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The cod stocks in the Baltic Sea are important not only for fisheries but for the entire ecosystem utilized by numerous stakeholders around the coast. All such activities have economic values. In this note the economics of the Swedish Baltic Sea cod fishery is estimated in relation to the sector's interaction with other users of the Baltic Sea ecosystem. The results show a negative resource rent for the fishery, € −5 million without public expenses (subsidies and administrative costs), and € −13 million including public expenses. The interactions between the fisheries and tourism, seal population, carbon dioxide emissions, recreational fishing, and discards are discussed, and when monetary estimates are available these are related to the estimated resource rent. 相似文献
34.
The contribution of organic bases to the alkalinity of the anoxic hypolimnetic water of a small lake has been studied. By means of potentiometric titrations the presence of a protolyte, best described as a one-protonic acid (HL) could be shown. The pka of HL was found to be 4.24±0.08 (3σ) and it reached a concentration of 0.4 mM close to the sediment surface. Because of precipitation reactions titration experiments could not be performed above pH≈6.8, but indications of additional bases having a pka >8were found. The results indicate the presence of low molecular weight carboxylic acids and free amino acids originating from bacterial decomposition of organic material. Polarographically measured Fe2+ concentrations, in situ pH measurements and various model ligands were used to assess the metal speciation in the hypolimnion. Although strong metal complexing agents such as citrate and glutamine may be present, the total concentrations of both Fe2+ (up to 0.6 mM) and ligands are too low to bind more than at maximum 20% of the ferrous iron. 相似文献
35.
In 1978 the food and habitat resource partitioning of three small and common fish species, viz. Pomatoschistus microps (Krøyer), Gasterosteus aculeatus (L.) and Pungitius pungitius (L.) were studied in river Broälven estuary on the Swedish west coast (58°22′N, 11°29′E). The area was divided into three habitats, based on environmental features. In July, September, and October stomach contents and size distribution of each species present were analysed.In July there was high food and habitat overlap between the species. Interference interactions probably occurred between some size classes of P. microps and the other two species. P. pungitius was exposed to both intra- and interspecific interactions. In September the food and habitat overlaps between G. aculeatus and P. pungitius were high, while both had low food and habitat overlaps in relation to P. microps. Interactions between G. aculeatus and P. pungitius were probably influenced by more severe abiotic conditions in one habitat, which caused lower abundances there, and higher abundances in the other two habitats. In October no interactions were observed. These results indicate that competition for food at least temporarily determines the species distribution in a temperate estuary, and that estuarine fish populations are sometimes food limited. 相似文献
36.
Abdirahman M. Omar Truls Johannessen Are Olsen Staffan Kaltin Francisco Rey 《Marine Chemistry》2007,104(3-4):203-213
The seasonal and interannual variability of the air–sea CO2 flux (F) in the Atlantic sector of the Barents Sea have been investigated. Data for seawater fugacity of CO2 (fCO2sw) acquired during five cruises in the region were used to identify and validate an empirical procedure to compute fCO2sw from phosphate (PO4), seawater temperature (T), and salinity (S). This procedure was then applied to time series data of T, S, and PO4 collected in the Barents Sea Opening during the period 1990–1999, and the resulting fCO2sw estimates were combined with data for the atmospheric mole fraction of CO2, sea level pressure, and wind speed to evaluate F.The results show that the Atlantic sector of the Barents Sea is an annual sink of atmospheric CO2. The monthly mean uptake increases nearly monotonically from 0.101 mol C m− 2 in midwinter to 0.656 mol C m− 2 in midfall before it gradually decreases to the winter value. Interannual variability in the monthly mean flux was evaluated for the winter, summer, and fall seasons and was found to be ± 0.071 mol C m− 2 month− 1. The variability is controlled mainly through combined variation of fCO2sw and wind speed. The annual mean uptake of atmospheric CO2 in the region was estimated to 4.27 ± 0.68 mol C m− 2. 相似文献
37.
Lorenzo?SpadiniEmail author Paul?W.?Schindler Staffan?Sj?berg 《Aquatic Geochemistry》2005,11(1):21-31
Summary The complexation of aluminium(III) and silicon(IV) was studied in a simplified seawater medium (0.6 M Na(Cl)) at 25 °C. The
measurements were performed as potentiometric titrations using a hydrogen electrode with OH
− ions being generated coulometrically. The total concentrations of Si(IV) and Al(III) respectively [Si
tot
] and [Al
t
ot], and −log[H
+] were varied within the limits 0.3 < [Si
tot
] < 2.5 mM, 0.5 < [Al
tot
] < 2.6 mM, and 2 ≤ -log[H
+] ≤ 4.2. Within these ranges of concentration, evidence is given for the formation of an AlSiO(OH)
3
2+
complex with a formation constant log β1,1-1 = −2.75 ± 0.1 defined by the reaction
Al
3++Si (OH)4 ↔ AlOSi(OH)
3
2+
+H
+
An extrapolation of this value to I=0 gives log β1,1-1 = −2.30. The calculated value of log K (Al
3++SiO(OH)
3
−
↔ AlOSi(OH)
3
2+
) = 6.72 (I=0.6 M) can be compared with corresponding constants for the formation of AlF
2+ and AlOH
2+ , which are equal to 6.16 and 8.20. Obviously, the stability of these Al(III) complexes decreases within the series OH
−>SiO(OH)
3
−
> F
− 相似文献
38.
The strength of complexation in the system H+Al3+B(OH)3 has been studied. It is shown, on the basis of three independent types of measurement (H+ potentiometry, 27Al NMR and 11B NMR), that no, or at least very weak, aluminium-borate complexes form. An apparent solubility for freshly precipitated Al(OH)3(s) is reported. 相似文献
39.
The removal of Cd from aqueous solutions by hydroxyapatite (HAP) was investigated with and without EDTA being present. Batch experiments were carried out using synthetic hydroxyapatite with Ca/P 1.57 and a specific surface area of 37.5 m2/g in the pH range 4–9 (25 °C; 0.1 M KNO3). The surface composition of the solid phases were analysed by X-ray Photoelectron Spectroscopy (XPS). The surface layer of HAP was found to undergo a phase transformation with a (Ca + Cd)/P atomic ratio of 1.4 and the involvement of an ion exchange process (Ca2+ ↔ Cd2+). The amount of Cd removed from the solution increased with increasing pH, reaching ≈100% at pH 9. In the presence of EDTA Cd removal was reduced due to the formation of [CdEDTA]2− in solution. The solubility of HAP increases in the presence of EDTA at pH values above 5, mainly due to the formation of [CaEDTA]2−. In contrast to this, the solubility was found to decrease in the presence of Cd2+ and CdEDTA2−. Using XPS the formation of a Cd-enriched HAP surface was found, which was interpreted as the formation of a solid solution of the general composition: Ca8.4-xCdx(HPO4)1.6(PO4)4.4(OH)0.4. 相似文献