SWAT—A Semi-empirical Model to Predict Concentrations of Pesticides Entering Surface Waters from Agricultural Land     

Colin D. Brown  John M. Hollis 《Pest management science》1996,47(1):41-50

A semi-empirical model called SWAT has been developed to predict concentrations of agriculturally applied pesticides moving to surface waters, an aspect which is not well described by current models for pesticide fate. The model is based upon a direct hydrological link established between soil type and the amount of water moving rapidly to streams in response to rainfall. Attenuation factors describe the decrease in concentrations of pesticide between field application and loss in water moving from the site into surface waters. Evaluation of model predictions against available field data from three sites and four soil types in England shows that SWAT is capable of predicting the transient peak concentrations of a wide range of pesticides during rapid water movement to streams in response to rainfall. Predicted concentrations were too great when rainfall initiated water movement to streams very soon after pesticide application, particularly for the more mobile pesticides, and some predictions for pesticides sorbed very strongly to soil were relatively poor. Almost all of the predicted concentrations were within one order of magnitude of measured values.  相似文献   

Annual reproductive cycle of milkfish, Chanos chanos Forskal,in Hawaiian waters     

Ching-Ming Kuo  Colin E. Nash 《Aquaculture (Amsterdam, Netherlands)》1979,16(3):247-251

The monthly mean values of gonadosomatic index (GSI) over a continuous 36-month period show that the population of milkfish, C.chanos Forskal, in Hawaiian waters has a short breeding season between June and August. In these months, the GSIs of the mature individual males are between 3.19 and 5.36%, and of the mature individual females between 7.07 and 9.76%.These figures plus histological data suggest a synchronous spawning behavior for the species. Mature oocytes (stage III) are larger than 0.7 mm in diameter, which increases to about 1.2 mm at the time of ovulation and about 1.35 mm at the time of spawning  相似文献   

Operational procedures for rearing larvae of the grey mullet (Mugil cephalus L.)     

Colin E. Nash  Ching-Ming Kuo  Susan C. McConnel 《Aquaculture (Amsterdam, Netherlands)》1974,3(1):15-24

Larvae of the grey mullet Mugil cephalus L. can be reared successfully using careful procedures following induced spawning of the adults with purified salmon gonadotropin or human chorionic gonadotropin.Preliminary incubation of the eggs to the gastrula stage at high density for 12 h at 22°C is preferred, using stirred irradiated seawater (32‰ salinity) and the antibiotics penicillin (80 IU/ml) and streptomycin (0.05 mg/ml). The eggs are transferred before hatching to circular rearing tanks at a density of 250 eggs/l.The mouths of the larvae are open and ossified and the eyes are sufficiently pigmented for the larvae to begin feeding on the third day. The larvae are fed cultured phytoplankton and rotifers supplemented with available natural plankton. Nauplii of Artemia are provided on the seventh day.The migratory behavior of the larvae during early development and their physiology are discussed, being relevant to the procedures and the techniques applied.Mass propagation in large (over 12-ft diameter) circular tanks with total light control is recommended.  相似文献   

Biodegradation of oak (Quercus alba) wood during growth of the shiitake mushroom (Lentinula edodes): a molecular approach     

Vane CH  Drage TC  Snape CE 《Journal of agricultural and food chemistry》2003,51(4):947-956

The chemical transformations that occur during growth of the shiitake mushroom (Lentinula edodes) on oak (Quercus alba) were investigated to improve mushroom cultivation and utilization of the spent substrate. Oak logs were decayed by L. edodes over 8 years, during which time they were sampled at six intervals (30, 40, 66, 76, 77, and 101 months). Fresh and decayed oak samples were analyzed using solid-state (13)C NMR and pyrolysis-gas chromatography-mass spectrometry as well as off-line thermochemolysis with tetramethylammonium hydroxide. Degraded oak exhibited lower carbon contents and increased oxygen content compared to the control. Solid-state (13)C NMR analysis revealed that polysaccharides were the major component of both fresh and decayed oak but that L. edodes mediated the preferential loss of cellulose and xylans as compared to lignin, which remained in an altered form. Several trends point toward the degradation of lignin, including a decrease in the proportion of syringyl units as compared to guaiacyl units and a reduction in side-chain length. An increase in guaiacyl and syringyl acid-to-aldehyde ratios occurred with growth, which suggested that the fungus had caused oxidation of Calpha-Cbeta bonds. The overall effect of L. edodes on oak is similar to that of many white-rot fungi, which simultaneously degrade all cell wall components.  相似文献   

Lysimeter experiment to investigate the potential influence of diffusion-limited sorption on pesticide availability for leaching     

van Beinum W  Beulke S  Fryer C  Brown C 《Journal of agricultural and food chemistry》2006,54(24):9152-9159

