Characteristics of oxytetracycline sorption and potential bioavailability in soils with various physical-chemical properties

Veterinary antibiotics are widely used for disease treatment, prevention and animal growth promoting. Frequent detection of veterinary antibiotics in environments, caused by land application of untreated or even treated antibiotics-containing animal wastes, has posed the growing concern of their adverse effect on natural ecosystems. Oxytetracycline (OTC) is one of the most widely-used veterinary antibiotics in livestock industry. OTC present as a cation, zwitterions, or net negatively charged ion in soils complicates predicting its sorption characteristics and potential bioavailability and toxicity. This study was to identify soil properties influencing OTC sorption and its subsequent bioavailability in five soils with various physical-chemical properties. A solution used to determine bioavailable analytes in soils and sediments, 1 M MgCl₂ (pH 8.5), was chosen to desorb the potentially bioavailable fraction of OTC sorbed onto soils. Our results demonstrated that soils with higher illite content and permanent cation exchange capacity have higher OTC sorption capacity, but increase the availability of sorbed OTC indicated by higher release of sorbed OTC from soils into aqueous phase in 1 M MgCl₂ (pH 8.5). Reversely, soil organic matter (SOM), clay, kaolinite, variable cation exchange capacity, DCB-Fe and -Al have lower OTC sorption capacity, but decrease the release of sorbed OTC from soils into 1 M MgCl₂. These findings indicate that SOM and clay greatly influence OTC adsorption and potential availability. This study contributes significantly to our understanding of the potential bioavailability of sorbed OTC and the effects of soil properties on OTC sorption behaviors in soils.     

Polybrominated diphenyl ethers in soils of the modern Yellow River Delta, China: occurrence, distribution and inventory

The Yellow River is the second largest river in China. In this study, the levels of polybrominated diphenyl ethers (PBDEs) in the modern Yellow River Delta (mYRD) were firstly reported. Twenty PBDE congeners in soil/sediment samples from mYRD were measured. The total PBDE concentrations ranged from non-detectable to 18 257 ng kg⁻¹ with a mean value of 836 ng kg⁻¹. BDE-209 was the dominant congener, accounting for ∼86.1-99.5% of the total PBDEs. The congener profiles of PBDEs with higher abundances of BDE-153 and BDE-183 were similar to those in sediment of the Bohai Sea, indicating that they shared similar sources. The concentrations and congener patterns varied among different regions. Higher levels of PBDEs were found in the middle area (MA), and more complicated congener compositions were also observed in the MA, whereas lower levels of PBDEs were found in the modern course (MC) and the old course (OC). Much more PBDEs were detected in the top layer (TL) soil where more congeners were also held compared to lower soil layers, implying that more PBDEs were emitted into this area in recent years/decades. Organic matter controlled the PBDE distribution in the soil. Soil in this area might be a source of BDE209 for the Bohai Sea.     

2A97铝合金硫酸阳极氧化搅拌摩擦焊对接结构件在热带岛礁海洋大气环境暴露初期的失效行为

研究了铝合金搅拌摩擦焊对接结构硫酸阳极化试样在热带岛礁海洋大气环境暴露初期的失效行为,并对失效机理进行了阐述。通过对在热带岛礁大气环境中暴露初期的试样进行外观观察、光学显微观察、扫描电镜(SEM)观察和能谱分析(EDS)、以及电化学阻抗测试(EIS),阐述了相关变化过程。试样暴露1年后,在0.01Hz处的阻抗模值由初始的2.08×10~6Ω变为5.51×10~5Ω。试样在热带岛礁大气环境暴露1年后热影响区的阳极氧化膜有轻微褪化,电化学阻抗随暴露时间的增加而略有下降。     

油烟道火灾事故模糊事故树分析

本文利用事故树分析法对饮食业油烟道火灾进行分析,结合油烟道火灾事故案例建立事故树.从模糊概率排序以及分级可以得到,饮食业油烟道油垢没有及时清理是导致火灾的最危险的因素.因此要对这个因素进行严格管理.     

聚硅酸盐复合絮凝剂的研制

合成了聚环氧琥珀酸-聚硅酸铁锌复配物（PESA—PSFZ）,并对其稳定性和絮凝效果进行了研究。结果表明：PESA—PSFZ较聚环氧琥珀酸一聚硅酸复配物具有更高的Zeta电位及更好的去浊效果,沉降速率快,适用的pH范围广;当PESA—PSFZ加入量为6mg／L时,对模拟废水的浊度去除率达99．2％;当PESA—PSFZ加入量为20mg／L时,对印染废水的COD去除率达87.3％。     

