Biochemical and histological alterations in the prawn Macrobrachium lamerrei following exposure to automobile discharge

Polycyclic aromatic hydrocarbons (PAH), important constituents of petroleum products, are known to enter freshwater systems via industrial effluents. In the present study the possible toxicity of automobile effluent presumably containing PAH was demonstrated in the freshwater prawn Macrobrachium lamarrei. The prawns were exposed for 1, 8, 15 and 28 days to two sublethal concentrations (0.75% and 3.75%) of automobile effluent. A decrease was noted in the total protein content in haemolymph and hepatopancreas of prawns exposed for 28 days to both these sublethal concentrations. SDS-PAGE revealed that the effluent caused reduction in high molecular weight proteins (106-90 kD) of the haemolymph. The exposure to automobile effluent resulted in changes in the lamellar structure of the gills and shrinkage of hepatopancreatic cell types. Thus it is imperative to discard such wastes carefully ensuring that there is no entry into aquatic ecosystems.author for correspondence     

Accuracy analysis, dem generation and validation using russian tk-350 stereo-images

TK-350 stereo-scenes of the Zonguldak testfield in the north-west of Turkey have been analysed. The imagery had a base-to-height ratio of 0·52 and covered an area of 200 km × 300 km, with each pixel representing 10 m on the ground. Control points digitised from 1:25 000 scale topographic maps were used in the test. A bundle orientation was executed using the University of Hanover program BLUH and PCI Geomatica OrthoEngine AE software packages. Tests revealed that TK-350 stereo-images can yield 3D geopositioning to an accuracy of about 10 m in planimetry and 17 m in height. A 40 m resolution digital elevation model (DEM) was generated by the PCI system and compared against a reference DEM, which was derived from digitised contour lines provided by 1:25 000 scale topographic maps. This comparison showed that accuracy depends mainly on the surface structure and the slope of the local terrain. Root mean square errors in height were found to be about 27 and 39 m outside and inside forested areas, respectively. The matched DEM demonstrated a systematic shift against the reference DEM visible as an asymmetric shift in the frequency distribution. This is perhaps caused by the presence of vegetation and buildings.     

Water level observations from unmanned aerial vehicles for improving estimates of surface water–groundwater interaction

Integrated hydrological models are usually calibrated against observations of river discharge and piezometric head in groundwater aquifers. Calibration of such models against spatially distributed observations of river water level can potentially improve their reliability and predictive skill. However, traditional river gauging stations are normally spaced too far apart to capture spatial patterns in the water surface, whereas spaceborne observations have limited spatial and temporal resolution. Unmanned aerial vehicles can retrieve river water level measurements, providing (a) high spatial resolution; (b) spatially continuous profiles along or across the water body, and (c) flexible timing of sampling. A semisynthetic study was conducted to analyse the value of the new unmanned aerial vehicle‐borne datatype for improving hydrological models, in particular estimates of groundwater–surface water (GW–SW) interaction. Mølleåen River (Denmark) and its catchment were simulated using an integrated hydrological model (MIKE 11–MIKE SHE). Calibration against distributed surface water levels using the Differential Evolution Adaptive Metropolis algorithm demonstrated a significant improvement in estimating spatial patterns and time series of GW–SW interaction. After water level calibration, the sharpness of the estimates of GW–SW time series improves by ~50% and root mean square error decreases by ~75% compared with those of a model calibrated against discharge only.     

Effects of variable wind shear on the mesoscale circulation forced by slab‐symmetric diabatic heating

Abstract

We examine the response of stably stratified airflow to a slab‐symmetric diabatic forcing associated with condensation in long‐lasting precipitation bands. The steady‐state linearized Boussinesq equations are used to model the diagnostic relationship between the vertical motion field, the heating source and the ambient flow. The basic‐state flow is assumed to be horizontally uniform and non‐rotating, but the static stability and wind vary in the vertical. Linear theory shows that the speed of the along‐band wind component is unimportant for slab‐symmetric heating since it cannot contribute towards the advection of buoyancy or vertical motion.

