Detached live oak (Quercus virginianaMill.) leaves were immersed in aqueous solutions of 4-amino-3,5,6-trichloropicolinic acid (picloram) or (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T) for periods up to 4 hr. Herbicide concentration ranged from 10−3to 10−6M; solutions were adjusted to either pH 4, 6, 7, or 8. Absorption of picloram in the presence of equimolar concentrations of 2,4,5-T exceeded that noted for picloram alone. The presence of picloram in the treating solutions had no effect on absorption of 2,4,5-T. This technique allows evaluation of absorption and penetration characteristics of mixtures of herbicides, solvents, and adjuvants.
Soil residue levels were studied to a depth of 2.4 m for a period of 2 years after application of 1.12 kg/ha of 4-amino-3,5,6-trichloropicolinic acid (picloram). Thirty days after application 93 ppb were recovered in the top 15 cm of soil. Residues were less than 5 ppb at depths of 46 to 122 cm. Six months after application, residues were between 5 and 10 ppb down to 183 cm and less than 5 ppb between 198 and 244 cm. Residues to depths of 244 cm were less than 5 ppb 1 year after treatment. Residue levels to similar depths were studied in two soil types for a period of 1 year after application of conventional and polymerized picloram sprays and granules (3.4 kg/ha of picloram). Conventional sprays resulted in significantly higher soil residues for the sampling period than polymerized sprays. Residues from polymer granules were likewise significantly greater than from polymer sprays. Conventional and polymer formulations were identical with respect to movement through the soil.
Abstract:The 1994 Northwest Forest Plan (NWFP) shifted federal lands management from a focus on timber production to ecosystem management and biodiversity conservation. The plan established a network of conservation reserves and an ecosystem management strategy on ~10 million hectares from northern California to Washington State, USA, within the range of the federally threatened northern spotted owl (Strix occidentalis caurina). Several subsequent assessments-and 20 years of data from monitoring OPEN ACCESSForests 2015, 6 3327 programs established under the plan-have demonstrated the effectiveness of this reserve network and ecosystem management approach in making progress toward attaining many of the plan's conservation and ecosystem management goals. This paper (1) showcases the fundamental conservation biology and ecosystem management principles underpinning the NWFP as a case study for managers interested in large-landscape conservation; and (2) recommends improvements to the plan's strategy in response to unprecedented climate change and land-use threats. Twenty years into plan implementation, however, the U.S. Forest Service and Bureau of Land Management, under pressure for increased timber harvest, are retreating from conservation measures. We believe that federal agencies should instead build on the NWFP to ensure continuing success in the Pacific Northwest. We urge federal land managers to (1) protect all remaining late-successional/old-growth forests; (2) identify climate refugia for at-risk species; (3) maintain or increase stream buffers and landscape connectivity; (4) decommission and repair failing roads to improve water quality; (5) reduce fire risk in fire-prone tree plantations; and (6) prevent logging after fires in areas of high conservation value. In many respects, the NWFP is instructive for managers considering similar large-scale conservation efforts.
The effect of temperature and ultraviolet (uv) radiation on the persistence of methyl parathion (o,o‐dimethylo, p‐nitrophenyl phosphorothionate) and DDT [2,2 bis(pchlorophenyl)‐l,l,l‐trichloroethane] in soils was studied using controlled environmental conditions. Biologically effective uv radiation (300 to 400 nm) was used. Three alkaline soil types were used in the study: Houston Black clay, Pima silty clay, and Pinal gravelly loam. Soils in petri dishes were treated with a mixture of methyl parathion and DDT at 5, 20, or 1,000 µg/g. The 5 and 20 µg/g treatments were used to quantitate the amount of pesticide remaining in the soils at periodic intervals. The 1,000 #g/g treatment was used for qualitative studies of breakdown products. Standard samples of pesticides were irradiated with uv radiation for qualitative studies. The results indicated that both temperature and uv radiation accelerated the loss of pesticides from soils. Temperature appeared to play a more important role in the loss of DDT than in methyl parathion. At each temperature (30 and 50 C) the addition of uv radiation accelerated the loss of both methyl parathion and DDT. There was a 29% or greater loss of DDT (depending upon the soil type), above that observed in the 50 treatment not receiving uv radiation. The only identifiable breakdown product of DDT in the soil extracts was DDE [2,2 bis(p‐chlorophenyl)‐l,1‐ dichloroethylene]. There were no breakdown products for methyl parathion in the soil extracts. The breakdown products from the irradiated standard samples of DDT and DDE were numerous. For DDT they included DDE, DDD [2,2 bis (p‐chlorophenyl)‐l,l‐dichloroethane], DBP (4,4'‐dichlorobenzophenone), and DDMU [1‐chloro‐ 2,2‐bis(p‐chlorophenyl)ethylene]. The oxon derivative methyl parathion. At each temperature (30 and 50 C) the addition of uv radiation accelerated the loss of both methyl parathion and DDT. There was a 29% or greater loss of DDT (depending upon the soil type) above that observed in the 50 C treatment not receiving uv radiation. The only identifiable breakdown product of DDT in the soil extracts was DDE [2,2 bis(p‐chlorophenyl)‐1,1‐dichloroethylene]. There were no breakdown products for methyl parathion in the soil extracts. The breakdown products from the irradiated standard samples of DDT and DDE were numerous. For DDT they included DDE, DDD [2,2 his (p‐chlorophenyl)‐1,1‐dichloroethane], DBP (4,4'‐dichlorobenzophenone), and DDMU [1‐chloro‐2,2‐bis(p‐chlorophenyl)ethylene]. The oxon derivative of methyl parathion was tentatively identified as a break‐down product of methyl parathion.
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