Effects of Human Impact on the Wetland Ecosystem

(1)绘制了玉川河中游周边植被分布图。结果表明，人类活动导致植物区系组成简化，植物群落数量减少。据估计，1989年东京湾COD、N、P的输入量分别为300,320和26吨/天，其中玉川河的输入量仅占3.8%。1991年12月，玉川河河口潮滩的反硝化活动估计为178 mumol/m^2/h。在多摩川河河口，微生物活动对LAS的去除主要在夏季完全完成，冬季约80%。东京都多玛川河河口浮游植物的有机碳和有机氮产量分别为1880 gC/m^2/yr和281 gN/m^2/yr。(2)调查了Kasumigaura湖芦苇群落的分布、常绿蓄积量和芦苇附着藻的种类组成。在湖的大部分地区，芦苇群落受到海岸保护工程的严重影响和破坏。研究发现，芦苇带水体中硝酸盐和亚硝酸盐浓度变化较大，而锦藻带水体中硝酸盐和亚硝酸盐浓度变化较小，而沿岸水体中氧化亚氮浓度的变化与硝酸盐和亚硝酸盐浓度的变化似乎是耦合的。(3)研究了咸淡水湿地硫酸盐还原与甲烷生成的相互作用，以及甲烷向大气排放的来源和机制。结果表明，微咸水湿地中硫酸盐还原反应的优势抑制了甲烷的生成。对松卡湖的湖泊沉积物进行了调查，探讨了其在土地恢复中的应用价值。阐明了需要对重粘性沉积物进行有效的脱盐，脱盐后干燥，可作为退化地区的土壤修整材料应用于土地。少

(1) Vegetation distribution maps were prepared around the middle course of River Tamagawa. It was shown that man's influence caused simplification of the floristic composition of plant community and reduced the number of plant communities. The input of COD, N and P into Tokyo Bay in 1989 was estimated to be 300,320 and 26 tons/day, respectively, only 3.8% of which were contributed from River Tamagawa. Denitrification activity at tidal flat of the River Tamagawa estuary was estimated to be 178 mumol/m^2/h in December 1991. LAS were removed completely in summer and about 80% in winter mainly by microbial activities in the River Tamagawa estuary. Organic carbon production and organic nitrogen production by phytoplankton off the River Tamagawa estuary in Tokyo Bay Were estimated to be 1,880 gC/m^2/yr and 281 gN/m^2/yr,respectively. (2) Distributions of the Phragmites community and standing stock and species composition of algae attached to Phragmites were investigated in Lake Kasumigaura. … More In most part of the lake, Phragmites community has been heavily affected and destroyed by shore-protection works. It was found that variations of nitrate and nitrite concentrations in lake water were big in the Phragmites zone but small in the Nymphoides zone, and variations of nitrous oxide concentration in the littoral zone seemed to be coupled with those of nitrate and nitrite concentrations. (3) A study was carried out to clarify the interaction between sulfate reduction and methane formation in brackish water wetland and to identify the sources and mechanisms responsible for the emission of methane into atmosphere. The results showed that the predominance of sulfate reducing reaction may suppress methane formation in brackish water wetland. Lake sediments of Songkhla Lake were surveyed and examined for their possible use to land restoration. It was clarified that the efficient desalinization of heavy clayey deposits is needed, and after desalinization they are dried and can be applied for land as soil dressing materials in degraded areas. Less