Application of Adjoint Approach to Oil Spill Problems

Adjoint method is applied to various oil spill problems. A three-dimensional model for describing the dispersion of a quasi-passive substance (a pollutant or a nutrient) and its adjoint model are considered in a limited sea region. Direct and adjoint estimates are used to get dual (equivalent) estimates of the mean concentration of the substance in important zones of the region. The role of dual estimates is illustrated with a few examples. They include such oil spill problems as the search of the most dangerous point of the oil tanker route, the oil dispersion with a climatic velocity, and the dependence of the oil concentration estimates on the oil spill rate. One more example is the application of optimal bioremediation strategy for cleaning a few zones polluted by oil. In this case, instead of oil, the model describes the dispersion of a nutrient released to marine environment. Balanced, unconditionally stable second-order finite-difference schemes based on the splitting method for the solution of the dispersion model and its adjoint are suggested. The main and adjoint difference schemes are compatible in the sense that at every fractional step of the splitting algorithm, the one-dimensional split operators of both schemes satisfy a discrete form of Lagrange identity. In the special unforced and non-dissipative case, each scheme has two conservation laws. Every split one-dimensional problem is solved by Thomas’ factorization method.     

A Method for Ensemble Wildland Fire Simulation

An ensemble simulation system that accounts for uncertainty in long-range weather conditions and two-dimensional wildland fire spread is described. Fuel moisture is expressed based on the energy release component, a US fire danger rating index, and its variation throughout the fire season is modeled using time series analysis of historical weather data. This analysis is used to characterize the seasonal trend in ERC, autocorrelation of residuals, and daily standard deviation and stochastically generate artificial time series of afternoon fuel moisture. Daily wind speed and direction are sampled stochastically from joint probabilities of historical wind speed and direction for the date range of the fire simulation period. Hundreds or thousands of fire growth simulations are then performed using the synthetic fire weather sequences. The performance of these methods is evaluated in terms of the number of ensemble member simulations, one- versus two-dimensional fire spread simulations, and comparison with results from 91 fires occurring from 2007 to 2009. Simulations were found to be in consistent agreement with observations, but trends indicate that the ensemble average of simulated fire sizes were consistently larger than actual fires whereas the farthest extent burned by fires was underestimated.     

On-line dechlorination–hydrogenation of chlorinated paraffin mixtures using GC and GC/MS

Chlorinated paraffins (CPs) are straight chain hydrocarbons that are produced as complex mixtures and are used as flame retardants and paint additives. These mixtures are extremely difficult to characterize using conventional chromatographic methods, as conventional gas chromatography results in unresolved complex chromatograms that preclude the identification and quantification of individual congeners or any reasonable assessment of the average carbon chain length. Carbon chain length is an important parameter for assessing physical properties and the toxicity of these materials. We have modified and improved a previously published gas chromatography–flame ionization detector method that uses Pd catalyst held in the gas chromatograph injector to simultaneously dechlorinate the CPs and separate the resulting alkanes. In addition, we have adapted this method to gas chromatography–mass spectrometry. Dehalogenation of other compounds was also studied with this system to investigate potential application to other complex halogenated mixtures.     

Impact of Drip Irrigation Method,Soil, and Virus Type on Tomato and Cucumber Contamination

The goal of this study was to better quantify the degree of viral contamination of tomato and cucumber in relationship to virus type, soil type, and irrigation method. Tomatoes and cucumbers were grown in ten-gallon (37.8 L) buckets filled with Pima clay loam or Brazito sandy loam soils. Plants were irrigated with secondary wastewater effluent using surface drip irrigation or subsurface drip irrigation. At specified time intervals irrigation water was seeded with bacteriophages MS-2 and P22, poliovirus type 1 (PV1), enteric adenovirus 40 (Ead 40), and hepatitis A virus. Surface drip irrigation always resulted in viral contamination of both the above and below ground parts of both crops. The roots showed the greatest level of contamination, followed by leaves and fruits. In contrast, with subsurface drip irrigation no viruses were detected in any of the above ground plant surfaces. It was found that under similar soil type and irrigation method, risk of crop contamination was similar for all of the viruses studied. It can be concluded that method of irrigation is the single most critical factor in the contamination trend of different parts of crop plants. Plant parts can be categorized into three groups (root, stem, and leaf/fruit) based on the risk of viral contamination from irrigation water.     

Vietnam’s seafood boom: Economic growth with impoverishment?

