Spatial Variations of Heavy Metals in the East China Sea Continental Shelf Surface Sediments

Surface sediments collected from continental shelf of the East China Sea were analyzed for heavy metals (iron, manganese, copper, zinc, lead, cadmium), carbonate, organic carbon contents, and grain sizes. the range of concentrations observed were iron: 0.3-1.3 wt%, manganese: 2.3-14 μmole/g, copper: 7.1-184 μmole/g, zinc: 0.16-0.77μmiole/g, lead: 15-98 μmole/g, cadmium: 0.17-3.9 μmole/g, carbonate: 3.6-87 wt%, sand: 10-100%, silt: 0-70% and clay: 0-50%.

A zonal distribution pattern of the heavy metals was found in the East China Sea Continental shelf sediments. High concentrations of most heavy metals, organic carbon and fine-grained sediments were observed in the inner shelf zone, especially those near the discharge of the Yangtze River. Concentrations of these heavy metals decreased from the inner shelf to the shelf break region. High concentrations of metals were also found in sediments near Taiwan. Iron concentrations decreased north-east of the central shelf region. High concentrations of cadmium were found in the shelf break region where biogenic carbonate is predominant. This study showed that biogenic carbonate in the East China Sea shelf break region and the terrigenous sediments from the Yangtze River and island of Taiwan were the major sources of heavy metals. Heavy metal concentrations were strongly influenced by the content of the coarse-grained quartz sand present in the sediments.     

浅探新形势对科技期刊编辑要求

作为科研成果的信息载体,科技期刊有着重要的作用。而处于整个出版工作的中心环节的编辑更应在求新、求快的基础上,坚持求准的原则,不断学习,才能将科技期刊越办越好。     

Chemical defense of the ladybird beetle Epilachna paenulata

Summary. The defensive chemistry of the ladybird beetle Epilachna paenulata (Coleoptera: Coccinellidae) was characterized as a mixture of piperidine, homotropane and pyrrolidine alkaloids. Whole body extracts of adult beetles contain four major alkaloids: 1-(6-Methyl-2,3,4,5-tetrahydro-pyridin-2-yl)-propan-2-one; 1-(6-methyl-2-piperidyl)-propan-2-one; 9-aza-1-methyl-bicyclo[3.3.1]nonan-3-one and 1- (2′′- hydroxyethyl)-2-(12′-aminotridecyl)-pyrrolidine. Comparative studies of the defensive chemistry of eggs, larvae, pupae and adults showed both qualitative and quantitative differences in alkaloid composition among the four life stages, and also within adult age. Laboratory predation bioassays with wolf spiders showed that the adults are better protected than the larvae and pupae. Field tests showed the adult alkaloid extract to be deterrent to ants.     

Chemical defence in ladybird beetles (Coccinellidae). II. Amount of reflex fluid,the alkaloid adaline and individual variation in defence in 2-spot ladybirds (Adalia bipunctata)

Summary 2-spot ladybirds secrete alkaloid (adaline)-rich defence fluid (reflex blood) in response to predator attack. Reflex fluid was collected from individual ladybirds and weighed and the alkaloid content measured by GC. The amount of fluid produced built up rapidly following winter hibernation in animals feeding on aphids. The concentration of adaline in the fluid was highest in the first bleeding after winter hibernation. A large sample of beetles was reflex bled several times. Significant among beetle variation was found in the amount of fluid produced and the concentration of the reflex blood. The results are discussed in relation to the possibility that 2-spot ladybirds are Batesian mimics of 7-spot ladybirds and to the possible functions of adaline.     

Variation of pyrrolizidine alkaloids in Ithomiinae: A comparative study between species feeding on Apocynaceae and Solanaceae

Summary The primitive, Apocynaceae-feeding Ithomiine,Tithorea harmonia, incorporates dehydropyrrolizidine alkaloids (PAs) from its larval foodplant (Prestonia acutifolia), rarely visiting PA sources pharmacophagously in the adult; females show higher concentrations of PAs than males, with similar variance. The close relativeAeria olena (feeding onP. coalita, without PAs) shows similar PA concentrations in both sexes and greater variation in males, like more advanced Solanaceae-feeding Ithomiine such asMechanitis polymnia, which likeA. olena obtain PAs by pharmacophagy in the adult (mainly males). This difference is due to the dynamics of PA incorporation in these species. Little variation in PA content was found among allopatric populations of the same species, but variation in available PA sources in different months was correlated with different average storage levels in the butterflies.     

Conservation Genetics of Potentially Endangered Mutualisms: Reduced Levels of Genetic Variation in Specialist versus Generalist Bees

Abstract:  Oligolectic bees collect pollen from one or a few closely related species of plants, whereas polylectic bees visit a variety of flowers for pollen. Because of their more restricted range of host plants, it maybe expected that specialists exist in smaller, more isolated populations, with lower effective population sizes than generalists. Consequently, we hypothesized that oligolectic bees have reduced levels of genetic variation relative to related polylectic species. To test this hypothesis, we used five phylogenetically independent pairs of species in which one member was oligolectic and the other was polylectic. We assayed genetic variation in our species pairs at an average of 32 allozyme loci. Within each species pair, the oligolectic member had fewer polymorphic loci, lower average allelic richness, and lower average expected heterozygosity than its polylectic relative. Averaged over all species pairs, this corresponds to a 21% reduction in allelic richness, a 72% reduction in the proportion of polymorphic loci, and an 83% reduction in expected heterozygosity in specialists compared with generalists. Our data support the hypothesis of reduced effective population size in oligolectic bees and suggest that they may be more prone to extinction as a result. We suggest that in instances in which bee specialists are involved in mutually codependent relationships with their floral hosts, these mutualisms may be endangered for genetic and ecological reasons.     

