Reducing the carbon footprint of diets across socio-demographic groups in Finland: a mathematical optimisation study.

OBJECTIVES: To characterise nutritionally adequate, climate-friendly diets that are culturally acceptable across socio-demographic groups. To identify potential equity issues linked to more climate-friendly and nutritionally adequate dietary changes. DESIGN: An optimisation model minimises distance from observed diets subject to nutritional, greenhouse gas emissions (GHGE) and food-habit constraints. It is calibrated to socio-demographic groups differentiated by sex, education and income levels using dietary intake data. The environmental coefficients are derived from life cycle analysis and an environmentally extended input-output model. SETTING: Finland. PARTICIPANTS: Adult population. RESULTS: Across all population groups, we find large synergies between improvements in nutritional adequacy and reductions in GHGE, set at one-third or half of the current level. Those reductions result mainly from the substitution of meat with cereals, potatoes and roots and the intra-category substitution of foods, such as beef with poultry in the meat category. The simulated more climate-friendly diets are thus flexitarian. Moving towards reduced-impact diets would not create major inadequacies related to protein and fatty acid intakes, but Fe could be an issue for pre-menopausal females. The initial socio-economic gradient in the GHGE of diets is small, and the patterns of adjustments to more climate-friendly diets are similar across socio-demographic groups. CONCLUSIONS: A one-third reduction in GHGE of diets is achievable through moderate behavioural adjustments, but achieving larger reductions may be difficult. The required changes are similar across socio-demographic groups and do not raise equity issues. A population-wide policy to promote behavioural change for diet sustainability would be appropriate.

Water accounting as a tool for tracing the industries responsible for the point-source loads into water bodies.

Returning flows of water from the economy to the environment, particularly wastewaters, are highly important contributors to the quality of freshwater resources and the health of aquatic ecosystems. While the total loads of various harmful substances received by wastewater treatment facilities are often measured and reported, the origins of these loads are generally not allocated to specific industries. Instead, they pass from treatment facilities to the environment and are thus simply attributed to arising from the sewerage industry. In this study, we introduce a method for employing high-quality water accounting of the phosphorous and nitrogen loads and apply it to the Finnish economy. We also introduce a means for assessing the quality of the resulting accountancies and, for our Finnish case study, we show a close correspondence between independent top-down and bottom-up calculations, indicating the figures are highly reliable. We thus conclude, firstly, that the presented methodology can produce versatile and reliable data on different wastewater-related loads in the water; secondly, that such data can assist in developing appropriate mitigation strategies; and, thirdly, that the data may also be applied in further sustainability analyses, such as in environmentally extended input-output modelling.

Efficient protection of the Baltic Sea needs a revision of phosphorus metric.

Eutrophication of the Baltic Sea is driven by phosphorus and nitrogen. While the anthropogenic point source loads of both nutrients have decreased markedly, further reductions are needed. This is true particularly for phosphorus, as highlighted by its stringent abatement targets in HELCOM's Baltic Sea Action Plan. To meet the targets, more results need to be achieved in non-point source abatement, specifically from agricultural sources. The growing pressure for phosphorus abatement from agriculture may lead to environmentally and economically inefficient outcomes unless we account for the variability in how different forms of phosphorus respond to abatement measures, and how these forms contribute to eutrophication. The precautionary and efficiency improving way to advance policies is to either replace or supplement the Total Phosphorus metric with a metric more accurate in reflecting the biologically available phosphorus. This policy fix becomes more important as the relative share of agricultural emissions of total pollution increases.

Ethanol-based in situ bioremediation of acidified, nitrate-contaminated groundwater.

A novel approach for the in situ bioremediation of acidified, nitrate-contaminated groundwater was developed. Ethanol was introduced into the groundwater to enhance the activity of intrinsic denitrifying micro-organisms. Infiltration of the carbon source was made via an infiltration gallery constructed in the unsaturated zone to avoid clogging problems and to allow wider distribution of ethanol in the groundwater. The changes in the groundwater geochemistry and soil gas composition were monitored at the site to evaluate the efficiencies of the infiltration system and nitrate removal. Moreover, the impact of pH and ethanol addition on the denitrification rate was studied in laboratory. A reduction of 95% was achieved in the groundwater nitrate concentrations during the study. Neither clogging problems nor inefficient introduction of ethanol into the saturated zone were observed. Most crucial to the denitrifying communities was pH, values above 6 were required for efficient denitrification.

