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361.
362.
Bingli Lei Yu Wen Xuetong Wang Jinmiao Zha Wei Li Zijian Wang Yanfeng Sun Jia Kang Yipei Wang 《Chemosphere》2013
The fertilized eggs of Japanese medaka (Oryzias latipes) were exposed to estrone (E1) at 5–5000 ng L−1 for 15 d, and the hatched fry were exposed continuously to the same concentrations for the additional 15 d. Adverse effects on hatchability, time to hatching, and gross abnormalities occurred at 50 ng L−1 or above. Then the fry were divided into a continual exposure group, and a water recovery group. When the fry were exposed to E1 for another 60 d, there was a decrease in the hepatosomatic index (HSI) of males and the influence disappeared in the water recovery group. The gonadosonatic index (GSI) of females at 500 ng L−1 decreased significantly in another 60 d exposure. While the fry were maintained in dechlorinated tap water for 60 d, a significant decrease in female GSI was observed at 50 ng L−1 or above. An increased GSI was found in males in both continual exposure and water recovery groups at all E1 treatments. Quantitative RT-PCR showed that vitellogenin-I (Vtg-I) gene expressions in the female liver were significantly down-regulated at 50 ng L−1 in the continual exposure group, and at 500 ng L−1 in the water recovery group, while male Vtg-I genes were significantly up-regulated for all E1 treatments. In addition, all E1 treatments caused sex reversal of males. These results suggest that E1 at 5 ng L−1 or above have unrecoverable impacts on the gonadal growth and development of medaka, even if only early life stages were exposed to E1. 相似文献
363.
Some potential hazardous trace elements contamination and their ecological risk in sediments of western Chaohu Lake, China 总被引:3,自引:0,他引:3
Liu-Gen Zheng Gui-Jian Liu Yu Kang Ren-Kang Yang 《Environmental monitoring and assessment》2010,166(1-4):379-386
The Chaohu is one of the largest five freshwater lakes in China. It provides freshwater for agriculture, life, and part of industry. The quality of water becomes worst and worst due to the toxic matter. In this study, we collected the samples from the sedimentary mud in the lake. The distribution of some potential hazardous trace elements (Cu, Ni, Cr, As, Pb, Cd, and Hg) in the sediments of western Chaohu Lake, has been determined and studied, and the enrichment factors, the index of geoaccumulation, and potential ecological risk were analyzed and calculated. The results show that: the levels of selected potential hazardous trace element vary from different sampling sites and significant anthropogenic impact of Pb and Cd occur in sediments. The contamination rank of Pb and Cd are moderate, and Pb has a light potential ecological risk, but Cd is heavy. The total potential ecological risk of the selected hazardous trace elements in this study in Chaohu Lake is moderate. Cluster and correlation analysis indicate that the selected potential hazardous trace element pollutant has different source and co-contamination also occur in sediments. 相似文献
364.
Effects of acid and nitrogen depositions on soil microbial activities were studied in a laboratory-based experiment. Five treatments were added to forest soil for five weeks, and soil enzyme activities were determined along with chemical properties. There was little change in pH and nitrogen availability. Dehydrogenase, phosphatase and arylsulphatase activities were decreased by all the acidic treatments compared to the control, while urease activity was increased by the pH 4 treatment. at the same pH treatment, different nitric acid contents induced different urease activities. the results suggest that acid deposition would inhibit microbial activities and that more study is needed to elucidate the impact on nitrogen cycling in forests. 相似文献
365.
Zhaofu Hu Shichang Kang Xiaobo He Fangping Yan Yulan Zhang Pengfei Chen Xiaofei Li Shaopeng Gao Chaoliu Li 《环境科学学报(英文版)》2020,32(1):389-397
Carbonaceous matter has an important impact on glacial retreat in the Tibetan Plateau, further affecting the water resource supply. However, the related studies on carbonaceous matter are still scarce in Geladaindong (GLDD) region, the source of the Yangtze River. Therefore, the concentration, source and variations of carbonaceous matter at Ganglongjiama (GLJM) glacier in GLDD region were investigated during the melting period in 2017, which could deepen our understanding on carbonaceous matter contribution to glacier melting. The results showed that dissolved organic carbon (DOC) concentration of snowpit samples (283?±?200?μg/L) was much lower than that of precipitation samples (624?±?361?μg/L), indicating that large parts of DOC could be rapidly leached from the snowpit during the melting process. In contrast, refractory black carbon (rBC) concentration measured by Single Particle Soot Photometer of snowpit samples (4.27?±?3.15?μg/L) was much higher than that of precipitation samples (0.97?±?0.49?μg/L). Similarly, DOC with high mass absorption cross-section measured at 365?nm value was also likely to enrich in snowpit during the melting process. In addition, it was found that both rBC and DOC with high light-absorbing ability began to leach from the snowpit when melting process became stronger. Therefore, rBC and DOC with high light-absorbing ability exhibited similar behavior during the melting process. Based on relationship among DOC, rBC and K+ in precipitation, the main source of carbonaceous matter in GLJM glacier was biomass burning during the study period. 相似文献
366.
