Influence of form and quantity of selenium on the development and survival of an insect herbivore

Even plants classified as 'nonaccumulators' can sequester concentrations of sodium selenate, sodium selenite, selenocystine and selenomethionine that can strongly influence insect development and survival. These forms of selenium (Se), tested in diet-incorporation bioassays, proved toxic to larvae of a generalist insect herbivore at relatively low levels. Sodium selenite was the most toxic form tested against Spodoptera exigua (Hübner), with an LC(50) of 9.14 microg g(-1) wet wt (21.11 microg g(-1) dry wt). Selenocystine was intermediate with an LC(50) of 15.2 microg g(-1) wet wt. The least toxic forms, sodium selenate and selenomethionine, had LC(50)s below 50 microg g(-1) dry wt, the upper level for tissues of plants classified as nonaccumulators. Ingestion of some forms of Se also affected growth and development. Increasing concentrations of sodium selenate and sodium selenite decreased pupal weight and added significantly to the time needed for development to the pupal and adult stages. The time required to complete the larval stage increased by over 25% and the time from egg to adult emergence was extended by 22% to nearly 30%. Selenocystine and selenomethionine did not significantly increase developmental times, even at concentrations that killed 90% or more of the test populations. Analyses of relative growth rate, relative growth index, and an analysis of covariance technique for measuring growth indicated that the form of Se affected growth rates, growth inhibition responses of the larvae, and toxicological effects. Thus, quantity and the form of Se accumulating in plants grown on Se-contaminated sites are likely to influence the population dynamics of insect herbivores. The implications of these results for the ecology of contaminated sites are discussed.     

Environmental management in an international consumer goods company

Many management processes and tools can provide companies with information to support their environmental decision making. Risk assessment, environmental auditing, life cycle assessment and environmental reporting are but a few examples. Each of these has typically evolved independently as the need for it has arisen. Today, however, this abundance of tools can lead to confusion: What is the exact objective of each tool? How do they differ? Are some ‘better’ than others? Should they be used in parallel, sequentially or in place of each other? More importantly, how do they fit together into a coherent environmental management framework that will ensure sound environmental and economic decision making in a company? This paper seeks to answer these questions. It describes the overall environmental framework that has been developed internally within Procter & Gamble and which allows the company to make coherent economically and environmentally sound decisions, in both the short- and long-term.     

REGIONAL RAINFALL INTENSITY-DURATION-FREQUENCY CURVES FOR PENNSYLVANIA1

ABSTRACT: A statistical analysis of all available continuous hourly and 15-minute duration rainfall records for Pennsylvania was performed to develop an updated procedure to estimate design storms. As a resuit of this study, Pennsylvania was divided into five homogeneous rainfall regions and a set of rainfall intensity-duration curves developed for each region, for return periods of 1 to 100 years and durations ranging from 5 minutes to 24 hours. The PDT-IDF curves were judged to be a better representation of Pennsylvania rainfall than the nationwide TP-40 maps, particularly for storm events of 10-years and lower return periods. The average time distribution of 24-hour storms in Pennsylvania was found to be well represented by the SCS Type II distribution. The Corps of Engineers SPS 24-hour distribution was found to differ appreciably from both the SCS Type H and the Pennsylvania 24-hour storm distribution. For storm durations between 15 and 90 minutes the standard Yarnell intensity-duration curves closely resemble Pennsylvania storm distributions.     

Environmental monitoring of carbaryl applied in urban areas to control the glassy-winged sharpshooter in California

Carbaryl insecticide was applied by ground spray to plants in urban areas to control a serious insect pest the glassy-winged sharpshooter, Homalodisca coagulata (Say), newly introduced inCalifornia. To assure there are no adverse impacts to human health and the environment from the carbaryl applications, carbaryl was monitored in tank mixtures, air, surface water, foliage and backyard fruits and vegetables.Results from the five urban areas – Porterville, Fresno, Rancho Cordova, Brentwood and Chico – showed there were no significanthuman exposures or impacts on the environment. Spray tank concentrations ranged from 0.1–0.32%. Carbaryl concentrationsin air ranged from none detected to 1.12 g m^-3, well below the interim health screening level in air of 51.7 g m^-3. There were three detections of carbaryl in surface water nearapplication sites: 0.125 ppb (parts per billion) from a water treatment basin; 6.94 ppb from a gold fish pond; and 1737 ppbin a rain runoff sample collected from a drain adjacent to a sprayed site. The foliar dislodgeable residues ranged from 1.54–7.12 g cm^-2, comparable to levels reported forsafe reentry of 2.4 to 5.6 g cm^-2 for citrus. Carbarylconcentrations in fruits and vegetables ranged from no detectableamounts to 7.56 ppm, which were below the U.S.EPA tolerance, allowable residue of 10 ppm.     

Statistical comparison of heavy metal concentrations in various louisiana sediments

The use of statistical t tests were used to determine lead, zinc, and cadmium enrichment in various Louisiana sediments. Both absolute metal concentrations and trace metal/conservative metal concentration ratios were used in comparing sampled sites to a 110 m deep background core taken just off the mouth of the Mississippi River. Concentration ratios were used to reduce the effects of certain chemical and physical sediment characteristics on the quantity of metal contained in a given sediment.Results from the comparison of sample sites to the background reveal metal enrichment at several sites. The University Lake sampling sites exhibit both lead and zinc enrichment when using both the concentration alone and ratio methods of comparison. Additionally, cadmium enrichment is indicated in the sediments of University Lake when using only the ratio method of comparison. Several sampled sediments in and around the New Orleans metropolitan area exhibited lead and cadmium enrichment.     

