Reproductive Success of Marginal Populations of Dactylorhiza maculata (L.) Soó (Orchidaceae)

Russian Journal of Ecology - Populations at the border of ranges are considered more vulnerable than those in the center. However, some recent reviews contradict this hypothesis. We have studied...     

Removal and desorption of chromium in synthetic effluent by a mixed culture in a bioreactor with a magnetic field

Two chromium removal experiments were performed in bioreactors with and without a magnetic field under the same conditions.The release of the chromium present in the biomass was tested in two experiments one with the initial pH of the medium and one with pH 4.0.The objective was to remove Cr(Ⅵ) and total Cr from the effluent,this was carried out by placing biological treatments of synthetic effluent contaminated with 100 mg/L of Cr(Ⅵ) in a bioreactor with neodymium magnets that applied a magnetic field(intensity85.4 mT) to the mixed culture.The removal of Cr(Ⅵ) was approximately 100.0% for the bioreactor with a magnetic field and 93,3% for the bioreactor without a magnetic field for9 hr of recirculation of the synthetic effluent by the bioreactor.The removal of total Cr was61.6% and 48.4%,with and without a magnetic field,respectively;for 24 hr.The desorption of Cr(VI) in the synthetic effluent was 0.05 mg/L,which is below the limit established by Brazilian legislation(0.1 mg/L) for the discharge of effluent containing Cr(Ⅵ) into bodies of water.The results obtained for the removal of chromium in synthetic effluent suggested that there was no significant influence on the viable cell count of the mixed culture.The desorption of Cr(Ⅵ) in synthetic effluent after bioadsorption of chromium by the mixed culture in the process of removal of chromium in bioreactors with and without a magnetic field was not significant in either of the experiments with different initial pHs.     

Discrete event simulation to aid decision-making and mitigation in solid waste management

This article aims to evaluate municipal solid waste (MSW) management schemes in order to promote sustainability and eco-efficiency, core elements in global mitigation strategies in both public and private policies. A discrete event simulation (DES) approach was used to integrate the economic, environmental, and social aspects related to aseptic carton packages (ACP) in Itajuba, Brazil. The simulated scenarios consider three alternatives for disposing ACP: landfills, recycling, and incineration with energy recovery. According to our findings, incineration alternatives are preferred from an eco-efficiency perspective, given the potential greenhouse gas (GHG) emissions reductions and due to the possibility of energy recover, which reinforces the contribution of this technology to promote sustainability as largely found in the international literature. Given the context of MSW management in Brazil, this represents a significant opportunity to increase the effectiveness of mitigation strategies adopted in the country. Taking into account that this is by far the least applied technology, the authors strongly advocate that global strategies for mitigation consider different approaches to integrate carbon dioxide (CO₂) emission reductions related to the entire MSW management system and its alternatives, thus advancing from a waste disposal-oriented system to a life cycle–oriented system.

     

Mangrove forest structure and productivity in the Fly River estuary,Papua New Guinea

In April, July and August 1989 and February 1990, the delta region of the Fly River was surveyed to establish the aerial extent of mangrove forests, their species composition, tree densities and basal areas, and potential net primary production. Mangrove forests cover 87 400 ha, mainly on islands within the delta. Twentynine mangrove plant species were recorded, but there were only three major forest types in the delta.Rhizophora apiculata-Bruguiera parviflora forests (hereafterRhizophora-Bruguiera forests) predominated in regions where river water salinities were >10. These forests covered 31 500 ha and had mean total tree densities and basal areas of 2027 stems ha^–1 and 21 m² ha^–1, respectively. Forests of the palmNypa fruticans (hereafterNypa forests) covered 38 400 ha, mainly in regions where river salinities were ~1 to 10, and had mean total densities and basal areas of 4431 stems ha^–1 and 38 m² ha^–1, respectively. Forests dominated byAvicennia marina and/orSonneratia lanceolata (hereafterAvicennia-Sonneratia forests) predominated on accreting banks of sediment and covered 17 500 ha. In very low-salinity (< 1) regions there are large monospecific stands ofS. lanceolata. Mean total densities and basal areas forAvicennia-Sonneratia forests were 7036 stems ha^–1 and 22 m² ha^–1, respectively. Mean net primary productivity (kg C ha^–1 d^–1) was estimated to be 26.7, 27.1 and 19.0 forRhizophora-Bruguiera, Nypa andAvicennia-Sonneratia forests, respectively. Total daily net primary production by all mangrove forests was estimated at 2214 t carbon. Using assumptions based on work in tropical Australia, it was estimated that ~678 t carbon (or 31% of primary production) were exported daily from mangrove forests to the waters of the delta.Contribution No. 550 from the Australian Institute of Marine Science     