By 2050 most seafood will be sourced through aquaculture, with a range of production intensities being required to sustain livelihoods and to meet future needs from seafood. This makes Vietnam a particularly insightful case, since Vietnam is at the forefront of the trend toward greater aquaculture production. Our aim in this paper is to examine the social-ecological sustainability of small producer livelihoods contributing to Vietnam’s seafood boom. This paper uses original survey data to understand the range of fishery-based livelihoods that have contributed to Vietnam being a leading global exporter of seafood. We investigate the kinds of fishery-based livelihood activities that households are engaged in, consider the type and amount (kilograms) of species caught or farmed annually, and examine household perceptions’ of change in species quantity. We find that Vietnam’s seafood sector is facing real sustainability challenges: Nearly 30 % of small producers—fishers and fish farmers—within our sample rest at or below Vietnam’s rural poverty line. Ecological decline and disease in farmed fish is perceived to be a serious issue for all fishers. In this context, policy and management interventions need to better reflect social and ecological variability, adopt an integrated coastal systems perspective across fisheries and aquaculture, and consider the most impact-effective poverty interventions.     

Assessment of Eutrophication in Estuaries: Pressure–State–Response and Nitrogen Source Apportionment

A eutrophication assessment method was developed as part of the National Estuarine Eutrophication Assessment (NEEA) Program. The program is designed to improve monitoring and assessment of eutrophication in the estuaries and coastal bays of the United States with the intent to guide management plans and develop analytical and research models and tools for managers. These tools will help guide and improve management success for estuaries and coastal resources. The assessment method, a Pressure-State-Response approach, uses a simple model to determine Pressure and statistical criteria for indicator variables (where applicable) to determine State. The Response determination is mostly heuristic, although research models are being developed to improve that component. The three components are determined individually and then combined into a single rating. Application to several systems in the European Union (E.U.), specifically in Portugal, shows that the method is transferable, and thus is useful for development of management measures in both the Unites States and E.U. This approach identifies and quantifies the key anthropogenic nutrient input sources to estuaries so that management measures can target inputs for maximum effect. Because nitrogen is often the limiting nutrient in estuarine systems, examples of source identification and quantification for nitrogen have been developed for 11 coastal watersheds on the U.S. east coast using the WATERSN model. In general, estuaries in the Northeastern United States receive most of their nitrogen from human sewage, followed by atmospheric deposition. This is in contrast to some watersheds in the Mid-Atlantic (Chesapeake Bay) and South Atlantic (Pamlico Sound), which receive most of their nitrogen from agricultural runoff. Source identification is important for implementing effective management measures that should be monitored for success using assessment methods, as described herein. For instance, these results suggest that Northeastern estuaries would likely benefit most from improved sewage treatment, where as the Mid and South Atlantic systems would benefit most from agricultural runoff reductions.     

LEAST COST SOLUTIONS TO THE PROBLEM OF EFFLUENT ABATEMENT IN URBAN SYSTEMS1

ABSTRACT: There is a significant misallocation of resources in the construction and operation of municipal sewage treatment systems in North America. Central to this misallocation is the inadequate evaluation of alternative treatment technologies, alternative distributions of responsibility for waste treatment, and alternative mechanisms for inducing compliance with treatment system requirements. Perverse incentives in the current institutional structure limit the scope of alternatives examined by decisionmakers. Determination of the least cost solution to the problem of urban effluent abatement requires mathematical modeling for the delineation of optimal treatment strategies on a system wide basis. The adoption of modern methods of systems analysis can identify significant opportunities for the reduction of economic waste in the treatment of municipal sewage.     

Anishnaabe Aki: an indigenous perspective on the global threat of invasive species

Conservation discourses tend to portray invasive species as biological entities temporally connected to colonial timelines, using terms such as “alien”, “colonizing”, “colonial”, and “native”. This focus on a colonial timeline emerges from scientific publications within conservation biology and invasion ecology and is enacted through invasive species management by state and NGO actors. Colonialism is influential for indigenous nations in myriad ways, but in what ways do indigenous understandings of invasive species engage with colonialism? We conducted ethnographic research with indigenous Anishnaabe communities to learn about the ways Anishnaabe people conceptualize invasive species as a phenomenon in the world and were gifted with three primary insights. First, Anishnaabe regard plants, like all beings, as persons that assemble into nations more so than “species”. The arrival of new plant nations is viewed by some Anishnaabe as a natural form of migration. The second insight highlights the importance of actively discovering the purpose of new species, sometimes with the assistance of animal teachers. Lastly, while Anishnaabe describe invasive species as phenomenologically entangled with colonialism, the multiple ways Anishnaabe people think about invasive species provide alternatives to native–non-native binaries that dominate much of the scientific discourse.     

Increasing the sustainability of a resource development: Aboriginal engagement and negotiated agreements

While the role Aboriginal people play in environmental governance programs are often underpinned by the Crown, Aboriginal peoples are ratifying negotiated agreements with mining proponents to ensure their issues and concerns are addressed. This paper examines Aboriginal participation in mine development to show how more inclusive social and environmental development models can support a more sustainable development. Through two complementary processes, negotiated agreements and environmental impact assessment, Aboriginal peoples are maximizing their benefits and minimizing the adverse impacts of a project to create a more sustainable resource development. Case study analysis of the Galore Creek Project in northwestern British Columbia, Canada, illustrates how environmental impact assessment and negotiated agreements can co-exist to positively contribute to a successful mineral development, and hence operationalize sustainability within this context.