黄土丘陵区林草退耕年限对土壤团聚体特征的影响 总被引:8,自引:0,他引:8
随着国家退耕还林还草战略的实施、植被覆盖的变化,林、草地植被恢复进程中土壤团聚体特征的变化受到广泛关注.本研究以黄土丘陵区西部的官山林场退耕后栽植的刺槐林地、撂荒草地为对象,选取退耕年限为10、25 a的林、草地,采用湿筛法测定各样地0~30 cm土壤的水稳性团聚体组成,比较退耕还林、还草和退耕年限(10、25 a)对土壤水稳性团聚体平均质量直径(MWD)和分形维数(D)的影响.结果表明:退耕10 a的林地0~30 cm土层水稳性大团聚体含量(R0.25)、MWD和D分别为57.60%、1.91 mm和2.73;退耕25 a的林地分别为60.17%、1.88 mm和2.74;退耕10 a的草地分别为59.89%、1.82 mm和2.74;退耕25 a的草地分别为72.69%、2.71 mm和2.61.进一步分析证明,随着退耕年限的增加,土壤团聚性增强;但林草地的变化存在差异:恢复10 a阶段,土壤团聚性林地尚优于草地,25 a后草地优于林地.各样地土壤的SOC含量与R0.25呈显著正相关关系(p0.01),与D呈显著负相关关系(p0.05).退耕类型和退耕年限对土壤团聚性有显著影响. 相似文献
367.
为研究气溶胶消光特性对城市灰霾特征及形成的影响机制,采用2010年1月─2013年12月4 a的苏州市逐时散射系数、能见度、颗粒物质量浓度以及风速、风向、气温、气压、相对湿度等数据,对该市气溶胶散射系数、消光特性及影响因子进行了研究. 结果表明:苏州市气溶胶散射系数为(301.1±251.3)Mm-1,日变化呈双峰型,早高峰出现在07:00─08:00,晚高峰出现在20:00─21:00;其年内变化呈夏季低、冬季高. 气溶胶散射系数与ρ(PM2.5)的相关系数为0.77,高于与ρ(PM1)和ρ(PM10)的相关性,PM2.5散射效率为6.08 m2/g. 气溶胶散射系数受风速、风向等气象要素的影响:风速<4 m/s时,气溶胶散射系数下降迅速;风速在4~6 m/s时,气溶胶散射系数随风速下降缓慢. 苏州市气溶胶单次散射反照率平均值为0.84,散射消光比平均值为0.79,说明该地区气溶胶消光以散射性气溶胶为主. 气溶胶散射消光、气溶胶吸收消光、空气分子散射消光、NO2吸收消光分别占大气消光的82.33%、13.63%、2.72%和1.32%. 研究表明,对气溶胶散射消光贡献最大的非吸收性PM2.5是苏州市能见度下降、灰霾增加的最重要原因. 相似文献
368.
珠穆朗玛峰地区新降雪的化学特征 总被引:10,自引:1,他引:10
根据1998年8、9月份在珠穆朗玛峰东侧东绒布冰川源头所采集的新降雪样的化学成分资料并与不同时期前人在该地区采集的降水样进行对比,初步探讨了该地区降水的化学特征及其气候环境意义.结果表明,珠峰地区夏末降水非常纯净,主要离子浓度可与南极和格陵兰地区相当,代表了全球偏远地区的大气环境本底值;珠峰地区不同季节降水的化学成分有明显的差异,反映了不同的水汽来源和气候状况.8~9月的水汽主要来源于南亚季风;4~5月的降水深受中亚干旱、半干旱区粉尘的影响,说明其降水的化学特征具有气候敏感性. 相似文献
369.
Chemical characterization of size-resolved aerosols in four seasons and hazy days in the megacity Beijing of China 总被引:2,自引:0,他引:2
Kang Sun Xingang Liu Jianwei Gu Yunpeng Li Yu Qu Junling An Jingli Wang Yuanhang Zhang Min Hu Fang Zhang 《环境科学学报(英文版)》2015,27(6):155-167
Size-resolved aerosol samples were collected by MOUDI in four seasons in 2007 in Beijing. The PM10 and PM1.8mass concentrations were 166.0 ± 120.5 and 91.6 ± 69.7 μg/m~3, respectively,throughout the measurement, with seasonal variation: nearly two times higher in autumn than in summer and spring. Serious fine particle pollution occurred in winter with the PM1.8/PM10 ratio of 0.63, which was higher than other seasons. The size distribution of PM showed obvious seasonal and diurnal variation, with a smaller fine mode peak in spring and in the daytime. OM(organic matter = 1.6 × OC(organic carbon)) and SIA(secondary inorganic aerosol) were major components of fine particles, while OM, SIA and Ca_2+were major components in coarse particles. Moreover, secondary components, mainly SOA(secondary organic aerosol) and SIA,accounted for 46%–96% of each size bin in fine particles, which meant that secondary pollution existed all year. Sulfates and nitrates, primarily in the form of(NH_4)_2SO_4, NH_4NO_3, Ca SO_4, Na_2SO_4 and K_2SO_4, calculated by the model ISORROPIA II, were major components of the solid phase in fine particles. The PM concentration and size distribution were similar in the four seasons on non-haze days, while large differences occurred on haze days, which indicated seasonal variation of PM concentration and size distribution were dominated by haze days. The SIA concentrations and fractions of nearly all size bins were higher on haze days than on non-haze days, which was attributed to heterogeneous aqueous reactions on haze days in the four seasons. 相似文献
370.
建立了挖掘机驾驶舱有限元的结构和声学耦合模型,分别考虑了驾驶舱内吸声材料及门板孔缝对车厢内噪声的影响,利用ACTRAN软件的直接频响方法计算出驾驶员耳旁噪声及驾驶舱内的声场分布,并对不同的结果进行了对比。该方法及结果对挖掘机驾驶舱的降噪具有实际的参考意义。 相似文献