Reclamation of copper mine tailings using sewage sludge

Tailings are the fine-grained fraction of waste produced during mining operations. This work was carried out on tailings from the Aitik copper mine in northern Sweden. Establishment of vegetation on the Aitik mine tailings deposit is planned to take place at closure of the mine, using sewage sludge as fertiliser. However, the tailings contain traces of metal sulphides, e.g. pyrite, FeS2, and chalcopyrite, CuFeS2. When the sulphides are oxidised, they start to weather and release metals and strong acid, affecting the plant establishment. This thesis investigated physical and chemical growing conditions for plants in tailings with and without sewage sludge, and how these conditions changed when the tailings were oxidised. Studies on tailings properties were related to growth and metal uptake by barley (Hordeum vulgare) and red fescue (Festuca rubra) cultivated on the tailings. Fine sand particles (diameter 0.06-0.2 mm) and moderately large pores (diameter 30-300 μm) dominated the tailings. Oxidation processes resulted in a slightly higher percentage of fine pores (diameter ≤5μm) due to the formation of aggregating iron(III)hydroxide and in a pH decrease due to the acid produced as sulphides oxidised. As oxidation proceeded and pH decreased from neutral to 4.5, Al, Cd, Cu, Pb and Zn concentrations in tailings solution increased by 2-3 orders of magnitude. Compared with mineral fertiliser, sewage sludge consistently increased plant biomass production, due to the contribution of nutrients and organic matter, and increased the percentage of large pores (30-300 μm) and fine pores (<5 μm). The effect of the sludge on pH was generally limited. In the field trial, higher levels of Al, As, Cr, Cu, Pb and Zn were found in red fescue grown in sludge-treated tailings compared with tailings treated with mineral fertiliser. In the climate chamber experiment, sludge effects on Cu in tailings and plants depended on the degree of oxidation of the material. In unoxidised tailings, sewage sludge slightly increased Cu levels in solutions and fescue shoots, but in oxidised tailings the opposite occurred. In general, the sewage sludge did not counteract the toxic conditions caused by sulphide oxidation, but had beneficial effects on plant growth irrespective of oxidation degree of the tailings material

Typområden på jordbruksmark i Örebro län

Under 15 år har två avrinningsområden (T9 och T10) i Örebro län undersökts inom miljöövervakningsprogrammet Typområden på jordbruksmark. Kontinuerliga mätningar av vattenflödet samt halter av kväve och fosfor har möjliggjort beräkningar av årliga näringsämnestransporter i områdenas bäckar. Undersökningarna upphörde i december år 2008. Syftet med denna rapport har varit att sammanställa och utvärdera data från hela undersökningsperioden. I båda områden dominerades åkermarken av vårsådd spannmål. I T9 utgjorde även energiskogsodlingar en stor andel av den odlade marken. Långtidsmedel för årsmedeltransporten av kväve var störst i T10 (4 680 kg/km2), med kväverika mulljordar som dominerande jordart. I detta område har både avrinning och kvävehalter legat på högre nivåer under de senaste 6 åren jämfört med tidigare år. De högre kvävehalterna under senare år kan ha ett samband med att vatten har börjat pumpats ut under en större del av året än tidigare, vilket kan ha medfört förändrade fuktighetsförhållanden, och därmed en ökad kvävemineralisering i marken. Långtidsmedel för de årliga fosfortransporterna var däremot högre i T9 (85 kg/km2) än i T10 (27 kg/km2). De höga fosforförlusterna kan ha orsakats av att T9 domineras av lerjordar, där fosfor till stor del transporteras bort från åkermarken i partikulärt bunden form, det vill säga fosfor bunden till bland annat ler-partiklar. I trendtest med flödesnormaliserade transporter kunde inga signifikanta förändringar med tiden säkerställas för något av områdena, varken i avrinning, fosfor- eller kvävetransporter

Optimizing Species Richness in Mosaic Landscapes: A Probabilistic Model of Species-Area Relationships

Most landscapes are comprised of multiple habitat types differing in the biodiversity they contain. This is certainly true for human modified landscapes, which are often a mix of habitats managed with different intensity, semi-natural habitats and even pristine habitats. To understand fundamental questions of how the composition of such landscapes affects biodiversity conservation, and to evaluate biodiversity consequences of policies that affect the composition of landscapes, there is a need for models able to translate information on biodiversity from individual habitats to landscape-wide predictions. However, this is complicated by species richness not being additive. We constructed a model to help analyze and solve this problem based on two simple assumptions. Firstly, that a habitat can be characterized by the biological community inhabiting it; i.e., which species occur and at what densities. Secondly, that the probability of a species occurring in a particular unit of land is dictated by its average density in the associated habitats, its spatial aggregation, and the size of the land unit. This model leads to a multidimensional species-area relation (one dimension per habitat). If the goal is to maximize species diversity at the landscape scale (γ-diversity), within a fixed area or under a limited budget, the model can be used to find the optimal allocation of the different habitats. In general, the optimal solution depends on the total size of the species pool of the different habitats, but also their similarity (β-diversity). If habitats are complementary (high β), a mix is usually preferred, even if one habitat is poorer (lower α diversity in one habitat). The model lends itself to economic analyses of biodiversity problems, without the need to monetarize biodiversity value, i.e., cost-effectiveness analysis. Land prices and management costs will affect the solution, such that the model can be used to estimate the number of species gained in relation to expenditure on each habitat. We illustrate the utility of the model by applying it to agricultural landscapes in southern Sweden and demonstrate how empirical monitoring data can be used to find the best habitat allocation for biodiversity conservation within and between landscapes

Population trends of waders on their boreal and arctic breeding grounds in northern Europe

Waders form a conspicuous part of the bird fauna in boreal and arctic areas, where they inhabit forests, wetlands, mires and tundra. These are important breeding areas for a large set of wader species, and may be particularly vulnerable to climate change. However, large-scale and systematic monitoring data from the breeding grounds of boreal and arctic waders are largely lacking. We present population trends for 22 wader species breeding in the boreal and arctic parts of Fennoscandia (Norway, Sweden and Finland) between 2006 and 2018. The trends are based on 9,713 surveys of 1,505 unique routes (6–8 km), each surveyed in at least two years, evenly distributed over an area of ~1 million km2. The trends were significantly negative for three species: Red-necked Phalarope Phalaropus lobatus (–7.9% year-1), Broad-billed Sandpiper Calidris falcinellus (–5.4% year-1), and Whimbrel Numenius phaeopus (–1.3% year-1). The trends were significantly positive for three species: Oystercatcher Haematopus ostralegus (+4.9% year-1), Dunlin Calidris a. alpina (+4.2% year-1) and Wood Sandpiper Tringa glareola (+0.8% year-1). For the remaining species, we found no statistically significant trends. On average, as shown by a multi-species indicator, there was no general change in numbers over time. On 1,539 routes with at least one survey, wader species richness as well as total number of wader pairs increased significantly with increasing latitude. Species population trend was not correlated with breeding latitude, but population trends of long-distance migrants tended to be more negative than those of medium-distance migrants. The recent fortunes of waders breeding in northern Fennoscandia have been more buoyant than those in other parts of Europe, but the trends for some species are worrying. © 2019, International Wader Study Group. All rights reserved.Peer reviewe