Trace Organic Matter in the Ria Formosa,Portugal

The Ria Formosa lagoon, Portugal, receives organic matter from many natural and anthropogenic sources. This paper presents an overview of the contribution these sources made through the use of lipid biomarkers. Sixty-one surface sediment samples were collected and analysed for a range of lipids. Sewage materials were confined to regions within 2 km of discharge points; phytoplankton biomarkers (sterols and fatty acids) suggest production was greatest in the inner parts of the lagoon that also have greatest inorganic nutrient enrichment; terrestrial organic matter was present in relatively low concentrations as shown by both sterol and fatty alcohols; bacteria were widespread although the Sulphate Reducing Bacteria (SRBs, shown by the presence of 3-OH fatty acids) were located near but not adjacent to sewage discharge points.     

Changes in pH as a measure of photosynthesis by marine macroalgae

An automatically operated method for high precision measurements of steady-state photosynthesis by macroalgae was developed. Changes in pH and oxygen content of seawater passing the algae in a flowthrough system, could be measured with extremely high accuracy over very long periods of time. The method is especially suitable for measurements on flowthrough systems with high rates of water exchanges (i.e. short retention time), and can be used to study exchange processes for marine plants, animals and small ecosystems. Since the same measuring unit is used for several flowthrough chambers, the method is very suitable for comparisons between different species, or between differently pretreated specimens of the same species (e.g. in toxicological studies). The method was used to study the ratio: [oxygen production] to [CO₂+H⁺ uptake] at different light intensities for several macroalgae belonging to different systematic groups and from different habitats. At lower photosynthetic rates this ratio was similar for all of the algae studied (1.17±0.02). For brown algae of the fucacean family, the ratio increased by 0.08 units at higher photosynthetic rates. This increase was thought to be related to the crassulacean acid metabolism (CAM)-like strategies connected to these algae. For all other algae studied, the ratio remained constant or decreased slightly (at most by 0.04 units) at higher photosynthetic rates. The relations between the abovementioned ratio and the photosynthetic quotient are discussed on a theoretical basis.     

Observations on the function of the glands of the foot of the pediveliger of Ostrea edulis during settlement

The use during settlement of secretions of the 9 different types of gland in the foot of the pediveliger of Ostrea edulis L. was examined experimentally. During settlement, there is a progressive decrease in the crawling speed of the larva and a strengthening of its bond with the substratum. Both changes are related to (a) a change from ciliary to muscular pedal locomotion; (b) the increasing acidity and viscosity of the mucoid secretions used; (c) the secretion of a byssus thread by the glands of the byssus duet; (d) changes in the form and composition of this byssus. At the termination of settlement, the entire contents of 2 types of gland are discharged. Their secretions give rise to the cement which permanently fixes the larva to the substratum. The 9 types of gland are utilised sequentially in a manner closely related to the 6 phases recognised in settlement behaviour.     

Behavioral aspects of sperm competition in cuttlefish, Sepia officinalis (Sepioidea: Cephalopoda)

Sexual selection studies in cephalopods indicate that sperm competition is a central feature of their mating systems, yet this has not been studied experimentally in any detail. In 1998 we staged 20 matings of the cuttlefish, Sepia officinalis L., in the laboratory. Males rapidly initiated mating in the “head-to-head” position, with no apparent courtship. Mating lasted an average of 10 min (range 7 to 14 min). For the first 6 min (on average 63% of the mating duration), the male flushed strong jets of water directly at the female's buccal membrane, which sometimes resulted in the expulsion of parts of spermatangia placed there in recent matings. Then, in a single discrete movement that lasted an average of only 14 s, the male's modified fourth left arm – the hectocotylus – wrapped around a single large bundle of spermatophores (ca. 150 to 300) and transferred them to the female's buccal membrane. For the remainder of the mating (average 3 min, range 1.5 to 5.0 min), the hectocotylus repeatedly broke the spermatophores open, and manipulated them, so that sperm were released and many spermatangia were attached along the ventral buccal membrane, near the paired seminal receptacles. Approximately 140 spermatangia were attached in rows 3 to 5 deep around the ventral buccal membrane in a single mating; the rest were usually discarded during mating. Histology revealed that each of the seminal receptacles consists of a series of sperm storage bulbs connected by a central duct, which leads to a single pore at the surface of the buccal membrane. Baseline data on sperm motility were obtained, but the mechanism by which sperm enter the seminal receptacle remains unknown. Females seemed to initiate termination of mating, then males guarded their mates temporarily. These results, combined with other recent laboratory experiments, provide evidence that sperm competition may be a major feature of the mating system of S. officinalis. Received: 4 January 1999 / Accepted: 18 May 1999     

