Monitoring Regional Riparian Forest Cover Change Using Stratified Sampling and Multiresolution Imagery1

Claggett, Peter R., Judy A. Okay, and Stephen V. Stehman, 2010. Monitoring Regional Riparian Forest Cover Change Using Stratified Sampling and Multiresolution Imagery. Journal of the American Water Resources Association (JAWRA) 46(2):334-343. DOI: 10.1111/j.1752-1688.2010.00424.x Abstract: The Chesapeake Bay watershed encompasses 165,760 km² of land area with 464,098 km of rivers and streams. As part of the Chesapeake Bay restoration effort, state and federal partners have committed to restoring 26,000 miles (41,843 km) of riparian forest buffers. Monitoring trends in riparian forest buffers over large areas is necessary to evaluate the efficacy of these restoration efforts. A sampling approach for estimating change in riparian forest cover from 1993/1994 to 2005 was developed and implemented in Anne Arundel County, Maryland, to exemplify a method that could be applied throughout the Bay watershed. All stream reaches in the county were stratified using forest cover change derived from Landsat imagery. A stratified random sample of 219 reaches was selected and forest cover change within the riparian buffer of each sampled reach was interpreted from high-resolution aerial photography. The estimated footprint of gross change in riparian forest cover (i.e., the sum of gross gain and gross loss) for the county was 1.83% (SE = 0.22%). Stratified sampling taking advantage of a priori knowledge of locations of change proved to be a practical and efficient protocol for estimating riparian forest buffer change at the county scale and the protocol would readily extend to much broader scale monitoring.     

Improvements to lawn and garden equipment emissions estimates for Baltimore, Maryland

Lawn and garden equipment are a significant source of emissions of volatile organic compounds (VOCs) and other pollutants in suburban and urban areas. Emission estimates for this source category are typically prepared using default equipment populations and activity data contained in emissions models such as the U.S. Environmental Protection Agency's (EPA) NONROAD model or the California Air Resources Board's (CARB) OFFROAD model. Although such default data may represent national or state averages, these data are unlikely to reflect regional or local differences in equipment usage patterns because of variations in climate, lot sizes, and other variables. To assess potential errors in lawn and garden equipment emission estimates produced by the NONROAD model and to demonstrate methods that can be used by local planning agencies to improve those emission estimates, this study used bottom-up data collection techniques in the Baltimore metropolitan area to develop local equipment population, activity, and temporal data for lawn and garden equipment in the area. Results of this study show that emission estimates of VOCs, particulate matter (PM), carbon monoxide (CO), carbon dioxide (CO2), and nitrogen oxides (NO(x)) for the Baltimore area that are based on local data collected through surveys of residential and commercial lawn and garden equipment users are 24-56% lower than estimates produced using NONROAD default data, largely because of a difference in equipment populations for high-usage commercial applications. Survey-derived emission estimates of PM and VOCs are 24 and 26% lower than NONROAD default estimates, respectively, whereas survey-derived emission estimates for CO, CO2, and NO(x) are more than 40% lower than NONROAD default estimates. In addition, study results show that the temporal allocation factors applied to residential lawn and garden equipment in the NONROAD model underestimated weekend activity levels by 30% compared with survey-derived temporal profiles.     

Smokeless Stacks—Industry’s Big Problem

There seems to be a general impression on the part of the public and many technical people that dust collecting systems on the open hearth furnace are simply a matter of giving a contract for a duplicate system to that previously installed; signing a check for a sum to cover the cost of the cleaning equipment itself, pressing the start-up button and then sitting back to receive the plaudits of a grateful community. This paper will briefly present some of the problems common to all of the installations to date. It will also explain why the cost of the cleaning equipment itself is such a small portion of the total cost.     

A Model for Gaseous Pollutant Sorption by Leaves

A model simulating pollutant exchange with isolated leaves that integrates factors which have been found to be important in regulating pollutant uptake by leaves is presented. The model is patterned after an electrical analogue simulator and was designed to emphasize the effects of pollutant and leaf properties on the process. The article discusses the relative significance of factors affecting gas transfer, sorption of pollutants by leaf surfaces, and pollutant solubility and fate on the uptake process. Data is presented showing uptake of ozone by exposed mesophyll and several epidermal surfaces chosen for their different surface characteristics. The model was used to derive a mathematical expression for the exchange process which was rearranged to define internal (average) pollutant solute concentration in terms of external concentration, leaf and boundary layer diffusion resistance, surface sorption and pollutant solubility. The importance of estimating internal solute concentration is discussed.     

