Low uptakes of Cd,Cu, and Zn in Dugesia japonica,a freshwater planarian with higher tolerance to metals

Although a freshwater planarian is proposed as a potential model for studying toxicities of environmental pollutants, they are less sensitive to metal exposures, compared to other freshwater invertebrates. We hypothesised that the metal uptake is low in treated planarians, which may lead to their higher tolerance to metals. The acute toxicities of Cu and Zn to Dugesia japonica were determined. The 24- and 48-h median lethal concentrations were 4.50 and 3.46?mg?L^?1, respectively, for Cu, and 41.97 and 37.79?mg?L^?1, respectively, for Zn. Accordingly, combining with the data on Cd in our previous study, higher tolerance of planarians to metals was revealed. Also, tissue levels of Cd, Cu, and Zn in treated D. japonica were determined, and their dissolved uptake rate constants (k₁) were calculated. Results showed that bioaccumulations of these metals in D. japonica were, indeed, lower than that in other freshwater invertebrates having higher susceptibilities to these metals.     

Trace element content in soils of the King George and Elephant islands,maritime Antarctica

Trace element concentrations were studied in soils of the King George and Elephant islands in the maritime part of West Antarctica. The lowest concentrations of Cu, Pb, Cd, Zn, Ni and Mn were typical for the pristine soil of Elephant Island. The highest concentrations of these elements were found in the Fildes Peninsula and revealed the influence of human activities in the area of the Bellingshausen station and adjacent waste disposal sites. Ornithogenic soils of the Fildes Peninsula have shown low concentrations of Cd and As. Using geoaccumulation indexes, all the pristine soils of King George and Elephant islands and ornithogenic soils of the Fildes Peninsula were classified as unpolluted; the human-affected soils were mainly identified as moderately polluted. Obtained data can be used as background concentration levels for further researches.     

Evidence of new particle formation during post monsoon season over a high-altitude site of the Western Ghats,India

The formation of ultrafine particles, their growth, and associated characteristic features has been studied during new particle formation events over a high-altitude station of the Western Ghats during the 2014 post-monsoon season. Most of the events were observed during noon time where particle bursts in the nucleation-mode size range from 5 to 25 nm followed by sustained growth in size. This phenomenon persists for ～4–8 h with a growth rate of 1–2 nm h^–1. Peak concentrations of nucleation-mode particles during the event generally vary from 2300 to 5000 cm^–3. The mean growth rate is 1.4 ± 0.42 nm h^–1, particle formation rate is 1.14 ± 0.22 cm^–3 s^–1, coagulation sink is 0.35 ± 0.22 cm^–3 s^–1, and condensational sink is 15.4 ± 2.6?×?10^–3 s^–1. All these values are comparable with earlier results from Indian region. Comparison of size-segregated particle number concentration during days of new particle formation events and those without new particle formation were carried out showing a distinct variation in nucleation and Aitken mode with least variability associated with the accumulation mode.     

The fetal behavioural states: An ultrasonic study

In order to accurately detect the fetal behavioural state, we simultaneously measured fetal heart rate and multiple fetal activities in 27 healthy pregnant women at 38 to 40 weeks of gestation. We ultrasonically identified gross body movements, breathing movements and micturition. Analysis of fetal heart rate allowed us to distinguish two different patterns of fetal behaviour: active and quiet phases. The frequency distribution of the analysed fetal events was significantly different in these two phases. These data suggest that a complete biophysical profile of the fetus is effective in differentiating behavioural states and may improve the predictive accuracy of fetal heart rate analysis alone.     

