Foliage visible injury in the tropical tree species,Astronium graveolens is strictly related to phytotoxic ozone dose (PODy)

Environmental Science and Pollution Research - The present study evaluates the development of visible injury related to phytotoxic ozone dose (PODy) in native tropical species Astronium graveolens...     

Identification of some plasticizers compounds in landfill leachate

In this work it was described a simple method for extraction of plasticizer compounds (mainly phthalate esters and bisphenol A (BPA)) from landfill leachate samples. The samples were submitted to an extraction procedures based on precipitation, solid phase extraction (SPE) and ionic exchange chromatography (IEC). Firstly the landfill leachate sample was acidified by addition of HCl concentrated, in order to precipitate the organic compounds that are less soluble in water. The precipitate was washed with several solvents. The aqueous phase was then submitted to SPE with XAD-4 resin and IEC with Amberlyst A-27 resin. The instrumental analysis was performed by gas chromatography with mass spectrometer detector (GC/MSD) and the compounds were identified by the GC/MSD library (Wiley) and by using some standard substances. These methodologies allow the isolation and identification of the following compounds: dioctylphthalate, diisobutilphthalate, BPA, benzoic acid, palmitic acid and diisopentylphthalate. The methods are very simple, rapid and selective, for plasticizers extraction from landfill leachate matrices.     

Cover crops and natural vegetation mulch effect achieved by mechanical management with lateral rotary mower in weed population dynamics in citrus

The aim of this study was to obtain information on practical weed management in order to reduce the use of herbicides thereby contributing to the sustainable development of citrus crop. The experiment was carried out under field conditions at the experimental area of the Department of Vegetal Production at the College of Agriculture "Luiz de Queiroz," Piracicaba, SP, Brazil, during the season 2002-2003. Influence of mulches produced by four types of vegetations on the dynamic population of weeds in the line of citrus crop (Citrus sinensis (L.) Osbeck) was evaluated. The experimental design was of factorial randomized blocks (4 x 2), where the treatments were: (i) four types of vegetation: Dolichos lablab L., Cajanus cajan (L.) Millsp, Penisetum glaucum (L.) Leeke, and the natural infestation composed basically by Panicum maximum Jacq.; and (ii) two types of fertilization: directed under canopy and broadcast. Mechanical management of the different vegetations was accomplished using a lateral rotary mower, KAMAQ, I model NINJA MAC 260, projected to release the green cut material under crop canopy, forming a mulch layer. The studied parameters were: (i) counting of weeds per m2 in the crop line after 30, 60, 90, 180, and 210 days following the cutting of existing vegetation; (ii) percentage of covered area by weeds; and (iii) some chemical properties of the soil. It was observed that the natural infestation showed a better weed control when compared with the other treatments, and that the broadcast fertilization, regardless of coverage used, presented a lower number of weeds.     

Allelopathic potential and systematic evaluation of organic extracts from Canavalia ensiformis leaves (Jack beans)

This article describes the assessment of possible allelopathic potential of organic extracts obtained from leaves of Canavalia ensiformis under laboratory conditions. Furthermore, a systematic evaluation of these extracts was carried out using specific protocols developed in capillary electrophoresis (CE) to determine some groups of secondary metabolites. After the identification and quantification of compounds, the effects of compounds on germination of some common weeds was investigated, which are becoming a real problem in pastures in the state of Pará, Brazil.     

Absorption and translocation of 2,4-D in plants of Memora peregrina

The objective of this work was to evaluate absorption and translocation of the herbicide 2,4-D in plants of Memora peregrina. The herbicide 2,4-D was used alone with the formulation DMA 806 BR and associated with the herbicide picloram in the commercial product Padron. Levels of radioactivity on the treated leaves were determined in sample obtained after washing them with methanol and chloroform at different times after the application of the radiolabelled formulation (1, 2, 4, 8, 24, and 48 h). Translocation was evaluated by cutting plants between stem and root. The parts obtained were: root, stem, leaf treated, leaves above the leaf treated, leaves below the leaf treated, and leaf opposite of the leaf treated. These parts were weighted, dried, ground, burnt, and radioactivity in the samples was determined. The results suggest that the translocation of the radioactive herbicide 2,4-D was insignificant in plants of M. peregrina in the two treatments evaluated. Absorption of 14C 2,4-D in the treatment with DMA 806 BR and the mixture of DMA 806 BR plus Padron had the same behavior. These observations explain the inefficient control obtained with this herbicide in plant species under study.     

Abnormal gonadal morphology in intersex,<Emphasis Type="Italic"> Echinogammarus marinus</Emphasis> (Amphipoda): a possible cause of reduced fecundity?

