Low accessibility and chemical activity of PAHs restrict bioremediation and risk of exposure in a manufactured gas plant soil

Composting of manufactured gas plant soil by a commercial enterprise had removed most of its polycyclic aromatic hydrocarbons (PAHs), but concentrations remained above regulatory threshold levels. Several amendments and treatments were first tested to restart the PAH degradation, albeit with little success. The working hypothesis was then that PAHs were “stuck” due to strong sorption to black carbon. Accessibility was measured with cyclodextrin extractions and on average only 4% of the PAHs were accessible. Chemical activity of the PAHs was measured by equilibrium sampling, which confirmed a low exposure level. These results are consistent with strong sorption to black carbon (BC), which constituted 59% of the total organic carbon. Composting failed to remove the PAHs, but it succeeded to minimize PAH accessibility and chemical activity. This adds to accumulating evidence that current regulatory thresholds based on bulk concentrations are questionable and alternative approaches probing actual risk should be considered.     

Reserves, resilience and dynamic landscapes

In a world increasingly modified by human activities, the conservation of biodiversity is essential as insurance to maintain resilient ecosystems and ensure a sustainable flow of ecosystem goods and services to society. However, existing reserves and national parks are unlikely to incorporate the long-term and large-scale dynamics of ecosystems. Hence, conservation strategies have to actively incorporate the large areas of land that are managed for human use. For ecosystems to reorganize after large-scale natural and human-induced disturbances, spatial resilience in the form of ecological memory is a prerequisite. The ecological memory is composed of the species, interactions and structures that make ecosystem reorganization possible, and its components may be found within disturbed patches as well in the surrounding landscape. Present static reserves should be complemented with dynamic reserves, such as ecological fallows and dynamic successional reserves, that are part of ecosystem management mimicking natural disturbance regimes at the landscape level.     

Reconnecting to the Biosphere

Humanity has emerged as a major force in the operation of the biosphere, with a significant imprint on the Earth System, challenging social-ecological resilience. This new situation calls for a fundamental shift in perspectives, world views, and institutions. Human development and progress must be reconnected to the capacity of the biosphere and essential ecosystem services to be sustained. Governance challenges include a highly interconnected and faster world, cascading social-ecological interactions and planetary boundaries that create vulnerabilities but also opportunities for social-ecological change and transformation. Tipping points and thresholds highlight the importance of understanding and managing resilience. New modes of flexible governance are emerging. A central challenge is to reconnect these efforts to the changing preconditions for societal development as active stewards of the Earth System. We suggest that the Millennium Development Goals need to be reframed in such a planetary stewardship context combined with a call for a new social contract on global sustainability. The ongoing mind shift in human relations with Earth and its boundaries provides exciting opportunities for societal development in collaboration with the biosphere--a global sustainability agenda for humanity.     

Socio-ecological implications of modifying rotation lengths in forestry

The rotation length is a key component of even-aged forest management systems. Using Fennoscandian forestry as a case, we review the socio-ecological implications of modifying rotation lengths relative to current practice by evaluating effects on a range of ecosystem services and on biodiversity conservation. The effects of shortening rotations on provisioning services are expected to be mostly negative to neutral (e.g. production of wood, bilberries, reindeer forage), while those of extending rotations would be more varied. Shortening rotations may help limit damage by some of today’s major damaging agents (e.g. root rot, cambium-feeding insects), but may also increase other damage types (e.g. regeneration pests) and impede climate mitigation. Supporting (water, soil nutrients) and cultural (aesthetics, cultural heritage) ecosystem services would generally be affected negatively by shortened rotations and positively by extended rotations, as would most biodiversity indicators. Several effect modifiers, such as changes to thinning regimes, could alter these patterns.     

An Experiment with Forced Oxygenation of the Deepwater of the Anoxic By Fjord,Western Sweden

In a 2.5-year-long environmental engineering experiment in the By Fjord, surface water was pumped into the deepwater where the frequency of deepwater renewals increased by a factor of 10. During the experiment, the deepwater became long-term oxic, and nitrate became the dominating dissolved inorganic nitrogen component. The amount of phosphate in the water column decreased by a factor of 5 due to the increase in flushing and reduction in the leakage of phosphate from the sediments when the sediment surface became oxidized. Oxygenation of the sediments did not increase the leakage of toxic metals and organic pollutants. The bacterial community was the first to show changes after the oxygenation, with aerobic bacteria also thriving in the deepwater. The earlier azoic deepwater bottom sediments were colonized by animals. No structural difference between the phytoplankton communities in the By Fjord and the adjacent Havsten Fjord, with oxygenated deepwater, could be detected during the experiment.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-014-0524-9) contains supplementary material, which is available to authorized users.     

