Spatial and temporal variability of Mehlich-1 extractable Fe, Mn and Zn over a rice field as a function of lime amendment

This study compares the effect of lime additions on the spatial variability of Fe, Mn and Zn extracted by Mehlich-1 during three different growth stages from an acid paddy soil, a Typic Plintacualf, in Corrientes, Argentina. Field trials were set up involving three treatments: control, without lime addition, plus two different dolomite doses of 625 and 1250 kg ha⁻¹. Soil was sampled first before sowing in aerobic conditions and then two more times in anaerobic conditions, i.e. by bunch formation and flowering. Ninety-six samples per plot were taken per lime treatment and sampling period, using a nested sampling strategy. Liming significantly increased extractable Fe and Mn, but decreased extractable Zn. The spatial variability of the studied soil properties was assessed using semivariogram analysis and examination of kriging maps. Models were fitted to experimental semivariograms for 27 data sets, i.e. three different soil properties, each of them sampled in three treatments and during three dates. Soil extractable and Fe, Mn and Zn exhibited a rather strong spatial dependence, as nugget variance was either null or a small proportion of the total variance, and this all over the three different study periods and for the three lime treatments. Geostatistical analysis provided insight into possible processes responsible of the observed spatial variability patterns within the rice soil. Kriging was useful in mapping soil micronutrient variability allowing identifying microrregions with high or low Fe, Mn and Zn concentrations, which showed the presence of small scale variability. These findings indicate the potential for applying the principles of precision agriculture to control spatiotemporal variability in rice fields.     

Influence from Surrounding Land on the Turbulence Measurements Above a Lake

Turbulence measurements taken at a Swedish lake are analyzed. Although the measurements took place over a relatively large lake with several km of undisturbed fetch, the turbulence structure was found to be highly influenced by the surrounding land during daytime. Variance spectra of both horizontal velocity and scalars during both unstable and stable stratification displayed a low frequency peak. The energy at lower frequencies showed a daily variation, increasing in the morning and decreasing in the afternoon. This behaviour is explained by spectral lag, where the low frequency energy due to large eddies that originate from the convective boundary layer above the surrounding land. When the air is advected over the lake the small eddies rapidly equilibrate with the new surface forcing. However, the large eddies remain for an appreciable distance and influence the turbulence in the developing lake boundary layer. The variances of the horizontal velocity and scalars are increased by these large eddies, while the turbulent fluxes are mainly unaffected. The drag coefficient, Stanton number and Dalton number used to parametrize the momentum flux, heat flux and latent heat flux respectively all compare well with current parametrizations developed for open sea conditions. The diurnal cycle of the partial pressure of methane, $p\mathrm{CH}_{4}$ , observed at this site is closely related to the diurnal cycle of the lake-air methane flux. An idealized two-dimensional model simulation of the boundary layer at a lake site indicates that the strong response of $p\mathrm{CH}_{4}$ to the surface methane flux is due to the shallow internal boundary layer that develops above the lake, allowing methane to accumulate in a relatively small volume.     

Cytological and Population Genetic Changes in Northwestern Iberian Mussels After the Prestige Oil Spill

The ecological catastrophe produced by the Prestige oil spill (November 2002) caused severe damage in both North Spanish and French coastal communities. Wild mussel populations of Mytilus galloprovincialis in a zone with marginal introgression of Mytilus edulis were affected at all levels, from high DNA damage to increased polycyclic aromatic hydrocarbon content in tissues. In this article, we describe cytological and population genetic changes of wild mussel populations from the northwestern Iberian coast following the catastrophe. The micronucleus test was employed as an indicator of cytological damage, and the Barcoding mitochondrial cytochrome oxidase I (COI) and the nuclear Glu-5′ genes were analyzed for determining the species and assessing population genetic diversity. Immediate increase of micronuclei counts after the oil spill was found, with a further decrease in consecutive months although the counts did not recover pre-Prestige levels. Reduced variation at mitochondrial sequences in the most exposed areas and reduction of M. edulis traces in the regional genetic pool also suggest long-term impact that may result in evolutionary changes. These results highlight the need of adopting more strict measures in order to prevent this type of accidents and avoid long-term effects on wild populations.     