秸秆与生物炭还田对土壤团聚体及固碳特征的影响

揭示秸秆与生物炭还田对团聚体有机碳含量、分布、稳定性以及相对贡献率的影响,有利于明确秸秆与生物炭还田下土壤碳库的稳定性及其保护机制.采用田间试验方法研究了油菜/玉米轮作模式下,秸秆与生物炭还田对土壤团聚体及固碳特征的影响.结果表明:(1)秸秆与生物炭还田各处理均能提高土壤有机碳含量,其中生物炭还田(BC、16.88 g·kg~(-1))、秸秆+生物炭还田(CSBC、17.37 g·kg~(-1))效果优于秸秆还田(CS、13.76 g·kg~(-1))和秸秆+速腐剂还田(CSD、14.68 g·kg~(-1)).(2)与对照(CK)处理相比,CS、CSD处理能显著地提高大团聚体(2 mm)含量,增加率为94.00%~117.78%,同时显著提高了水稳性团聚体的平均重量直径(MWD)、几何平均直径(GMD)、R0.25,降低了分形维数(D),提高了团聚体稳定性(P0.05).(3)随着团聚体粒径的增大,团聚体有机碳含量呈现先降低再增高然后再降低,且粉黏粒(0.053 mm)对土壤有机碳贡献率最高(29.61%~42.18%),大团聚体有机碳贡献率最低(9.19%~17.81%).除CSD处理外,CS、BC、CSBC处理降低了较大团聚体(2~0.25 mm)和微团聚体(0.25~0.053 mm)有机碳贡献率.秸秆还田促进土壤团聚作用效果优于生物炭还田,而生物炭还田提高团聚体有机碳含量效果优于秸秆还田,秸秆新碳主要向大团聚体内分配,秸秆+速腐剂还田还能促进较大团聚体内不同组分结合新碳,生物炭、秸秆+生物炭还田主要向微团聚体中富集.     

Triton X-100对土壤中柴油的解吸特征及影响因素

为考察非离子表面活性剂Triton X-100对土壤中柴油解吸特性及土壤理化性质对其解吸的影响,通过振荡平衡法研究Triton X-100对浙江水稻土、重庆紫壤、江西红壤、海南沙土、青海灰漠土和黑龙江黑土中柴油解吸行为及其影响因素.结果表明,Triton X-100对浙江水稻土、重庆紫壤、江西红壤、海南沙土、青海灰漠土和黑龙江黑土中柴油的解吸均符合先快后慢、最后达到解吸平衡的规律,平衡时解吸量分别1.61、1.85、1.80、2.29、2.01和1.13 mg/g.其解吸动力学过程均符合准二级动力学模型（R2>0.99）;6种典型土壤中柴油的等温解吸特征可较好地用修正的米氏方程模型进行描述（R2>0.92）.Q_max（柴油最大解吸量）介于1.81~2.23 mg/g之间,浙江水稻土、重庆紫壤、江西红壤、海南沙土、青海灰漠土和黑龙江黑土中ρ_max（柴油最大解吸率）分别为73.20%、78.06%、75.63%、90.36%、79.89%和62.92%;土壤各理化性质对Triton X-100解吸土壤中柴油的影响起综合作用,其中土壤w（砂粒）与ρ_max呈显著正相关（R2=0.993 6,P < 0.01）,对Triton X-100解吸柴油的影响最大;而CEC（阳离子交换量）、w（OM）、w（黏粒）均与ρ_max呈显著负相关（P < 0.05）.研究显示,修正的米氏方程可用于描述柴油在土壤-水-表面活性剂Triton X-100系统中的解吸行为,w（砂粒）是影响不同土壤中柴油解吸的关键因子,可为应用Triton X-100修复柴油污染土壤提供理论基础.      