Relation of length and sex to selenium concentrations in mosquitofish

Analysis of mosquitofish, Gambusia affinis, has proven useful for monitoring contaminant levels in aquatic biota; however, the small size of this species often requires the compositing of several fish to provide sufficient biomass for selenium analysis. Such composites have usually been obtained without considering the length and sex of the individual fish. The present study found significant differences in mean lengths and sex ratios of mosquitofish sampled with small-mesh dip nets from five sites close to each other in the San Joaquin Valley, California. To test the effect of these different sample characteristics, fish from each site were divided by sex into five size classes (<20, 20-30, 31-45, 46-60, and >60mm total length) before analysis for total selenium. Altogether, fish from the San Luis Drain and Kesterson Ponds 2 and 7 contained 65-360 microg g(-1) selenium (dry weight basis), or about 28- to 300-fold more than concentrations in fish of the same length and sex from the Volta Wasteway and Volta Pond 26. Except for females 31-45 mm long from the San Luis Drain that had higher concentrations than either smaller or larger females, selenium concentrations did not differ significantly among size classes. Although concentrations differed between sexes in samples from the San Luis Drain, Kesterson Pond 2, and Volta Pond 26, neither males nor females consistently had the higher concentrations. In the San Luis Drain, 20-30 and 31-45 mm long females had higher concentrations than did males of the same size classes; in Kesterson Pond 2 and Volta Pond 26, however, 20-30 mm long males had higher concentrations than did females of the same size class. Although no consistent patterns were observed, the occasional differences in selenium concentrations in fish of different length and sex indicate that these variables should be considered when surveys and monitoring studies are designed.     

The fate of metal contaminated sediments in Foundry Cove, New York

The distribution of heavy metal contaminated sediments in Foundry Cove, a freshwater embayment of the Hudson River, was examined twelve years after the discharging of wastes from a battery factory had ceased. Concentrations of Cd, Ni and Co were measured in surficial sediments (top 5 cm) and seven detailed depth profiles. Comparison with earlier surveys showed that metal levels of surficial sediments have been considerably reduced throughout the cove. Evidence suggests that this reduction may be largely due to burial rather than transport of metals out of the cove or a redistribution (via sediment resuspension and redeposition) within the cove. This is suggested by the presence of a peak in metal concentrations at a depth of several centimetres in depositional environments, a calculation showing the loss of waterborne cadmium to be much less than the amount of cadmium lost from the surficial sediment, and the absence of increased pollution in the cleaner parts of the cove. Despite improvement, metal levels remain extremely high, including a persistent 'hot-spot' with levels higher than 10 000 ppm Cd.     

铬渣的热解无害化处理

采用热解工艺无害化处理铬渣,探讨了稻秆在铬渣无害化处理中的作用.研究了热解温度、稻秆与铬渣质量比、铬渣粒径及保温时间对铬渣热解无害化处理的影响,并分析了热解前后热解产物中铬元素形态的变化.结果表明,热解工艺能有效地将铬渣中Cr(Ⅵ)还原,稻秆热解过程中产生的气相挥发分对Cr(Ⅵ)的还原起核心作用.较为适宜的热解条件:热解温度为400 ℃,稻秆与铬渣质量比为0.10,铬渣粒径<2 000 μm,保温时间为10 min.在该热解条件处理下,热解产物中的Cr(Ⅵ)质量浓度为121 mg/kg,低于热解前铬渣中的Cr(Ⅵ)(3 400 mg/kg).热解后,可交换态及碳酸盐结合态铬含量降低,大部分铬转化成了稳定的有机结合态和残渣态,极大地降低了铬渣的危害.第一作者:张大磊,男,1982生,博士研究生,研究方向为固体废弃物热处理.     

Hydrocarbon emission fingerprints from contemporary vehicle/engine technologies with conventional and new fuels

