Subpopulations of the Hawaiian striped mullet Mugil cephalus: analysis of variations of nuclear eye-lens protein electropherograms and nuclear eye-lens weights

The method of electrophoretic separation of nuclear eye-lens proteins was applied to a study of the population structure of the striped mullet Mugil cephalus L. in Hawaii. Electropherograms produced 5 pattern types, with most variations due to non-developmental genetic polymorphism. Some variations, however, were associated with size, and an ontogenetic basis was considered. The frequencies of the pattern types were significantly (p<0.005) independent among the three geographical subpopulations examined: Kaneohe Bay, Oahu; Diamond Head, Oahu; and Kawaihae Bay, Hawaii. Growth rates of mullet eye-lens nuclei demonstrated significant (p<0.05) differences between sexes and localities, except for Kaneohe Bay males versus Diamond Head males, which were nearly significant (p 0.075). These variations in eye-lens nuclei growth rates are probably regulated by genetic factors. Nearly complete genetic isolation is evident for the three subpopulations of mullet in the Hawaiian Islands. The occurrence of genetic interchange in apparently less frequent between the Oahu and Hawaii populations than between the two Oahu populations, in accordance with their respective geographical distances.Oceanic Institute Contribution No. 72.     

Light and carbon balance in the seagrass Thalassia testudinum : evaluation of current production models

The production dynamics and carbon balance of Thalassia testudinum in the lower Laguna Madre, Texas, USA, were examined during the 1995 summer period based on in situ photosynthesis vs irradiance (PI) measurements and continuous measurements of underwater photon-flux density (PFD). The validity of applying the H _sat model, used to calculate production for Zostera marina as the product of the maximum rate of photosynthesis (P _max) and daily hours of saturating irradiance (H _sat) was assessed for T. testudinum by comparison with integrated production estimates derived through numerical integration. Gross integrated production values were combined with dark-respiration measurements of photosynthetic (PS) and non-photosynthetic (NPS) tissues and areal biomass to generate daily whole-plant carbon balance. Production and whole-plant carbon balance are discussed in relation to surface and underwater PFD measurements, biomass and other physical and chemical parameters collected during a 1 yr period from January to December 1995. The H _sat model significantly underestimated production during all summer months, averaging 70% of integrated production over the entire study period. Gross integrated production ranged between 11.5 mg C g⁻¹ leaf dry wt d⁻¹ in June (during a period of unseasonably low PFDs caused by a drift-alga mat covering the seagrass bed) to 26.7 mg C g⁻¹ leaf dry wt d⁻¹ in July. Modeled net carbon gain was highest in July at 454 mg C m⁻² d⁻¹ (1.4 g dry wt m⁻² d⁻¹), sufficient to account for measured rates of leaf production in the study area and representative of T. testudinum populations of low productivity. During part of the summer period, however, the population was in negative carbon balance. The relatively low productivity of this population and the periods of negative carbon balance are attributed to low net photosynthesis:dark respiration (P _net:R _d) ratios, sporadic low-light periods, the small fraction of PS tissue relative to whole-plant biomass (5 to 13%) and nutrient limitation. Production models are sensitive to both light availability and the proportion of PS tissue supporting NPS biomass as reflected in whole-plant P _net:R _d ratios. Received: 13 August 1997 / Accepted: 6 March 1998     

Do pronghorn mothers reveal the locations of their hidden fawns?

Summary Success of the hider strategy in ungulates depends, in part, on the mother's ability to minimize information she transmits about her young's hiding place while remaining close enough to distract or drive away a predator. We predicted that pronghorn (Antilocapra americana) mothers should: (1) maintain minimum distances from their hidden fawns sufficient to cause the expected energy gain for a ground predator, systematically searching around the mother, to fall below that expected when searching for some other prey; (2) orient the axes of either head or trunk towald the hidden fawn no more frequently than would be expected by chance; (3) schedule behavior so that no activity is more likely than another to occur when a visit to the hidden fawn is imminent. At the National Bison Range, where coyote (Canis latrans) predation on pronghorn fawns is frequent, pronghorn mothers conform to predictions (1) and (3), but not (2). Within the first 10% of their time away from fawns, mothers reached an average distance of 70.4 m from their fawns' biding places and remained at that distance until 95% of their time away was clapsed. At this mother-fawn distance a coyote, using the mother's position to begin a systematic search for the fawn, and searching at a rate of 4 m²/s, would gain energy at a lower rate than it would hunting ground squirrels (Spermophilus columbianus). Mothers pointed both head and trunk toward their hidden fawns more frequently than would be expected by chance and coyotes, able to use this information to establish a 90° quadrant to search, could expect rates of gain higher than those obtainable in 360° search. Mothers especially tended to orient both head and trunk toward their fawns when standing or moving. Coyotes that begin a 90° search based on the mother's head or trunk position only when mothers were standing or moving, could expect rates of energy gain almost double those expected in 360° search or ground squirrel hunting. Maternal activities (stand, feed, recline, or move) were distributed evenly across all mother-fawn distances and across percent total time away from the fawn. Thus, activity was not a good predictor of a mother's likelihood of soon returning to her fawn. Mothers also remained away from their fawns long enough to cause the expected rate of energy gain for a coyote hiding and watching for the mother's return to the fawn to fall well below the rate expected for searching or ground squirrel hunting.     