Absorption of Gaseous Air Pollutants By a Standardized Plant Canopy

Concentration profiles for hydrogen fluoride(HF), sulfur dioxide(SO₂), ozone (O₃), nitrogen dioxide(NO₂), and nitric oxide(NO) generated in a standardized alfalfa canopy are presented. Wind, light, temperature, and carbon dioxide(CO₂) profiles, canopy pollutant uptake rates, and canopy structural data are also given. Canopy pollutant concentration profile characteristics were studied to evaluate the relative potentials for major air pollutants to penetrate into canopies. The study was conducted in an environmental growth chamber equipped to control automatically environmental conditions and monitor continuously gas exchange rates. HF, SO₂, and NO₂ profiles suggested that these gases were removed efficiently by the upper portion of the canopy as well as by the immediate subsurface vegetation. The steady state HF profile showed the greatest displacement within the canopy. The NO profile was displaced the least. The uptake rate of NO by plants was apparently too slow in comparison with gas transport and mixing within the canopy to affect the internal profile substantially. O₃ appeared to be readily deposited on the surface tissues, but the deeper tissues in the canopy had less effect on the concentration profile. Data are also presented to show the relationship between NO₂ concentration within the canopy and changes in the air concentration above the vegetation. The results indicated that gas transport between the atmosphere and canopy interior was rapid. The data presented should be of current interest to agriculturists, researchers, administrators, and environmental planners concerned with effects of air pollutants on plants and on the fate of pollutants in the microenvironment.     

The Effect of Building Fan Operation on Indoor-Outdoor Dust Relationships

As part of an energy conservation program recently implemented by the Bell System, fans in many telephone equipment buildings now operate only when necessary to bring the temperature within allowable limits, rather than continuously. In the study reported here the effects of fan operation on indoor-outdoor dust relationships were monitored at 2 representative telephone offices. Automatic dichotomous samplers were used to collect fine and coarse aerosol particles inside telephone equipment buildings at Wichita, KS and Lubbock, TX. At both sites, outdoor samples (roof top) were collected at the same time as the indoor samples. During the tests the building fans were repetitively cycled between 2-week intervals of continuous fan operation and 2-week intervals of intermittent fan operation. The indoor dust concentrations typically increased when the fans were off. The results indicate that this increase was due to loss of constant filtration, but not due to loss of building pressurlzation (i.e., filtration of the recirculated air is largely responsible for the lower dust levels when the fans are running continuously). An expression is derived for the relative dust increase when the building fans are switched off. Among other factors, the relative increase is directly proportional to the efficiency of the building filters and to the rate at which air is recirculated through them. The present findings can be extended to similar buildings.     

Environmental Auditing—A Timely and Effective Tool

The requirements of environmental regulations imposed on industry are complex and expensive. As these regulations have developed, corporate compliance programs have had to become more sophisticated. For many, this means that an environmental auditing program is now timely (or overdue) for organizing their approach to meeting the constraints of these regulations. Contributing to this timeliness is a renewed emphasis by regulators on enforcement activities. This paper discusses what environmental auditing is and what it consists of, gives examples from a few approaches which are currently being used, and reviews some of its benefits and liabilities.     

Intermittent agitation of liquid manure: effects on methane,microbial activity,and temperature in a farm-scale study

Liquid manure storages are a significant source of methane (CH₄) emissions. Farmers commonly agitate (stir) liquid manure prior to field application to homogenize nutrients and solids. During agitation, manure undergoes mechanical stress and is exposed to the air, disrupting anaerobic conditions. This on-farm study aimed to better understand the effects of agitation on CH₄ emissions, and explore the potential for intentional agitation (three times) to disrupt the exponential increase of CH₄ emissions in spring and summer. Results showed that agitation substantially increased manure temperature in the study year compared to the previous year, particularly at upper- and mid-depths of the stored manure. The temporal pattern of CH₄ emissions was altered by reduced emissions over the subsequent week, followed by an increase during the second week. Microbial analysis indicated that the activity of archaea and methanogens increased after each agitation event, but there was little change in the populations of methanogens, archaea, and bacteria. Overall, CH₄ emissions were higher than any of the previous three years, likely due to warmer manure temperatures that were higher than the previous years (despite similar air temperatures). Therefore, intermittent manure agitation with the frequency, duration, and intensity used in this study is not recommended as a CH₄ emission mitigation practice.

Implications: The potential to mitigate methane emissions from liquid manure storages by strategically timed agitation was evaluated in a detailed farm-scale study. Agitation was conducted with readily-available farm equipment, and targeted at the early summer to disrupt methanogenic communities when CH₄ emissions increase exponentially. Methane emissions were reduced for about one week after agitation. However, agitation led to increased manure temperature, and was associated with increased activity of methanogens. Overall, agitation was associated with similar or higher methane emissions. Therefore, agitation is not recommended as a mitigation strategy.     

Guidance for the Field Demonstration of Remediation Technologies

This paper will focus on the demonstration of hazardous waste cleanup technologies in the field. The technologies will be at the pilot- or full-scale, and further referred to as field-scale. The main objectives of demonstration at the field-scale are development of reliable performance and cost data. Technology demonstrations provide performance, cost effectiveness, and reliability data so that potential technology users have sufficient information to make effective decisions as to the applicability of the technology to a specific situation. The demonstration and evaluation of a technology should be conducted with the purpose of characterizing performance, need for pre- and post-processing of the waste feed, identification of waste type and constituents applicable to the technology, system throughput, problems and limitations of the technology, and operating and maintenance costs. Table I provides a summary of remediation activities for demonstration projects.