| 1. |
- Petersen, S. O., et al.
(författare)
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In-vitro method and model to estimate methane emissions from liquid manure management on pig and dairy farms in four countries
- 2024
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Ingår i: Journal of Environmental Management. - : Academic Press. - 0301-4797 .- 1095-8630. ; 353
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Tidskriftsartikel (refereegranskat)abstract
- Methane (CH4) emissions from manure management on livestock farms are a key source of greenhouse gas emissions in some regions and for some production systems, and the opportunities for mitigation may be significant if emissions can be adequately documented. We investigated a method for estimating CH4 emissions from liquid manure (slurry) that is based on anaerobic incubation of slurry collected from commercial farms. Methane production rates were used to derive a parameter of the Arrhenius temperature response function, lnA', representing the CH4 production potential of the slurry at the time of sampling. Results were used for parameterization of an empirical model to estimate annual emissions with daily time steps, where CH4 emissions from individual sources (barns, outside storage tanks) can be calculated separately. A monitoring program was conducted in four countries, i.e., Denmark, Sweden, Germany and the Netherlands, during a 12-month period where slurry was sampled to represent barn and outside storage on finishing pig and dairy farms. Across the four countries, lnA' was higher in pig slurry compared to cattle slurry (p < 0.01), and higher in slurry from barns compared to outside storage (p < 0.01). In a separate evaluation of the incubation method, in-vitro CH4 production rates were comparable with in-situ emissions. The results indicate that lnA' in barns increases with slurry age, probably due to growth or adaptation of the methanogenic microbial community. Using lnA' values determined experimentally, empirical models with daily time steps were constructed for finishing pig and dairy farms and used for scenario analyses. Annual emissions from pig slurry were predicted to be 2.5 times higher than those from cattle slurry. Changing the frequency of slurry export from the barn on the model pig farm from 40 to 7 d intervals reduced total annual CH4 emissions by 46 %; this effect would be much less on cattle farms with natural ventilation. In a scenario with cattle slurry, the empirical model was compared with the current IPCC methodology. The seasonal dynamics were less pronounced, and annual CH4 emissions were lower than with the current methodology, which calls for further investigations. Country-specific models for individual animal categories and point sources could be a tool for assessing CH4 emissions and mitigation potentials at farm level.
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| 2. |
- Tonderski, Karin S., et al.
(författare)
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Våtmarker : Närsaltsfällor och/eller myllrande mångfald?
- 2003
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Ingår i: Vatten: tidskrift för vattenvård. - Nykvarn : Föreningen Vatten. - 0042-2886. ; 59:4, s. 259-270
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Tidskriftsartikel (refereegranskat)abstract
- This paper summarizes the state-of-the-art with respect to wetlands for nutrient removal and biodiversity enhancement, as expressed at a research workshop in December 2002. In the end of 2002, 260 and 884 wetlands had been constructed in Sweden with subsidies from LIP and the European Union, respectively. Most frequently, the aims were to remove nutrients from water and enhance biodiversity. The question raised is if we know how to design multifunctional wetlands. Should a wetland be deep or shallow, with or without macrophytes to be an efficient nutrient sink? Diverging opinions are presented, but generally it appears that fairly shallow wetlands at least partly covered by emergent macrophytes are favourable. The importance of extreme high flows and hydraulic short-circuiting is highlighted, and Danish and Norwegian approaches to wetlands construction are presented. Also, there is a risk that nutrient retaining wetlands develop a fairly trivial flora and fauna unless special care is taken. Intentional establishment of desirable and less common species, as well as creation of a variation of depth gradients to favour such species are such measures. Others are allowing for water level variations, as well as vegetation management such as grazing and harvesting.
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| 3. |
- Kalogirou, S., et al.
(författare)
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Shrimp trap selectivity in a Mediterranean small-scale-fishery
- 2019
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Ingår i: Fisheries Research. - : Elsevier BV. - 0165-7836. ; 211, s. 131-140
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Tidskriftsartikel (refereegranskat)abstract
- Small-scale shrimp trap fisheries, which have received very little attention in areas with limited potential for economic diversification, could offer a sustainable and socially beneficial option for profitable businesses in these regions. This study explores the effect of mesh size on selectivity of the commercially important narwal shrimp, Plesionika narval, in the Mediterranean Sea. Three different mesh sizes (8 × 8, 12 × 12 and 12 × 25 mm) were tested in fishing trials, with a theoretical Minimum Landing Size (MLS) using a defined maturity size of 12 mm to support interpretation of the results. Using the retention rates and the estimations on population fractions above and below MLS, we show that the use of the smallest- and largest-sized meshes would not support sustainable or efficient fishery. The results demonstrate a significant decrease in capture probability of undersized narwal shrimps with increased mesh size. The medium-sized mesh traps prove to be the best compromise for the fishery with high catch efficiency of commercial size shrimp and a low capture probability of undersized individuals. The results outlined in this article could be used to develop management plans for small-scale trap fisheries as a basis for developing viable enterprises in remote coastal communities. © 2018 Elsevier B.V.
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