Comparative toxicity of six test chemicals to lettuce using two root elongation test methods

Lettuce (Lactuca sativa L., cv buttercrunch) was used to evaluate and compare the results from two different root elongation phytotoxicity test methods with the same six test substances. Seeds were either germinated in the dark on an inclined filter paper substrate with one end immersed in test solution or germinated in 0.1 strength nutrient solution with a 16 hr light period in a glass bulb mixed and aerated with compressed air. Sodium fluoride, monosodium methanearsonate and monuron reduced lettuce root length at similar concentrations for both methods, while cadmium chloride and 2,4-D root inhibition occurred at concentrations approximately one order of magnitude smaller in the solution culture method than in the substrate method. Two orders of magnitude difference were observed between the two methods for silver nitrate. The results indicate that the solution method is at least as sensitive for all the chemicals tested and much more sensitive for some.     

Latency to resume calling after disturbance in the field cricket,<Emphasis Type="Italic"> Teleogryllus oceanicus</Emphasis>, corresponds to population-level differences in parasitism risk

A possible parasitoid-evasion behavioral adaptation is examined in male field crickets, Teleogryllus oceanicus, from three Hawaiian islands where parasitoid prevalence varies naturally among islands. Ormia ochracea, the parasitoid fly that parasitizes T. oceanicus on these islands, uses male calling song to locate its hosts. We used laboratory-reared males from three Hawaiian islands to determine if there are population differences in the time it takes for calling males to resume calling after a standardized disturbance. Males follow the expected pattern; males from the island with the greatest risk of parasitism have the longest latency to resume calling, and males from the island with the least risk of parasitism have the shortest latency to resume calling. Results are discussed in the context of behavioral adaptations to differing parasitism levels, and trade-offs between natural and sexual selection.Communicated by D. Gwynne     

Municipal solid waste in situ moisture content measurement using an electrical resistance sensor

Moisture content (MC) is a crucial parameter for degradation of solid waste in landfills. Present MC measurement techniques suffer from several drawbacks. A moisture sensor for measurement of in situ moisture content of solid waste in landfills was developed. The sensor measures the electrical resistance across the granular matrix of the sensor, which in turn can be correlated to moisture content. The sensor was also equipped with a thermocouple and tubing that permits simultaneous measurement of temperature and gas sampling. The electrical conductivity of the surrounding moisture and the temperature in the matrix both affect the resistance measurements. This paper describes the results of laboratory experiments designed to select the appropriate granular media particle size, measure the influence of moisture electrical conductivity and temperature, and develop calibration relationships between measured resistance and gravimetrically determined moisture content. With a few limitations, the sensor is able to detect MC of solid waste under conditions allowing moisture movement into the sensor. The application of this technique shows promise for use in bioreactor landfills where high moisture contents are expected and desired.     

COMBINED SEWER OVERFLOW CONTROL THROUGH IN-RECEWING WATER STORAGE: AN EFFICIENCY EVALUATION1

ABSTRACT: A demonstration and efficiency evaluation project was conducted for the flow balancing method (FBM) facility, a combined sewer overflow (CSO) storage facility at Fresh Creek in Brooklyn, New York City. The FBM is a curtained tank located directly in the receiving water that captures CSO. The CSO floats on top of and displaces Fresh Creek saltwater before it is pumped back to the publicly owned treatment works (POTW). The facility was a pilot scale subject to the full CSOs. The purpose of the project was to show how the FBM can withstand severe weather and tidal conditions and to develop a procedure for estimating CSO control efficiency (percentage of CSO pumped back to the POTW). The procedure proved successful and incorporated specific conductivity as a tracer in mass balance equations. These equations provided estimates of the net percent, capture-pumpback of the CSO using the FBM, including the amount of Fresh Creek water that was included in the pumpback to the P01W. The efficiency was directly related to the volume of the CSO and the pumpback rate and ranged from a low of 3.3 percent for the largest event to a high of 76.9 percent for the smallest event. Recent FBM enlargement should result in substantial increases in CSO control. The FBM facility has operated successfully for over five years, withstanding ice storms, near hurricane force winds and up to 7 ft tidal range.     

