层状氧化物NaCo_2O_4热催化H_2O_2降解亚甲基蓝

采用固相烧结法制备了NaCo_2O_4催化剂,构建了NaCo_2O_4-H_2O_2热催化体系降解亚甲基蓝(MB)。XRD和SEM表征结果显示,合成的NaCo_2O_4催化剂具有良好的稳定性。NaCo_2O_4对H_2O_2具有良好的热催化性能,反应温度越高,反应速率常数k越大,该催化反应符合一级动力学方程。NaCo_2O_4-H_2O_2体系对MB具有较好的降解效果,在反应温度为50℃、NaCo_2O_4加入量为50 mg、MB溶液加入量为100 mL、MB初始质量浓度为30 mg/L、H_2O_2加入量为1.00 mL的最优条件下,反应340 min时,MB降解率达87.00%;催化剂重复使用三次,MB降解率仍可达85%以上;经捕获剂效果对比实验发现,催化反应体系中存在h~+、·OH等催化活性物种。     

基于压力响应关系法的湖泊营养物基准制定

湖泊富营养化与氮、磷及有机物含量过高密切相关,建立数字型营养物基准能够防止富营养化对水体指定用途造成影响.太湖流域是我国华东地区经济腹地,近年来流域内湖泊水质每况愈下,对其基准研究可为湖泊治理提供依据.详细介绍了压力响应关系法制定湖泊营养物基准的步骤,并将此方法运用到太湖流域营养物基准制定研究中.为满足大多数水体指定用途,研究中将该流域湖泊基本功能确定为娱乐、永生生物栖息地及饮用水,以此构建流域概念模型.选择压力变量为总氮(TN)、总磷(TP)和有机物,响应变量为叶绿素a(chl-a).用非参数分析法和线性回归法分别建立压力-响应模型,通过2种方法相互验证得到TN、TP和CODMn基准分别为0.593、0.067和4.092 mg/L.     

河口切变锋引起的滩槽泥沙交换效应

切变锋是河口湾锋系中最为常见和最易观察到的锋面类型。本文对长江口的切变锋进行现场观察和滩，槽同步水文资料分析，简述了长江口切变锋发生的部分和基本特性，提出了切变锋引起的滩，槽泥沙呈现螺旋形交换形式等论点。     

Dynamics of growth and seed production in the Siberian stone pine: The level and pattern of variation in characters

A statistical analysis of interannual variation in a set of vegetative and generative characters over 13 years has been performed to characterize the growth and seed production dynamics of the Siberian stone pine (Pinus sibirica Du Tour) in the southeast of the forest zone in western Siberia. The results have shown that the range of fluctuations in most of vegetative characters is ordinary and their distribution is close to normal. The range of fluctuations in many generative characters is enormous (from 0 to +∞), and the distribution of their values is usually skewed, with low values being recorded several times more frequently than high values. Most variable are the proportion of abortive cones and other characters that are determined mainly in the spring of the pollination year. These characters account for a very high level of variation in the total seed production.     

Long term changes in atmospheric N and S throughfall deposition and effects on soil solution chemistry in a Scots pine forest in the Netherlands

In a Scots pine forest the throughfall deposition and the chemical composition of the soil solution was monitored since 1984. (Inter)national legislation measures led to a reduction of the deposition of nitrogen and sulphur. The deposition of sulphur has decreased by approximately 65%. The total mineral-nitrogen deposition has decreased by ca. 25%, which is mainly due to a reduction in ammonium-N deposition (−40%), since nitrate-N deposition has increased (+50%). The nitrogen concentration in the upper mineral soil solution at 10 cm depth has decreased, leading to an improved nutritional balance, which may result in improved tree vitality. In the drainage water at 90 cm depth the fluxes of NO₃⁻ and SO₄²⁻ have decreased, resulting in a reduced leeching of accompanying base cations, thus preserving nutrients in the ecosystem. It may take still several years, however, before this will meet the prerequisite of a sustainable ecosystem.     

Soil and vegetation carbon stocks in Brazilian Western Amazonia: relationships and ecological implications for natural landscapes

The relationships between soils attributes, soil carbon stocks and vegetation carbon stocks are poorly know in Amazonia, even at regional scale. In this paper, we used the large and reliable soil database from Western Amazonia obtained from the RADAMBRASIL project and recent estimates of vegetation biomass to investigate some environmental relationships, quantifying C stocks of intact ecosystem in Western Amazonia. The results allowed separating the western Amazonia into 6 sectors, called pedo-zones: Roraima, Rio Negro Basin, Tertiary Plateaux of the Amazon, Javari-Juruá-Purus lowland, Acre Basin and Rondonia uplands. The highest C stock for the whole soil is observed in the Acre and in the Rio Negro sectors. In the former, this is due to the high nutrient status and high clay activity, whereas in the latter, it is attributed to a downward carbon movement attributed to widespread podzolization and arenization, forming spodic horizons. The youthful nature of shallow soils of the Javari-Juruá-Purus lowlands, associated with high Al, results in a high phytomass C/soil C ratio. A similar trend was observed for the shallow soils from the Roraima and Rondonia highlands. A consistent east–west decline in biomass carbon in the Rio Negro Basin sector is associated with increasing rainfall and higher sand amounts. It is related to lesser C protection and greater C loss of sandy soils, subjected to active chemical leaching and widespread podzolization. Also, these soils possess lower cation exchangeable capacity and lower water retention capacity. Zones where deeply weathered Latosols dominate have a overall pattern of high C sequestration, and greater than the shallower soils from the upper Amazon, west of Madeira and Negro rivers. This was attributed to deeper incorporation of carbon in these clayey and highly pedo-bioturbated soils. The results highlight the urgent need for refining soil data at an appropriate scale for C stocks calculations purposes in Amazonia. There is a risk of misinterpreting C stocks in Amazonia when such great pedological variability is not taken into account.     

Distribution of Zooplankton along the Longitudinal Profile of Two Disturbed Small Rivers of the Upper Volga Basin

The abundance and trophic structure of zooplankton along the longitudinal profile of two typical rivers in the Yaroslavl sector of the Volga region are determined by anthropogenic and zoogenic factors. The distribution of zooplankton under the influence of these factors is described by the concept of patch dynamics. The abundance of zooplankton reaches the highest values in the ameliorated upper reaches of rivers and in beaver ponds.     

Long-Term Changes in the Fauna of Diurnal Lepidopterans (Lepidoptera,Diurna) in the Northern Taiga Subzone of the Western Russian Plain

In the diurnal lepidopteran fauna of the northern taiga subzone in the western Russian Plain, the species inhabiting primary biotopic complexes typical of this subzone currently account for slightly more than 60% of the total species richness and abundance. A large part of the fauna is represented by the species of more southern origin, whose expansion to the northern taiga was caused by anthropogenic transformation of landscapes between the 12th and 20th centuries and recent climate warming.     

Analysis of Survival of the Red Fox (Vulpes vulpes L.) at the Phases of Population Growth and Decline

Changes in the survival parameters of the red fox were analyzed at different phases of the population cycle. It was found that the survival rate in all age classes, including newborns, drastically increased at the phase of population growth. The relationship between the general mortality rate and population size was determined. A hypothesis concerning the mechanism of these changes in the general mortality rate is suggested.