油田废弃核桃壳滤料的污染物分析及其对土壤的影响研究

核桃壳滤料广泛应用于油田污水处理,每年因此产生大量的废弃核桃壳滤料,由于将其露天堆砌在地面上,滤料上的污染物在降水、风力、地表径流等的作用下发生迁移,直接影响到堆砌场地周边的土壤、大气、水源的质量。采用标准方法对油田废弃核桃壳滤料上的污染物组成进行分析的结果表明,主要污染物为原油、CaCO3和Cd2＋、Pb2＋重金属离子,污染物总含量较高,与原油组成相比,废弃核桃壳滤料上的芳烃含量增加较多,饱和烃和胶质有所减少。借助一维对流-弥散方程建立了模拟石油类污染物在土壤中迁移转化规律的数学模型,通过室内土柱实验确定模型参数,同时验证模型的准确性。将实验及模拟的结果相结合可知,该模型可以用来模拟石油类污染物在土壤中的迁移规律,符合y=y0＋A1exp（-x/t1）＋A2exp（-x/t2）规律。研究结果为油田废弃滤料对土壤环境的影响及治理提供了参考。     

Phylogeographic study based on intraspecific sequence variation of chloroplast DNA for the conservation of genetic diversity in the Japanese endangered species Primula sieboldii

To gather information on intraspecific phylogeography for use in conservation programs for the endangered species Primula sieboldii in Japan, we analyzed sequence variation in five noncoding regions of chloroplast DNA. Twenty-two distinct haplotypes were recognized in total. The distribution of most haplotypes was geographically confined, but one haplotype was widely distributed throughout northern Japan, and several haplotypes were found in geographically distant regions. Three major clades were revealed by phylogenetic analysis of the haplotypes. Clade I was distributed in Kyushu and central Honshu, clade II in western Honshu and Hokkaido, and clade III from central Honshu to Hokkaido. According to analysis of molecular variance, 59.9% of the total cpDNA variation existed among regions, 32.5% among populations within regions, and 7.6% within populations. Therefore, if genetic conservation of the species is valued, transplanting of P. sieboldii among regions should be avoided. Multiple lineages often existed even in geographically narrow areas (e.g., within a 20-km range), so transplantation between adjacent populations in restoration activities should be carefully designed so as not to change the gene pool of local populations significantly. Also, the geographical distribution of cpDNA haplotypes may allow us to confirm the origin of plants collected for commercial purposes.     

Conservation implications of land use practices on the plant and carabid beetle communities of two turloughs in Co. Galway, Ireland

Turloughs, which are unique to Ireland and are priority habitats under the European Habitats Directive, are seasonally flooded depressions found predominantly in the west of Ireland. In 1999, adjacent fields with different stocking densities were selected within two turloughs and plant/carabid beetle communities investigated using relevés and pitfall traps, respectively. Overall a positive relationship between % soil moisture and plant/carabid species richness was detected and there was a negative correlation between % cover of bare ground (caused by poaching) and carabid species richness. In one turlough, the number of ruderal plant species was markedly higher in the field where the stocking density was more than twice that of the adjacent field. The results suggest that, while edaphic factors (such as soil moisture) play a role in determining the plant/carabid communities of the turloughs, high stocking levels, which cause excessive poaching, are likely to seriously affect both communities.     

Allelopathy variation in dryland winter wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) accessions grown on the Loess Plateau of China for about fifty years

In this study, we investigated the genetic variation of allelopathic potential, its grey correlation with important agronomic characters, and rank analysis on allelopathic stability of fifteen wheat accessions commonly grown in arid regions of the Loess Plateau in China. The genetic variation of allelopathic property in dryland winter wheat showed significant differences between accessions. Allelopathic effects exhibited high heritability (55–95%) throughout the life cycle of wheat. Heritability was highest in the tillering stage and weakest in the seed filling stage. Allelopathic potential varied and was discontinuous throughout the wheat life cycle. Grey correlation analysis indicated a close relationship between allelopathic potential dependant on growth phase and agronomic characters. Allelopathic expression during some growth periods induced a partial correlation effect on some important agronomic characters that affected wheat yield. Allelopathic heritability and its degree of influence on yield were more evident in the vegetative growth stage compared to the reproductive stage. A multiple linear regression was built between allelopathic potential during different growth periods and agronomic characters pursued in wheat breeding. Allelopathic potential had a linear effect on production traits cultivated in wheat breeding. When allelopathic intensity varied from 0 to 1 in the reproductive stage, plant height ranged from 44 to 108 cm, spike length from 6.4 to 9.2 cm, number of spikelets with seeds from 13.4 to 21.0, mean seed number per spike from 41.5 to 50.3 and thousand seed weight from 36.2 to 38.3 g. Based on rank analysis, we concluded that there was a synergistic relationship between allelopathic potential in wheat and genetic, chemical and ecological factors. Triticum aestivum L. ‘No 6 Lankao’ and T. aestivum L. ‘No 22 Xiaoyan’ were identified as stable and relatively strong allelopathic accessions, whereas T. aestivum L. ‘Lankao 95–25’ was a stable but relatively weak allelopathic cultivar. Other varieties showed unstable allelopathic potential.     

A phylogenetic analysis of the genus Carica L. (Caricaceae) based on restriction fragment length variation in a cpDNA intergenic spacer region

The phylogenetic relationships among twelve wild and cultivated species of Carica (Caricaceae) were analyzed using restriction fragment length variation in a 3.2-kb PCR amplified intergenic spacer region of the chloroplast DNA. A total of 138 fragments representing 137 restriction sites accounting for 5.8% of the amplified region were examined. Both parsimony and neighbor joining cluster analyses confirmed the close association among South American wild Carica species. However, cpDNA data did not support the traditional monophyly hypothesis for the evolution of Carica. Further, cpDNA analyses showed two basic evolutionary lineages within the genus Carica, one defined by cultivated C. papaya and another consisting of the remaining wild species from South America in a well resolved but poorly supported monophyletic assemblage. This evolutionary split in Carica strongly suggests that C. papaya diverged from the rest of the species early in the evolution of the genus and evolved in isolation, probably in Central America.