Secular trends of atmospheric methane (CH4)

Due partly to human activities the present yearly emissions of CH₄ exceed the atmospheric sinks, thus leading to a 1.2–1.9% per year atmospheric increase in the concentration of CH₄. New evidence based on studies of polar ice cores suggests that several hundred years ago the concentrations of CH₄ were perhaps only half of current values. These diverse findings are tied together in a single unified logistic model of atmospheric concentrations past, present and future. Using realistic growth rates of the sources of CH₄ caused by human activities, the model explains the concentrations and current growth rates. It also predicts that a doubling of CH₄ relative to present levels is possible given the long (9-year) atmospheric lifetime. Such increases of CH₄ concentrations may have already perturbed our global environment and may continue to do so in the future. The environmental effects include increased surface temperature of the earth, additional O₃ and CO in the clean non-urban atmosphere, depletions of tropospheric OH radicals, but perhaps also protection of the stratospheric ozone layer from destruction by man-made fluorocarbons.     

A risk perspective suitable for resilience engineering

In recent years, resilience engineering has been given considerable attention among safety researchers and analysts. The area represents a new way of thinking about safety. Whereas conventional risk management approaches are based on hindsight knowledge, failure reporting and risk assessments calculating historical data-based probabilities, resilience engineering looks for ways to enhance the ability of organisations to be resilient in the sense that they recognise, adapt to and absorb variations, changes, disturbances, disruptions and surprises. The implications of this shift in thinking are many. We focus in this paper on the understanding of the risk concept and how risk can be assessed and treated. The traditional ways of looking at risk are not suitable for use in resilience engineering, but other risk perspectives exist. A main purpose of this paper is to draw attention to such perspectives, in particular one category of perspectives where probability is replaced by uncertainty in the definition of risk. We argue that the basic ideas of resilience engineering can be supported by such risk perspectives.     

Effect of Fuel Properties on Mutagenic Activity in Extracts of Heavy-duty Diesel Exhaust Particulate

The effect of varying fuel properties on the emission of mutagenic materials was studied in diesel exhaust particles from a heavy duty engine run under transient speed and load conditions while using nine fuels varying in aromatics, sulfur and boiling point. Mutagenic activity of the soluble organic fraction (SOF) of the particulate was determined using the Ames Salmonella test system with strain TA98 with and without S9 activation. Increasing mutagenic activity relative to fuel consumed (mutants/lb fuel) or to engine work output (mutants/hp-h) was correlated with increasing fuel aromatics (p < 0.05), but not with fuel sulfur. Increased fuel sulfur levels were correlated with increased amounts of SOF but with decreasing mutagenic activity of the SOF (mutants/microgram SOF) (p < 0.05). As a result, mutants/hp-h were essentially the same for high- and low-sulfur fuels with high aromatics. No association was found between the fuels’ boiling points and the mutagenic activity of the SOF. Mutagenic activity with S9 was generally lower than without, but the correlations were not changed.     

Carbon Monoxide in an Urban Environment: Application of a Receptor Model for Source Apportionment

