Comparisons of soil surface sealing methods to reduce fumigant emission loss

State and federal regulatory agencies depend on quality field data for determining the effects of agricultural management practices on fumigant emissions to develop sound, science-based policies and regulations on preplant soil fumigants. Field plot tests, using growers' standard field operation procedures, were used to simultaneously determine the effectiveness of several commonly proposed emission reduction methods, in a trial involving shank injection of Telone II [a.i. 1,3-dichloropropnene (1,3-D)] to a sandy loam soil to a target rate of 372 kg ha(-1). The experiment was conducted in late September 2008 in the San Joaquin Valley of California. Fumigant emissions were captured using dynamic flux chambers. The results showed that virtually impermeable film (VIF) reduced emissions >95% when compared to bare soil, and the glue joints in the film did not significantly affect the tarp performance. The VIF also created a more uniform distribution of gaseous fumigant in the soil profile, which would likely benefit pest control efficacy. Standard high-density polyethylene (HDPE) tarp reduced total 1,3-D emissions about 50% (higher than most reported values) in this trial, whereas postfumigation intermittent water treatments (seals) reduced cumulative emission losses by approximately 20%. Adding 49.4 Mg ha (equivalent to 20 tons per acre) of composted dairy manure to surface soils did not reduce 1,3-D emissions during this experiment. Use of VIF was the most promising technique in reducing emissions and has the potential to allow lower application rates while providing satisfactory pest control.     

Field evaluation of a new plastic film (vapor safe) to reduce fumigant emissions and improve distribution in soil

Preplant soil fumigation is an important pest management practice in coastal California strawberry production regions. Potential atmospheric emissions of fumigants from field treatment, however, have drawn intensive environmental and human health concerns; increasingly stringent regulations on fumigant use have spurred research on low-emission application techniques. The objectives of this research were to determine the effects of a new low-permeability film, commonly known as totally impermeable film (TIF), on fumigant emissions and on fumigant distribution in soil. A 50/50 mixture of 1,3-dichloropropene (1,3-D) and chloropicrin (CP) was shank-applied at 314 kg ha in two location-separate field plots (0.4 ha each) in Ventura County, California, in fall 2009. One plot was surface-covered with standard polyethylene (PE) film, and the other was covered with TIF immediately after fumigant application. Data collection included emissions, soil-gas phase concentration profile, air concentration under the film, and soil residuals of the applied fumigants. Peak emission flux of 1,3-D and CP from the TIF field was substantially lower than from the PE field. Total through-film emission loss was 2% for 1,3-D and <1% for CP from the TIF field during a 6-d film covering period, compared with 43% for 1,3-D and 12% for CP from the PE field. However, on film-cutting, greater retention of 1,3-D in the TIF field resulted in a much higher emission surge compared with the PE field, while CP emissions were fairly low in both fields. Higher concentrations and a more uniform distribution in the soil profile for 1,3-D and CP were observed under the TIF compared with the PE film, suggesting that the TIF may allow growers to achieve satisfactory pest control with lower fumigant rates. The surging 1,3-D emissions after film-cutting could result in high exposure risks to workers and bystanders and must be addressed with additional mitigation measures.     

Challenges to the implementation of a sustainable development certification programme for the minerals and metals industry

Private, voluntary eco-labelling and certification programmes are being developed for a number of industries to promote and verify higher environmental, economic and social standards. In some cases, these initiatives have developed regardless of whether there is initial, broad support within industry. This article seeks to identify some of the challenges inherent in the implementation of a sustainable development certification programme for the minerals and metals industry. The article looks for guidance from initiatives that are drawn for the most part from other resource industries, most notably forestry. While the article takes a Canadian perspective, many of the challenges raised in the article are also applicable internationally. The article concludes that stakeholders can learn from other resource industries if a decision is made to develop a certification programme for the minerals and metals industry. Crucial to the long-term success of such a programme will be the establishment of a true partnership among stakeholders throughout the initiative's development. Crown Copyright.     