Monitored natural attenuation.

Monitored natural attenuation (MNA) is an in situ remediation technology that relies on naturally occurring and demonstrable processes in soil and groundwater which reduce the mass and concentration of the contaminants. Natural attenuation (NA) involves both aerobic and anaerobic degradation of the contaminants due to the fact that oxygen is used up near the core of the contaminant plume. The aerobic and anaerobic microbial processes can be assessed by microbial activity measurements and molecular biology methods in combination with chemical analyses. The sampling and knowledge on the site conditions are of major importance for the linkage of the results obtained to the conditions in situ. Rates obtained from activity measurements can, with certain limitations, be used in modeling of the fate of contaminants whereas most molecular methods mainly give qualitative information on the microbial community and gene abundances. However, molecular biology methods are fast and describe the in situ communities and avoid the biases inherent to activity assays requiring laboratory incubations.

Acetate and ethanol as potential enhancers of low temperature denitrification in soil contaminated by fur farms: a pilot-scale study.

Ethanol and acetate were examined as potential candidates to enhance denitrification at low temperature in soils contaminated by fur farms. Five pilot-scale sand and gravel columns with a top layer of soil from a fur farm were set up and fed with nitrate-containing water (influent concentration of 100 and 200 mg L(-1)) for 459 days at 6+/-2 degrees C. Two of the columns also received acetate and two other ethanol while one received no additional C-substrate. During the experiment, various C:N-ratios were tested to find the most optimal concentration of the added C-substrates, and effluent concentrations of nitrate, nitrite, and TOC were monitored. At the end of the experiments, soils in the columns were unpacked and the soils were used to measure a pattern of enzyme activities and the rates of denitrification in microcosms. The fur farm contaminated soil appeared to harbour a good intrinsic potential for denitrification, which could be greatly enhanced by the introduction of ethanol or acetate. Consequently, in the C-substrate-fed columns, 95-100% of the influent nitrate was removed after an acclimatization period of some weeks. Ethanol with C:N-ratio of ca. 6 at the nitrate level 200 mg L(-1) proved to be the most promising candidate to be used in field trials.

Functional gene abundances (nahAc, alkB, xylE) in the assessment of the efficacy of bioremediation.

In this study, we compared the mineralization rates of three selected (14)C-labeled hydrocarbon compounds, octacosane, toluene, and naphthalene, with the presence of the corresponding functional genes (alkB, xylE, nahAc) in a large number of soil samples representing different types of soil and petroleum hydrocarbon contamination. Functional genes were enumerated by the replicate limited dilution (RLD) polymerase chain reaction (PCR) technique. RLD-PCR was further compared to real-time PCR measurements for nahAc and xylE for some samples. At a heating oil-contaminated site, octacosane mineralization rates were higher (on average 0.0015 day(-1)) when compared to aerobic naphthalene and toluene mineralization (on average 0.00003 and 0.0007 day(-1)). The corresponding gene abundances measured by RLD-PCR were on average 0.95, 0.3, and 0.13 x 10(3) gene copies g(-1) soil for alkB, nahAc, and xylE, respectively. At a site contaminated with gasoline, the situation was the opposite: Toluene mineralization was the highest (on average 0.0031 day(-1)), and only xylE genes could be detected (on average 0.13 x 10(3) gene copies g(-1) soil by RLD-PCR). XylE and nahAc gene abundances were correlated with the (14)C-toluene and naphthalene mineralization activities, respectively, in samples from aerobic layers. AlkB gene abundances were not correlated with the octacosane mineralization. Real-time PCR was a more sensitive method than RLD-PCR by a factor of 1,200 for nahAc and 300 for xylE. In conclusion, functional gene abundances seemed to reflect the type of the contamination. With optimized assays, the gene abundances can be used to assess bioremediation efficacy.

Degradation rates of aged petroleum hydrocarbons are likely to be mass transfer dependent in the field.