Treatment of mature landfill leachate by biofilters and Fenton oxidation

A series of processes by biofilter and Fenton oxidation to treat mature landfill leachate has been devised. At a hydraulic loading rate of 20 l m^?3 d^?1, a biofilter packed with aged refuse is found to remove 80% of chemical oxygen demand (COD), 89% of ammonia nitrogen and 96% of total phosphorus (TP). Particularly, TP levels dropped below 1 mg l^?1. The optimal condition for Fenton oxidation was selected to be an initial pH of 5, a dosage of 0.01 and 0.02 mol l^?1 of FeSO₄ and H₂O₂, respectively, and a duration of 3 h, where COD removal efficiency reaches 58.6%, and BOD₅/COD ratio is raised from 0.05 to 0.20. Subsequent treatment by a biofilter packed with slag reduces COD, ammonia nitrogen levels to less than 100, 25 mg l^?1, respectively. A pilot scale experiment conducted in situ demonstrates that this series of processes exhibits a high efficiency in removing pollutants from mature landfill leachate and it is viable for application.     

Performance of Trickle-Bed Air Biofilter: A Comparative Study of a Hydrophilic and a Hydrophobic Voc

Two lab-scale trickle-bed air biofilters were operated for investigating the difference in performance between a hydrophilic and a hydrophobic volatile organic compound (VOC). Methyl isobutyl ketone (MIBK) and styrene were selected as a model hydrophilic and hydrophobic VOCs, respectively. Effects of loading rates, biofilter re-acclimation, removal profile along biofilter depth, nitrogen consumption, and CO₂ production were compared under three operating conditions, namely, backwashing and two non-use periods (starvation and stagnant). Consistent over 99% removal efficiency up to loading rates of 3.26 kg COD/m³-day was obtained for the MIBK biofilter at 0.76 min empty bed retention time (EBRT) and 1.5 L/d nutrient flow. A similar performance for the styrene biofilter was obtained for loading rates up to 1.9kg COD/m³-day at 2.02 min EBRT and 2.4 L/d nutrient flow. The MIBK biofilter required only an initial acclimation period of 16 days while styrene biofilter required 46 days. Non-use periods can be used as another means of biomass control for both biofilters when the employed loading rate did not exceed 1.27 and 2.17 kg COD/m³-day for styrene and MIBK biofilters, respectively. The re-acclimation of both biofilter was delayed with increase of loading rate. MIBK biofilter re-acclimated in 90 min, while styrene biofilter re-acclimated in more than 600 min. Under similar loading rates, MIBK biofilter utilized less biofilter depth than styrene biofilter. Nitrogen consumption behaviors were apparently different between the two biofilters. Styrene biofilter had higher CO₂ production than MIBK biofilter and its CO₂ production was closely related to the theoretical complete chemical oxidation.     

Seasonal Variation of Inorganic Nutrient Uptake by Heterotrophic Bacterioplankton in Jiaozhou Bay,North China

The distribution patterns and factors affecting uptake rates and turnover times of dissolved inorganic nutrients by heterotrophic bacterioplankton (HB) in Jiaozhou Bay were studied based on in situ surveys and laboratory culturing. The uptake rates of dissolved inorganic phosphorus (DIP) and dissolved inorganic nitrogen (DIN) by HB are limited by the temperature of the water and the concentration of dissolved organic carbon. The turnover times of DIP and DIN by HB are regulated by the concentrations of the nutrients and the numbers of HB, which show significant spatiotemporal variability in Jiaozhou Bay. HB may aggravate the P-limitation of phytoplankton by competing for phosphorus in summer in Jiaozhou Bay. HB play an important role in the biogeochemical cycling of nutrients and may increase the N:P ratio and the accumulation of DIN, thereby accelerating the imbalance of the N:P ratio in Jiaozhou Bay.     

