Acute Toxicity of Hg, Cd, Zn and Mn to Postlarvae of Penaeus japonicus Bate

在恒温(28±0.5℃)和充气条件下,研究了Hg--(2+)、Cd--(2+)、zn--(2+)、Mn--(2+)对日本对虾仔虾的急性致毒效应.结果表明,Hg--(2+)、Cd--(2+)、zn--(2+)、Mn--(2+)对日本对虾仔虾的毒性顺序为Hg--(2+)>Cd--(2+)>zn--(2+)>Mn--(2+).根据重金属对日本对虾仔虾的96HlC_(50)值计算的Hg--(2+)、Cd--(2+)、zn--(2+)、Mn--(2+)的安全浓度分别为0.0012、0.0342、0.0449、0.0950Mg/dM--3.The effects of acute toxicity of Hg2+, Cd2+, Zn2+ , Mn2+ under the condition of aeration postlarvae of Penaeus japonicus Bate have been studied at the temperature of 28±0.5℃.The results show that the order of toxicity of Hg2+, Cd2+ , Zn2+, Mn2+for postlarvae is Hg2+>Cd2+ >Zn2+>Mn2+.The "safe level" of Hg2+, Cd2+ , Zn2+ , Mn2+ to the larvae is 0.0012, 0.0342, 0.0449, 0.0950 mg/dm3 on the basis of the 96h LC50 value calculated for postlarvae

农用土地质量评价研究进展

科学地进行土地评价,实现土地评价的定量化、综合化、信息化、精准化、动态化、信息化,有利于实时掌握土地利用结构和产业布局的变化,有利于提出合理的可持续发展的土地评价方法,为解决人口的不断增长和环境问题的日益恶化提供保障。本文对国内外土地评价的研究进展进行归纳,并对土地评价的发展趋势进行了分析

Phenanthrene sorption by sediments from Yellow River Estuary: Effects of environmental factors

To understand the environmental behaviors and ecological risks of polycyclic aromatic hydrocarbons(PAHs)in the transport processes from the river to the estuary, and subsequently coastal waters, the sorption of phenanthrene on the Yellow River estuary sediments was investigated under varying conditions including sediment concentrations, dissolved organic matter(DOM), temperature, and salinity. Phenanthrene sorption by estuarine sediments and marine sediments were also compared. The results showed that sediments with low concentration exhibited high sorption capacity for phenanthrene. Phenanthrene sorption was enhanced in the presence of DOM, and the effect of humic acid(HA)was more significant than that of fulvic acid(FA). The sorption capacity declined with increasing temperature, whereas it increased with increasing salinity. Surface adsorption and partitioning of phenanthrene occur simultaneously on the sediments. For estuarine sediments, adsorption was predominant, while partitioning was the main mechanism for marine sediments. Moreover, the sorption capacity of marine sediments was higher than that of estuarine sediments. Based on these results, it can be concluded that phenanthrene is inclined to be adsorbed on sediments in the transport processes from the river to the estuary, and subsequently coastal waters, which may reduce the ecological damage in water, but raise the potential health risks to benthonic organisms in offshore marine areas

水酶法提取红瓜子仁油工艺条件优化及其挥发性成分分析Optimization of aqueous enzymatic extraction of red melon seed kernel oil and its volatile components analysis

为了获得红瓜子仁水酶法提油的最佳工艺条件，了解红瓜子仁油贮藏过程中挥发性成分的变化，以红瓜子仁油提取率为指标，采用单因素试验和正交试验对红瓜子仁油的水酶法提取工艺条件进行优化，并采用HS-GC-IMS技术对贮藏0 d和1年(4 ℃冰箱中存放)的红瓜子仁油的挥发性成分进行分析。结果表明：水酶法提取红瓜子仁油最佳工艺条件为料液比1∶ 5、碱性蛋白酶添加量5%、酶解温度50 ℃、酶解时间3 h、pH 10，在此条件下红瓜子仁油提取率为75.68%；红瓜子仁油中主要的挥发性成分有25种，不同贮藏时间下红瓜子仁油中挥发性成分的含量存在差异，其中3-甲基-1-丁醇和3-羟基-2-丁酮可初步确定为新鲜红瓜子仁油挥发性成分的标志物。研究结果说明水酶法提取红瓜子仁油可以获得较高的油脂提取率，贮藏时间影响红瓜子仁油中挥发性成分的组成及含量。 In order to obtain the optimal process conditions of extracting oil from red melon seeds with aqueous enzymatic method and understand the changes of volatile components of the red melon seed kernel oil during storage, with the extraction rate as the index, the extraction process conditions of red melon seed kernel oil were optimized by single factor experiment and orthogonal experiment, and the volatile components of red melon seed kernel oil stored for 0 d and 1 year (stored in a refrigerator at 4 ℃) were analyzed by HS-GC-IMS. The results showed that the optimal process conditions for aqueous enzymatic extraction of red melon seed kernel oil were obtained as follows: solid-liquid ratio 1∶ 5, enzyme dosage of alkali protease 5%, enzymatic hydrolysis temperature 50 ℃, enzymatic hydrolysis time 3 h, and pH 10. Under the optimal conditions, the extraction rate of red melon seed kernel oil was 75.68%. There were 25 main volatile components in the red melon seed kernel oil, and there were differences in the content of volatile components in red melon seed kernel oil under different storage time, among which 3-methyl-1-butanol and 3-hydroxyl-2-butanone could be preliminarily identified as a marker of volatile components in fresh red melon seed kernel oil. In conclusion, the aqueous enzymatic extraction of red melon seed kernel oil can obtain higher oil extraction rate, and the storage time affects the composition and content of volatile components in red melon seed kernel oil