueous biodegradation half-life by scaling factors of 50 and 150.     

Elimination of 10 polybrominated diphenyl ether (PBDE) congeners and selected polychlorinated biphenyls (PCBs) from the freshwater mussel, Elliptio complanata

Mussel biomonitors are widely used as screening tools for polybrominated diphenyl ethers (PBDEs) in marine and aquatic environments. This study determined elimination rate coefficients (k(tot)) for eight PBDE and five PCB congeners in the freshwater mussel, Elliptio complanata, over a 120d depuration period. Elimination of BDE 15, 28, 47, 75 and 100 was similar to PCBs of equivalent hydrophobicity and negatively related to chemical K(OW). Rapid elimination of BDE 190 and an inferred rapid elimination of BDE 183 indicate mussels are capable of biotransformation of certain highly brominated PBDEs. Time to 90% steady state ranged from 48 to 66d for di- and tribromoDE congeners and from 91 to >250d for tetra- to hexabromoDE congeners. Given the long time periods required for steady state, mussel accumulated PBDE residues should be interpreted in the context of calibrated bioaccumulation models.     

Evaluation of wireless sensor networks (WSNs) for remote wetland monitoring: design and initial results

Here, we describe and evaluate two low-power wireless sensor networks (WSNs) designed to remotely monitor wetland hydrochemical dynamics over time scales ranging from minutes to decades. Each WSN (one student-built and one commercial) has multiple nodes to monitor water level, precipitation, evapotranspiration, temperature, and major solutes at user-defined time intervals. Both WSNs can be configured to report data in near real time via the internet. Based on deployments in two isolated wetlands, we report highly resolved water budgets, transient reversals of flow path, rates of transpiration from peatlands and the dynamics of chromophoric-dissolved organic matter and bulk ionic solutes (specific conductivity)—all on daily or subdaily time scales. Initial results indicate that direct precipitation and evapotranspiration dominate the hydrologic budget of both study wetlands, despite their relatively flat geomorphology and proximity to elevated uplands. Rates of transpiration from peatland sites were typically greater than evaporation from open waters but were more challenging to integrate spatially. Due to the high specific yield of peat, the hydrologic gradient between peatland and open water varied with precipitation events and intervening periods of dry out. The resultant flow path reversals implied that the flux of solutes across the riparian boundary varied over daily time scales. We conclude that WSNs can be deployed in remote wetland-dominated ecosystems at relatively low cost to assess the hydrochemical impacts of weather, climate, and other perturbations.     

Evaluating Japanese policy instruments for the promotion of renewable energy sources

In Japan, the Renewable Portfolio Standard (RPS) and the Feed-in-Tariff (FIT) have been used for the exploitation of renewable energy sources (RES). Although these are significant to enhance the use of RES, the RES penetration is not reaching the expected percentage. The identification of their strengths/weaknesses will allow their improvement for achieving the target. This paper concerned the evaluation of RPS and FIT using a multi-criteria evaluation method. First, official data/information were used to assess their performance using the method. Second, national experts were asked about their performance to verify the outcomes. We found FIT was more effective than RPS.     

Hydrocarbon Production and Photochemical Ozone Formation in Forest Burn Plumes

The purpose of this paper is to describe ozone production in forest slash burn plumes. Plumes from controlled fires in the state of Washington were monitored using an instrumented aircraft. Ozone, oxides of nitrogen, condensation nuclei, and visual range (nephelometer) were measured continuously on board the plane. Airborne grab samples were collected for detailed hydrocarbon analysis.

The slash burn plumes were found to contain significant quantities of ozone. A buildup of 40–50 ppb above the ambient background ozone concentrations was not unusual. Hydrocarbon analyses revealed the presence of many photochemically reactive olefins in the plume. Hydrocarbon/NO _x ratios were favorable for photochemical oxidant production.