深圳大气中VOCs的二次有机气溶胶生成潜势

使用气溶胶生成系数法和产率法,对深圳四季5种芳香烃和异戊二烯所生成的二次有机气溶胶(SOA)量分季节计算并比较得出:四季中除春季外,其余三季产率法计算得到的SOA量均高于生成系数法计算的结果,四季所生成SOA的平均值分别为(2.48±2.02)μg/m3和(2.10±1.21)μg/m3. 2种方法计算结果均为夏季SOA的生成量最大,秋季和冬季次之,春季最小.生成系数法计算得出人为源和天然源的贡献分别为96%和4%,而产率法得到两种源的贡献分别为86%和14%.将生成系数法和产率法计算得到的夏季SOA值与实测值进行比较,发现计算值均低于实测值,分别占实测值的21%和31%.最后计算芳香烃和异戊二烯的自由基反应速率得出,与OH自由基反应是其生成SOA最主要的途径,比例为75%,与NO3自由基和O3的反应比例分别为22%和3%.在生成SOA速度上,苯乙烯的速度最快,苯的速度最慢.     

基于改进IPAT模型的中国未来碳排放预测

在"碳排放量与能源消费成正比"假设的基础上,对中国1987—2010年的历年碳排放量和人均碳排放量进行了分区域研究与计算.经数据分析,发现以2002年为界线,前后两个时期中国碳排放变化缺乏内在的连贯性,2002年以前的碳排放曲线无法表征未来年份碳排放趋势.在此发现的基础上,以2002—2010年碳排放数据为基础,引入表征科技进步的变量,对IPAT模型进行改进,进而对2010—2050年中国碳排放进行了预测和分析.结果表明:中国排放峰值发生在2030年,全国碳排放总量将达到3684.1636Gg,人均碳排放为2.6476t;在2030年之前中国碳排放量将以平均每年2.89%的速度持续增加.2030—2050年碳排放量将以每年2.09%的速度减少,至2050年,全国碳排放量为2366.4522Gg,人均碳排放为1.8521t.本研究为中国未来碳排放政策的制定提供了方法与数据支持.     

紫外辐照改性生物炭对VOCs的动态吸附

采用365 nm紫外光辐照改性椰壳生物炭,以提升对挥发性有机污染物(VOCs)的吸附性能.选取苯和甲苯两种典型的VOCs为吸附质,考察了改性前后生物炭的吸附穿透曲线.结果表明,紫外辐照改性后的生物炭其吸附性能显著增加,对苯和甲苯的饱和吸附量分别由7.27 mg·g~(-1)和7.98 mg·g~(-1)提升至122.80 mg·g~(-1)和236.36 mg·g~(-1),吸附穿透时间也由1 min和2 min大大延长至390 min和620 min.生物炭表面理化特征分析表明,紫外辐照增大了生物炭表面含氧官能团的含量和外比表面积,这可能是改性生物炭吸附性能提升的关键因素.Yoon-Nelson、Thomas和BDST模型均能很好地模拟改性生物炭对不同浓度苯和甲苯的吸附过程,其相关系数大于0.992.热重分析结果表明,紫外辐射对生物炭的热稳定性影响甚微.改性生物炭吸附饱和后,可经热再生后重复利用,对甲苯的吸附重复利用5次后仍有较高的吸附能力.     

基于集合均方根滤波的太湖叶绿素a浓度估算与预测

叶绿素a浓度作为表征水质状况的重要参数之一,反映了水体富营养化程度和藻类含量,是决定水体的反射光谱特征的重要因素,也是水质遥感领域研究较多的一项水质参数.研究叶绿素a浓度的遥感定量反演可以为湖泊水质监测与评价提供新的思路和方法.本研究发展了一个基于集合均方根滤波和风生流的污染物扩散模型的数据同化方案,并结合2010年5月20日的太湖3个浮标观测站点的观测数据进行了同化实验.首先对太湖叶绿素a浓度进行同化估算,然后利用优化后的估算结果对太湖叶绿素a浓度进行了为期6 h的预报.在同化阶段,均方根误差分别从1.58、1.025、2.76降低到了0.465、0.276、1.01,平均相对误差也从0.2降低到了0.05、0.046、0.069.在预报阶段,均方根误差从1.486、1.143、2.38降低到了0.017、0.147、0.23,平均相对误差也从0.2降低到了0.002、0.025、0.019.结果表明,利用集合均方根滤波的数据同化方法可以有效地提高太湖叶绿素a浓度的估算与预报精度.     

太湖流域丹阳市水体纳污能力分析及总量控制规划

文章分析了太湖流域丹阳市的水质状况及废水排放情况,并根据丹阳市各条河流的水质管理目标,由各河流水文资料及相关参数计算出水体纳污能力,同时提出了太湖流域丹阳市各条河流的NH3-N和COD总量控制方案,为水资源保护与管理提供依据。