Evidence for on site biodegradation may be difficult to provide at heterogeneous sites without additional experiments in controlled laboratory conditions. In this study, microbial activities measured as CO2 and CH4 production were compared in situ, in intact soil cores and in bottle microcosms containing sieved soils. In addition, biodegradation rates were determined by measuring the decrease in petroleum hydrocarbon concentrations at 7 degrees C in aerobic and anaerobic conditions. Elevated concentrations of CO2 and CH4 in the soil gas phase indicated that both the aerobic and anaerobic microbial activity potentials were high at the contaminated site. Aerobic and anaerobic microbial degradation rates in laboratory experiments of petroleum hydrocarbons were highest in soils from the most contaminated point and degradation in the aerobic and anaerobic microcosms was linear throughout the incubation, indicating mass-transfer-dependent degradation. Different results for microbial activity measurements were obtained in laboratory studies depending on pretreatment and size of the sample, even when the environmental conditions were mimicked. These differences may be related to differences in the gas exchange rates as well as in changes in the bioavailability of the contaminant in different analyses. When predicting by modeling the behavior of an aged contaminant it is relevant to adapt the models in use to correspond to conditions relevant at the contaminated sites. The variables used in the models should be based on data from the site and on experiments performed using the original aged contaminant without any additions.

Occurrence and rates of terminal electron-accepting processes and recharge processes in petroleum hydrocarbon-contaminated subsurface.

The occurrence and rates of terminal electron acceptor processes, and recharge processes in the unsaturated zone of a boreal site contaminated with petroleum hydrocarbons in the range C(10) to C(40) were examined. Soil microcosms were used to determine the rates of denitrification, iron (Fe) reduction, sulfate (SO(4)) reduction, and methanogenesis in two vertical soil profiles contaminated with oil, and in a noncontaminated reference sample. Furthermore, the abundances of the 16S rRNA genes belonging to Geobacteracaea in the samples were determined by real-time quantitative polymerase chain reaction (PCR). Analyses of ground water chemistry and soil gas composition were also performed together with continuous in situ monitoring of soil water and ground water chemistry. Several lines of evidence were obtained to demonstrate that both Fe reduction and methanogenesis played significant roles in the vertical profiles: Fe reduction rates up to 3.7 nmol h(-1) g(-1) were recorded and they correlated with the abundances of the Geobacteracaea 16S rRNA genes (range: 2.3 x 10(5) to 4.9 x 10(7) copies g(-1)). In the ground water, ferrous iron (Fe(2+)) concentration up to 55 mg L(-1) was measured. Methane production rates up to 2.5 nmol h(-1) g(-1) were obtained together with methane content up to 15% (vol/vol) in the soil gas. The continuous monitoring of soil water and ground water chemistry, microcosm experiments, and soil gas monitoring together demonstrated that the high microbial activity in the unsaturated zone resulted in rapid removal of oxygen from the infiltrating recharge thus leaving the anaerobic microbial processes dominant below 1.5 m depth both in the unsaturated and the saturated zones of the subsurface.

Use of potassium formate in road winter deicing can reduce groundwater deterioration.

We present here an aquifer scale study on the fate of potassium formate, an alternative, weakly corrosive deicing agent in soil and subsurfaces. Potassium formate was used to deice a stretch of a highway in Finland. The fate of the formate was examined by monitoring the groundwater chemistry in the underlying aquifer of which a conceptual model was constructed. In addition, we determined aerobic and anaerobic biodegradation rates of formate at low temperatures (-2 to +6 degrees C) in soil microcosms. Our results show that the formate did not enter the saturated zone through the thin vadose zone; thus, no undesirable changes in the groundwater chemistry were observed. Furthermore, the conceptual model explained the distribution of chloride in the aquifer used in deicing for the past 30 years. We recorded mineralization potential up to 97% and up to 17% within 24 h under aerobic and anaerobic conditions, respectively, in the soil and subsurface samples obtained from the site. This demonstrates that biodegradation in the topsoil layers was responsible for the removal of the formate. We conclude that the use of potassium formate can potentially help diminish the negative impacts of road winter deicing on groundwater without jeopardizing traffic safety.

Degradation of potassium formate in the unsaturated zone of a sandy aquifer.

