Integrated Constructed Wetlands (ICW) for livestock wastewater management

Social, economic and environmental coherence is sought in the management of livestock wastewater. Wetlands facilitate the biogeochemical processes that exploit livestock wastewater and provide opportunities to achieve such coherence and also to deliver on a range of ecosystem services. The Integrated Constructed Wetland (ICW) concept integrates three inextricably linked objectives: water quantity and quality management, landscape-fit to improve aesthetic site values and enhanced biodiversity. The synergies derived from this explicit integration allow one of the key challenges for livestock management to be addressed. An example utilizing twelve ICW systems from a catchment on the south coast of Ireland demonstrates that over an eight year period mean reduction of total and soluble phosphorus (molybdate reactive phosphorus) exceeded 95% and the mean removal of ammonium-N exceeded 98%. This paper reviews evidence regarding the capacity of ICWs to provide a coherent and sustainable alternative to conventional systems.     

L'épithélium absorbant des vésicules coxales des Machilides (Insecta Thysanura)

Résumé Les Machilides présentent une série de vésicules abdominales paires, sous forme de sacs exsertiles capables d'absorber l'eau d'un film liquide. Les coupes histologiques montrent qu'une partie de la paroi de ces vésicules est faite d'un épithélium particulier revêtu d'une intima cuticulaire plus épaisse que celle de l'épithelium banal. La microscopie électronique permet de préciser la structure des cellules absorbantes qui sont caractérisés essentiellement par des microvillosités apicales et de profondes invaginations de la membrane plasmique basale associées à des mitochondries allongées. Une comparison est faite avec d'autres types de cellules absorbantes connues chez les Arthropodes, notamment dans le rectum. Grâce à leurs vésicules abdominales, les Thysanoures possèdent des organes originaux jouant un rôle important dans l'équilibre hydrique de ces insectes.

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The absorbing epithelium of abdominal vesicles in machilida (Insecta thysanura)Histology and ultrastructure

Summary The Machilida are endowed with several abdominal vesicles which are protrusible sacs capable of absorbing water from the substrate surface. Histology shows that a part of their outer wall consists of a particular epithelium covered by a cuticular intima, which is thicker than the intima of the common epithelium. The absorbing cells are electronmicroscopically characterized by apical microvilli and deep infoldings of the basal plasma membrane which are associated with mitochondria. A comparison is drawn with other types of absorbing cells already known, especially with those in the rectum of insects. Thanks to their abdominal vesicles, the Thysanura possess unique organs which play an important role in the control of their water balance.

Nous exprimons nos remerciements à Monsieur le Professeur Ch. Noirot, qui a bien voulu nous faire part de ses remarques lors de la préparation de ce travail.     

Winter biology of the blacknose dace,Rhinichthys atratulus,in a southern Ontario stream

Synopsis The winter habitat of stream-dwelling blacknose dace Rhinichthys atratulus is identified and described from underwater observations in a southern Ontario stream. In late November as water temperatures declined below 5.0°C, dace moved into crevices beneath rubble with a mean maximum diameter of 15.9 cm. Focal point water depth was significantly greater in winter and mid-depth water velocity was significantly faster than measured in the summer. Dace were not observed in open water again until late March when water temperatures increased to 4.0°C. Winter diet analyses which showed minimal feeding were consistent with the seasonal changes in condition factor and percentage body water suggesting a general depletion of body reserves over winter. This physiological change was more pronounced in juveniles.     

野生大鲵繁殖洞穴生态环境的初步研究

为了探明野生大鲵(Andrias davidianus)自然繁殖所需要的主要生态条件,给人工养殖条件下大鲵的自然繁殖提供生态学依据,对张家界国家级大鲵保护区境内野生大鲵的栖息繁殖洞穴进行生态学考察。对海拔、洞口的宽度与高度等10个生态因子进行定量观测和主成分分析,结果表明,影响大鲵选择繁殖洞穴的主要因子是海拔、洞口高度、洞底组成,以及洞穴中水的透明度、pH、流速、饵料丰度7个因子。对大鲵繁殖洞穴相连河段进行调查,发现多为山溪流。对繁殖洞穴中水的溶解氧、化学耗氧量、硫化物等5项主要指标进行检测,除硫化物外,其他指标多达到国家饮用水的水质标准,可见大鲵自然繁殖对洞穴与水质的要求较高。     

Gabčíkovo River Barrage System: The Ecological Disaster and Economic Calamity for the Inland Delta of the Middle Danube

The Gabíkovo Water Project (GWP), a major construction of damming and canalizing on the upper part of the middle Danube was completed and put into operation in October 1992. It destroyed most of the 230km2 of wetlands. Two-thirds of the wetlands are becoming dry, discontinuous or severely changed which will ultimately destroy the original ecosystem and lead to a decline in biological diversity. Based upon detailed knowledge of the limnology and fish biology of this section of the Danube River the effects of the GWP were predicted as early as 1964. All the recent post-construction impact studies of the GWP report few negative effects and so the planners and builders defend the project. It is difficult to believe that all sides in the current GWP legal controversy have overlooked the most important point. Any effects immediately after construction are purely transitory. A large body of published empirical and theoretical information clearly shows that the mostly negative effects of such large water projects become apparent only several years or decades after construction. The value of the destroyed wetland and river floodplain is at least US $ 520 million per year, and clearly incriminates the VV (Vodohospodárska výstavba) of fraudulent representation of 'benefits'. The enormous flood of devious publications glorifying the work of the VV in recent years should be interpreted as a cover up for the bad conscience of the builders. The International Court of Justice in the Hague delivered its judgement on the GWP case on 25 September 1997. There were no winners in this case as both Slovakia and Hungary were said to have acted inappropriately: it was illegal for Hungary to stop its part on the project according to the treaty of 1977, and Slovakia had no right to put Gabíkovo into operation unilaterally. As the Court dealt little with the social, environmental and economic aspects of the GWP, the true losers became the inland delta of the Danube, the last large wetland of Europe, and the local inhabitants.     