Pesticide leaching from soil has been shown to decrease with increasing time from application to irrigation. It is hypothesized that the availability of compounds for leaching decreases due to diffusion and sorption inside soil aggregates. Previous work showed that pesticide sorption inside soil aggregates increases significantly during the first days after application. The study presented here tested if diffusion into aggregates could explain the leaching of four aged pesticides from manually irrigated soil cores. Azoxystrobin, chlorotoluron, cyanazine, and bentazone were applied to 30 undisturbed cores (25 cm long, 23.7 cm diameter) from a clay loam soil. The soil cores were irrigated 1, 3, 7, 14, and 28 days after application. Leachate was collected and analyzed. The amount of pesticide found in leachate decreased rapidly with time from application. Pesticide losses in leachate declined 2.5-27 times faster than total residues in soil. The decline was 4-5 times faster for the more strongly sorbed pesticides (azoxystrobin, chlorotoluron, and cyanazine) than for bentazone. In previous work, we derived a model to describe sorption and diffusion of the pesticides in small aggregates from the same soil. The diffusion model was used here to describe sorption inside the large aggregates in the soil cores and extended to describe pesticide leaching by interaggregate flow. The model showed a significant decline in leaching with time from application, which supports the theory that diffusion-limited sorption in aggregates influences the availability for pesticide leaching, although it does not exclude alternative explanations for this decline. The model well described the decline in leaching for three out of four pesticides. The interaggregate transport model could, however, not account for the amount of preferential flow in the cores and underestimated the leaching of bentazone.  相似文献   

The presence of antibiotic resistant bacteria along the River Lagan   总被引：1，自引：0，他引：1  

John E. Moore  Peter J.A. Moore  Colin E. Goldsmith  Paul J. Rooney 《Agricultural Water Management》2010,98(1):217-221

Antibiotic resistance (ABR) has now become a major public health issue. Relatively little work has been published on the incidence of ABR in environmental isolates within the environment, which is of importance to animal health, zoonotic transmission and human health. A study was performed to determine the diversity of total ABR (intrinsic + acquired resistance) in waterborne bacteria in a model watercourse system, namely the River Lagan, Northern Ireland, which is used a major source of drinking water by large populations of beef and dairy cattle. Total numbers of culturable bacteria at each sampling point ranged from 3.8 to 4.3 log colony forming units (cfu)/ml water, with a mean of 4. 1 ± 0.1 log cfu/ml. Total antibiotic resistance was observed to varying degrees and specific resistance levels were as follows with diminishing antibacterial effectiveness in the order: amikacin/aminoglycosides > carbapenems > fluoroquinolones > macrolides/tetracyclines/polymyxins > β-lactams/oxozolidones/rifampicin/trimethoprim/glycopeptides. Monitoring of the upstream ecology of waterways in terms of antibiotic susceptibility, from which agricultural animals gain their water, as well as the use of such water in agricultural crop irrigation is important, as well as the tracking of such organisms to their source may help determine the source of fecal pollution in aquatic ecosystems.  相似文献   

Global consequences of land use   总被引：83，自引：0，他引：83  

Foley JA  Defries R  Asner GP  Barford C  Bonan G  Carpenter SR  Chapin FS  Coe MT  Daily GC  Gibbs HK  Helkowski JH  Holloway T  Howard EA  Kucharik CJ  Monfreda C  Patz JA  Prentice IC  Ramankutty N  Snyder PK 《Science (New York, N.Y.)》2005,309(5734):570-574

Land use has generally been considered a local environmental issue, but it is becoming a force of global importance. Worldwide changes to forests, farmlands, waterways, and air are being driven by the need to provide food, fiber, water, and shelter to more than six billion people. Global croplands, pastures, plantations, and urban areas have expanded in recent decades, accompanied by large increases in energy, water, and fertilizer consumption, along with considerable losses of biodiversity. Such changes in land use have enabled humans to appropriate an increasing share of the planet's resources, but they also potentially undermine the capacity of ecosystems to sustain food production, maintain freshwater and forest resources, regulate climate and air quality, and ameliorate infectious diseases. We face the challenge of managing trade-offs between immediate human needs and maintaining the capacity of the biosphere to provide goods and services in the long term.  相似文献   

Effects of soil redistribution by tillage on subsequent transport of pesticide to subsurface drains     

Lily Summerton  Mark Greener  David Patterson  Colin D Brown 《Pest management science》2023,79(2):616-626

BACKGROUND

Tillage operations will change the distribution in soil for any pesticide residues still present from earlier applications. This redistributive effect of tillage has been neglected in the study of pesticide leaching behavior. This study reviews the literature to characterize this redistributive effect for different tillage operations and uses a pesticide leaching model to investigate the impact of redistribution on pesticide transport to subsurface drains which is a significant input route to surface water bodies.

RESULTS

Inversion ploughing moves the majority of any residues of pesticide present at or near the soil surface into the bottom two-thirds of the plough layer, whereas non-inversion ploughing has only a limited redistributive effect. Incorporating this redistributive effect into model simulations resulted in large changes (typically 5–10-fold difference) in both the maximum concentration and total mass of pesticide transported to drains over the winter following cultivation. More intense cultivation decreased subsequent leaching for relatively mobile compounds (Koc ≤1000 mL g⁻¹), but increased it for strongly sorbed pesticides (Koc ≥2000 mL g⁻¹).

CONCLUSION

The redistributive effect of soil tillage on pesticide residues can have a large effect on subsequent transport to subsurface drains. This effect has been neglected in the literature. Field research is required to validate the model simulations presented here, and consideration should be given as to whether the effect needs to be included within risk assessment procedures. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.  相似文献