This paper presents results from a lysimeter experiment on the fate of potassium formate, an alternative deicing agent. The experiment was performed through the winter and spring to identify any thermal sensitivity in the transport and biodegradation of formate in the lysimeter. Ninety-eight percent of the total quantity of formate applied was degraded while percolating through the 1.7-m-thick unsaturated sand layer within the lysimeter. Concomitantly, the bicarbonate concentration of the percolating water increased. The low concentrations of nitrogen (0.02 mg L(-1)) and phosphorous (<0.002 mg L(-1)) in the percolated water, however, potentially limited microbial activity. During the study period, 99% of the applied potassium was retained in the lysimeter, and the ion exchange between the potassium and a variety of monovalent and divalent ions was assumed to be responsible for the leaching of barium, calcium, magnesium, and sodium from the soil material. Except for manganese, the concentrations of the studied metals in the percolated water did not exceed the threshold values set for drinking water by the Council of the European Union. By contrast, the application of potassium formate had a detrimental effect on the vegetation on the lysimeter. To conclude, formate was effectively degraded in the sandy lysimeter and its application did not cause major undesirable changes in the quality of the percolating water. Further research at field scale is, however, needed for instance on the biodegradation of potassium formate and on its impacts on roadside vegetation.

Potential for aerobic and anaerobic biodegradation of petroleum hydrocarbons in boreal subsurface.

We studied the role of aerobic and anaerobic petroleum hydrocarbon degradation at a boreal, light-weight fuel and lubrication oil contaminated site undergoing natural attenuation. At the site, anoxic conditions prevailed with high concentrations of CH4 (up to 25% v/v) and CO2 (up to 18% v/v) in the soil gas throughout the year. Subsurface samples were obtained mainly from the anoxic parts of the site and they represented both the unsaturated and saturated zone. The samples were incubated in microcosms at near in situ conditions (i.e. in situ temperature 8 degrees C, aerobic and anaerobic conditions, no nutrient amendments) resulting in the removal of mineral oil (as determined by gas chromatography) aerobically as well as anaerobically. In the aerobic microcosms on average 31% and 27% of the initial mineral oil was removed during a 3- and 4-month incubation, respectively. In the anaerobic microcosms, on average 44% and 15% of the initial mineral oil was removed during a 12- and 10-month anaerobic incubation, respectively, and e.g. n-alkanes from C11 to C15 were removed. A methane production rate of up to 2.5 microg CH4 h(-1) g(-1) dwt was recorded in these microcosms. In the aerobic as well as anaerobic microcosms, typically 90% of the mineral oil degraded belonged to the mineral oil fraction that eluted from the gas chromatograph after C10 and before C15, while 10% belonged to the fraction that eluted after C15 and before C40. Our results suggest that anaerobic petroleum hydrocarbon degradation, including n-alkane degradation, under methanogenic conditions plays a significant role in the natural attenuation in boreal conditions.

The abundance of nahAc genes correlates with the 14C-naphthalene mineralization potential in petroleum hydrocarbon-contaminated oxic soil layers.

In this study, we evaluated whether the abundance of the functional gene nahAc reflects aerobic naphthalene degradation potential in subsurface and surface samples taken from three petroleum hydrocarbon contaminated sites in southern Finland. The type of the contamination at the sites varied from lightweight diesel oil to high molecular weight residuals of crude oil. Samples were collected from both oxic and anoxic soil layers. The naphthalene dioxygenase gene nahAc was quantified using a replicate limiting dilution-polymerase chain reaction (RLD-PCR) method with a degenerate primer pair. In the non-contaminated samples nahAc genes were not detected. In the petroleum hydrocarbon-contaminated oxic soil samples nahAc gene abundance [range 3 x 10(1)-9 x 10(4) copies (g dry wt soil)(-1)] was correlated (Kendall non-parametric correlation r2=0.459, p<0.01) with the aerobic 14C-naphthalene mineralization potential (range 1 x 10(-5)-0.1 d(-1)) measured in microcosms at in situ temperatures (8 degrees C for subsurface and 20 degrees C for surface soil samples). In these samples nahAc gene abundance was also correlated with total microbial cell counts (r2=0.471, p<0.01), respiration rate (r2=0.401, p<0.01) and organic matter content (r2=0.341, p<0.05). NahAc genes were amplified from anoxic soil layers indicating that, although involved in aerobic biodegradation of naphthalene, these genes or related sequences were also present in the anoxic subsurface. In the samples taken from the anoxic layers, the aerobic 14C-naphthalene mineralization rates were not correlated with nahAc gene abundance. In conclusion, current sequence information provides the basis for a robust tool to estimate the naphthalene degradation potential at oxic zones of different petroleum hydrocarbon-contaminated sites undergoing in situ bioremediation.