天津市城市扬尘及土壤尘单颗粒质谱特征

为探究城市扬尘及不同类型的土壤尘单颗粒质谱特征,使用SPAMS（单颗粒气溶胶质谱仪）对天津城市扬尘及不同类型土壤尘（菜地、果园、林地、农田）进行分析.结果表明:天津城市扬尘粒径在0.5~1.0 μm之间的占比较高;4种土壤尘在不同粒径段的分布略有差异,整体而言小粒径段（0.2~1.0 μm）占比低于大粒径段（1.0~2.0 μm）,说明土壤尘更易分布在大粒径段.在小粒径段,天津城市扬尘颗粒含有更多的碳组分及硫酸盐,大粒径段含有较多的金属、氯、硝酸盐、磷酸盐及硅酸盐组分.与城市扬尘相比,土壤尘中23Na+、46NO₂-峰强显著降低,39K+、35Cl-、42CNO-峰强增高,通过其峰强比值分布可将城市扬尘与土壤尘明显区分.与城市扬尘相比,土壤尘中含碳颗粒显著减少,同时出现钾类颗粒.城市扬尘作为一种混合源,含碳颗粒可能受多种排放源（机动车、燃煤等）影响,而土壤尘中钾类颗粒可能与农作物施肥有关.两种源类含27Al+、26CN-、35Cl-、42CNO-、46NO₂-、76SiO₃-、79PO₃-的颗粒占比均高于50%,其中40Ca+、46NO₂-和62NO₃-颗粒在天津城市扬尘中占比更高,76SiO₃-颗粒在土壤尘中占比更高,表明天津城市扬尘中更多的颗粒含有钙和硝酸盐组分,土壤尘中含硅酸盐颗粒较多.与机动车尾气、生物质燃烧等排放的颗粒物相比,天津城市扬尘及土壤尘中含97HSO₄-颗粒占比较低,表明天津城市扬尘及土壤尘颗粒中含有更少的硫酸盐,可作为将天津城市扬尘、土壤尘与其他源类区分的指标.      

采用大涡PIV研究Taylor-Couette流及其对混凝过程的影响

采用大涡PIV方法对Taylor-Couette流场的湍动能及湍动能耗散率进行了估算,并利用数值模拟对其进行验证,结合絮凝实验,综合对比速度矢量、湍动能分布、湍动能耗散率分布及对应流场中混凝过程的絮体图像,探究了湍动能与湍动能耗散率对絮凝效能的影响.结果表明,大涡PIV法与数值模拟在雷诺数较高的情况下有较好的一致性,且雷诺数越大一致性越好.在Taylor-Couette涡流场中,随着雷诺数的增大,湍动能与湍动能耗散率数值不断增大,且在流场中的分布由规律有序到紊乱最终趋于各向均匀一致.而混凝过程中湍动能与湍动能耗散率的数值大小及其在流场中的空间分布情况,均对产生絮体的大小和浊度去除率有较大影响.     

气候变化对太岳山中部油松单萜烯排放的影响

以全球气候模式NorESM1-M产生的RCP2.6,RCP4.5,RCP6.0和RCP8.5气候变化情景数据和植物VOCs排放计算模型,模拟分析了气候变化对山西太岳山中部油松叶片单萜烯排放速率的影响.结果显示,未来气候变化影响下山西太岳山中部气温呈上升趋势,降水和辐射强度波动大.在RCP2.6,RCP4.5,RCP6.0和RCP8.5情景与基准情景下,油松单萜烯日排放速率在1~210d呈上升趋势,在210~365d呈下降趋势;在未来气候变化情景下比基准情景下高约2μg/（g·d）,在RCP8.5情景下最高;油松单萜烯日排放速率在未来气候变化情景与基准情景下差异在1~95d和296~365d较小,在96~295d波动较大.同时,相比基准情景,单萜烯日排放速率增幅在1~190d较高（增加12%~14%以上）,在191~315d较小（增加9%~13%以上）,在316~365d增加12%~18%以上,在RCP8.5情景下增幅最大（增加14%以上）.另外,油松单萜烯年排放速率在未来气候变化情景下比基准情景下平均高约1000μg/（g·a）以上,在RCP8.5情景下增幅最大（约12%）.说明,未来气候变化将使油松单萜烯排放速率增加.     

黄土高原不同地貌类型区农田土壤有机碳采样布点方法研究

采样设计是土壤有机碳研究中面临的首要问题。论文对黄土高原不同地貌类型区农田土壤有机碳进行抽样样本代表性评价,对比分析了不同采样方法的样点布设效率,结果表明：1）高塬区合理采样布点方法应为网格布点法,采样点布设格网间隔4 km,网格布点法较随机布点法和联合单元布点法效率分别提高64.3%和31.8%;2）平原区合理采样布点方法应为网格布点法,采样点布设格网间隔2 km,网格布点较随机布点和联合单元布点效率分别提高64.8%和128.8%;3）丘陵区合理采样布点方法应为联合单元布点法,样点布设密度为1个/1 314 hm²,联合单元布点较随机布点和网格布点效率分别提高205.8%和294.2%。