摘要:

AbstractDirect effects of simulated acidic deposition on vegetation were studied in the laboratory under controlled conditions for three commercially important resources: slash pine, Floradade tomato and Valencia orange. Treatment was similar to convective rain in Florida in ion composition, total volume, frequency and rate of application, intensity and sulfate/nitrate ratio. The surface of the growth medium was covered with plastic during application of the solution. Water and nutrients optimum for growth were provided directly to the growth medium. No visible injury resulted from application of the simulated rain. No effects of pH treatments on vegetative growth of slash pine, orange or tomato were observed. However, fruit yield of tomato and orange differed significantly between plants subjected to different pH treatments. The yield of tomato was lower and that of orange was higher at the lower pH treatments. Calcium and magnesium levels were highest in the foliage of tomato plants receiving the pH 5.5 treatment. No differences in element levels of orange foliage were observed.

ISSN:0730-7268    

DOI:10.1002/etc.5620050111

出版商:Wiley Periodicals, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractThe acute and chronic toxicities of the herbicide fluridone to aquatic invertebrates and fish were evaluated. The acute median lethal concentrations (LC50s) of fluridone were 4.3 ± 3.7 mg/L (x̄±SD) for invertebrates (n= 15) and 10.4±3.9 mg/L for fish (n= 28). In chronic studies, no effects were detected when daphnids (Daphnia magna) were continuously exposed to fluridone concentrations of 0.2 mg/L or less for 32 d, amphipods (Gammarus pseudolimnaeus) to 0.6 mg/L or less for 60 d or midge larvae (Chironomus plumosus) to 0.6 mg/L or less for 30 d. Fathead minnows (Pimephales promelas) were not affected by continuous exposure to fluridone concentrations of 0.48 mg/L or less over their life cycle. The growth and survival of channel catfish (Ictalurus punctatus) were not adversely affected by continuous exposure to fluridone concentrations of 0.5 mg/L or less for 60 d after hatching. The channel catfish accumulated fluridone concentrations two to nine times greater than that in the water. The recommended application rate of 1 lb/acre of fluridone to a pond with an average depth of 3 ft provides a theoretical concentration of 0.1 mg/L. Thus, an initial fluridone concentration of 0.1 mg/L or less is recommended to control weeds in ponds. Consequently, fluridone is not expected to have adverse effects on the species tested or on similar nontarget aquatic organi

ISSN:0730-7268    

DOI:10.1002/etc.5620050112

出版商:Wiley Periodicals, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractThis study deals with cultures ofTropocyclops prasinus mexicanus, a Cyclopoid copepod from three Quebec lakes (one polluted and two unpolluted), in a comparative toxicity test involving four heavy metals. Experiments were performed according to a static toxicity protocol. The 48‐h EC50 of each individual metal and of the combination of metals were determined for each culture. The overall toxicity trend is mixture>Hg>Cu ≥ Cd ≥ Zn. Cultures from unpolluted and low‐hardness lakes showed lower EC50 mean values than did the strain originating from the polluted lake with high water h

ISSN:0730-7268    

DOI:10.1002/etc.5620050113

出版商:Wiley Periodicals, Inc.    

年代:1986

数据来源: WILEY