Life cycle assessment of disposal of residues from municipal solid waste incineration: recycling of bottom ash in road construction or landfilling in Denmark evaluated in the ROAD-RES model

Two disposal methods for MSWI bottom ash were assessed in a new life cycle assessment (LCA) model for road construction and disposal of residues. The two scenarios evaluated in the model were: (i) landfilling of bottom ash in a coastal landfill in Denmark and (ii) recycling of bottom ash as subbase layer in an asphalted secondary road. The LCA included resource and energy consumption, and emissions associated with upgrading of bottom ash, transport, landfilling processes, incorporation of bottom ash in road, substitution of natural gravel as road construction material and leaching of heavy metals and salts from bottom ash in road as well as in landfill. Environmental impacts associated with emissions to air, fresh surface water, marine surface water, groundwater and soil were aggregated into 12 environmental impact categories: Global Warming, Photochemical Ozone Formation, Nutrient Enrichment, Acidification, Stratospheric Ozone Depletion, Human Toxicity via air/water/soil, Ecotoxicity in water/soil, and a new impact category, Stored Ecotoxicity to water/soil that accounts for the presence of heavy metals and very persistent organic compounds that in the long-term might leach. Leaching of heavy metals and salts from bottom ash was estimated from a series of laboratory leaching tests. For both scenarios, Ecotoxicity(water) was, when evaluated for the first 100 yr, the most important among the twelve impact categories involved in the assessment. Human Toxicity(soil) was also important, especially for the Road scenario. When the long-term leaching of heavy metals from bottom ash was evaluated, based on the total content of heavy metals in bottom ash, all impact categories became negligible compared to the potential Stored Ecotoxicity, which was two orders of magnitudes greater than Ecotoxicity(water). Copper was the constituent that gave the strongest contributions to the ecotoxicities. The most important resources consumed were clay as liner in landfill and the groundwater resource which was potentially spoiled due to leaching of salts from bottom ash in road. The difference in environmental impacts between landfilling and utilization of bottom ash in road was marginal when these alternatives were assessed in a life cycle perspective.     

Process modeling of chemical looping combustion (CLC) of municipal solid waste

Journal of Material Cycles and Waste Management - Chemical Looping Combustion (CLC) of MSW could serve as a potential treatment method for the disposal of MSW and the recovery of energy because it...     

Large-scale experiments for microbiological evaluation of measures for safeguarding sulfidic mine waste

In the framework of a German-Romanian scientific cooperation, experiments were performed to evaluate feasible and cheap techniques for the safe storage of mine waste to prevent acid rock drainage (ARD). A large four-chamber percolator (4CP) was installed in a waste heap at Ilba Mine, Romania, to test the effect of biocides and alkaline layers on the bacteria causing acid rock drainage (ARD). The 4CP consisted of four chambers each containing 65 m3 of sulfidic waste material. The 4CP enabled the transfer of laboratory results to a technical scale. The detergent sodiumdodecylsulfate (SDS) was proved to be active against the leaching bacteria. Organotrophic micro-organisms were not effected by the SDS application. The alkaline layers caused an increase of pH, however, a decrease of cell numbers was measured only in adjacent ore layers, but not in the whole ore body. A rapid evaluation of the effects of these countermeasures on ARD formation became possible by microcalorimetric activity measurements for bioleaching.     

Optimisation of MSW collection routes for minimum fuel consumption using 3D GIS modelling

Collection of municipal solid waste (MSW) may account for more than 70% of the total waste management budget, most of which is for fuel costs. It is therefore crucial to optimise the routing network used for waste collection and transportation. This paper proposes the use of geographical information systems (GIS) 3D route modelling software for waste collection and transportation, which adds one more degree of freedom to the system and allows driving routes to be optimised for minimum fuel consumption. The model takes into account the effects of road inclination and vehicle weight. It is applied to two different cases: routing waste collection vehicles in the city of Praia, the capital of Cape Verde, and routing the transport of waste from different municipalities of Santiago Island to an incineration plant. For the Praia city region, the 3D model that minimised fuel consumption yielded cost savings of 8% as compared with an approach that simply calculated the shortest 3D route. Remarkably, this was true despite the fact that the GIS-recommended fuel reduction route was actually 1.8% longer than the shortest possible travel distance. For the Santiago Island case, the difference was even more significant: a 12% fuel reduction for a similar total travel distance. These figures indicate the importance of considering both the relief of the terrain and fuel consumption in selecting a suitable cost function to optimise vehicle routing.