淦河流域底栖藻类生长特征研究

为更全面地了解淦河流域生态系统的健康状况,于2012年初春测定了淦河干流及其主要支流的水体理化指标、底栖藻类叶绿素a(Chl a)含量和无灰干重(AFDM),同时测定了部分样点底栖藻垫的磷含量及形态组成。结果显示:淦河上游各支流及干流水体的总磷(TP)、总氮(TN)和化学需氧量(COD)分别为0.014~0.072、0.282~1.204、0.77~13.26 mg·L-1,水质较好;流经市区的干流下游河段水体受到一定程度的污染,TP、TN和COD分别为0.214~0.252、2.039~2.748、9.09~16.48 mg·L-1;就总氮、总磷的含量来看,样点S1到S15的水质为Ⅱ类水,S16~S20超过Ⅴ类。各支流底栖藻类Chl a的含量在6.6~16.1μg·cm-2之间,而淦河干流样点为13.5~47.3μg·cm-2,所有样点底栖藻类的AFDM(645~3050μg·cm-2)和Chl a显著相关。底栖藻类对磷的滞留能力在一定范围内随水体营养浓度的增加而增强,下游底栖藻垫的总磷含量比上游高,最高可达82μg·cm-2;底栖藻垫中的磷形态组成以铁结合态磷(Fe-P)为主,占总磷的34%~73%,说明Fe-P对底栖藻类-水界面的磷循环起着主要的作用。研究结果对提高水体监测的认识,加强淦河流域管理和完善淦河生态系统健康状况评价具有一定的参考价值。

Growth Characteristics of Benthic Algae in Gan River

There are increasing public concerns over the ecological risks of transgenic plants. Under field conditions, the diversity and composition of bacterial community in soils grown with three insect non-resistant transgenic cottons(high-yield transgenic cotton expressing the RNA recognition motif 2 gene, disease-resistant transgenic cotton expressing the gastrodia antifungal protein and high-quality transgenic cotton expressing the 1-aminocyclopropane-1-carboxylate(ACC)oxidase]) and one conventional cotton CCRI 12(as control) were evaluated at the boll-opening stage by denaturing gradient gel electrophoresis(DGGE). The results showed that planting three transgenic cottons did not show significant effects on Shannon-wiener index(H), evenness(E_H) and richness(S) of soil bacteria. High degree of similarity in community structure was observed between transgenic and conventional cottons, indicating no influence of transgenic cottons on bacterial community diversity in the short term. High-yield RRM2 transgenic cotton, disease-resistant GAFP transgenic cotton, high-quality ACO2 transgenic cotton and conventional cotton had 67% similarity in community levels and were thus regarded as one group. According to the sequence analysis of DGGE dominant bands, microorganisms which presented the highest homology belonged to families of Flavobacteria, Bacteriovorax, Segetibacter, alpha proteobacterium, Geobacte, Paenisporosarcina, and Acidobacterium, respectively, and all of them were not cultivatable.