Changes in soil chemical and microbiological properties during 4 years of application of various organic residues

A 4-year field trial was established in eastern Sweden to evaluate the effects of organic waste on soil chemical and microbiological variables. A simple crop rotation with barley and oats was treated with either compost from household waste, biogas residue from household waste, anaerobically treated sewage sludge, pig manure, cow manure or mineral fertilizer. All fertilizers were amended in rates corresponding to 100kgNha(-1)year(-1). The effects of the different types of organic waste were evaluated by subjecting soil samples, taken each autumn 4 weeks after harvest, to an extensive set of soil chemical (pH, Org-C, Tot-N, Tot-P, Tot-S, P-AL, P-Olsen, K-AL, and some metals) and microbiological (B-resp, SIR, microSIR active and dormant microorganisms, PDA, microPDA, PAO, Alk-P and N-min) analyses. Results show that compost increased pH, and that compost as well as sewage sludge increased plant available phosphorus; however, the chemical analysis showed few clear trends over the 4 years and few clear relations to plant yield or soil quality. Biogas residues increased substrate induced respiration (SIR) and, compared to the untreated control amendment of biogas residues as well as compost, led to a higher proportion of active microorganisms. In addition, biogas residues increased potential ammonia oxidation rate (PAO), nitrogen mineralization capacity (N-min) as well as the specific growth rate constant of denitrifiers (microPDA). Despite rather large concentrations of heavy metals in some of the waste products, no negative effects could be seen on either chemical or microbiological soil properties. Changes in soil microbial properties appeared to occur more rapidly than most chemical properties. This suggests that soil microbial processes can function as more sensitive indicators of short-term changes in soil properties due to amendment of organic wastes.     

Water chemistry in 179 randomly selected Swedish headwater streams related to forest production,clear-felling and climate

From a policy perspective, it is important to understand forestry effects on surface waters from a landscape perspective. The EU Water Framework Directive demands remedial actions if not achieving good ecological status. In Sweden, 44 % of the surface water bodies have moderate ecological status or worse. Many of these drain catchments with a mosaic of managed forests. It is important for the forestry sector and water authorities to be able to identify where, in the forested landscape, special precautions are necessary. The aim of this study was to quantify the relations between forestry parameters and headwater stream concentrations of nutrients, organic matter and acid-base chemistry. The results are put into the context of regional climate, sulphur and nitrogen deposition, as well as marine influences. Water chemistry was measured in 179 randomly selected headwater streams from two regions in southwest and central Sweden, corresponding to 10 % of the Swedish land area. Forest status was determined from satellite images and Swedish National Forest Inventory data using the probabilistic classifier method, which was used to model stream water chemistry with Bayesian model averaging. The results indicate that concentrations of e.g. nitrogen, phosphorus and organic matter are related to factors associated with forest production but that it is not forestry per se that causes the excess losses. Instead, factors simultaneously affecting forest production and stream water chemistry, such as climate, extensive soil pools and nitrogen deposition, are the most likely candidates The relationships with clear-felled and wetland areas are likely to be direct effects.     

Urban mining: hibernating copper stocks in local power grids

Large technical systems serving the everyday needs of people, such as water supply systems, power grids or communication networks, are rich in accumulated metals. Over time, parts of these systems have been taken out of use without the system infrastructure being removed from its original location. Such metal stocks in hibernation thus constitute potential resource reservoirs accessible for recovery. In this paper, obsolete stocks of copper situated in the local power grids of two Swedish cities are quantified. Emphasis is also on economic conditions for extracting such “hibernating” cables. The results show that on a per customer basis, the two power grids contain similar amounts of copper, i.e. 0.04–0.05 tonnes per subscriber. However, the share of the copper stock that is in hibernation differs between the grids. In the larger grid of Gothenburg, almost 20% of the copper accumulated in the grid is no longer in use, while the obsolete share does not exceed 5% in the city of Linköping. For managers of local power grids, recovery of hibernating cables could be beneficial if integrated with other maintenance work on the grid. At the present price of copper, however, separate recovery of obsolete cables is not economically justified.     

Simulating transport of non-Chernobyl (137)Cs and (90)Sr in the North Atlantic-Arctic region

The spatial and temporal distributions of the anthropogenic radionuclides (137)Cs and (90)Sr, originating from nuclear bomb testing and the Sellafield reprocessing plants in the Irish Sea, are simulated using a global version of the Miami Isopycnic Coordinate Ocean Model (MICOM). The physical model is forced with daily atmospheric re-analysed fields for the period 1950 to present. Comparison of temporal evolution of observed and simulated concentrations of (137)Cs have been conducted for the regions east of Scotland, west of central Norway and at the entrance of the Barents Sea. It follows that the radionuclides from the Sellafield discharge reach the Barents Sea region after 4-5 years, in accordance with observations. The simulation provides a detailed distribution and evolution of the radionuclides over the integration time. For the Atlantic waters off the coast of Norway and in the southern Barents Sea, the atmospheric fallout dominates over the Sellafield release up to the mid 1960s and from the early 1990s, whereas Sellafield is the main source for the two radionuclides in the 1970s and 1980s. It is furthermore argued that model systems like the one presented here can be used for future prediction of radioactive contaminations in the Nordic Seas and the Arctic Ocean, for instance under various global warming scenarios.     

