Effects of Contaminants on Toxicity of the Lampricides TFM and Bayer 73 to Three Species of Fish

Waters in the Great Lakes basin contain more than 400 contaminant chemicals that potentially affect fishery resources, commerce, and human inhabitants. We determined in the laboratory the effects of selected contaminants on the toxicity of the widely used lampricides TFM (3-trifluoromethyl-4-nitrophenol) and Bayer 73 (2′,5-dichloro-4′-nitrosalicylanilide) to three species of fish—rainbow trout (Salmo gairdneri), white sucker (Catostomus commersoni), and fathead minnow (Pimephales promelas). The fish were exposed to paired mixtures of lampricides and selected contaminants in standardized, acute static toxicity tests to determine the resulting type of response—less than additive, additive, or greater than additive (synergistic). As expected, the toxicities of combinations of lampricides with organic pesticides, metal, industrial or municipal pollutants, and tannic acid were mostly additive. However, the toxicity of a combination of TFM, Delnav, and malathion was synergistic, and extremely small quantities of each chemical became lethal when mixed. The concentration that produced 50% mortality was 1.64 mg/L for TFM alone but only 0.041 mg/L for TFM with the pesticides. Toxicities of the pesticides in the combination also increased commensurately. The triple combination of chemicals produced extraordinary synergism and effectively demonstrated the hazards that may result if certain chemical combinations occur in the aquatic environment. However, synergism is not the only kind of toxic action that produces hazards to aquatic organisms. All three types of toxic action are of concern because toxic units produced by contaminant chemicals add to the toxic units of applied management chemicals. Since the toxicity of the majority of chemical combinations is simply additive, this cumulative toxic action contributes more total units to aquatic environments than the extreme actions of less than additive and synergism. The toxicity of the lampricide TFM, as well as other management chemicals, is reinforced by the presence of any contaminant that contributes additional units of toxicity. Therefore, all types of cumulative toxic action should be of concern to people and agencies involved with protecting the environment.     

Stormwater reuse: designing biofiltration systems for reliable treatment.

Stormwater reuse is increasing in popularity as a technique for overcoming water shortages in urban Australia. However, technology for the reliable treatment of stormwater for reuse is still not fully developed. This paper presents the first steps in refining biofilters for stormwater reuse. Six different filter media were selected, to target specific stormwater pollutants, as well as support plant growth. They were tested in the laboratory, where the filters were dosed three times per week with semi-synthetic stormwater for five weeks. Pollutant removal performance was monitored, and revealed that all soil-based filters performed similarly (while sand filters behaved somewhat differently). All filters removed more than 80% of solids and greater than 90% of lead, copper, and zinc. Three filter types were able to remove some phosphorus (particularly in the top 30 cm of the media). Apart from sand, all filter media were net producers of nitrogen, leading to an important conclusion that non-vegetated, soil-based filters are not suitable for targeting nutrients. However, since heavy metals are the primary pollutant of concern with respect to stormwater reuse for irrigation (the most popular end-use), it was concluded that biofilters may be promising technologies for treatment of stormwater for reuse.     

Off flavours in large waterbodies: physics, chemistry and biology in synchrony.

The Laurentian Great Lakes of North America are a drinking water source for millions of Canadian and US consumers. These waterbodies have undergone extensive change over the past century as a result of widespread degradation and remediation. Many of the Lakes are prone to taste and odour (T&O), and although these outbreaks have been poorly monitored, evidence suggests that they are increasing in frequency. Tracing and controlling T&O in such large systems presents a challenging task, due to their physical size and complexity. This paper presents an overview of recent investigative and management approaches to T&O in Lake Ontario and its outflow, the St. Lawrence River. We have identified three distinct patterns of T&O in these source-waters, caused by geosmin and 2-methylisoborneol and differing in their planktonic and benthic sources, and temporal and spatial dynamics. Each pattern has required a different approach by scientists and management, in partnership with the water industry. We have shown these T&O outbreaks are caused and moderated by physical, chemical and biological mechanisms over a spectrum of spatial and temporal scales. Canadian municipalities affected by these outbreaks have been key to the investigation of the links between T&O and ecosystem processes with the aim to develop more proactive water treatment and long-term management.     

The effect of the textile industry dye bath additive EDTMPA on colour removal characteristics by ozone oxidation.