Labeling Products of Biotechnology: Towards Communication and Consent

Recently, both consumers and producers ofbiotechnology products have insisted thatcommunication between the two be improved. The formerdemand more democratic participation in the riskassessment process of biotechnology products. Thelatter seek to correct misinformation regardingalleged risks from these products. One way to resolvethese concerns, I argue, is through the use ofbiotechnology labels. Such labeling fosters consumerautonomy and moves toward more participatory decisionmaking, in addition to ensuring that informed consentfrom consumers is maintained. Furthermore, althoughvoluntary biotech-free labeling in lieu of biotechlabels may uphold consumer sovereignty, the latterremains a more effective strategy for achievingethical communication between consumers and producersof biotechnology products.     

Retrospective assessment of dryland soil stability in relation to grazing and climate change

Accelerated soil erosion is an aspect of dryland degradation that is affected by repeated intense drought events and land management activities such as commercial livestock grazing. A soil stability index (SSI) that detects the erosion status and susceptibility of a landscape at the pixel level, i.e., stable, erosional, or depositional pixels, was derived from the spectral properties of an archived time series (from 1972 to 1997) of Landsat satellite data of a commercial ranch in northeastern Utah. The SSI was retrospectively validated with contemporary field measures of soil organic matter and erosion status that was surveyed by US federal land management agencies. Catastrophe theory provided the conceptual framework for retrospective assessment of the impact of commercial grazing and soil water availability on the SSI. The overall SSI trend was from an eroding landscape in the early drier 1970s towards stable conditions in the wetter mid-1980s and late 1990s. The landscape catastrophically shifted towards an extreme eroding state that was coincident with the “The Great North American Drought of 1988”. Periods of landscape stability and trajectories toward stability were coincident with extremely wet El Niño events. Commercial grazing had less correlation with soil stability than drought conditions. However, the landscape became more susceptible to erosion events under multiple droughts and grazing. Land managers now have nearly a year warning of El Niño and La Niña events and can adjust their management decisions according to predicted landscape erosion conditions.     

Tracking Fragmentation of Natural Communities and Changes in Land Cover: Applications of Landsat Data for Conservation in an Urban Landscape (Chicago Wilderness)

Abstract: Greater Chicago is home to a surprisingly high concentration of globally significant natural communities. Within the metropolis survive some of the world's best remaining examples of eastern tallgrass prairie, oak savanna, open oak woodland, and prairie wetland. Chicago Wilderness is more than 81,000 ha of protected areas in the urban and suburban matrix. It also is the name of the coalition of more than 110 organizations committed to the survival of these natural lands. The long-term health of these imperiled communities depends on proper management of the more extensive, restorable lands that surround and connect the patches of high-quality habitat. Information critical to the success of conservation efforts in the region includes (1) a current vegetation map of Chicago Wilderness in sufficient detail to allow quantitative goal setting for the region's biodiversity recovery plan; (2) quantified fragmentation status of the natural communities; and (3) patterns of land-cover change and their effects on the vitality of communities under threat. We used multispectral data from the Landsat thematic mapper (October 1997) and associated ground truthing to produce a current vegetation map. With multitemporal remote-sensing data (acquired in 1972, 1985, and 1997), we derived land-cover maps of the region at roughly equivalent intervals over the past 25 years. Analyses with geographic information system models reveal rapid acceleration of urban and suburban sprawl over the past 12 years. Satellite images provide striking visual comparisons of land use and health. They also provide banks of geographically referenced data that make quantitative tracking of trends possible. The data on habitat degradation and fragmentation are the biological foundation of quantitative goals for regional restoration.     

