沉积物中2,2',4,4'-四溴联苯醚(BDE-47)在铜锈环棱螺体内的毒代动力学及其繁殖毒性

多溴联苯醚(PBDEs)是一种全球性的新型持久性有毒污染物,沉积物中高浓度的PBDEs是水生态系统的巨大风险源,2,2’,4,4’-四溴联苯醚(BDE-47)在PBDEs同系物中,目前分布最广,生物毒性最强。为评价沉积物中BDE-47向底栖动物体内转移的潜力及其对底栖动物的潜在繁殖毒性,将实验室培养的铜锈环棱螺(Bellamya aeruginosa)暴露于BDE-47加标沉积物中,研究了BDE-47在铜锈环棱螺体内的毒代动力学特性及其对铜锈环棱螺潜在繁殖力的影响。结果表明,铜锈环棱螺对沉积物中BDE-47吸收较快,代谢速度相对较慢,BDE-47在铜锈环棱螺体内具有较强的生物积累性。生物积累达理论平衡时,铜锈环棱螺体内BDE-47浓度为1440.67ng·g-1(以样品干质量计)。BDE-47在铜锈环棱螺体内的生物积累和生物净化过程较好地符合一级动力学模型,摄入速率常数、清除速率常数和生物-沉积物累积因子分别为0.10、0.038和2.75,生物半衰期为18d。铜锈环棱螺体内BDE-47达到90%稳定状态所需的理论时间约为60d。低浓度BDE-47(160ng·g-1)暴露对铜锈环棱螺的潜在繁殖力没有影响,但当浓度≥640ng·g-1时,铜锈环棱螺的繁殖力下降50%,这表明BDE-47对铜锈环棱螺具有繁殖毒性。铜锈环棱螺可作为指示沉积物中底栖生物长期暴露于BDE-47的良好检测模型。     

环境雌激素o,p′-DDT和抗雌激素氟维司群对斑马鱼胚胎的复合效应

为探究雌激素与抗雌激素的复合效应,将斑马鱼(Danio rerio)的胚胎暴露于o,p′-DDT和氟维司群2种典型的环境内分泌干扰物中,考察胚胎孵化率、孵化时间和总畸形率,并用实时荧光定量PCR技术检测Vtg1、Vtg2和ERα等雌激素效应相关基因的mRNA转录水平.结果显示,与单一化合物的暴露相比,o,p′-DDT和...     

Competitive adsorption and desorption of copper and lead in some soil of North China

The competitive adsorption and desorption of Pb(II) and Cu(II) ions in the soil of three sites in North China were investigated using single and binary metal solutions with 0.01 mol·L^-1 CaCl₂ as background electrolyte. The desorption isotherms of Pb(II) and Cu(II) were similar to the adsorption isotherms, which can be fitted well by Freundlich equation (R₂>0.96). The soil in the three sites had greater sorption capacities for Pb(II) than Cu(II), which was affected strongly by the soil characteristics. In the binary metal solution containing 1∶1 molar ratio of Pb(II) and Cu(II), the total amount of Pb(II) and Cu(II) adsorption was affected by the simultaneous presence of the two metal ions, indicating the existence of adsorption competition between the two metal ions. Fourier transform infrared (FT-IR) spectroscopy was used to investigate the interaction between soil and metal ions, and the results revealed that the carboxyl and hydroxyl groups in the soil were the main binding sites of metal ions.     

Characterization of soil low-molecular-weight organic acids in the Karst rocky desertification region of Guizhou Province, China

Soil low-molecular-weight (LMW) organic acids play important roles in the soil-forming process and the cycling of nutrients in Karst regions. In this study, we quantified the contents of LMW organic acids (including lactate, acetate, formate, malate, and oxalate) in soil solution over the Karst region of Guizhou Province, China using ion chromatography. The concentration of total LMW organic acids in topsoil solution ranged from 0.358 to 1.823 μmol·g^-1, with an average of 0.912 μmol·g^-1. The mean concentrations of lactate, acetate, formate, malate, and oxalate were 0.212±0.089, 0.302±0.228, 0.301±0.214, 0.014±0.018 and 0.086±0.118 μmol·g^-1, respectively. There were also significant difference in the contents of these acids among four phases of rocky desertification, and their concentrations decreased with the aggravation of rocky desertification. The concentrations of the LMW organic acids were significantly positive correlated each other. Significant positive correlations were also observed among individual LMW organic acids in soil solution, and between them and soil available P, available K, exchangeable Ca, respectively. Furthermore, the concentrations of LMW organic acids were significantly positively correlated with inorganic anions (chlorides, nitrates, and sulfates) in Karst topsoil solution. Therefore, the concentrations of soil LMW organic acids might be one of driving force in the Karst rock desertification process in Guizhou Province.     

城市公园绿化养护方式探究

为提升城市公园绿化养护水平,介绍了城市公园绿化养护方式,包括公园管理方自行管养,社会化承包绿化管养,部分要素社会化外包.对比了各类养护方式的优劣势,提出公园绿化养护工作建议:重视日常管理,提高专业素质,引导审美素养,实行一园一策模式,为居民增加休憩舒适度,给游客带来更好的游览体验,使公园呈现生机勃勃的景象.     