In this study, the effects of the phosphonic acid based sequestering agent EDTMPA used in the textile dye baths on colour and organic matter removal by ozone oxidation was experimentally investigated. Procion Navy HEXL dyestuff that has been commonly used for the reactive dyeing of cellulose fibers was selected as the model component. The organic matter oxidation by ozone was determined to obey the pseudo-first order kinetics as they are treated singly or in combination. COD removal rates obtained from pseudo-first order reaction kinetics showed that oxidation of Navy HEXL alone (0.0947 L/min) was faster than that of EDTMPA (0.0171 L/min) and EDTMPA with dye (0.0155 L/min) at pH 3.0. It was also found that reaction rates of single EDTMPA removal and EDTMPA and dye mixture removal increased as the reaction pH was increased from 3.0 to 10.5.     

The Relation Between Insider-Trading Restrictions and Executive Compensation

In this study I investigate the relation between firm‐level insider‐trading restrictions and executive compensation. Using a trading‐window proxy for the existence of such restrictions, I test predictions that insiders will demand compensation for these restrictions and that firms will need to increase incentives to restricted insiders. I find that firms that restrict insider trading pay a premium in total compensation relative to firms not restricting insider trading, after controlling for economic determinants of pay. Furthermore, these firms use more incentive‐based compensation and their insiders hold larger equity incentives relative to firms that do not restrict insider trading. These results hold after controlling for the endogenous decision to restrict insiders and are consistent with the notion that insider trading plays a role in rewarding and motivating executives.     

Business portfolio restructuring,prior diversification posture and investor reactions

This study examined firm performance in market reaction to two types of business portfolio restructuring announcements: refocusing and repositioning. We predicted that market performance effects for these two types of strategic restructurers would be moderated by prior diversification posture. The theory behind these expectations was built on a general premise that restructuring strategy would be more favorably viewed by the market as performance enhancing when it offered greater potential for organizational transformation. Results showed strong support for our conclusion that prior diversification posture poses a significant contingency factor in restructuring firms' strategic choices. Further, the market tended to respond more favorably with this sample to repositioning restructuring choices. Copyright © 2003 John Wiley & Sons, Ltd.     

Quasi‐rational and ex ante price expectations in commodity supply models: an empirical analysis of the US broiler market

A statistically optimal inference about agents' ex ante price expectations within the US broiler market is derived using futures prices of related commodities along with a quasi‐rational forecasting regression equation. The modelling approach, which builds on a Hamilton‐type framework, includes endogenous production and allows expected cash price to be decomposed into anticipated and unanticipated components. We therefore infer the relative importance of various informational sources in expectation formation. Results show that, in addition to the quasi‐rational forecast, the true supply shock, future prices, and ex post commodity price forecast errors have, at times, been influential in broiler producers' price expectations. Copyright © 2003 John Wiley & Sons, Ltd.     

Exploring the future for pensions pillarisation

The pensions pillarisation agenda envisages a reduction in the role of social insurance while simultaneously advocating the parallel expansion of fully funded private sector, occupational and personal retirement contingencies. Widespread perception of looming state failure in the field of pensions delivery highlights the inherent limitations of current pension delivery arrangements. However, moves to de-emphasise the provision afforded by, predominantly, monopillar state-mandated pension systems by expanding private privision represent short-term palliative responses to deep rooted structural and demographic problems. Multipillar systems appear no more capable of guaranteeing system funding in the face of demographic ageing and structural unemployment than existing monopillar systems. Moreover, a diminished role for social insurance will leave the low paid and unemployed significantly more vulnerable in old age. Consequently, this paper argues for a pension reform agenda which, in terms of levels of income substitution, will secure an adequate social insurance element into the future.     

UNIT MANAGEMENT BUYOUTS, STOCKHOLDER WEALTH, AND SELLING FIRMS' CHARACTERISTICS

Previous research on unit management buyouts, UMBs, has shown that selling firms benefit from the selloff transaction. The current research demonstrates that when the selling firm has either poor liquidity or poor earnings, selling firm shareholders do not benefit as much. We hypothesize that the unit managers have knowledge about the selling firm's difficulties so they do not pay as large a premium for the assets. Since the unit managers technically are employed by the selling firm shareholders, their bargaining to achieve a better price is an agency cost. Finally, selloff frequency does not affect seller abnormal returns.     

High school athletics and the wages of black males

This article examines the effects of high school athletic participation on the future wages of black males. Our evidence suggests that former black male athletes receive significantly greater wages than their otherwise comparable counterparts. Data from the National Longitudinal Survey of Youth was used for the analysis and allows for comparisons of the athlete premium to be made at different points in time. Both the human capital and signaling models are discussed. There appears to be a once and for all enhancement to human capital that accrues to black males who participated in high school athletics. The article adds to the literature on determinants of black male wages and on the earnings effects of athletic participation.