A VOLUME BALANCE SOLUTION FOR WATER FLOW OVER FLAT SOIL SURFACES1

ABSTRACT: This paper presents the development of a mathematical model to compute the advance of water flowing over flat soil surfaces. The solution is of interest to the design and management of irrigation systems, and the model can also be applied to overland flow problems. The hydraulics of water flow during the advance phase is simulated by the Lewis-Milne integral equation. The general solution to this equation is obtained by using the Laplace transform theory. A particular solution was developed, based on series expansions, that uses the modified Kostiakov equation to predict infiltration. The solution is given by a double infinite series that has terms of alternate sign. Results from this model show satisfactory agreement when compared with field data collected by the author.     

西印度洋地区海草生态系统

海草是海洋被子植物,广泛分布在温带和热带的海岸带水域,是地球上水生生态系统中最具生产力的生物之一.     

<Emphasis Type="Italic">Dinoponera lucida</Emphasis> Emery (Formicidae: Ponerinae): the highest number of chromosomes known in Hymenoptera

We report the remarkable karyotype of Dinoponera lucida, a Brazilian endemic ponerine ant. Its chromosome number is 2n=106, most of the chromosomes are acrocentric and of very small size, and the karyotype formula is 88A+18M. A chromosome pair of the AM^t type is reported. This is the largest number of chromosomes reported for the Hymenoptera order until now.     

INTEGRATING LANDSCAPE ASSESSMENT AND HYDROLOGIC MODELING FOR LAND COVER CHANGE ANALYSIS1

ABSTRACT: Significant land cover changes have occurred in the watersheds that contribute runoff to the upper San Pedro River in Sonora, Mexico, and southeast Arizona. These changes, observed using a series of remotely sensed images taken in the 1970s, 1980s, and 1990s, have been implicated in the alteration of the basin hydrologic response. The Cannonsville subwatershed, located in the Catskill/Delaware watershed complex that delivers water to New York City, provides a contrast in land cover change. In this region, the Cannonsville watershed condition has improved over a comparable time period. A landscape assessment tool using a geographic information system (GIS) has been developed that automates the parameterization of the Soil and Water Assessment Tool (SWAT) and KINEmatic Runoff and EROSion (KINEROS) hydrologic models. The Automated Geospatial Watershed Assessment (AGWA) tool was used to prepare parameter input files for the Upper San Pedro Basin, a subwatershed within the San Pedro undergoing significant changes, and the Cannonsville watershed using historical land cover data. Runoff and sediment yield were simulated using these models. In the Cannonsville watershed, land cover change had a beneficial impact on modeled watershed response due to the transition from agriculture to forest land cover. Simulation results for the San Pedro indicate that increasing urban and agricultural areas and the simultaneous invasion of woody plants and decline of grasslands resulted in increased annual and event runoff volumes, flashier flood response, and decreased water quality due to sediment loading. These results demonstrate the usefulness of integrating remote sensing and distributed hydrologic models through the use of GIS for assessing watershed condition and the relative impacts of land cover transitions on hydrologic response.     

Voltammetric detection of trifluralin in tap water,fruit juice,and vegetable extracts in the presence of surfactants

This study describes a novel electrochemical method to determine the herbicide trifluralin in samples of water, fruit juice, and vegetable extracts in the presence of surfactants, using a glassy carbon electrode (GCE). In acidic media, trifluralin was irreversible on the glassy carbon electrode surface at ?0.5 V vs. Ag/AgCl. Surfactant presence on the electrode–solution interface modified current intensities and shifted the reduction peak potential of trifluralin. Different types of surfactant and their concentrations were investigated. The anionic surfactant significantly enhanced the peak current intensity of trifluralin. Under optimal analytical conditions, an analytical curve was obtained in the concentration range of 0.48–32.20 µM. The limits of detection and quantification were estimated at 0.031 and 0.104 µM, respectively. The method was successfully applied to quantify trifluralin in samples of water, orange and tomato juice, and green pepper, carrot, and onion extracts, with recovery rates of 97.9–102.1%. The results were in good agreement with those obtained using high-performance liquid chromatography, indicating that the proposed electrochemical method can be employed to quantify trifluralin in various types foods, with sensitivity, specificity, selectivity and reproducibility.     

