Response of Nitrogen Loading to the Chesapeake Bay to Source Reduction and Land Use Change Scenarios: A SPARROW‐Informed Analysis

In response to concerns regarding the health of streams and receiving waters, the United States Environmental Protection Agency established a total maximum daily load for nitrogen in the Chesapeake Bay watershed for which practices must be in place by 2025 resulting in an expected 25% reduction in load from 2009 levels. The response of total nitrogen (TN) loads delivered to the Bay to nine source reduction and land use change scenarios was estimated using a Spatially Referenced Regression on Watershed Attributes model. The largest predicted reduction in TN load delivered to the Bay was associated with a scenario in which the mass of TN as fertilizer applied to agricultural lands was decreased. A 25% decrease in the mass of TN applied as fertilizer resulted in a predicted reduction in TN loading to the Bay of 11.3%, which was 2.5–5 times greater than the reductions predicted by other scenarios. Eliminating fertilizer application to all agricultural land in the watershed resulted in a predicted reduction in TN load to the Bay of 45%. It was estimated that an approximate 25% reduction in TN loading to the Bay could be achieved by eliminating fertilizer applied to the 7% of subwatersheds contributing the greatest fertilizer‐sourced TN loads to the Bay. These results indicate that management strategies aimed at decreasing loading from a small number of subwatersheds may be effective for reducing TN loads to the Bay, and similar analyses are possible in other watersheds.     

Soil acidification and foliar nutrient status of Ontario's deciduous forest in 1986 and 2005

To assess the impacts of the decline in sulphur (S) deposition over the past 20 years in Ontario, soil chemistry and sugar maple (Acer saccharum Marsh) foliar chemistry were measured at 17 sites in south and central Ontario in 2005 and compared with archived samples collected in 1986. Foliar S concentrations were lower in 2005, reflecting the decline in S deposition whereas foliar N remained unchanged, reflecting the lack of change in N deposition in Ontario. Mineral soil pH, exchangeable base cations were lower in 2005 whereas total S, N and cation exchange capacity (CEC) were unchanged. Foliar concentrations of Ca were positively related to soil Ca levels in the A-horizon and were lower in 2005. Despite evidence of increasing soil acidity and losses of calcium, foliar base cation concentrations at most sites were adequate for sugar maple and forest health in terms of canopy appearance (Decline Index) improved.     

下辽河平原多熟种植农业生态模式知识库研建

本文以下辽河平原为背景,应用专家系统开发工具建立了多熟种植农业生态模式知识库,提出了建立该专家系统知识库的步骤：包括知识获取、知识表达、编码及证实。该专家系统知识库的建立能将有关多熟种植领域的专门知识和领域专家的经验以可接受的方式传递给农业决策者,从而提高农业决策的自动化和科学化。     

A laboratory study of sediment and contaminant release during gas ebullition

Significant quantities of gas are generated from labile organic matter in contaminated sediments. The implications for the gas generation and subsequent release of contaminants from sediments are unknown but may include enhanced direct transport such as pore water advection and diffusion. The behavior of gas in sediments and the resulting migration of a polyaromatic hydrocarbon, viz phenanthrene, were investigated in an experimental system with methane injection at the base of a sediment column. Hexane above the overlying water layer was used to trap any phenanthrene migrating out of the sediment layer. The rate of suspension of solid particulate matter from the sediment bed into the overlying water layer was also monitored. The experiments indicated that significant amounts of both solid particulate matter and contaminant can be released from a sediment bed by gas movement with the amount of release related to the volume of gas released. The effective mass transfer coefficient of gas bubble-facilitated contaminant release was estimated under field conditions, being around three orders of magnitude smaller than that of bioturbation. A thin sand-capping layer (2 cm) was found to dramatically reduce the amount of contaminant or particles released with the gas because it could prevent or at least reduce sediment suspension. Based on the experimental observations, gas bubble-facilitated contaminant transport pathways for both uncapped and capped systems were proposed. Sediment cores were sliced to obtain phenanthrene concentration. X-ray computed tomography (CT) was used to investigate the void space distribution in the sediment penetrated by gas bubbles. The results showed that gas bubble migration could redistribute the sediment void spaces and may facilitate pore water circulation in the sediment.     

Remote sensing-based neural network mapping of tsunami damage in Aceh, Indonesia

In addition to the loss of human life, the tsunami event of 26 December 2004 caused extensive damage to coastal areas. The scale of the disaster was such that remote sensing may be the only way to determine its effects on the landscape. This paper presents the results of a neural network-based mapping of part of the region of Aceh, Sumatra. Before-and-after satellite imagery, combined with a novel neural network methodology, enabled a characterisation of landscape change. The neural network technique used a threshold of acceptance for identification, in combination with a bootstrapped identification method for identifying problem pixels. Map analysis allowed identification of urban areas that were inaccessible by road, and which aid agencies could therefore only reach by air or sea. The methods used provide a rapid and effective mapping ability and would be a useful tool for aid agencies, insurance underwriters and environmental monitoring.     

