Can Human-made Saltpans Represent an Alternative Habitat for Shorebirds? Implications for a Predictable Loss of Estuarine Sediment Flats

Estuarine areas worldwide are under intense pressure due to human activities such as upstream dam building. Shorebirds strongly depend on estuarine intertidal flats during migration and wintering periods and so are particularly vulnerable to such impacts, whose magnitude will depend on the availability of alternative feeding habitats. In this study we analyze if man-made saltpans can represent an alternative habitat for wintering and migrating shorebirds in the Guadiana estuary, a wetland that is already experiencing environmental changes due to the building of the Alqueva reservoir, the largest in Western Europe. We compared the use of mudflats and saltpans as feeding areas by several shorebird species before the construction of the dam. A dataset with 26 years of counts data was also analyzed in order to detect any long-term trend in shorebirds abundance. We concluded that saltpans, in particular the fully mechanized, can be used as an alternative habitat by larger species during winter and southward migration, thus playing a major role in minimizing the possible effects of sediment loss due to dam building. In contrast, smaller species were particularly dependent on mudflats to feed. A significant change in population trends, from positive to negative, was detected for two species. Although we still have no evidence that this is directly linked to dam building, this result and documented changes that limit primary productivity justifies the implementation of a long-term monitoring scheme of shorebird populations in this estuary. We also reinforce the need to manage the saltpans as key habitats for shorebirds.     

Wet oxidation: a pre-treatment procedure for sludge

Wet oxidation process is specially effective for wastes with a high organic matter which can not be removed by conventional treatment methods. The digested and raw activated sludges of PAKMAYA yeast factory are treated by wet oxidation process. The liquid-phase organic matter concentration [as total organic carbon (TOC)] was increased by 16.5% in 10 min during the wet oxidation in the presence of Cu as catalyst and H2O2. Lenghtening the period of the wet oxidation, the TOC-concentration was increased by 66% in 120 min. The biodegradability of the sludge after wet oxidation process was also examined. A very little development in the biodegradability was observed, when wet oxidation was applied as pre-treatment to the digested sludge (5% decrease as TOC, in the presence of Cu catalyst and H2O2). However, in the case of digestion of the raw sludge after the application of wet oxidation, the biodegradability increased significantly (approximately 75%, as TOC). Moreover, wet oxidation improved the ability of settling of sludge solids, as well as enhancing the treatment efficiency. Finally, the volume of settled solids was decreased by 80% in the presence of Cu and H2O2. NH3+-N, NO2(-)-N and NO3(-)-N concentrations in the supernatant decreased with the wet oxidation. pH value of the sludge increased from 6.6 to 7.8-8.0. Since stable sludge was taken from the digester where the nitrification process was progressing, a decrease in the nitrite concentration, with an increase in nitrate was observed in the digestion continuing after the wet oxidation pre-treatment. However, in the raw activated sludge, there was a nitrite formation only in the non-pretreated sludge.     

A mathematical model for the anaerobic treatment of Baker's yeast effluents

Baker's yeast fermentation produces high strength wastewaters containing high concentrations of organic materials that cannot easily be degraded by biological processes. A two-stage (anaerobic-aerobic) treatment system has been used in order to treat this effluent efficiently. Most of the COD reduction takes place during the anaerobic degradation. The objective of this study was to generate a simple mathematical model for the anaerobic stage. The model, which is based on the elimination of COD, assumes that only three consecutive reactions namely hydrolysis, acidogenesis and methanogenesis are significant. In the laboratory-scale experiments, feed strength was increased from 3600 to 14,000 mg O2 l-1 in a batch reactor. Three reaction rate constants were found as 0.08, 0.004, 0.06 h-1 by analyzing data from the laboratory experiments. The model was tested and found to be congruent with the daily operation data, which were collected from the Pakmaya Baker's Yeast Kocaeli Factory Plant. This plant contains three Upflow Anaerobic Sludge Blanket reactors, which are run in series. The rate constants of the hydrolysis and methanogenesis were similar to the batch experiment case.     

An experimental study of an LPG tank at low filling level heated by a remote wall fire

This paper describes an experimental study of 2300 L pressure vessels exposed to remote fire heating by a natural gas fuelled wall fire simulator. The tanks were filled to 15% capacity with commercial liquid propane. The flame intensity and distance were varied to study the effect of different heating levels on the tank and its lading.The fire simulator is first characterized with tests including fire thermocouples, radiative flux meters and thermal imaging. With the appropriate positioning of a target tank it is possible to get very realistic fire heat fluxes at the tank surface.Three tests were conducted with the 2300 L tanks filled to 15% capacity with propane. The tanks were positioned at three different distances from the wall fire resulting in measured average peak heat flux at the tank surfaces ranging between 24 and 43 kW m^?2. The data shows rapid rise in vapour space wall temperatures, significant temperature stratification in the vapour space, and moderate rate of pressure rise. These results provide excellent data for the validation of computer models used to predict the response of pressure vessels exposed to moderate heating from a remote fire.     

World mineral production and consumption in 1978

This article is an abridged version of a report on the status of world mineral production and consumption in 1978. Various indexes are used to assess the position in 1978 in comparison with that of earlier periods (1950 and 1973). The data given in this article are based on the calculation of mining production in terms of value. 51 major minerals are dealt with — six fuel materials, 22 metal materials, and 23 non-metal materials.     