Stakeholder participation in sustainability assessment of non-wicked problems: The case of a future seaweed industry in Sweden

Acceptance by, and cooperation with relevant stakeholders in developing new sustainability initiatives when they are generally perceived as positive, is one of the keys for successful implementation of such new sustainability initiatives later on. It is remarkable, however, that ample literature exists about involving stakeholders in research projects focusing on problems with diverging views (controversy) around facts and values (wicked problems), but there is very little literature addressing whether and how to involve relevant stakeholders in case of initiatives where diverging norms and values do not play a (substantial) role, like in sustainability assessment for a future seaweed industry. This perspectives paper addresses that gap, and explores how to design such sustainability assessment, illustrated by how stakeholder interaction influenced the assessment and its results for a future seaweed industry in Sweden, followed by a discussion whether and how a similar approach may benefit sustainability assessment of other non-wicked sustainability initiatives.     

Environmental impact of packaging and food losses in a life cycle perspective: a comparative analysis of five food items

The environmental concern and development issues regarding packaging has for 20 years to a high extent been on packaging when it has become waste. To reduce the environmental impact from the whole food packaging system it is also important to develop the packaging’s ability to reduce food waste. In some cases it may be necessary to increase the environmental impact of packaging in order to reduce food waste. In this paper, the environmental impact of packaging and food losses and the balance between the two has been examined for five different food items. The results show that packaging’s that reduce food waste can be an important tool to reduce the total environmental impact, even if there is an increase in impact from the packaging itself. This is especially true for food items where the environmental impact of the food is high relative the packaging, for example cheese, and for food items with high losses, for example bread. It is important to analyse the risk of increasing food losses when packaging design changes, for example, when the aim is less packaging material, which is the main intention of the packaging and packaging waste directive of the European Union.     

Testing a post-copulatory pre-zygotic reproductive barrier in a passerine species pair

Sexual selection may drive speciation, but most research focuses on pre-copulatory sexual selection, overlooking post-copulatory processes. Post-copulatory sexual selection in allopatric populations could drive divergence in post-copulatory pre-zygotic (PCPZ) phenotypes, limiting gene flow upon secondary contact. Here, we performed in vitro experiments examining one potential PCPZ barrier between two closely related passerine species, house sparrows (Passer domesticus) and Spanish sparrows (Passer hispaniolensis). In birds, crossing in the vagina may be particularly challenging for sperm, so we tested the effect of female reproductive tract fluids on sperm swimming speed and motility. If a PCPZ barrier exists at this stage of the fertilization process, heterospecific female fluids are predicted to reduce sperm swimming speed or motility relative to conspecific female fluid. We found that house sparrow female fluids affected the two species’ sperm asymmetrically, depending on the control sperm velocity and male species. Overall, however, sperm performed equally in conspecific and heterospecific female fluids, and the species had similar sperm morphology and sperm swimming performance. Low divergence in PCPZ phenotypes between species, perhaps because post-copulatory sexual selection is stabilizing or only moderately strong in these taxa, may be insufficient to cause an overall PCPZ barrier. Reinforcement may be unlikely to drive PCPZ barriers for this species pair, because relatively effective pre-copulatory barriers exist between the species, and because hybrids can be quite successful. Testing the role of PCPZ barriers in birds with more divergent PCPZ phenotypes will improve our understanding of speciation in passerines.     

Bacterial removal and protozoan grazing in biological sand filters

The objective of the study was to investigate the importance of protozoan predation as a biological removal mechanism in sand filters used for purification of bacteria from wastewater. Eleven sand filter columns were seeded with a high dose of wastewater (70 mm d(-1)) and a high concentration (10(8) colony forming units [CFU] mL(-1)) of Aeromonas hydrophila (American Type Culture Collection [ATCC] 14715) for a period of 30 d. Water samples from three filter outlets were analyzed for the concentration of A. hydrophila. In addition, one filter column was sacrificed each sampling day for the quantification of A. hydrophila, culturable bacteria (heterotrophic plate counts, HPC), total bacterial counts, and protozoa in the sand. The mean removal efficiency of A. hydrophila in the sand filter columns was 4.7 log units. The concentration of A. hydrophila in the sand filter effluent, however, had a clearly time-dependent pattern from high (log 6) and unstable concentrations to low and more stable levels (log 2). The removal efficiency of A. hydrophila correlated significantly (P = 0.0005, r2 = 0.6) with numbers of protozoa in the sand filters. Significantly higher (P < 0.05) concentrations of A. hydrophila were observed in sand filter effluents from columns treated with the protozoan inhibitor cycloheximide, compared with nontreated columns. Results from the present study show that protozoan grazing plays an important role as a bacterial removal mechanism in sand infiltration systems.