Saltcedar control and water salvage on the Pecos river, Texas, 1999-2003

A large scale ecosystem restoration program was initiated in 1997 on the Pecos River in Western Texas. Saltcedar (Tamarix spp.), a non-native invasive tree, had created a near monoculture along the banks of the river by replacing most native vegetation. Local irrigation districts, private landowners, federal and state agencies, and private industry worked together to formulate and implement a restoration plan, with a goal of reducing the effects of saltcedar and restoring the native ecosystem of the river. An initial management phase utilizing state-of-the-art aerial application of herbicide began in 1999 and continued through 2003. Initial mortality of saltcedar averaged about 85-90%. Monitoring efforts were initiated at the onset of the project to include evaluating the effects of saltcedar control on salinity of the river water, efficiency of water delivery down the river as an irrigation water source, and estimates of water salvage. To date, no effect on salinity can be measured and irrigation delivery was suspended in 2002-2003 due to drought conditions. Water salvage estimates show a significant reduction in system water loss after saltcedar treatment. However, a flow increase in the river is not yet evident. Monitoring efforts will continue in subsequent years.     

Young females' attention toward road safety images: An ERP study of the revised reinforcement sensitivity theory

Objective: This study examined whether reward and punishment sensitivities, as conceptualized by Gray and McNaughton's revised reinforcement sensitivity theory (RST), influenced young female drivers' attention toward a series of positive and negative antispeeding advertisement images. Young females' increasing crash risk is associated with their engagement in risky behaviors, which, in turn, has been associated with a stronger behavioral approach system (BAS; sensitive to rewards). It was predicted that individuals with a stronger BAS would elicit larger N100 and N200 mean amplitudes (reflecting greater attention) toward the positive images. Similar associations were predicted in relation to the fight–flight–freeze system (FFFS; sensitive to punishments) for negative images.

Method: Twenty-four female drivers (17–25 years; final N = 16) completed Corr-Cooper's RST-Personality Questionnaire, prior to undergoing an event-related potential computerized visual task (i.e., oddball paradigm) that included positive, negative, and neutral images as targets against checkerboard image distractors.

Results: Contrary to expectations, individuals with a stronger BAS (Reward Reactivity and Impulsivity) demonstrated significantly larger N200 mean amplitudes at the Cz electrode site on presentation of the negative images than those with a weaker BAS. No other significant RST effects were found.

Conclusions: These findings provide some preliminary objective support for the use of negative emotion-based road safety advertisements for young females. Further, this study provides support for using psychophysiological measures to enhance understanding of traffic injury persuasion.     

An integrated decision-support process for adaptation planning: climate change as impetus for scenario planning in an agricultural region of Canada

The amount of information required to adapt to climate change is vast: downscaled climate projections, information on environmental impact, sectoral performance, external drivers, regional strategies, policies and practices. It can be argued that most of this information is accessible at the community/regional level, and thus, the important challenges to adaptation are not information gaps, but constraints created by fragmented planning decisions and a sector-by-sector basis for financial and human resource allocations. To strategically address this through adaptation planning, we developed and tested a place-based decision-making framework that creates an integrated platform for considering regional and global sectoral drivers in Eastern Ontario, Canada. Using available socioeconomic and biophysical information from regional authorities, alternative future scenarios were used to describe the range of socioeconomic futures and their vulnerabilities to climate change. We found that: (1) integration of diverse sets of available data (rather than narrowly focused sectoral assessments) helped identify shared common objectives (maximizing the long-term environmental, economic, social well-being within the region), (2) a high degree of congruence existed as the key drivers of change, irrespective of sector, (3) exploring the future scenarios highlighted shared regional priorities and helped identify adaptation priorities requiring more integrated regional planning.     

Chemical and Physical Controls on the Oxygen Regime of Ice‐Covered Arctic Lakes and Reservoirs1

Abstract: We examined the chemical, morphological, and anthropogenic controls on winter‐oxygen biogeochemistry in ice‐covered lakes and reservoirs on the North Slope of Alaska. We measured dissolved oxygen (DO), solute concentrations, water depth, and ice thickness at three natural thaw lakes and four reservoirs (flooded gravel mines) for two winters. In all seven study sites, DO concentration and pH decreased with depth, and temporally through the winter (November to April). DO concentration was four to six times greater in the deeper reservoirs (8‐13 mg/l) compared with shallow natural lakes (ca. 2 mg/l). Lakes and reservoirs with high dissolved organic carbon (DOC) concentration were susceptible to large decreases in oxygen over the winter. DO concentration differed markedly between years, but was not attributed to changes in water‐use or winter water‐chemistry. Alternatively, we suggest that dissolved oxygen concentration was lower during freeze‐up, possibly associated with higher lake‐productivity during the summer. Our results suggest that current water‐use practices on the North Slope of Alaska caused little to no change in DO concentration over the winter. In particular, considering the high pumping activity and shallow depth, lakes with low DOC concentration (≤6 mg/l) showed strong resilience to change in chemistry over the winter. We suggest that both lake and reservoir depth, and DOC concentration are key factors influencing oxygen consumption in ice‐covered arctic lakes and reservoirs.