Brown rust disease control in winter wheat: I. Exploring an approach for disease progression based on night weather conditions

An empirical approach for simulating the infection and progress of leaf rust (caused by Puccinia triticina) during stem elongation on winter wheat was analysed for the 2000 to 2006 growing seasons. The approach was elaborated based on night weather conditions (i.e., air temperature, relative humidity and rainfall) and leaf rust occurrences. Data from three consecutive cropping seasons (2000–2002) at four representative sites of the Grand-Duchy of Luxembourg were used in the set-up phase. The capability to correctly simulate the occurrence expression of P. triticina infections on the upper leaf layers was then assessed over the 2003–2006 period. Our study revealed that the development of leaf rust required a period of at least 12 consecutive hours with air temperatures ranging between 8 and 16 °C, a relative humidity greater than 60 % (optimal values being 12–16 °C and up to 80 % for air temperatures and relative humidity, respectively) and rainfall less than 1 mm. Moreover, leaf rust occurrences and infections were satisfactorily simulated. The false alarm ratio was ranged from 0.06 to 0.20 in all the study sites. The probability of detection and critical success index for WLR infection were also close to 1 (perfect score).     

A fully reproductive fighting morph in a soldier clade of gall-inducing thrips (Oncothrips morrisi)

We present the first life history data for Oncothrips morrisi, a species in a clade of haplodiploid, Australian gall-inducing thrips that has a micropteran fighting morph in the first generation of the gall. Micropterans in other species in the clade have lower fecundity than their mother, and these species are considered eusocial. There is no such reproductive skew in O. morrisi, and the species is not eusocial by any definition. The volume of O. morrisi galls is between 4 and 20 times greater in than eusocial species in the clade and the dispersing-brood size varies between 5 and 15 times larger than that of other species. The lack of skew in O. morrisi could be associated with large gall volume, reducing competition between females for space and feeding sites for their offspring. As O. morrisi is in a lineage basal to eusocial Oncothrips, we also discuss selective factors for the evolution of a non-dispersing fighting morph in this clade. The costs involved in dispersal and latency to reproduction may have lowered the selective threshold for the evolution of a non-dispersing morph. Once non-dispersal evolved, selection to defend one's offspring may have promoted the evolution of soldier-like morphology and behaviour.     

Sociological dimension in the handling habit and sanitary quality of hand-dug well water from oil-producing area of Nigeria

A previous report showed that the physical and sanitary quality of hand-dug wells from an oil-producing area of Nigeria was poor in spite of the presence of well protective features. The hypothesis that handling habits is associated with the well water quality was therefore, tested. A structured questionnaire with scales for measuring handling habits was administered to 60 female (>18 years) hand-dug well users/owners randomly selected from three towns in the oil-producing area. The respondents’ wells were analysed for coliform bacteria. The findings showed that poor handling habits were the trend (habit score: Mean, 9.23 vs. 20 total available points). Handling habit indicated by scores, significantly negatively correlated (−0.89; P < 0.01) with coliform counts (indicator of poor sanitary quality). While the data collected and discussions with respondents indicated awareness of the risk of drinking well water, widespread skepticism of the potential hazards of non-drinking domestic uses (e.g., cooking, washing of plates, cups, cutleries etc.) was evident. Discontent with some aspects of science was indicated. It is concluded that there is need for social discourse and more public health campaign aimed at transforming skepticism to consent.     

Exploratory study of suspended sediment concentrations downstream of harvested peat bogs

Peat bog harvesting is an important industry in many countries, including Canada. To harvest peat, bogs are drained and drainage water is evacuated towards neighboring rivers, estuaries or coastal waters. High suspended sediment concentrations (SSC) were found in the drainage water at one particular site during the 2001–2002 spring seasons in New Brunswick (Canada). The main objective of this study was to verify this observation at other sites, compare SSC levels leaving harvested peat bogs with those leaving an unharvested bog, and to determine if high SSC events happen only in Spring or all year round. Suspended sediment concentrations were monitored downstream of three harvested peat bogs and an unharvested reference bog located in New Brunswick during the ice free seasons of 2003–2004. On average, SSC at the harvested sites exceeded 25 mg/l, which is the recommended daily maximum concentration, 72% of the time, while the same concentration was exceeded 30% of the time at the unharvested sites. SSC were found to be significantly higher at harvested sites than at the reference sites for all seasons. The highest SSC medians were recorded in the Fall but SSC was elevated in all seasons. High SSC levels in receiving waters may be caused by field ditching activities and insufficient sediment controls. Findings suggest the NB Peat Harvesting 25 mg/l SSC guideline should be reviewed.     