Fates of cadmium introduced into channels microcosm

Five 10 μg Cd·l^?1 were continuously input to aquatic microcosm channels for one year. Cadmium accumulation in both biotic and abiotic components was determined. Cadmium inputs and outputs equilibrated within approximately 20 days of initial Cd inputs. Most community components accumulated Cd proportional to Cd water concentrations. Equilibrium Cd concentrations of sediments, aufwuchs, macrophytes, chironomids, and mosquito fish exposed to 10 μg Cd·l^?1 were 0.59, 55, 250, 40, and 40 μg Cd·g^?1, dry weight, respectively. Cadmium was rapidly eliminated from all biotic components when Cd inputs were terminated. Cadmium concentrations were similar to those in control channels within a few weeks in the aufwuchs community to a few months in macrophytes after Cd inputs were terminated. Cadmium uptake fluxes by the aufwuchs community and mosquito fish were first order, with respect to Cd concentration in the water. The rate constants for uptake and depuration for the aufwuchs community were 0.42 and 0.66 d^?1, respectively (concentration basis). The rate constants for uptake and depuration of Cd by mosquitofish were approximately 25 and 0.004 d^?1, respectively (concentration basis). Cadmium concentrations in organic headpool sediments had not significantly decreased six months after cessation of Cd inputs, which indicates that the abiotic half time for contaminated organic sediments is very long. Half times for elimination from channel sand sediments were 72 and 38 d for 5 and 10 μg·l^?1 exposure, respectively, after Cd inputs were terminated Cd concentrations in macroinvertebrates varied seasonally. The carrying capacity of the channels microcosm limited the number of samples of secondary and tertiary consumers which could be sampled. It was concluded that concluded that experimental channels of the size described here were not appropriate as screening tools for the fates of trace contaminants, but were effective for the study of trace contaminants, especially in conjunction with mathematical modeling efforts and less complex laboratory studies.     

Modeling sorbent injection for mercury control in baghouse filters: II--pilot-scale studies and model evaluation

Activated carbon injection for Hg control in a 500-lb/hr pilot-scale coal-fired furnace equipped with a fabric filter for particulate control was evaluated at different operating conditions. The pilot-scale tests showed that Hg removal was improved at lower temperatures and higher C/Hg ratios. The two-stage mathematical model developed to describe Hg removal using powdered activated carbon injection upstream of a baghouse filter was used to obtain Langmuir isotherm parameters as a function of temperature by fitting the model to a subset of experimental data. The predictive capability of the model was then tested by comparing model calculations with additional experimental data from this system obtained using different operating temperatures and sorbent to Hg ratios. Model predictions were in good agreement with experimentally measured Hg removal efficiency. Based on the model predictions, Hg removal in the duct appears to be limited and higher C/Hg ratio, lower operating temperature, and longer cleaning cycle of the baghouse filter should be utilized to achieve higher Hg removal in this system.     

Formation of radioactivity enriched soils in mountain areas

A field study was carried out in the Mercantour Mountains at 2200 m altitude to investigate the processes of soil enrichment in atmospheric Chernobyl (137)Cs. Soils with high (137)Cs activities have been collected in the pasture areas with frequently measured (137)Cs activity values of the order of 7000 Bq m(-2). At some single spots (about 6% of the studied area), activity in soils reached 300000 Bq m(-2), which represents 44% of the (137)Cs of the total area. Data further showed that spatial distribution of Cs depends widely on its origin: Chernobyl Cs is mainly concentrated in "enriched" soils, whereas older Cs and (241)Am fallout from nuclear weapons tests (NWTs) and natural atmospheric (210)Pb in soils is less heterogeneously distributed.In order to elucidate the processes which have led to the enrichment in Chernobyl (137)Cs in the Alps in May of 1986, we have studied the repartition of atmospheric (7)Be isotope (half-life=53.3 d) in the pasture compartments (soil, litter, grass, and snow). Snow (7)Be data give evidence that fallout enrichment is related to snow accumulation (snow drift). The transfer of beryllium occurs rapidly to the grass and litter, where the strongest pollutant accumulations were measured. However, (7)Be transport to the soil required more than 8 months.     

Towards a clean Izmit Bay

The elongated semi-enclosed Bay of Izmit, which receives both domestic and industrial wastes, has been monitored by measuring its physical and biochemical parameters for 2 years, 1994-1995. It is clear that there are two distinct water masses. The upper layer has been occupied by the less saline (22-26 ppt) waters of the Black Sea origin; whereas the lower layer contains saline (38.5 ppt) Mediterranean waters. The seasonal variations in the biochemical characteristics were dependent on the bay's two-layer flow system. If one considers the distribution of transparency in the upper bay waters, it has been observed that the Secchi disk depth (SDD) decreases from west to east. Furthermore, these depths are limited by the high primary productivity associated with the low concentrations of nutrients observed during the spring. Discharges of wastes into the surface waters significantly affect the biological production and oxygen consumption in the lower layer. Within the last 10 years, 80% of organic matter has been removed from industrial wastewater. However, organic loads from the domestic wastewaters have doubled because of the growth in the surrounding population. Fortunately, as a result, the total organic loads in the bay have not changed significantly within the last 10 years.     

The Effect of UV-B Irradiation on the Biodegradability of Poly-β-Hydroxybutyrate (PHB) and Poly-ɛ-Caprolactone (PCL)

The biodegradability of poly--hydroxybutyrate and poly--caprolactone in soil compostage before and after irradiation of the polymers for 192, 425, and 600 h in a Weather-Ometer was examined. The biodegradability tests were done in soil compostage at pH 7.0, 9.0, and 11.0 to assess the influence of this parameter on degradation. The rate of degradation was directly proportional to the soil alkalinity. Poly--hydroxybutyrate showed the greatest weight loss and aging in a Weather-Ometer did not significantly increase the biodegradation, except when the polymer was aged for 425 h and buried in soil compostage of pH 11.0.