During the winter of 1985-86 the authors took 6-h integrated air samples and measured the concentrations of carbon monoxide and other gases at a residential site in Olympia, Washington. The 6-h average concentrations were between about 0.2 and 3.2 ppmv. For each 6-h period the observed concentration of CO was apportioned among its sources which were residential wood burning and automobiles. Small and generally insignificant amounts of CO were also observed from unidentified sources. A chemical mass balance (CMB) was formulated and applied to apportion the observed CO among its sources. Methylchloride (CH₃CI), in excess of background levels, was used as a unique tracer of wood burning and excess hydrogen (H₂) served as a tracer of CO from automobiles. The source emission factors to carry out the calculations were estimated from other experiments. The results showed that in Olympia, wood burning can often contribute as much CO as automobiles during winter. The maximum 6-h average contribution of CO from wood burning was about 2 ppmv and from automobiles it was 2.2 ppmv, and the average ambient concentration was about 1 ppmv. When pollution from wood burning was present, it contributed 0.5 ppmv on average while automobiles also contributed 0.5 ppmv. Unidentified sources contributed 0.1 ppmv and the background level was 0.15 ppmv. During the winter many times wood burning did not affect CO concentrations, while CO from automobiles was always present. On average, during the winter, automobiles contributed some 50 percent of the CO mass to the lower urban atmosphere and wood burning contributed about 30 percent. Diurnal cycles became evident in the calculated concentrations of CO from wood burning and automobiles even though the measured concentrations did not show strong diurnal variations. Wood burning contributed most during evening and nighttime and very little during the day, while automobiles contributed most during the morning and evening hours and very little at night. These patterns lend support to the accuracy of the model and source emission factors since they are as expected from the diurnal variations of the sources and atmospheric mixing.     

The impacts of local farming system development trajectories on greenhouse gas emissions in the northern mountains of Vietnam

The northern mountain region of Vietnam (NMR) is dominated by swidden/fallow farming systems. The fallow land of these systems is populated by small trees and bushes. Since the 1960s the government of Vietnam has tried to limit or stop swiddening and replace it with permanent upland agricultural fields, paddy, fruit trees and animal husbandry. Discussion in the policy debate and literature focuses on the impacts these changes have on local people’s livelihoods. There have been no attempts to evaluate the impact of these changes on greenhouse gas (GHG) emissions. This paper examines the realities of current farming system changes taking place at the hamlet level and other changes that could take place due to government land use policies and extension programs. The paper answers the following questions: How could farming system changes influence net GHGs? Which farming system changes in the NMR, the trajectories of changes that are currently observed or those that would be followed if farmers adhere strictly to government policies and programs, will have a greater affect on the GHG contributions from agriculture in the region? Could ‘clean development mechanism’ (CDM) projects make a difference in the profitability of the pathways mentioned? Results show: (1) if farming systems in the NMR continue along currently observed change trajectories there will be increases in GHG emissions; (2) if the NMR farming systems change according to government policies and programs there will be a net sequestration of carbon in regrowing vegetation during the initial 20 years; (3) over the longer term, in areas where systems change to fit government policies, increased GHG emissions from other changes in the farming systems (e.g. increased paddy and increased pig raising in sties) will overtake the amounts of carbon sequestered in vegetation; (4) CMD projects only make a difference if (a) maximum biomass potential of regrowing fallow can be reached; (b) a favourable baseline is chosen; (c) timing and length of the accounting period is correct; and (d) farmers do not take compensatory action in response to government policies. Given these conditions it does not appear that currently envisioned clean development mechanisms would be beneficial to farmers in the NMR.     

Experimental evaluation of the usefulness of feathers as a non-destructive biomonitor for polychlorinated biphenyls (PCBs) using silastic implants as a novel method of exposure

Risk assessment of pollutants requires both monitoring studies in the field and experimental exposure studies. In this study, we evaluated silastic implants as an alternative method of exposure for use in toxicological studies and at the same time evaluated the usefulness of feathers as a non-destructive biomonitor for PCBs. European starlings (Sturnus vulgaris) were exposed to different doses (including a control group) of environmentally relevant concentrations of PCB 153 during a 15-week period using silastic implants with both ends/only one end sealed. After implantation, there was a rapid and significant increase in PCB 153 blood concentration in the exposed groups. The significant differences in blood concentrations among the treatment groups show that silastic implants are useful as a method of exposure. Moreover, the ratio between the tissue concentrations of two treatment groups reflected the difference in implantation doses between these groups. There was also a clear difference in tissue concentrations among the treatment groups, although we could not test this statistically due to the small sample sizes. The slow release kinetics for a prolonged period and the relatively stable blood concentrations during the 15-week period render silastic tubes very interesting to study the effects of chronic exposure to pollutants. Our results also revealed that sealing both ends of the implant instead of only one did not significantly affect the exposure. There were strong, significant positive correlations between the blood and the tissues, which confirm the use of blood to monitor PCBs. To evaluate the usefulness of feathers as a non-destructive biomonitor for PCBs, we plucked the original and newly grown wing and tail feathers. We observed strong, significant positive correlations between the concentrations in the newly grown feathers and concentrations in the muscle, liver, brain and blood. PCB 153 concentrations in the newly grown feathers differed among the treatment groups. To our knowledge, our results provide the first experimental evidence that feathers are useful as a non-destructive biomonitoring tool for PCBs.     