Chemically mediated interactions between the red algaPlocamium hamatum (Rhodophyta) and the octocoralSinularia cruciata (Alcyonacea)

Interactions between the red algaPlocamium hamatum J. Agardh (Rhodophyta) and other benthic organisms including the alcyonacean soft coralSinularia cruciata (Tixier-Durivault) were investigated on an inshore fringing reef environment in whichP. hamatum was the dominant large fleshy alga. Field observations of sessile reef organisms including octocorals and sponges living in close proximity toP. hamatum revealed that varying degrees of tissue necrosis were suffered by the invertebrates when in physical contact with the alga. In order to establish whether the chemical constituents of the alga, especially chloromertensene, played a role in this necrosis, manipulative field experiments were carried out in the Pelorus Channel, Palm Island group (18°34S; 146°29E), North Queensland, Australia, in November and December 1988. The first experiment involved the relocation of healthy plants and soft corals into contact and non-contact situations on a mesh grid. In all cases of contact betweenP. hamatum andS. cruciata, the soft coral suffered tissue necrosis (n=6,p=0.0022). The second experiment had the same design, but involved the use of artificial plants both uncoated and coated with natural levels of chloromertensene, in contact withS. cruciata. In all cases of contact with coated treatments, necrosis was observed inS. cruciata (n=4,p=0.025). In cases where uncoated artificial fronds were placed in contact with soft corals,S. cruciata showed minor abrasion effects, but no appreciable necrosis. Coated treatments were not fouled by epiphytes during the experiment and were not consumed by predators. Uncoated treatments were rapidly reduced in size by predation and any remaining material was biofouled. These experiments thus demonstrated that the deleterious effects observed in soft corals in the field were caused by contact with the algaP. hamatum, that these effects were indeed chemically mediated by chloromertensene, and that physical contact without chemical intervention caused no such deleterious effects. This is the first experimental evidence which conclusively demonstrates allelopathy between an alga and other marine organisms and identifies the compound responsible for the observed allelopathic effects.     

Temperature and metabolic rate in sedentary fish from the Antarctic,North Sea and Indo-West Pacific Ocean

Resting metabolic rate was measured in demersal stages of the teleostNotothenia neglecta Nybelin from the South Orkney Islands, Antarctica, from 1985 to 1987. The relationship between and body mass (Mb) conformed to the general relationship , wherea is a proportionality constant andb is the scaling exponent. (mg O₂ h^–1) was found to scale toMb ^{(0.82±0.011)} in the summer (November to April, 1.6 to 1 850 g,n=56) and toMb ^{(0.76±0.013)} in the winter (May to October, 0.9 to 1 850 g,n=57) (values ofb are means ± SD). Although the scaling exponents were significantly different (P<0.01), was similar in the juvenile stages of summer- and winter-caught fish matched for body mass. The effects of activity on oxygen consumption was studied using a Brett respirometer. Adult stages had a factorial aerobic scope for activity of 5.7, which is similar to that reported for demersal fish from temperate latitudes. The effects of temperature on resting metabolism was investigated in fish with similar sedentary lifestyles from the North Sea (Agonus cataphractus andMyoxocephalus scorpius) and the Indo-West Pacific (Paracirrhites forsteri, P. arcatus, Neocirrhites armatus andExallias brevis). Extrapolated values of for the tropical species approached zero at 5 to 10°C. For a standard 50 g fish, for the tropical species at 25°C was in the range 3.4 to 4.4 mg O₂ h^–1, compared with 1.3 mg O₂ h^–1 forNotothenia neglecta at its acclimation temperature. Thus, the maximum metabolic rate of sedentary tropical species at 24°C is likely to be 2 to 4 times higher than inN. neglecta at 0°C. This suggests that the energy available for sustained activity is significantly lower in cold- than in warm-water fish.     