How Certain Are Salmon Recovery Forecasts? A Watershed-scale Sensitivity Analysis

Complex relationships between landscape and aquatic habitat conditions and salmon (Oncorhynchus spp.) populations make science-based management decisions both difficult and essential. Due to a paucity of empirical data, models characterizing these relationships are often used to forecast future conditions. We evaluated uncertainties in a suite of models that predict possible future habitat conditions and fish responses in the Lewis River Basin, Washington, USA. We evaluated sensitivities of predictions to uncertainty in model parameters. Results were sensitive to 60% of model parameters but substantially so (|partial regression coefficients| >0.5) to <10%. We also estimated accuracy of several predictions using field surveys. Observations mostly fell within predicted ranges for riparian shade and fine-sediment deposition, but large woody debris estimates matched only half the time. We provide suggestions to modelers for improving model accountability, and describe how managers can incorporate prediction uncertainty into decision-making, thereby improving the odds of successful salmon habitat recovery.     

The mini mobile environmental monitoring unit: a novel bio-assessment tool

This paper introduces a new bio-assessment tool, the mini-mobile environmental monitoring unit (MMU). The MMU is a portable, lightweight, energy-efficient, miniaturized laboratory that provides a low-flow system for on-site exposure of aquatic animals to local receiving waters in a protected, controllable environment. Prototypes of the MMU were tested twice in week-long studies conducted during the summers of 2008 and 2009, and in a 12-day study in 2010. In 2008, fathead minnows and polar organic chemical integrative samplers (POCIS) were deployed downstream from the Hastings, Nebraska wastewater treatment plant (WWTP), a waterway known to contain estrogenic contaminants in biologically active concentrations. In 2009, minnows and POCIS were deployed downstream, upstream and within the Grand Island, Nebraska WWTP, a site where the estrogenic contaminants had been detected, but were found at levels below those necessary to directly impact fish. In 2010, an advanced prototype was tested at the Sauk Center, Minnesota WWTP to compare its performance with that of traditional fish exposure methods including caged fish and static-renewal laboratory testing of effluent. Results from the prototype illustrate the capabilities of the MMU and offer an inexpensive monitoring tool to integrate the effects of pollutant sources with temporally varying composition and concentration.     

Audience Response to Values-based Marketplace Advocacy by the Fossil Fuel Industries

A form of issue advocacy, marketplace advocacy campaigns often arise in response to burgeoning societal concerns, especially those faced by energy industries. Although these campaigns may include brief and selective references to corporate activities, most campaigns place a much stronger emphasis on commonly shared societal values. This study examines audience response to values-based environmental marketplace advocacy messages by the fossil fuel industries through a series of focus groups. Four instrumental values were identified in campaign videos (innovation, community, resilience, and patriotism), and the terminal value of pragmatism, especially as it relates to environmental issues, was identified as a result of identification with one or more of the instrumental values. The findings are discussed through the lens of extant research on marketplace advocacy and organizational values as well as Habermas's theory of refuedalization, shedding light on the ways corporations appeal to commonly held societal values in an effort to generate support for a given industry.     

Comparison of Observed and Predicted Sector-Averaged Air Concentrations for Elevated Releases of Fluorescein Particles

The DWNWND gaussian plume computer code was used to calculate normalized 22.5° sector-averaged dispersant concentrations at distances from 400 to 7000 meters downwind from a 56 m high release point. These results were compared to sector average values obtained in fluorescein release experiments performed at Hanford, WA between 1967 and 1973. Pasquill-Gifford (PG) and Brookhaven National Laboratory (BNL) dispersion parameterization schemes were used, and atmospheric stability classes were determined from temperature gradient (Δr/ΔZ) and wind direction standard deviation (σ_θ) measurements. Comparisons between calculated values and experimental results were made as functions of changes in dispersion parameterization, stability class determination method, deposition velocity v _d , and gravitational fall velocity v _g . Values of the correlation coefficient ranged from significant (p < 0.01) to insignificant (p > 0.05). Best agreement between comparisons was found with v _g = v _d = 1.8 cm/s and Pasquill-Gifford parameters based on stability classes determined using wind direction standard deviation, σ_θ, rather than temperature gradient, ΔT/ΔZ. The best agreement gave a Pearson’s correlation coefficient r = 0.41 (significant at p < 0.01).