Changes in the activity budgets of yellow baboons (Papio cynocephalus) during sexual consortships

Summary The energetic cost of guarding estrous females has been assumed to be a potentially major factor in limiting the duration of male consortships in a number of polygamous species. This issue has been examined in the present study by assessing changes in the usual activity budgets of 13 male and 20 female yellow baboons which occurred during their consortships.The percent of time adult males spent feeding was strongly related to their agonistic rank: Higher-ranking males fed proportionately more than lower-ranking males while not in consort, and they showed a relatively greater decrease in feeding time during consortships.The proportion of time females spent feeding was related to their agonistic rank and (to a lesser degree) to their parity. Higher-ranking females fed more than lower-ranking females outside of consortships, and showed a relatively greater decrease in time spent feeding while in consort. Nulliparous females tended to feed more than parous females while not in consort; during consortships, the feeding time of nulliparous females decreased, while that of parous females increased slightly.The activity of male and female consort partners was most coordinated during the fertile cycle stage of the female partner, and least coordinated once the female had passed the fertile stage.Although reductions in feeding time during consortships were generally much more pronounced in males than in females, neither males nor females appeared to attain the undisturbed optimal feeding level for their sex while in consort.     

In Flanders Fields: De/politicization and Democratic Debate on a GM Potato Field Trial Controversy in News Media

In May 2011, a highly mediatized direct action in the form of a “field liberation” took place in Flanders, Belgium, against a field trial of genetically modified potatoes. This direct action and its aftermath revealed the conflictual and antagonistic nature of the genetically modified organisms debate in Flanders. Consequently, it serves as a particularly suitable case to investigate the post-political thesis with regard to environmental discourse and politics. The aim of this paper is to investigate in what ways news media in their reporting contribute to processes of depoliticization and, resultantly, impede a democratic debate on the issues at stake. This paper attempts to provide an answer to this question based on a critical discourse analysis of the reporting by Flanders’ two generalist, elite newspapers, De Standaard and De Morgen and the alternative online news site DeWereldMorgen. The findings reveal the existence of three ideological cultures, which are characterized by different degrees of de/politicization. We conclude by discussing how this study adds to our understanding of the relation between the depoliticization of environmental discourse, democratic debate and twenty-first-century news media.     

THE ATMOSPHERIC WATER BALANCE AND THE HYDROLOGY OF LARGE RIVER BASINS1

The concept of using the atmospheric water balance technique in the study of the hydrology of large (greater than 10⁵km²) river basins is described. The atmospheric water balance technique consists of determining the spacial and time distributions and fluxes of water vapor through the atmospheric volume overlying the basin. The quantity precipitation minus evaporation at the earth's surface is determined as a residual of the computation. A review of the results of various experiments employing this technique is provided. The incorporation of the technique in a study of the hydrology of a large river basin is demonstrated by showing the results of a study of the hydrometeorology of the Upper Colorado River Basin. The example covers the study of eleven winter seasons, November through April, 1957–1968. The seasonal accumulation of water over the basin as determined by the atmospheric water balance is highly correlated with annual runoff. Correlation coefficient r = .8. The daily evaporation rate during dry days varies by a factor of two over the winter season, and is shown to be related to the incoming solar radiation intensity.