The acute toxic effects of mercury (Hg) and bromoxynil (BX) on Enchytraediae Fridericia bulbosa in OECD soil were investigated. The results suggested there was statistically significant differences (p<0.05) between negative controls and exposure experiments except the lowest concentration of single pollutant. The 14-d LC50 values for F. bulbosa exposed to Hg and BX were 0.73 and 0.48 mg kg-1, respectively. The concentration of BX significantly influenced to the mortality of earthworms by Hg,and BX was the main contributive factor of the combined toxic effects. The interactive effects between Hg and BX were synergistic when the concentrations of BX were 0.25 and 1 mg kg-1. While BX concentration was 4 mg kg-1, the interactive effects were antagonistic. It can be concluded that F. bulbosa is a suitable test species to measure the acute toxicity of HM and pesticide, and the morality may be considered as a valuable and sensitive biomarker diagnose adverse effects of Hg or BX in soil environment.
Drip fertigation was applied to evaluate the effects on nutrient losses and crop production in a pear orchard at Chongming Dongtan in Yangtze River Estuary in 2006 and 2007, compared to conventional irrigation and fertilization practices. Based on runoff paddocks and leaching pipes construction, the volumes of runoff and leaching water, and the corresponding concentrations of nitrogen and phosphorus were measured and estimated. The results indicated that, under the experimental conditions, N and P losses through runoff and leaching occurred mainly in the period of rain season from June to October, and leaching was the dominating pathways for N loss while runoff was the main pathways for P loss. Compared with the conventional irrigation and fertilization system, under the consistency of crop yields, the drip fertigation system could decrease the total amounts of nitrogen and phosphorus losses through runoff and leaching by 36.4% and 16.5%, and reduce the total amounts of nitrogen and phosphorus consumptions of chemical fertilizer application by 73.4% and 61.1%, respectively.
By taking advantage of the model of wheat-straw returning to field, we investigated the survey on the transitional trend of the temperature, pH, DO, COD and the bacterial number of the overlying temperature when wheat-straw returned to field. The result indicated that on the 22nd day of the test, the pH (7.60) and DO value (4.12 mg/L) of the wheat-straw returning stimulation area were obviously lower than the pH(7.85) and DO value (6.98 mg/L) of the control area. However, the COD value (35.0 mg/L) was clearly higher than that of the control area (26.0 mg/L). The result showed that the organic content among the overlying water in the straw returning stimulation area was improved and meanwhile the capacity of the self-purification of water is lower. At the same time, there was no significant difference of the total number of bacteria between the overlying water and the control area (p=0.656218). However, the proportion of cellulose bacteria was the 75 times of that in the control area, with the absolute growth advantages.
The water quality and Carassius auratus growth status in nearby rivers was studied during the commwassioning of ±800KV DC transmwassion grounding electrode. The result shows that there was favorable relativity between water temperature and the temperature of the day in nearby river(r≥0.9), but there was no obvious change in PH, conductivity, salinity and DO. Significant analyswas result of fry death rate and assume growth rate shows that almost two month commwassioning has no obvious effect on larva growth of Carassius auratus.
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