Potential of SARAL/AltiKa for Inland Water Applications

SARAL uses the same orbit as ERS and Envisat and can be used to extend inland water height time series derived from these missions. This article investigates the potential of SARAL for this application over the Great Lakes and the Amazon basin. SARAL/AltiKa is the first altimeter using Ka-band that is rarely influenced by ionospheric effects but susceptible for atmospheric water. Our investigations show clear waveform disruptions for SARAL due to precipitation. It is demonstrated that the quality of water heights improved when using alternative retracker products, for example, the ice-1 product. The improvement depends on the weather and yields up to 3.8 cm for wet conditions. The advantage of the smaller footprint of SARAL is demonstrated for land-water transitions where SARAL provides better water level heights up to 6 km to the lakeshore whereas Envisat is limited to about 11 km. SARAL provides also more reliable water level heights for narrow Amazon rivers than Envisat. Furthermore, the hooking effect is decreased for SARAL. Comparing water level time series of SARAL-only, Envisat-only, and multi-mission with in-situ data demonstrates that SARAL has the potential to extend Envisat long-term time series and to decrease the RMS by about 10% for large lakes and 40% for selected rivers.     

Strukturverfeinerung von Libethenit Cu2(OH)PO4

Inhalt Eine mit zweidimensionalen Fouriermethoden durchgeführte Strukturverfeinerung bestätigt die vonH. Heritsch (1940) für Libethenit bestimmte Struktur. Von der daraus resultierenden kristallchemischen Formel Cu^[4+2] Cu^[5] (OH) [PO₄] ist sowohl die Strukturanalogie mit Andalusit und Adamin als auch die zu gleichen Teilen auftretende Sechser- und Fünferkoordination des zweiwertigen Kupfers in Libethenit abzulesen.

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Fisheries and aquaculture industries involvement to control product health and quality safety to satisfy consumer-driven objectives on retail markets in Europe

Over the past years the export of agricultural and fishery products from developing countries has substantially increased to markets within the OECD. Retailers and importers are expanding their international operations to meet consumer demands for year-round delivery of products. Moreover, consumers have become increasingly concerned about the safety of food, including those derived from aquatic resources [FAO/NACA/WHO Joint Study Group, 1999. Report food safety issues associated with products from aquaculture. WHO Technical Report Series No 883: VII, pp. 1-55]. Governments and leading businesses are responding by imposing new safety regulations and standards to the international food system (e.g. HACCP, EUREP-GAP), product liability and labeling [Reilly, A., Howgate, P., K?ferstein, F., 1997. Safety hazards and the application of HACCP in aquaculture. In: Proceedings of the Second International Conference on Fish Inspection and Quality Control: A Global Focus, Arlington, VA, 19-24 May 1996. Technomic Publishing, Lancaster, PA, pp. 353-373]. Initial concerns for imports of aquacultural products from developing to industrialized countries focussed on bacterial contamination [Buras, N. 1993. Microbial safety of produce from wastewater-fed aquaculture. In: Pullin, R.V.C., Rosenthal, H., MacLean, J.L.(Eds.), Proceedings of ICLARM Conferences, vol. 31, pp. 285-295]. Today, if trade opportunities are to be maintained, these countries must adapt to a full array of regulations and standards. This paper describes four scenarios in aquaculture and fishing product trade between developing countries and countries in the European Union.     

Connectivity analyses of valley patterns indicate preservation of a preglacial fluvial valley system in the Dyfi basin, Wales

Coastal valleys in the west part of Mid-Wales, such as the Mawddach, Dysynni, Tal-y-llyn and Dyfi, acted as corridors for ice which drained the Welsh Ice Cap during the Devensian. Analyses of detailed digital elevation models, and interpretation of satellite images and aerial photographs, show the existence of large variations in the amount of glacial modification between these valleys. Although all the valleys are glacially over-deepened along late Caledonian fault lines, only the Dyfi basin exhibits a dendritic pattern, with V-shaped cross-profiles and valley spurs typical of valleys formed by fluvial processes. Connectivity analysis of the Dyfi basin shows that it exhibits an almost completely dendritic pattern with connectivity α and β values of 0.74 and 1.01, respectively, with little glacial modification of the preglacial fluvial valley pattern in the form of glacial valley breaching. Several examples of glacial meltwater incision into a well-developed pre-existing river valley system, causing river capture across watersheds, have been identified in the Dyfi basin. The degree of preservation of the preglacial fluvial valley system within the Dyfi basin indicates limited modification by glacial processes, despite the area being subjected to glacier activity during the Late Devensian at least. It is possible that major parts of the basin were covered by cold-based or slow-moving ice, close to, or under, a migrating ice-divide, with the major ice drainage occurring along the weaker zone of the Pennal Fault along which teh Dyfi valley is located, causing minor adjustments to the surrounding interfluves and uplands. It is proposed here that the general river valley morphology of the Dyfi basin is of a pre-Late Devensian age.