STUDIES ON THE PURIFYING SPACE IN ARTIFICIAL WETLANDS WITH CATTAIL AND RUSH

调查了人工湿地水生植物根区理化特性，根系扩展的深度和位置，微生物和酶的分布状况；比较了不同深度人工湿地污水净化效果；探讨了人工湿地污水处理系统最佳净化空间位点。通过对香蒲、灯心草人工湿地的研究，发现植物的根系主要分布在基质上层２５ｃｍ区域内，在５到１０ｃｍ区域内，微生物数量最多，２５ｃｍ区域次之，３５ｃｍ以下较少。系统表层磷酸酶，葡聚糖脱水酶和蛋白酶的活性较２０ｃｍ区域内各酶活性强。对于废水的净化而言，系统２０ｃｍ和６０ｃｍ处的净化效果差别很小。结果表明，人工湿地废水处理系统上部区域为较佳净化空间。

Morphology, biometry and distribution of Difflugia biwae Kawamura, 1918 (Protozoa : Rhizopoda)

The freshwater testate amoeba Difflugia biwae Kawamura, 1918, isolated from Mulan Lake, Hubei Province, China is investigated using light microscopy and scanning electron microscopy. The morphology, biometry and distribution of this little known species are supplied. After careful comparison with three other similar species, including D. delicatula Gauthier-Livre et Thomas, D. elegans Penard and D. oblonga caudata Stepanek, we believe that the characteristics of smooth fusiform shell, conspicuous great collar flare (always larger than body-width) around the aperture, constriction behind the aperture and a somewhat curved aboral horn set D. biwae apart from all other Difflugia species. This species shows a great diversity in total length, collar height and aboral horn length which have high variability (CV between 11.76 and 24.52). However, body width, collar diameter, neck width, body length and aperture diameter are fairly constant with low variability (CV between 5.34 and 8.79) which shows a remarkable uniformity of D. biwae. Also, the size frequency distributions of both body width and body length yield bell-shaped (normally distributed) curves and indicate that D. biwae is a size-monomorphic species, characterized by a main-size class and a small size range. D. biwae is probably endemic to East Asia (China and Japan) because it has such a large size (165-306 mu m) that it would have been easily found in Europe and North America, if it were there. Consequently, D. biwae must have a restricted geographical distribution, disproving the old hypothesis that microscopic organisms are cosmopolitan.