For typical atmospheric stratification and a moving heating source associated with a cloud band, the Taylor‐Goldstein equation is solved numerically. The numerical results show that the cross‐band wind shear tilts the updraft core and broadens it. While the magnitude of the shear is increased, the circulation becomes stronger. The details of the wind profile are also important in determining the intensity and structure of the circulation. When the wind profile indicates a convex bulge (i.e. the low‐level shear is weaker than the upper‐level shear), the circulation becomes slightly weaker in comparison with the linear wind profile. Conversely, the circulation becomes stronger when the wind profile has a concave shape. Increasing the concave bulge tends to enhance the circulation but not in a monotonic fashion. This non‐monotonic relation between the vertical motion and the parabolic wind profile is interpreted in terms of kinetic energy changes of parcels that interchange their altitudes.     

Observations on mineralogical and ore-genetic problems at Mangula

Following the author's previous paper on the broad outline of the Geology of the Mangula Copper Deposits (Jacobsen, in print), a few of the more complex problems of mineralisation are discussed. Introduction of iron, manifested by widespread, often structurally controlled martitisation, is shown to be likely. Origin of copper and iron bearing veins by lateral secretion is rejected. General silicification, potassium and boron metasomatism and intense chloritisation at Norah Mine in particular are interpreted as further proof of hydrothermal activity emanating from intruding granites. Close relationship of the mineralogical phenomena to those described recently byDarnley (1960) andVaes (1960) from Northern Rhodesia and Katanga leads to a discussion of genetic theories on the Northern Rhodesia copper deposits. Their classifications into one regional metallo-genetic epoch and province during the late algonkian Katanga-Lomagundi orogeny is proposed. Hydrothermal origin in the wake of syn-or postkinematic granite intrusions under hypothermal or even granitising conditions is accepted for all deposits within the Katanga-Lomagundi geosyncline.

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Zusammenfassung Im Anschluß an eine frühere Arbeit des Autors über die Geologie der Kupferlagerstätte von Mangula (Jacobsen, im Druck) werden hier ein paar Probleme der Mineralisation angeschnitten. Auf Grund von weitverbreiteter, strukturgebundener Martitisierung wird Eisenimprägnation für wahrscheinlich gehalten.Die allgemeine Einkieselung, die Kalium und Bor Metasomatose und die intensive Chloritisierung in der Norah-Grube deuten auf hydrothermale Aktivität intradierender Granite hin.Auf Grund ähnlicher mineralogischer Verhältnisse, wie sie kürzlichDarnley (1960) undVaes (1960) aus Nordrhodesien und Katanga beschrieben haben, werden Theorien zur Genese der Kupferlagerstätten Nordrhodesiens diskutiert. Der Autor schlägt ihre Zuordnung zu einer regionalen, metallgenetischen Epoche und Provinz während der spätalgonkischen Katanga-Lomagundi-Gebirgsbildung vor. Unter hypothermalen oder granitisierenden Bedingungen wird für alle Ablagerungen innerhalb der Katanga-Lomagundi-Geosynklinale hydrothermale Entstehung infolge von syn- oder postkinematischen Granitintrusionen angenommen.

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Résumé Venant après une note antérieure sur l'allure générale de la Géologie des dépôts de cuivre du Mangula (Jacobsen, en presse), l'auteur discute ici quelques problèmes plus complexes de la minéralisation. L'introduction de fer, exprimée par la martitisation bien répandue et souvent conditionnée par la structure, semble être vraisemblable. L'origine par secrétion latérale de veines chargées de cuivre et de fer est rejetée. La silicification générale, le métasomatisme avec apport de potassium et bore et la chloritisation intense à Norah Mine en particulier, sont interprétés comme une preuve supplémentaire en faveur d'une activité hydrothermale émanant de granites intrusifs. Des relations étroites des phénomènes minéralogiques avec ceux décrits récemment parDarnley (1960) etVaes (1960) en Rhodésie du Nord et au Katanga conduisent à discuter les théories génétiques des dépôts de cuivre de Rhodésie du Nord. L'auteur propose de les classer dans une seule époque et province métallogénique datant de la fin de l'orogenèse algonkienne du Katanga-Lomagundi. Il admet pour tous les dépôts du géosynclinal du Katanga-Lomagundi une origine hydrothermale à la suite d'intrusions de granites syn-ou postcinématiques dans des conditions hypothermales ou même granitisantes.