Positive vs. false detection: A comparison of analytical methods and performance for analysis of cyclic volatile methylsiloxanes (cVMS) in environmental samples from remote regions

Contamination and analytical variation can significantly hinder trace analysis of cyclic methyl volatile siloxanes (cVMS); potentially resulting in the report of false positives at concentrations approaching detection limits. To assess detection and variation associated with trace cVMS analysis in environmental matrices, a co-operative laboratory comparison for the analysis of octametylcyclotetrasiloxane (D4), decamethylcylcopentasiloxane (D5), and dodecametylcyclohexasiloxane (D6) in sediment and biota from the Svalbard Archipelago was conducted. Two definitions of detection limits were evaluated in this study; method detection limits (MDL, matrix defined) and limits of detection (LOD, solvent defined). D5 was the only cVMS detected above both LOD (0.08–0.81 ng g⁻¹ ww) and MDL (0.47–2.36 ng g⁻¹ ww) within sediment by all laboratories where concentrations ranged from 0.55 to 3.91 ng g⁻¹ ww. The percentage of positive detects for D5 decreased by 80% when MDL was defined as the detection limit. D5 was also detected at the highest frequency among all laboratories in fish liver with concentrations ranging from 0.72 to 345 ng g⁻¹ ww. Similar to sediment, percentage of positive detects for D5 decreased by 60% across all laboratories for fish livers when using MDL (0.68–3.49 ng g⁻¹ ww). Similar observations were seen with both D4 and D6, indicating that sample matrix significantly contributes to analytical response variation. Despite differences in analytical methods used between laboratories, good agreement was obtained when using MDL to define detection limits. This study shows the importance of incorporating variation introduced by sample matrices into detection limit calculations to insure data accuracy of cVMS at low concentrations.     

Validity of Ambient Levels of Fine Particles as Surrogate for Personal Exposure to Outdoor Air Pollution—Results of the European EXPOLIS-EAS Study (Swiss Center Basel)

ABSTRACT

To evaluate the validity of fixed-site fine particle levels as exposure surrogates in air pollution epidemiology, we considered four indicator groups: (1) PM₂₅ total mass concentrations, (2) sulfur and potassium for regional air pollution, (3) lead and bromine for traffic-related particles, and (4) calcium for crustal particles. Using data from the European EXPOLIS (Air Pollution Exposure Distribution within Adult Urban Populations in Europe) study, we assessed the associations between 48-hr personal exposures and home outdoor levels of the indicators. Furthermore, within-city variability of fine particle levels was evaluated.

Personal exposures to PM_2.5 mass were not correlated to corresponding home outdoor levels (n = 44, r_{S (S)} =r o v ' Spearman (Sp) 0.07). In the group reporting neither relevant indoor sources nor relevant activities, personal exposures and home outdoor levels of sulfur were highly correlated (n = 40, r_Sp = 0.85). In contrast, the associations were weaker for traffic (Pb: n = 44, r_Sp = 0.53; Br: n = 44, r_Sp = 0.21) and crustal (Ca: n = 44, r_Sp = 0.12) indicators. This contrast is consistent with spatially homogeneous regional pollution and higher spatial variability of traffic and crustal indicators observed in Basel, Switzerland.

We conclude that for regional air pollution, fixed-site fine particle levels are valid exposure surrogates. For source-specific exposures, however, fixed-site data are probably not the optimal measure. Still, in air pollution epidemiology, ambient PM_2.5 levels may be more appropriate exposure estimates than total personal PM_2.5 exposure, since the latter reflects a mixture of indoor and outdoor sources.     

Hydrogen sulfide flux measurements from construction and demolition debris (C&D) landfills

Hydrogen sulfide (H2S) has been identified as a principal odorous component of gaseous emissions from construction and demolition debris (C&D) landfills. Although several studies have reported the ambient concentrations of H2S near C&D landfills, few studies have quantified emission rates of H2S. One of the most widely used techniques for measuring surface gas emission rates from landfills is the flux chamber method. Flux measurements using the flux chamber were performed at five different C&D landfills from April to August, 2003. The flux rates of H2S measured in this research were between 0.192 and 1.76 mg/(m2-d).