Vested Interest theory and disaster preparedness

Three studies were designed to extend a combination of vested interest theory (VI) and the extended parallel process model of fear appeals (EPPM) to provide formative research for creating more effective disaster preparedness social action campaigns. The aim was to develop an effective VI scale for assessing individual awareness and ‘vestedness’ relevant to disaster preparedness. Typical preparedness behaviours are discussed with emphasis on earthquakes and tornados in particular. Brief overviews of VI and the EPPM are offered, and findings are presented from three studies (one dealing with earthquakes, and two with tornados) conducted to determine the factor structure of the key VI components involved, and to develop and test subscales derived from the two theories. The paper finishes with a discussion of future research needs and suggestions on how the new subscales may be applied in the design and execution of more effective disaster preparedness campaigns.     

Evaluation of the QUIC-URB fast response urban wind model for a cubical building array and wide building street canyon

This paper describes the QUIC-URB fast response urban wind modeling tool and evaluates it against wind tunnel data for a 7 × 11 cubical building array and wide building street canyon. QUIC-URB is based on the Röckle diagnostic wind modeling strategy that rapidly produces spatially resolved wind fields in urban areas and can be used to drive urban dispersion models. Röckle-type models do not solve transport equations for momentum or energy; rather, they rely heavily on empirical parameterizations and mass conservation. In the model-experiment comparisons, we test two empirical building flow parameterizations within the QUIC-URB model: our implementation of the standard Röckle (SR) algorithms and a set of modified Röckle (MR) algorithms. The MR model attempts to build on the strengths of the SR model and introduces additional physically based, but simple parameterizations that significantly improve the results in most regions of the flow for both test cases. The MR model produces vortices in front of buildings, on rooftops and within street canyons that have velocities that compare much more favorably to the experimental results. We expect that these improvements in the wind field will result in improved dispersion calculations in built environments.     

The Decline of Amphibians in California's Great Central Valley

Declines in amphibian populations are rarely reported on the community or ecosystem level. We combined broad-scale field sampling with historical analyses of museum records to quantify amphibian declines in California's Great Central Valley. Overall, amphibians showed an unambiguous pattern of decline, although the intensity of decline varied both geographically and taxonomically. The greatest geographical decline was detected in the counties of the Sacramento and San Joaquin Valleys. Two species, Rana aurora and Bufo boreas were identified as the most affected by decline, whereas Pseudacris regilla was the least affected. The Coast Range counties had little or no detectable decline. We provide new evidence implicating introduced predators as a primary threat. Introduced predators occur at lower elevations than native species, and our data indicate that for some native species there has been significant restriction to higher elevation sites from a formerly broader distribution. Our historical approach provides a strategy for identifying declining amphibian communities that complements more detailed, long-term monitoring programs and provides an assessment of the pattern of change that is a necessary prerequisite for the development of field experiments that test hypothesized mechanisms of change.     

Environmental sampling of volatile organic compounds during the 2018 Camp Fire in Northern California

Trace analysis of volatile organic compounds (VOCs) during wildfires is imperative for environmental and health risk assessment. The use of gas sampling devices mounted on unmanned aerial vehicles (UAVs) to chemically sample air during wildfires is of great interest because these devices move freely about their environment, allowing for more representative air samples and the ability to sample areas dangerous or unreachable by humans. This work presents chemical data from air samples obtained in Davis, CA during the most destructive wildfire in California's history - the 2018 Camp Fire – as well as the deployment of our sampling device during a controlled experimental fire while fixed to a UAV. The sampling mechanism was an in-house manufactured micro-gas preconcentrator (µPC) embedded onto a compact battery-operated sampler that was returned to the laboratory for chemical analysis. Compounds commonly observed in wildfires were detected during the Camp Fire using gas chromatography mass spectrometry (GC–MS), including BTEX (benzene, toluene, ethylbenzene, m+p-xylene, and o-xylene), benzaldehyde, 1,4-dichlorobenzene, naphthalene, 1,2,3-trimethylbenzene and 1-ethyl-3-methylbenzene. Concentrations of BTEX were calculated and we observed that benzene and toluene were highest with average concentrations of 4.7 and 15.1 µg/m³, respectively. Numerous fire-related compounds including BTEX and aldehydes such as octanal and nonanal were detected upon experimental fire ignition, even at a much smaller sampling time compared to samples taken during the Camp Fire. Analysis of the air samples taken both stationary during the Camp Fire and mobile during an experimental fire show the successful operation of our sampler in a fire environment.     