Recent reports have demonstrated a cost associated with intersexuality in Amphipoda, including reduced fecundity and fertility. In this study, the gross morphology of the gonads in normal and intersex Echinogammarus marinus (Amphipoda) were compared to determine whether resource allocation to gonadal tissue accounted for this reduced fitness. Evidence for the presence of the male sex-determining hormone, androgenic gland hormone (AGH), was compared between sexual phenotypes using MALDI mass spectrometry. Two distinct intersex phenotypes (male intersex and female intersex) were found, with variation in gonadal structure corresponding with external phenotype. Examination of male intersexes revealed normal testicular development (testes, seminal vesicles and vas deferens), but also revealed the formation of an oviduct. Ovaries of intersex females showed normal ovarian development, but were reduced in length by approximately 20% due to the presence of vas deferens. The number of vas deferens in intersex females was equal to the number (one or two) of genital papillae. We hypothesise that the reduced ovarian length observed in intersex females is a likely cause of the reduced brood size previously reported in intersex females of this species. Variation in the sexual phenotype corresponded both to development of the androgenic gland and to expression of a peptide fragment corresponding to the A chain of androgenic gland hormone (AGH). Androgenic glands and a putative AGH peptide were present in males. However, in both normal and intersex females, the androgenic glands were only present in a rudiment form and the peptide was not detected. Intersex males were found to possess abnormal glands that appeared hypertrophied. However, AGH peptides were not detected, supporting the suggestion that the intersex phenotype is manifested via perturbations of AGH.An erratum to this article can be found at Communicated by J.P. Thorpe, Port Erin     

Modelling the Optimal Strategies of Fertiliser Application Using the Game-Theoretic Approach

This paper is a case study which describes the application of game-theoretic approach in resource management with specific emphasis on developing optimal strategies of phosphorus applications for soil fertilisation. The approach adopted allows resource managers to consider not only competitive strategies, which were treated as the Nash equilibrium game solutions, but also strategies which imply cooperation between farmers. These strategies were modelled as the cooperative Pareto optima of the game. The objective function of the game has been developed in order to reflect both economic advantages of phosphorus applications and the environmental losses associated with these applications expressed as dollar values. The paper presents algorithms for finding competitive and cooperative solutions of the game for the particular case when no time scheduling is included in the game parametrisation. The results obtained in the paper showed that the cooperative solutions lead to much lesser environmental impacts than that in the case of non-cooperative strategies.     

The influence of axle position and the use of accessories on the activity of upper limb muscles during manual wheelchair propulsion

Introduction. Wheelchair configuration is an important factor influencing the ergonomics of the user–device interface and, from a biomechanical point of view, small changes in chair setup may have a positive influence on the demand on the upper limbs during manual propulsion. This study aimed to investigate the influence of the position of the rear wheels’ axle and the use of accessories on the activity of upper limb muscles during manual wheelchair propulsion. Methods. Electromyography signals of the biceps, triceps, anterior deltoids and pectoralis major were collected for 11 able-bodied subjects in a wheelchair propulsion protocol with four different wheelchair configurations (differing in axle position and the use of accessories) on a straightforward sprint and a slalom course. Results. With accessories, moving the axle forward led to a decrease in the activity of all muscles in both the straightforward sprint (significant differences in triceps, anterior deltoids and biceps) and the slalom course (significant difference in anterior deltoids and biceps). However, when propelling the chair without accessories, no difference was found related to axle position. Conclusion. Changes in wheelchair configuration can influence the ergonomics of manual wheelchair propulsion. Reducing the biomechanical loads may benefit users’ mobility, independence and social participation.     

A net water production model for ultrafiltration including flow direction reversal and chemically assisted backwashing.

Flow direction reversal (FDR) was proposed as a novel method to increase net water production (NWP) during cross-flow ultrafiltration. The design of the pilot-plant study allowed measurement of specific flux recovery after each chemically assisted backwash (BW) combined with FDR and after each FDR at the midpoint of each BW/FDR cycle. The percent recovery of specific flux was higher following FDR (55%) than combined BW and FDR (53%) at lower chemical dosages; however, the percent increase in specific flux recovery by FDR was much lower (20%) when the chemical dose was doubled. A mathematical model was developed to predict the NWP achieved by any combination ofBW/ FDR and FDR frequency. For example, the advantage of introducing FDR was demonstrated at the lower chlorine dose, whereby the percent increase in NWP by alternating 15-minute intervals of BW/FDR with FDR over BW/ FDR alone was 10% for 30-minute BW/FDR intervals and 2% for 15-minute BW/FDR intervals.