Temperature acclimation of respiration and photosynthesis in the brown algaLaminaria saccharina

Sporophytes of the brown algaLaminaria saccharina (L.) Lamour grown at 15°C contained significantly more chlorophylla (chla) than did similar plants grown at 5°C. The increase in chla in 15°C plants was due to increased numbers of photosystem II reaction centes, and possibly to increased photosynthetic unit size, compared with 5°C plants. These changes were associated with increased values (photosynthetic efficiencies) in 15°C-grownL. saccharina relative to 5°C-grown plants. The changes in together with reduced respiration rates allowed 15°C-grownL. saccharina to achieve net photosynthesis and light-saturated photosynthesis at a lower photon fluence rate (PFR) than 5°C plants when both groups were assayed at the same temperature (15°C). The photon fluence rates necessary to reach the compensation point and achieve light-saturated photosynthesis (I _c andI _k , respectively) increased with increasing incubation temperature inL. saccharina grown at both 5 and 15°C. However, acclimation responses to growth temperature compensated for the short-term effect of temperature onI _c andI _k . Consequently, plants grown at 5 and 15°C were able to achieve similar rates of light-limited photosynthesis, and similarI _c andI _k values at their respective growth temperatures. These responses are undoubtedly important for perennial seaweeds such asL. saccharina, which frequently grow in light-limited habitats and experience pronounced seasonal changes in water temperature.Please address all correspondence and requests for reprints to I.R. Davison     

Disappearance of bromopropylate residues in artichokes, strawberries and beans

Residues of Bromopropylate were determine in artichokes, strawberries and beans after foliar spray of acaricide at two rates. The rates used were 1 g/l formulated product (normal recommended) and 1.5 g/l. The residue levels of bromopropylate in the three crops after 14 days were lower than 0.7 ppm and did not exceed the Maximum Residual Level (MRL) recommended by FAO. In the artichokes and strawberries, the total concentration of residues decreased by 50% of the initial level after 2-3 days. Only trace levels of the bromopropylate residues (less than 0.01 ppm) were detected in the "hearts" of the artichokes. Bromopropylate residues in the green beans were also less than 0.8 ppm after the first day of foliar spraying. The kinetic of degradation occurred in two different steps. In the first step (4-6 days) the dissipation of bromopropylate was faster whereas in the second step (7-14 days) the loss of residues was much slower.     

Air Pollution in Singapore: Its Multielemental Aspect as Measured by Nuclear Analytical Techniques

Aerosol samples were collected in 1994 in Singapore on two occasions: once in June during the normal meteorological conditions and later in October during a long haze period caused by the heavy forest fire in Indonesia. Filtration and impaction collection methods were used simultaneously so that detailed elemental analysis of bulk as well as of different size fractions could be performed. Accelerator based nuclear analytical techniques such as Particle Induced X-Ray Emission (PIXE), Rutherford Backscattering (RBS) and Nuclear Microscopy (NM) were used for analysis. These techniques are fast, truly multielemental and perfectly suited for routine analysis of a large number of aerosol samples. Typically all samples were analysed for the following 24 elements: Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Mn, Cr, Fe, Co, Ni, Cu, Zn, Ga, As, Br, Rb, Sr and Pb. Detection limits for bulk analysis were generally below ng/m3 and for single particle analysis absolute detectable mass was approximately 10-17 g. Additionally, trace elements such as Cd, Sn, Sb and Ba whose characteristic X-ray lines were normally "obscured" by the lines of other more abundant elements, were detected when analysing by nuclear microscope in single particle mode.Judging by the average concentrations of lead and sulphur which are good indicators of industrial component of air pollution the situation in Singapore is satisfactory. Pb was typically found in concentrations of 5 to 50 ng/m3 and sulphur in concentrations of 1 to 2 µg/m3. These concentrations are well below limits set by the World Health Organisation (1500 ng/m3 and 40 µg/m3, respectively). On the other hand during the haze period the average concentrations of elements like S, K, Ti, V, Mn, Ni, As and Pb were found to be 3 to 6 times higher than usual. Results are presented and discussed.