The present paper presents results from the analysis of 29 individual C₂–C₉ hydrocarbons (HCs) specified in the European Commission Ozone Directive. The 29 HCs are measured in exhaust from common, contemporary vehicle/engine/fuel technologies for which very little or no data is available in the literature. The obtained HC emission fingerprints are compared with fingerprints deriving from technologies that are being phased out in Europe. Based on the total of 138 emission tests, thirteen type-specific fingerprints are extracted (Mean ± SD percentage contributions from individual HCs to the total mass of the 29 HCs), essential for receptor modelling source apportionment. The different types represent exhaust from Euro3 and Euro4 light-duty (LD) diesel and petrol-vehicles, Euro3 heavy-duty (HD) diesel exhaust, and exhaust from 2-stroke preEuro, Euro1 and Euro2 mopeds. The fuels comprise liquefied petroleum gas, petrol/ethanol blends (0–85% ethanol), and mineral diesel in various blends (0–100%) with fatty acid methyl esters, rapeseed methyl esters palm oil methyl esters, soybean oil methyl or sunflower oil methyl esters. Type-specific tracer compounds (markers) are identified for the various vehicle/engine/fuel technologies.An important finding is an insignificant effect on the HC fingerprints of varying the test driving cycle, indicating that combining HC fingerprints from different emission studies for receptor modelling purposes would be a robust approach.The obtained results are discussed in the context of atmospheric ozone formation and health implications from emissions (mg km^?1 for LD and mopeds and mg kW h^?1 for HD, all normalised to fuel consumption: mg dm^?3 fuel) of the harmful HCs, benzene and 1,3-butadiene.Another important finding is a strong linear correlation of the regulated “total” hydrocarbon emissions (tot-HC) with the ozone formation potential of the 29 HCs (ΣPO₃ = (1.66 ± 0.04) × tot-RH; r² = 0.93). Tot-HC is routinely monitored in emission control laboratories, whereas C₂–C₉ are not. The revealed strong correlations broadens the usability of data from vehicle emission control laboratories and facilitates the comparison of the ozone formation potential of HCs in exhaust from of old and new vehicle/engine/fuel technologies.     

Electrochemical oxidation of bisphenol A. Application to the removal of bisphenol A using a carbon fiber electrode

Leachate samples with a high strength of ammonium-nitrogen (NH4+-N) were collected from a local landfill site in Hong Kong. Two experiments were carried out to study (1) the inhibition of microbial activity of activated sludge by NH4+-N and (2) the chemical precipitation of NH4+-N from leachate as a preliminary treatment prior to the activated sludge process. The experimental results demonstrated that the efficiency of COD removal decreased from 97.7% to 78.1%, and the dehydrogenase activity of activated sludge decreased from 9.29 to 4.93 microg TF/mg MLSS, respectively, when the NH4+-N concentration increased from 53 to 800 mg/l. The experiment also demonstrated that the NH4+-N in the leachate can be quickly precipitated as MgNH4PO4 x 6H2O after addition of MgCl2 x 6H2O + Na2HPO4 x 12H2O. The NH4+-N concentration was reduced from 5618 to 112 mg/l within 15 min when a molar ratio of Mg2+:NH+:PO4(3-) = 1:1:1 was used. The optimum pH to reach the minimum solubility of MgNH4PO4 x 6H2O was found to be in the range of 8.5-9.0. Attention should be given to the high salinity formed in the treated leachate by using MgCl2 x 6H2O + Na2HPO4 x 12H2O, which may affect microbial activity in the following biological treatment processes. Using two other combinations of chemicals [MgO + 85%H3PO4 and Ca(H2PO4)2 x H2O + MgSO4 x 7H2O] could minimise salinity generation after precipitation, while they were less efficient for NH4+-N removal.     

Agriculture's share in the emission of trace gases affecting the climate and some cause-oriented proposals for sufficiently reducing this share

This paper discusses agriculture's share in the world-wide emissions of climate-affecting gases and in the global warming potential (GWP). Proposals also are presented to reduce these emissions adequately, using a cause-oriented approach. Largely due to the fertilization and cultivation of agriculture as well as the burning of biomass, agriculture has a very high share in the anthropogenic emissions of NH(3), N(2)O, CH(4) and CO at >95%, 81%, 70% and 52%, respectively, while its share in the NO(x) and CO(2) emissions is relatively small at 35% and 21%. The GWP of agriculture, based on annually 16.1 x 10(9) tons of CO(2), approaches 63% of the GWP of the energy sector or 80% of the GWP of its CO(2) emissions. At 34% and 32%, respectively, the main originators in the GWP of agriculture would seem to be CO(2) (changing land use) and CH(4) (animal husbandry/rice cropping/biomass burning) followed at 15% by NO(2) (technical and biological N fixation/(cultivation and recultivation/biomass burning) and 10% and 9% by CO and NO(x). The GWP of 3 German dairy cows corresponds with 13.2 tonnes CO(2) per year the GWP of two average German automobiles. However, the ozone-destroying effect of N(2)O and the climate-relevant effects of NH(3) are not yet included here. As with the therapy for other 'modern' boundary-crossing environmental damages, such as acidification or eutrophication, global climate change therapy likewise needs a therapy for the respective effects of reactive compounds of carbon, nitrogen, phosphorous, and sulfur also emitted by agriculture. Proposals for reducing these emissions within the agricultural sector include need-oriented plant, animal and human nutrition, more efficient external and internal nutrient recycling, the cessation of further clearing by burning, along with intensified afforestation mainly in the tropics, targeted measures to reduce nutrient losses/emissions, and measures for more efficient use of nutrients in plant, animal and human nutrition. These measures would at best result in reduced pollution of the global environment but not put it to an end. Decisive, therefore, is both the tolerable extent of mankind and its long-term sustainable way of life.