川西亚高山冷杉林和白桦林土壤酶活性季节动态

研究了川西亚高山冷杉林和白桦林中与土壤碳氮元素循环有关的土壤脲酶、蛋白酶、转化酶、过氧化氢酶、多酚氧化酶和脱氢酶活性的季节变化规律．结果表明：(1)在两个群落中，腐殖质层(A)中6种土壤酶活性均高于淀积层(B)和母质层(C)中的酶活性；(2)白桦林A层土壤酶活性显著高于冷杉林A层土壤，而C层的脲酶和过氧化氢酶活性以冷杉林明显高于白桦林，但C层的其它4种酶活性没有明显差异；(3)土壤酶活性的高峰期主要出现在温度较高的7、8月份(冷杉林A层土壤中的蛋白酶、过氧化氢酶和脱氢酶，白桦林A层土壤中的蛋白酶、蔗糖酶和脱氢酶)，或是凋落物高峰期的10月份(冷杉林A层土壤中的脲酶、多酚氧化酶和蔗糖酶，白桦林A层土壤中的多酚氧化酶)．可见，不同土壤酶的活性对温度的敏感程度是不一样的，有一些土壤酶的活性(如多酚氧化酶)明显受凋落物动态的影响．图1表2参18     

Ranking of individual mountain birch trees in terms of leaf chemistry: seasonal and annual variation

Summary. The quality of tree leaves as food for herbivores changes rapidly especially during the spring and early summer. However, whether the quality of an individual tree in relation to other trees in the population changes during the growing season and between years is less clear. We studied the seasonal and annual stability of chemical and physical traits affecting leaf quality for herbivores. Rankings of trees in terms of the contents of two major groups of phenolics in their leaves, hydrolyzable tannins and proanthocyanidins (condensed tannins), were very stable from the early spring to the end of the growing season. There were also strong positive within-season correlations in the levels of some other groups of phenolics in the leaves (kaempferol glycosides, myricetin glycosides and p-coumaroylquinic acid derivatives). The contents of individual sugars and the sum content of protein-bound amino acids showed patterns of seasonal consistency in mature leaves, but not in young developing leaves. The seasonal correlations in leaf water content and toughness were also strongest in mature leaves. The correlations between two years at corresponding times of the growing season were strongly positive for the major groups of phenolics throughout the season, but were more variable for the contents of proteins and some sugars. Leaf toughness and water content showed strong positive correlations in mature leaves. Despite the consistency of tree ranking in terms of leaf phenolics, the relative resistance status of trees may, however, change during a growing season because there was a negative correlation between the content of hydrolyzable tannins (early-season resistance compounds) in leaves early in the season and the content of proanthocyanidins (late-season resistance compounds) late in the season, and vice versa. Thus, assuming that phenolics affect herbivore preference and performance, different plants may suffer damage at different times of the growing season, and the overall variation between trees in the fitness consequences may be low. In addition, the adaptation of herbivorous insects to mountain birch foliage in general, as well as to specific tree individuals, may be constrained by variation in the relative resistance status of the trees.     

Application of the One-Migrant-per-Generation Rule to Conservation and Management

Abstract:  Endangered species are commonly found in several (partially) isolated populations dispersed on different fragments of a habitat, natural reserve, or zoo. A certain level of connectivity among such populations is essential for maintaining genetic variation within and between populations to allow local and global adaptation and for preventing inbreeding depression. A rule of thumb widely accepted by the conservation community is that one migrant per generation (OMPG) into a population is the appropriate level of gene flow. This rule is based on Wright's study of his island model under a long list of simplifying assumptions. I examined the robustness of the OMPG rule to the violation of each of the many assumptions, quantifying the effect with population genetics theory. I showed that, when interpreted as one effective migrant per generation, OMPG is generally valid for real populations departing from the ideal model in the discrepancies of actual (  N ) and effective (  N_e  ) population sizes and actual ( m ) and effective ( m_e  ) migration rates. I also addressed the issue of converting the effective number of migrants (  M_e= N_em_e  ) into the actual number of migrants ( M = Nm  ) of a certain age and sex. In particular, N_e < N , a case common for natural populations, did not necessarily require M > M_e to maintain a certain level of differentiation among populations. Rather, translating the elusive M_e into the manageable M depends on the specific causes (e.g., biased sex ratio, reproductive skew) that lead to N_e < N .     

长春市南湖大气降尘长期演变规律

本文统计分析了１９８４－１９９３年长春市南湖大气降尘数据，探讨了冬季与夏季的代表月份以及１０年间的代表年份大气降尘长期演变规律。１０年间冬季降法量呈波浪式递减趋势；从统计来看，冬季１月份降尘最是夏季７朋份降尘量的２．３倍左右；同年度内冬季、春季大风时段的除尘量一般高于夏、秋季；冬季煤烟型大气污染已逐年在所改善，一些自然因素对大气除尘的影响逐渐突出。