Determination of 14 amines in air samples using midget impingers sampling followed by analysis with ion chromatography in tandem with mass spectrometry

An Ion Chromatography-Mass Spectrometry (IC-MS) method was developed for the simultaneous quantification of 14 volatile amines in air. The method includes collection of compounds into two midget impingers in a row filled with 15 ml of ultrapure water. The analytical performances with mass spectrometry detection were compared to those obtained with classical conductivity detection. The use of mass spectrometry detection (in SIM mode) overcomes most of the coelutions encountered with conductivity detection. Although the linearity domain of calibrations is reduced for the MS detection as compared with the CD detection, the detection limits in MS detection are highly lowered allowing the quantification of amines at the levels of μg m(-3) in air with a good accuracy for most compounds (RSD of less than 10%). This method was successfully applied to the analysis of amines released from polyurethane foams. Seven amines were identified and some in high concentrations, like dimethylaminoethanol, NIAX and TEDA.     

Automated Economic Analysis Model For Hazardous Waste Minimization

Abstract

The U.S. Army has established a policy of achieving a 50 percent reduction in hazardous waste generation by the end of 1992. To assist the Army in reaching this goal, the Environmental Division of the U.S. Army Construction Engineering Research Laboratory (USACERL) designed the Economic Analysis Model for Hazardous Waste Minimization (EAHWM). The EAHWM was designed to allow the user to evaluate the life cycle costs for various techniques used in hazardous waste minimization and to compare them to the life cycle costs of current operating practices. The program was developed in C language on an IBM compatible PC and is consistent with other pertinent models for performing economic analyses. The potential hierarchical minimization categories used in EAHWM Include source reduction, recovery and/or reuse, and treatment. Although treatment is no longer an acceptable minimization option, its use is widespread and has therefore been addressed in the model. The model allows for economic analysis for minimization of the Army’s six most important hazardous waste streams. These include, solvents, paint stripping wastes, metal plating wastes, industrial waste-sludges, used oils, and batteries and battery electrolytes. The EAHWM also includes a general application which can be used to calculate and compare the life cycle costs for minimization alternatives of any waste stream, hazardous or non-hazardous. The EAHWM has been fully tested and implemented in more than 60 Army installations in the United States.     

Impact of crude oil exposure on nitrogen cycling in a previously impacted Juncus roemerianus salt marsh in the northern Gulf of Mexico

This study investigated potential nitrogen fixation, net nitrification, and denitrification responses to short-term crude oil exposure that simulated oil exposure in Juncus roemerianus salt marsh sediments previously impacted following the Deepwater Horizon accident. Temperature as well as crude oil amount and type affected the nitrogen cycling rates. Total nitrogen fixation rates increased 44 and 194 % at 30 °C in 4,000 mg kg^?1 tar ball and 10,000 mg kg^?1 moderately weathered crude oil treatments, respectively; however, there was no difference from the controls at 10 and 20 °C. Net nitrification rates showed production at 20 °C and consumption at 10 and 30 °C in all oil treatments and controls. Potential denitrification rates were higher than controls in the 10 and 30?ºC treatments but responded differently to the oil type and amount. The highest rates of potential denitrification (12.7?±?1.0 nmol N g^?1 wet h^?1) were observed in the highly weathered 4,000 mg kg^?1 oil treatment at 30 °C, suggesting increased rates of denitrification during the warmer summer months. These results indicate that the impacts on nitrogen cycling from a recurring oil spill could depend on the time of the year as well as the amount and type of oil contaminating the marsh. The study provides evidence for impact on nitrogen cycling in coastal marshes that are vulnerable to repeated hydrocarbon exposure.     

Degradation of 17α-ethinylestradiol by ozonation--identification of the by-products and assessment of their estrogenicity and toxicity

The presence of the synthetic estrogen 17α-ethinylestradiol (EE2) in waters at low levels is a concern due to its ability to act as an endocrine disruptor. Ozone (O₃) is commonly used in water treatment and reacts with EE2 to form by-products having characteristics that are mostly unknown. The aim of this study was to identify the by-products of E2 and EE2 ozonation and determine their estrogenicity and toxicity relative to the parent compound. Ozonation by-products were identified via LC-MS analysis. The estrogenicity was measured using the YES assay, and toxicity was determined by monitoring effects on histology of fetal rat testes and testosterone secretion by these tissues. Two EE2 by-products were identified with open phenolic ring structures (masses 302 and 344 u). The Yeast Estrogen Screening (YES) assay showed a decreased but incomplete removal of estrogenicity after ozonation of EE2. Histological analysis of fetal testes revealed that neither E2 nor EE2, with or without ozonation, had any effect on seminiferous cord formation; however, a remarkable negative effect on testosterone secretion was observed, with EE2 by-products after ozonation showing the most rapid and extensive inhibition. These results show that the removal of EE2 via reaction with O₃ resulted in the formation of by-products that are less estrogenic (as demonstrated by the YES assay), but have a greater negative impact on testosterone secretion. Thus, the disappearance of the parent compound is not a sufficient endpoint, as the by-products created may be more toxic. Care should be taken when implementing oxidation applications such as ozone during waste water treatment.