Oxidative stress is an early symptom triggered by aluminum in Al-sensitive potato plantlets

The objective of this study was to evaluate whether the oxidative stress caused by aluminum (Al) toxicity is an early symptom that can trigger root growth inhibition in Macaca (Al-sensitive) and SMIC148-A (Al-tolerant) potato clones. Plantlets were grown in a nutrient solution (pH 4.00) with 0, 100 and 200 mg Al L⁻¹. At 24, 72, 120 and 168 h after Al addition, root length and biochemical parameters were determined. Regardless of exposure time, root length of the Macaca clone was significantly lower at 200 mg Al L⁻¹. For the SMIC148-A clone, root length did not decrease with any Al treatments. Al supply caused lipid peroxidation only in Macaca, in both roots (at 24, 72, 120 and 168 h) and shoot (at 120 and 168 h). In roots of the Macaca, catalase (CAT) and ascorbate peroxidase (APX) activity decreased at 72 and 120 h, and at 24, 72 and 120 h, respectively. At 168 h, both activities increased upon addition of Al. In roots of the SMIC148-A, CAT activity increased at 72 and 168 h, whereas APX activity decreased at 72 h and increased at 24, 12 and 168 h. The Macaca showed lower root non-protein thiol group (NPSH) concentration at 200 mg Al L⁻¹ in all evaluations, but the SMIC148-A either did not demonstrate any alterations at 24 and 72 h or presented higher levels at 120 h. This pattern was also observed in root ascorbic acid (AsA) concentration at 24 and 120 h. The cellular redox status of these potato clones seems to be affected by Al. Therefore, oxidative stress may be an important mechanism for Al toxicity, mainly in the Al-sensitive Macaca clone.     

Behavioral and demographic changes following the loss of the breeding female in cooperatively breeding marmosets

Recent models of the evolution and dynamics of family structure in cooperatively breeding vertebrates predict that the opening of breeding vacancies in cooperatively breeding groups will result in (1) dispersal movements to fill the reproductive position, and (2) within-group conflict over access to reproduction. We describe the behavioral and demographic changes that followed the creation of breeding vacancies in three wild groups of cooperatively breeding common marmosets (Callithrix jacchus). Replacement of the breeding female was rapid when no adult females remained in the group, but did not occur for several months when other adult females were present. Aggression of adult animals towards same-sex potential immigrants was associated with a period of reduced affiliation, increased intragroup agonism, no intragroup sexual behavior, and frequent extragroup copulations. This ended with the fissioning of groups along sexual lines. After replacement, multiple males copulated with multiple females and vice versa, with no increases in sexually related aggression. Female-female conflict was resolved through infanticide. The lack of direct conflict between males is consistent with cooperative polyandry. After a breeding vacancy appeared, marmoset groups showed conflict of interests among group members similar to those shown by cooperatively breeding birds, but they used different behavioral mechanisms to resolve those conflicts. Our data provide important evidence from a cooperatively breeding mammal to support Emlen’s model for the evolution of vertebrate families, but they suggest that species-specific inter- and intrasexual competitive strategies should be considered before the model can be applied to other cooperatively breeding vertebrates. Received: 23 November 1999 / Received in revised form: 28 March 2000 / Accepted: 1 April 2000     

Modeling Runoff Response to Land Cover and Rainfall Spatial Variability in Semi-Arid Watersheds

Hydrologic response is an integrated indicator of watershed condition, and significant changes in land cover may affect the overall health and function of a watershed. This paper describes a procedure for evaluating the effects of land cover change and rainfall spatial variability on watershed response. Two hydrologic models were applied on a small semi-arid watershed; one model is event-based with a one-minute time step (KINEROS), and the second is a continuous model with a daily time step (SWAT). The inputs to the models were derived from Geographic Information System (GIS) theme layers of USGS digital elevation models, the State Soil Geographic Database (STATSGO) and the Landsat-based North American Landscape Characterization classification (NALC) in conjunction with available literature and look up tables. Rainfall data from a network of 10 raingauges and historical stream flow data were used to calibrate runoff depth using the continuous hydrologic model from 1966 to 1974. No calibration was carried out for the event-based model, in which six storms from the same period were used in the calculation of runoff depth and peak runoff. The assumption on which much of this study is based is that land cover change and rainfall spatial variability affect the rainfall-runoff relationships on the watershed. To validate this assumption, simulations were carried out wherein the entire watershed was transformed from the 1972 NALC land cover, which consisted of a mixture of desertscrub and grassland, to a single uniform land cover type such as riparian, forest, oak woodland, mesquite woodland, desertscrub, grassland, urban, agriculture, and barren. This study demonstrates the feasibility of using widely available data sets for parameterizing hydrologic simulation models. The simulation results show that both models were able to characterize the runoff response of the watershed due to changes of land cover.     

