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1.
Ramsis B. Salama Richard Silberstein Daniel Pollock 《Water, Air, & Soil Pollution: Focus》2005,5(1-2):3-26
The flow pathways of water in the soils of the Gnangara Mound are highly irregular and depend upon the moisture content, the
repellency and preferential wettability potential of the soils. The occurrence of preferential flow is more evident in dry
soils. As the soil wets during the rainy season, the water repellence and differential wettability decreases, the fingering
and the preferential flow paths disappear. Most of the agricultural sites in the Spearwood Sands which showed more irregular
flow than the Bassendean Sands are under continuous irrigation during cultivation season. As the repellency problems are chemically
treated, it is therefore expected that the flow will be more uniform all the year round. Landuse is mainly responsible for
variation in recharge rates; however, the hydraulic properties control aquifer response and water level pattern to a greater
degree. Water levels in the mid 1970s were in a semi steady state. Since that time, a combination of increasing water use
by pine plantations, heavy pumping from private boreholes in market gardens and private homes and intensive pumping from the
Gnangara Mound for the metropolitan water supply have caused water levels to continually decline in the Superficial aquifer.
Nitrate and phosphate concentrations in the regional Superficial aquifer are generally very low. None of the tested pesticides
(atrazine, diazinon, dimethoate, endosulfan, fenamiphos, iprodione, malathion and chlorpyrifos) were detected in the groundwater
samples collected from the monitoring bores. 相似文献
2.
Regional Assessment of Nutrient and Pesticide Leaching in the Vegetable Production Area of Rattaphum Catchment, Thailand 总被引:1,自引:0,他引:1
Regional groundwater vulnerability maps to indicate the impact of leaching of chemicals under different management scenarios
were prepared for the Rattaphum Catchment using several leaching models and GIS techniques. The Attenuation Factor (AF) model
was used to simulate the leaching potential of several pesticides for selected soils in the catchment under different rates
of recharge from irrigation. The LEACHN model was used to simulate the NO3
− leaching potential and LEACHP was used to simulate leaching potential of metolachlor under different management scenarios.
The results showed that only a small number of pesticides have the potential to contaminate the shallow groundwater. However,
the risk of contamination with nutrients is much higher due to the mobility and conservative nature of the NO3
−. The LEACHP results indicated that the intensive use of agrochemicals in the vegetable growing area, especially during the
rainy season when the groundwater is near the surface, increases the risk of pesticide contamination. The results of upscaling
from the farm to the catchment scale using soil maps and GIS techniques under various management scenarios and chemical application
rates showed that the most effective strategy to reduce chemical leaching is by reducing pesticide application rates and optimizing
the application of irrigation water. The identification of potential high risk farms by ranking soils and agricultural practices
could be used to formulate management practices that reduce pesticide contamination of the surface and ground water resources
in the area. 相似文献
3.
Tommaso Tesi Stefano Miserocchi Leonardo Langone Laurita Boni Franca Guerrini 《Water, Air, & Soil Pollution: Focus》2006,6(5-6):593-603
In the framework of the EUROSTRATAFORM projects, a multidisciplinary research was focused on processes that involve transport
and deposition of riverine material in the Adriatic Sea. The aim of our contribution was to increase a more complete understanding
of organic matter deposition on the Adriatic shelf, also taking into account the role of Apennine rivers beyond the Po influence.
In order to characterize origin, fate and variability of sedimentary organic carbon we utilized elemental and stable carbon
isotope data in surficial sediments along shallow cross-shelf transects on the western Adriatic shelf. 相似文献
4.
Interannual Changes in the C:N:P Ratios of Seston and Zooplankton of a High Mountain Lake in Sierra Nevada,Spain 总被引:1,自引:0,他引:1
Villar-Argaiz M. Medina-Sánchez J. M. Carrillo P. 《Water, Air, & Soil Pollution: Focus》2002,2(2):359-378
We investigated the carbon, nitrogen and phosphorus content inthe seston and the zooplankton of a high-mountain lake duringthree years of contrasting physical and chemical conditions.Carbon in seston was ten times higher in 1995 than in 1996 and1997. Phosphorus content in seston was variable for the studyperiod, increasing gradually towards late summer in 1995, butpeaking abruptly in 1996 and 1997, reflecting atmosphericdepositions. Seston C:P were high and did not fit any definitepattern in 1995, and were particularly low after the thaw, increasing towards mid-summer in 1996 and 1997. As the seasonprogressed, major decreases in these ratios occurred coincidingwith important atmospheric inputs in the lake area. ZooplanktonN:P and C:P were negatively associated to the appearance ofrotifers and copepod nauplii in 1995, but positively correlatedto the ontogenetic development of the most abundant species,Mixodiaptomus laciniatus, in 1996. Seasonal variations inzooplankton N:P and C:P ratios showed limited interannual, butlarge intraannual variability. The comparison between the bulkcarbon in seston and zooplankton demands for this elementindicated that zooplankton were above food-quantity thresholdsfor maximum growth in 1995, 1996 and mid-season of 1997,therefore suffering only from food-quantity constraints afterthe thaw (nauplii dominance) and towards late season (adultdominance) in the latter year. The high C:P ratios in sestonrelative to zooplankton in 1995 imply that the zooplankton mayhave faced severe food-quality constraints (in terms ofphosphorus) during this year. Differences between bulkzooplankton and seston elemental nutrients are also discussed inrelation to the competitive abilities of species, andparticularly of Daphnia. 相似文献