Plasticity in metamorphic traits of <Emphasis Type="Italic">Rana kukunoris</Emphasis> tadpoles: The interactive effects of food level and rearing temperature

Larval amphibians are particularly likely to encounter variation in rearing temperature and resource availability due to variation in aquatic breeding habitats. In this study, plasticity in growth rates, larval mass, larval period, and size at metamorphosis were examined in Rana kukunoris Nikolskii, 1918 under different combinations of temperature and food level. Larval period and larval body mass was sensitive to food level, and varied with temperature. Tadpoles metamorphosed at an older age at low temperature than those reared at warm temperature. Food level was a significant affect on larval period at low temperature, but not at warm temperature. Mass was heavier for tadpoles reared at low temperatures than those reared at warm temperatures. The effect of food level depended on temperature, because larvae reared at low temperature that were offered a high food level achieved a larger size than larvae offered a low food level, but this did not occur at warm temperature. Therefore, we suggest that high food availability at low temperature prolonged developmental periods, thus larvae are larger as metamorphs than those reared at warm temperatures.     

Toxicity of sediment cores from Yangtze River estuary to zebrafish (<Emphasis Type="Italic">Danio rerio</Emphasis>) embryos

Toxicity evaluation is an important segment in sediment quality monitoring in order to protect aquatic organisms and human health. The purpose of this study is to assess the toxicity of sediments from three sediment cores in Yangtze River Estuary, China, using the zebrafish (Danio rerio) embryo tests. Fertilized zebrafish eggs were exposed to both whole sediments and sediment organic extracts prepared from collected sediments, in order to provide a comprehensive and realistic insight into the bioavailable toxicity potential of the sediments. As end points, development parameters (mortality, hatching rate, and abnormality) in the developing embryos were recorded during the 96-h exposure. The results showed that some samples increased mortality, inhibited the hatching of embryos, and induced morphological abnormalities. The embryonic toxicities presented serrated changes and irregular distribution with depth, which may be related to hydrodynamic effect and unstable environmental input. However, lethal and sub-lethal effects were more significant at the sub-surface sediments (10～40 cm), which indicated that the pollution is more serious in recent decades.     

Past,present, and future use of phosphorus in Chinese agriculture and its influence on phosphorus losses

Large inputs of phosphorus (P) in chemical fertilizers and feed supplements since 1978 have improved soil P status in arable land in China, but have also created challenges by increasing P concentrations in manure and exacerbating water quality degradation. Arable land in China can be divided into five management zones based on soil P chemistry, with 15–92 % of arable land having lower P status than the agronomic optimum and 0.3–7.2 % having severe risks of P leaching losses. A scenario analysis of soil P budget and agronomic P demand during 2011–2030 highlighted the great pressure China faces in sustainable P management and the need for drastic changes in current practices. This includes new policies to reduce P supplementation of feed and improved P use efficiency by livestock and programs to expand the adoption of appropriate fertilization, soil conservation, and drainage management practices to minimize P losses.     

北京市“十三五”大气污染物排放总量控制基本思路探讨

随着各项环保措施的深入实施,北京市大气环境质量进一步改善的难度逐渐加大。对北京市"十二五"时期的大气污染物排放总量控制工作进行了经验总结,并分析了"十三五"时期大气污染物的排放形势和减排压力。在此基础上,从6个方面提出了北京市"十三五"期间大气污染物排放总量控制的基本思路。     

工业搬迁区绿化带土壤铜污染及其在植物体内的迁移

老工业搬迁区主要道路两旁绿化带土壤由于历经老工业企业的变迁和环境的污染破坏,可在一定程度上对这一地区环境的历史变迁及重金属污染状况起到指示作用。采集沈阳铁西老工业搬迁区绿化带土壤及其绿化乔木和灌木植株样品,分析土壤中铜的总量及生物有效态含量,同时分别分析了绿化乔木(8种)和绿化灌木(6种)植株根、枝条和叶片的含铜量。结果表明,搬迁区绿化带土壤中含铜量为29.14~166.95mg/kg,显著高于沈阳市土壤铜元素的背景值;土壤有效态铜为0.23~1.72mg/kg,达到中等水平(0.3~1.0mg/kg)的占采样点总数的70.0%。数据还显示,绿化乔木和灌木对铜的蓄积能力依品种不同差异显著,同种植物不同部位(根、枝条和叶片)对铜的富集能力不同;总体上,绿化乔木植株体内含铜量的分布规律为根叶片枝条或叶片根枝条,绿化灌木植株体内含铜量的分布规律为根叶片枝条。对铜蓄积能力较强的绿化乔木为榆叶梅(Amygdalus triloba Lindl.)、垂柳(Salix babylonica Linn.)、旱柳(Salix matsudana Koidz.)和银杏(Ginkgo biloba),对铜蓄积能力较强的绿化灌木为大叶女贞(Ligustrum lucidum Ait.)、小叶女贞(Ligustrum quihoui Carr.)和紫叶小檗(Berberis thunbergii cv.Atropurpurea)。     

水体浊度对马来眼子菜和菹草生长的影响

研究了不同浊度(30、60和90 NTU)水体中,马来眼子菜及菹草的生长发育状况,并用水下饱和脉冲叶绿素荧光仪(Diving-PAM)测定其叶片荧光参数指标。结果表明,不同的浊度对马来眼子菜的叶片数及株高无显著影响,而对菹草的叶片数及株高生长速率有一定的影响。30 d胁迫下,浊度组马来眼子菜的最大光化学量子产量(maximum quantum yield,Fv/Fm)、光化学淬灭系数(photochemical quenching,q P)、非光化学淬灭系数(non-photochemical quenching,q N)、相对光合电子传递速率(electron transport rate,ETR)与对照组差异不显著(p>0.05),表明马来眼子菜对浑浊水体有较强的耐受能力;实验结束时,高浊度组(90 NTU)中,菹草Fv/Fm、q P、q N、ETR与对照组达到极显著差异(p<0.01),其余浊度组也相应受到影响,说明菹草的光系统II(PSII)受到破坏。该研究的成果可为沉水植物恢复研究与实践提供技术支撑。     

隔膜压滤机滤室最优空腔厚度

利用UG软件对隔膜压滤机滤室内流体进行三维建模,导入Gambit中进行网格划分及边界条件的设定,结合Fluent选用RNG k-ε湍流模型,采用多孔介质模型模拟隔膜压滤机滤室内固-液两相流分离,得到不同空腔厚度下滤室内流体的体积分数轮廓图、压强云图,得出滤饼含水率与空腔厚度大小的关系。实验结果表明,模拟和实验结果具有较好的一致性。在压滤机滤室空腔厚度为12 mm时,滤饼含水率为48%,每天污泥处理量为102 t,隔膜压滤机工作效率最高。