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Large bio-geographical shifts in the north-eastern Atlantic Ocean: From the subpolar gyre, via plankton, to blue whiting and pilot whales

Pronounced changes in fauna, extending from the English Channel in the south to the Barents Sea in the north-east and off Greenland in the north-west, have occurred in the late 1920s, the late 1960s and again in the late 1990s. We attribute these events to exchanges of subarctic and subtropical water masses in the north-eastern North Atlantic Ocean, associated with changes in the strength and extent of the subpolar gyre. These exchanges lead to variations in the influence exerted by the subarctic or Lusitanian biomes on the intermediate faunistic zone in the north-eastern Atlantic. This strong and persistent bottom-up bio-physical link is demonstrated using a numerical ocean general circulation model and data on four trophically connected levels in the food chain – phytoplankton, zooplankton, blue whiting, and pilot whales. The plankton data give a unique basin-scale depiction of these changes, and a long pilot whale record from the Faroe Islands offers an exceptional temporal perspective over three centuries. Recent advances in simulating the dynamics of the subpolar gyre suggests a potential for predicting the distribution of the main faunistic zones in the north-eastern Atlantic a few years into the future, which might facilitate a more rational management of the commercially important fisheries in this region.     

A Nd and Sr isotopic study of the Trinity peridotite; implications for mantle evolution

Field evidence indicates that the Trinity peridotite was partially melted during its rise as a part of the upwelling convecting mantle at a spreading center. A SmNd mineral isochron for a plagioclase lherzolite yields an age,T = 427 ± 32 Ma and initialε_Nd = + 10.4 ? 0.4 which is distinctly higher than that expected for typical depleted mantle at this time. This age is interpreted as the time of crystallization of trapped melt in the plagioclase lherzoliteP-T field. This time of crystallization probably represents the time when the massif was incorporated as a part of the oceanic lithosphere. The SmNd model age of the plagioclase lherzolite totalrock isT_CHUR^Nd = 3.4 AE. This suggests that the Trinity peridotite was derived from a mantle that was depleted rather early in earth history. The peridotite contains many generations of pyroxenite dikes and some microgabbro dikes. We report data for two dikes that clearly crosscut the main metamorphic fabric of the peridotite. A microgabbro dike yields a SmNd mineral isochron age ofT = 435 ± 21 Ma andε_Nd = + 6.7 ? 0.3. A pyroxenite dike yields an initialε_Nd = + 7.3 ± 0.4. The initialε_Nd values for the pyroxenite and gabbro dikes are fairly similar to those for the depleted mantle at this time and are distinct from the lherzolite—demonstrating that they are not genetically related. RbSr data do not give any coherent pattern. However, some bounds can be put on initial Sr values ofε_Sr ? ?21 for the plagioclase lherzolite andε_Sr ? ?8.7 for the microgabbro dike. It is plausible that the dikes represent cumulates left behind from island arc magmas that rose through the the oceanic lithosphere within the vicinity of a subduction zone. Major and trace elements and SmNd isotopic data indicate a multiple stage history for the Trinity peridotite; a small melt fraction was extracted from an undepleted source ～ 3.4 AE or more ago to produce the proto-lherzolite; a large fraction of melt (～ 12 to 23%) was extracted from the proto-lherzolite to produce the present rock; the lherzolite was then crosscut by dikes from average depleted mantle ～ 0.44 AE ago. The data are compatible with the depleted mantle source being formed very early in earth history. Although most available data indicate that the depleted upper mantle has been relatively well stirred through time, the Trinity data suggest that very ancient Nd isotopic values are preserved and thus chemical and physical heteorgeneities are sometimes preserved in the depleted source of mid-ocean ridge basalts as well as the oceanic lithosphere which they intrude.     

Succession of copepod species in a Middle Atlantic estuary

A study of the seasonal succession of dominant copepod species was conducted during the period May, 1972 to June, 1973 in the Navesink River estuary, a tributary of the New York Bight. The replacement of the copepod Acartia tonsa by Acartia clausi, a phenomenon well-documented in the middle Atlantic estuaries for the late winter and early spring seasons, was not observed during this study, indicating that this succession may not take place in the Navesink. Instead, the more brackish-water calanoids, Pseudodiaptomus coronatus and Eurytemora affinis replaced A. tonsa, increasing in numbers markedly as the A. tonsa population declined. Although A. clausi is known to occur in temperatures and salinities comparable to those of the Navesink, this study supports the results of Yamazi (1966) that the occurrence of A. clausi in the Navesink is a rarity.