EDDS and EDTA-enhanced zinc accumulation by Solanum nigrum inoculated with arbuscular mycorrhizal fungi grown in contaminated soil

The effect of two different chelating agents [EDTA and EDDS (S,S-ethylenediaminedissucinic acid)] on Zn tissue accumulation in Solanum nigrum L. grown in a naturally contaminated soil was assessed. Under those conditions, the response of the plant to the inoculation with two different isolates of arbuscular mycorrhizal fungi (AMF)--Glomus claroideum and Glomus intraradices--was also studied. Plants grown in the local contaminated soil (Zn levels of 433mg kg(-1)) accumulated up to 1191mg kg(-1) of Zn in the roots, 3747mg kg(-1) in the stems and 3409mg kg(-1) in the leaves. S. nigrum plants grown in the same soil spiked with extra Zn (Zn levels of 964mg kg(-1)) accumulated up to 4735, 8267 and 7948mg Zn kg(-1) in the leaves, stems and roots, respectively. The addition of EDTA promoted an increase in the concentration of Zn accumulated by S. nigrum of up to 231% in the leaves, 93% in the stems and 81% in the roots, while EDDS application enhanced the accumulation in leaves, stems and roots up to 140, 124 and 104%, respectively. In the stems, the presence of Zn was predominantly detected in the cortex collenchyma cells, the starch sheath and the internal phloem and xylem parenchyma, and the addition of chelating agents did not seem to have an effect on the localisation of accumulation sites. The devise of a chelate-enhanced phytoextraction strategy, using chelating agents and AMF, is discussed.     

Sub-soil contamination due to oil spills in six oil-pipeline pumping stations in northern Mexico

Mexico has a very important oil industry, comprehending the exploration, production, transformation, storage and distribution of crude oil and its fractions. Petroleos Mexicanos (PEMEX) is a state-owned monopoly in charge of these activities. Oil and oil-products transport is an extremely crucial operation for the cycle production-transformation-distribution. Pipeline system transport crude oil and sub-products along the country (including liquids, gases and mixtures). It has been reported that more than 30% of the oil ducts in Mexico have been operating for over 30 years, although their lifetime has been calculated in 25-30 years. This work is aimed at characterizing a zone around six oil-pipeline pumping stations located at northern Mexico. The specific places to evaluate soil contamination were (1) the distribution head of the Gomez Palacio (GOPA) pumping station; (2) the north side of the old ditch, the API oil separator and the wastewater zones of the Jimenez (JIM) pumping station; (3) the pumping stations of Ceballos (CE), Peronal (PER), Simon Bolivar (SIBO), and Mayran (MAY). The study comprehended sampling of the areas, delimitation of contamination in the vertical and horizontal extension, analysis of the sampled soils, regarding TPH and, in some cases, the 16 PAHs considered as a priority by USEPA, calculation of areas and volumes contaminated (according to the Mexican legislation, specifically NOM-EM-138-ECOL-2002) and, finally, a proposal for the best remediation techniques suitable for the encountered contamination levels and the localization of contaminants. In general, TPHs were found in all the pumping stations analyzed in this study. Regarding maximal TPHs concentrations at the stations, their order of contamination was as follows: SIBO>CE>PER>MAY>JIM>GOPA. PAHs were found only in a few points at concentrations above the detection limit. At the Jimenez, Gomez Palacio, Peronal, and Ceballos stations, only one point, with PAHs values over the detection limit was found, whereas two points were found at Mayran, and finally at the Simon Bolivar station there were four points with measurable amounts of PAHs. Given the areas and volumes that need to be treated (32835 m3), as well as the physical position of contaminants, it is considered that excavation of the contaminated soil is feasible and the cleaning process could be soil washing assisted with surfactants, though bioremediation should not been discharged as a possible remediation technique.