Effect of Light on Biodegradation of Estrone, 17β‐Estradiol,and 17α‐Ethinylestradiol in Stream Sediment

Biodegradation of [A‐ring ¹⁴C] Estrone (E1), 17β‐estradiol (E2), and 17α‐ethinylestradiol (EE2) to ¹⁴CO₂ was investigated under light and dark conditions in microcosms containing epilithon or sediment collected from Boulder Creek, Colorado. Mineralization of the estrogen A‐ring was observed in all sediment treatments, but not epilithon treatments. No difference in net mineralization between light and dark treatments was observed for ¹⁴C‐E2. Net mineralization of ¹⁴C‐E1 and ¹⁴C‐EE2 was enhanced in light treatments. Extents of ¹⁴CO₂ accumulation and rates of mineralization were significantly greater for E2 than E1 under dark conditions, but were comparable under light conditions. These results indicate substantial differences in the uptake and metabolism of E1 and E2 in the environment and suggest biorecalcitrance of E1 relative to E2 in light‐limited environments. The extent of ¹⁴CO₂ accumulation and rate of mineralization for EE2 in dark treatments were less than half of that observed for E2 and generally lower than for E1, consistent with previous reports of EE2 biorecalcitrance. However, ¹⁴CO₂ accumulation and rates of mineralization were comparable for EE2, E2, and E1 under light conditions. These results indicate photoactivation and/or phototransformation/photodegradation processes can substantially enhance heterotrophic biodegradation of estrogens in sunlit environments and may play an important role in estrogen transport and attenuation.     

The role of scientific studies in building consensus in environmental decision making: a coral reef example

We present a new approach for characterizing the potential of scientific studies to reduce conflict among stakeholders in an analytic-deliberative environmental decision-making process. The approach computes a normalized metric, the Expected Consensus Index of New Research (ECINR), for identifying where additional scientific research will best support improved decisions and resolve possible conflicts over preferred management actions. The ECINR reflects the expected change in agreement among parties over preferred management actions with the implementation and consideration of new scientific studies. We demonstrate the ECINR method based on a preliminary application to coral reef protection and restoration in the Guánica Bay Watershed, Puerto Rico, focusing on assessing and managing anthropogenic stressors, including sedimentation and pollution from land-based sources such as sewage, agriculture, and development. Structured elicitations of values and beliefs conducted at a coral reef decision support workshop held at La Parguera, Puerto Rico, are used to develop information for illustrating the methodology. The ECINR analysis was focused on a final study group of seven stakeholders, consisting of resource managers and scientists, who were not in agreement on the efficacy and respective benefits of reducing loadings from three sources: sewage, agriculture, and development. The scenario assumed that loadings would be reduced incrementally from each source through a series of management steps, which would be ranked in order of maximizing anticipated benefits. An examination of whether beliefs exhibited greater confidence and coherence between stakeholders when informed by plausible study results followed. The results suggest that new scientific research would be generally likely to bring people who initially disagreed to agree. Seventy-five percent of the hypothetical research results were projected to result in more agreement among the stakeholders. However, there can be situations where prior beliefs may be too different from the study results to shift perspectives enough to result in more agreement. Furthermore, in a few cases, hypothetical research results were projected to lead to more conflict among stakeholders. Priority research, according to the seven stakeholders, would be to quantify loadings from agriculture and sewage, and not loadings from development, since it is predicted to make little difference in the outcome. Assuming the stakeholders are conflict-averse, they would likely opt for research on sewage loadings as the highest priority. Though preliminary, these results suggest that ECINR can provide useful insights into the social implications of a research program.     

Practicing food justice at Dig Deep Farms & Produce,East Bay Area,California: self-determination as a guiding value and intersections with foodie logics

This article describes Dig Deep Farms & Produce, a food justice organisation and urban farm working to stimulate local economic development, create jobs, and improve the quality and accessibility of food in Ashland and Cherryland in California's Bay Area. Their practices are based on self-determined values although they take a flexible, anti-essentialist approach to foodie logics, which are prominent and problematic in the Bay Area. The case study then examines specific practices and strategies, as well as intersections with foodie logics, in three arenas – values determination, strategic partnerships, and foodways – that help to cultivate food justice and highlights key characteristics of food justice work: emphasising self-determination and working to fundamentally change the economic and social conditions of food apartheid.