WCDMA基站电磁辐射对周围环境的影响分析

随着移动通讯技术的发展,人们在享受移动通信技术带来的便捷服务同时,也在担忧通信基站产生的电磁辐射对人体健康的影响。采用选频监测仪器,对WCDMA基站在正常工作状态和最大发射功率状态下天线轴向不同距离上的功率密度进行监测,并通过理论计算进行验证,分析WCDMA基站对周围环境的影响。     

啤酒废水同步脱氮除磷工艺启动研究

为了将短程硝化反硝化与A/O法除磷同时应用于SBR工艺处理啤酒废水,通过改变序批式反应器(SBR)工艺运行方式,使活性污泥依次经历厌氧、好氧、缺氧3个阶段,控制ρ(MLSS)=4 700 mg/L、pH=7.5～8.0、DO=0.3～0.5 mg/L(好氧阶段)。反应器内短程硝化反硝化同步除磷效果明显,氨氮去除率大于90%,亚硝酸盐积累率大于85%,磷去除率大于98%。试验结果表明短程硝化反硝化与A/O法除磷可同时应用于SBR工艺处理啤酒废水。     

河源城南污水处理厂尾水深度处理效果的研究

河源市城南污水处理厂利用垂直流人工湿地对该厂A2-O工艺处理的尾水进行深度处理,研究了人工湿地对尾水中TN、NH4+-N、TP、COD、BOD5的去除效果。结果表明:人工湿地对污水处理厂尾水具有较好的深度处理效果,垂直流人工湿地处理系统对尾水中TN、NH4+-N、TP、COD和BOD5平均去除率分别达到97.4%、97.8%、95.06%、91.87%和95.87%以上,其出水水质基本达GB 18918—2002《城镇污水处理厂污染物排放标准》一级A标准,地表水Ⅲ类标准。     

水解溶菌酶污泥减量过程中的污泥特性

利用水解溶菌酶对从SBR系统中取出的部分污泥进行水解,然后再回流到SBR系统中,通过与未加水解溶菌酶的相同系统对比,研究了水解溶菌酶对SBR系统中污泥减量与污泥特性等方面的影响.结果表明,在连续50d的运行期间,水解溶菌酶作用下的SBR系统中剩余污泥减量总计达到76.29%,而该系统对COD与氨氮的降解效率与未加酶系统基本持平,分别为88.21%与68.72%,但其TP平均去除率较未加酶系统降低了17.2%;系统中由于水解溶菌酶的添加,污泥的微生物活性得到强化,比氧气吸收速率平均提高35%,ATP的平均值比对比系统提高了3.12nmol/mgMLSS.     

Changes in CO2 flux for different recovery processes of desertification in the alpine meadows of Northwest Sichuan北大核心CSCD

Desertification has emerged as a serious threat to the alpine meadows of Northwest Sichuan in recent decades. Artificial vegetation had certain effects on desertification recovery, while how the CO2 flux changed and its reasons are still unclear. During the growing season in 2016 (i.e., from July to September), we selected the desertified alpine meadows with different recovery degrees, including the early stage of restoration, the middle stage of restoration, the late stage of restoration, and control (the unrecovered desertification meadow) as four transects. CO2 flux was measured by the instrument LI-8100, and the microenvironment factors that affected CO2 flux changes were analyzed. The results showed that the carbon sequestration function of desertified alpine meadows gradually increased with the degree of recovery. Net ecosystem exchange (NEE) were -1.61, -3.55, and -4.38 μmol m-2 s-1 in the early, mid-term, and late transects, respectively, and the most dramatic changes occurred from the early stage to mid-term stage, increasing by 120.50%. Both ecosystem respiration (ER) and soil respiration (SR) were enhanced significantly with restoration (P < 0.05). In mid or late July, NEE, ER, and SR reached their maximum values, and thereafter, the indicators varied to near zero (P < 0.05). During the whole growing season, the daily dynamic in CO2 flux for the control alpine meadow was mild and retained the trend of continuous release all day, but that in the desertified alpine meadow was a single peak pattern. Moreover, with restoration process, the peak of CO2 flux increased and reached a peak in the late stage of the recovery process. The regression analysis showed that there was a significant positive correlation between CO2 flux and vegetation coverage, aboveground biomass, and soil moisture (0-5 cm) (P < 0.01), and a weak correlation with 0-5-cm soil temperature (P < 0.01). This indicates that topsoil moisture (5 cm) is a more significant factor for CO2 flux than topsoil temperature during the growing season in the restoration of desertified alpine meadows in Northwest Sichuan. In general, the vegetation recovery significantly improved the carbon-sequestration ability of the desertified alpine meadows during the growing season in Northwest Sichuan, and at the middle stage of restoration, the carbon-sequestration ability improved significantly due to vegetation restoration and increase in topsoil (0-5 cm) moisture. © 2018 Science Press. All rights reserved.