不同pH值对三角帆蚌珍珠质分泌的影响

运用多种组织化学方法和透射电镜技术,研究了５种ｐＨ水环境（ｐＨ５、６、７、８、９）对三角帆砷外套膜珍珠质分泌的影响机制,结果表明,在中性水环境中,贝体能积极地从外界水环境中吸收钙,并能旺盛地合成和分泌贝壳珍珠层及珍珠有机基质前体物质,持续的酸性水环境导致贝体的钙严重丢失,并引起珍珠质分泌细胞对有机基质前体物质的合成和分泌能力减弱,持续的碱性水环境虽能导致贝体对钙的积累,但珍珠质分泌细胞合成和分泌珍     

Hepatocyte growth factor attenuates cerebral ischemia-induced learning dysfunction

Hepatocyte growth factor (HGF) acts as an organotropic factor for regeneration and protection in various organs and has the ability to attenuate cerebral ischemia-induced cell death. However, the effect of HGF on learning and memory function after a cerebral ischemic event is unknown. We demonstrate here that administration of human recombinant HGF (hrHGF) into the ventricle reduced the prolongation of the escape latency in the acquisition and retention tests in the water maze task on days 12-28 after microsphere embolism-induced cerebral ischemia. In addition, disruption of the blood-brain barrier at the early stage after microsphere embolism, which was determined by FITC-albumin leakage, was markedly reduced by treatment with hrHGF. We demonstrated that this effect of hrHGF on the blood-brain barrier was associated with protection against the apoptotic death of the cerebral endothelial cells at the early stage after the ischemia. These results suggest that hrHGF can prevent the learning and memory dysfunction soon after sustained cerebral ischemia by protecting against injury to the endothelial cells. The use of HGF may be a potent strategy for the treatment of cerebrovascular diseases, including cerebral infarct and vascular dementia.     

Hg2+ and small-sized polyethylene glycols have inverse effects on membrane permeability, while both impair neutrophil cell motility

Toxic effects after exposure to mercury are well documented in human. Little is, however, known about how Hg(2+) affect host defense in general and neutrophil functions in particular. We show here that exposure of human neutrophils to HgCl(2) dose-dependently impairs chemoattractant-stimulated motility. Long-term exposure (5-10 min) to Hg(2+) yields a rapid influx of extracellular Ca(2+) followed by leakage of cytosolic fluorophores, as assessed using fura-2 and ratio imaging microscopy. The inhibition on motility was partly reversible, since pre-treated neutrophils placed in an Hg(2+)-free environment displayed higher migration rates. The Hg(2+)-induced fluxes were prevented by addition of small-sized polyethylene glycols (PEG 200-400), which also dose-dependently inhibited neutrophil transmigration. Localized, minute micropipette additions of Hg(2+) or PEG caused retraction of the leading edge and redirection of cell migration. Since Hg(2+) increases and PEGs decrease membrane permeability in a partially competitive manner, we suggest that the known aquaporin-inhibitor Hg(2+) alters membrane permeability by affecting the bidirectional flux through the leukocyte aquaporin-9 (AQP9) while small-sized PEGs yield decreased membrane permeability by becoming trapped in the promiscuous channel. The local additions of Hg(2+) or PEG probably force other cell regions to take over from those with blocked AQPs. Hence, the cells turn direction of motility away from the micromanipulator needle.     

Swelling of intercellular lipid lamellar structure with short repeat distance in hairless mouse stratum corneum as studied by X-ray diffraction

Lamellar structures of intercellular lipids in stratum corneum of hairless mouse were studied at various water contents by small-angle X-ray diffraction. At room temperature there are at least two lamellar structures, long and short lamellar structures, with repeat distances of 13.6 and around 6 nm, respectively. The long lamellar spacing is almost constant over the water content from 0% w/w to 80% w/w that is consistent with the previously reported results. For the short lamellar structure we found that with increasing the water content the lamellar spacing becomes larger, that is, from 12 to 50% w/w the short lamellar spacing increases from 5.8 to 6.6 nm. In addition to the previously reported result that at the water content of about 20% w/w the X-ray diffraction peak for the long lamellar structure becomes sharp, we found that this is also the case for the short lamellar structure. Below the water content of about 12% w/w the X-ray diffraction peak for the short lamellar structure dies out and conversely above the water content of about 50% w/w it becomes weak and finally merges into the second-order diffraction peak for the long lamellar structure. Considering the matching of the long lamellar spacing that is unchanged with the water content and twice the short lamellar spacing that changes as a function of the water content, it is likely that the swelling of the short lamellar structure plays an important role in the regulation of water stored in stratum corneum.     

The role of water in the thermodynamics of dilute aqueous solutions

Water plays a role in the thermodynamics of dilute aqueous solutions that is unusual in two ways. First, knowledge of hydration equilibrium constants of species is not required in calculations of thermodynamic properties of biochemical reactants and reactions at specified pH. Second, since solvent provides an essentially infinite source of oxygen atoms in a reaction system where water is a reactant, oxygen atoms are not conserved in the reaction system in dilute aqueous solutions. This is related to the fact that H₂O is omitted in equilibrium expressions for dilute aqueous solutions. Calculations of the standard transformed Gibbs energies of formation of total carbon dioxide and total ammonia at specified pH are discussed, and the average bindings of hydrogen ions by these reactants are calculated by differentiation. Since both of these reactants are involved in the urease reaction, the apparent equilibrium constants and changes in the numbers of hydrogen ions bound are calculated for this reaction as functions of pH.