Bone mineral density in male Baltic grey seal (Halichoerus grypus)

Bone mineral density (mg cm(-3)) was studied in male Baltic grey seals (4-23 years of age) by noninvasive computed tomography (pQCT). The material was grouped according to year of collection. Group A: 1850-1955, a period before the main introduction of organochlorines (OCs); Group B: 1965-1985, a period with very high OC contamination; and Group C: 1986-1997, a period with decreasing concentrations of OCs. The reproducibility of the measurements was good with a Coefficient of Variation (CV) ranging from 0.1% to 2.1%. Trabecular bone mineral density of the radius was significantly higher in specimens collected 1986-1997 than in those collected 1965-1985 (p < 0.05). Cortical bone mineral density of the mandible was significantly lower in specimens collected 1986-1997 compared with those collected 1850-1955 (p < 0.05). These results indicate different responses over time in trabecular and cortical bone. During the period of very high OC contamination (1965-1985), trabecular bone density was lowest, whereas cortical bone density was lowest in specimens collected 1985-1997, representing a period of fairly low OC contamination. The mechanisms behind these effects are not known. However, it can be assumed that OCs are involved. Information about residue levels of OCs in the studied individuals is lacking and, therefore, it was not possible to evaluate the impact of OCs in this respect.     

Methane oxidation in two Swedish landfill covers measured with carbon-13 to carbon-12 isotope ratios

The release of methane (CH4) from landfills to the atmosphere and the oxidation of CH4 in the cover soils were quantified with static chambers and a 13C-isotope technique on two landfills in Sweden. One of the landfills had been closed and covered 17 years before this investigation while the other was recently covered. On both landfills, the tops of the landfills were compared with the sloping parts in the summer and winter. Emitted CH4, captured in chambers, was significantly enriched in 13C during summer compared with winter (P < 0.0001), and was enriched relative to anaerobic-zone methane. The difference between emitted and anaerobic zone delta 13C-CH4 was used to estimate soil methane oxidation. In summer, these differences ranged from 9 to 26@1000, and CH4 oxidation was estimated to be between 41 and 50% of the produced CH4 in the new landfill, and between 60 and 94% in the old landfill. In winter, when soil temperature was below 0 degree C, no difference in delta 13C was observed between emitted and anaerobic-zone CH4, suggesting that there was no soil oxidation. The temperature effect shown in this experiment suggests that there may be both seasonal and latitudinal differences in the importance of landfill CH4 oxidation. Finally the isotopic fractionation factor (alpha) varied from 1.023 to 1.038 and was temperature dependent, increasing at colder temperatures. Methanotrophic bacteria appeared to have high growth efficiencies and the majority of the methane consumed in incubations did not result in immediate CO2 production.     

Heavy Metals in Stockholm Groundwater – Concentrations and Fluxes

Sampling of groundwater in theQuaternary deposits was carried out at 70 sitesin Stockholm for, among other things, metalanalyses. The objectives were to get a notion of the metal content and to get a basis for anestimation of the order of magnitude of thegroundwater transported metal contribution to themain surface water bodies in comparison to otherroutes. Thus, in three watershed areaswithin the Stockholm Town, groundwater flow andmetal concentration propagation were simulatedand metal fluxes were calculated. Theconcentrations of heavy metals were in generalfound to be very high in comparison withgroundwater in forested areas. This was mostpronounced for mercury (Hg) and copper (Cu). Themost remarkable result was a Hg concentration of4.57 g L^-1 in the vicinity of a closed downhospital. The annual contribution of heavy metals(kg) by groundwater to the main surface waterbodies was estimated to: As (2.2), Cd (0.20), Co(4.9), Cr (3.1), Cu (34), Hg (0.06), Ni (28), Pb(2.2) Zn (118). These fluxes are much smallerthan those in forest ecosystems, due to lowergroundwater recharge in urban areas, where agreat part of the runoff is diverted bylandsealing, drainage, tunnels etc. The modelingresults emphasize the importance of the sorptionprocesses indicating that the modeled areas arein a non-steady state condition. It also showsthat the sources generating elevatedconcentrations of the high adsorptive metals Pband Hg are likely to be nearby.     

Life cycle assessment of lithium-ion batteries for plug-in hybrid electric vehicles – Critical issues

The main aim of the study was to explore how LCA can be used to optimize the design of lithium-ion batteries for plug-in hybrid electric vehicles. Two lithium-ion batteries, both based on lithium iron phosphate, but using different solvents during cell manufacturing, were studied by means of life cycle assessment, LCA. The general conclusions are limited to results showing robustness against variation in critical data. The study showed that it is environmentally preferable to use water as a solvent instead of N-methyl-2-pyrrolidone, NMP, in the slurry for casting the cathode and anode of lithium-ion batteries. Recent years’ improvements in battery technology, especially related to cycle life, have decreased production phase environmental impacts almost to the level of use phase impacts. In the use phase, environmental impacts related to internal battery efficiency are two to six times larger than the impact from losses due to battery weight in plug-in hybrid electric vehicles, assuming 90% internal battery efficiency. Thus, internal battery efficiency is a very important parameter; at least as important as battery weight. Areas, in which data is missing or inadequate and the environmental impact is or may be significant, include: production of binders, production of lithium salts, cell manufacturing and assembly, the relationship between weight of vehicle and vehicle energy consumption, information about internal battery efficiency and recycling of lithium-ion batteries based on lithium iron phosphate.