Arcellacean (thecamoebian) evidence of land-use change and eutrophication in Frenchman’s Bay, Pickering, Ontario
Arcellacean (thecamoebian) evidence of land-use change and eutrophication in Frenchman’s Bay, Pickering, Ontario
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安大略省皮克林法国人湾土地利用变化和富营养化的 Arcellacean（thecamoebian）证据
DOI：
10.1007/s00254-004-1213-y
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
J. Boyce
中科院分区：
文献类型：
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作者：
E. Reinhardt;M. Little;S. Donato;D. Findlay;A. Krueger;C. Clark;J. Boyce
法国人湾位于安大略湖北岸，在过去 50 年里，由于城市化和化肥的使用，一直受到富营养化的负面影响。富营养化始于十九世纪中叶开始的大规模土地清理和农业实践，并随着二战后的城市化达到顶峰。通过对沉积物磁性和弧形动物（thecamoebian）微型动物的综合分析，研究了富营养化和土地利用变化对流域的影响。每 10 厘米（42 个样本）对两个 2 米长的岩心（FMB1 和 FMB2）进行微观古生物学分析，并以 2 厘米的间隔测量磁化率。两个岩心在 60 cm 和 110 cm 处都显示出明显的相关转变，其特点是膜细胞浓度快速增加（从大约 10×103 到 30×103 个样本/立方厘米）和 Cucurbitella tricuspis 大幅增加（从大约 10–20% 到 40–70%）。这种转变与同一深度的磁化率显着增加（150–200×10−8m3Kg−1）相关，这是由于流域土地清理和土壤侵蚀产生的碎屑磁性矿物水平升高所致。 210Pb数据表明，19世纪中叶（公元1850±56年）富营养化逐渐发生，210年代中期至1950年代后期增长更快。富营养化最初的增加是由于土地清理、农业发展和养分负荷增加造成的。 20世纪50年代主要的富营养化增加是由于城市化和雨水管道排放的草坪和花园中含有高产化肥。这种高浓度的营养物质导致湿地内的富营养化达到前所未有的程度。
Frenchman’s Bay, on the northern shore of Lake Ontario, has been negatively impacted by eutrophication in the last 50 years through urbanization and the use of chemical fertilizers. Eutrophication began with wholesale land clearance and agricultural practises beginning in the mid-nineteenth century and reached a peak with urbanization after World War II. Eutrophication and the effects of land-use changes on the watershed were investigated by a combined analysis of the sediment magnetic properties and arcellacean (thecamoebian) microfauna. Micropaleontological analyses were conducted on two 2-m-long cores (FMB1 and FMB2) every 10 cm (42 samples) and magnetic susceptibility was measured at 2-cm intervals. Both cores showed a distinct correlative transition at 60 cm and 110 cm that was marked by a rapid increase in thecamoebian concentrations (from approx. 10×103to 30×103specimens per cc) and a large increase inCucurbitella tricuspis(from approx. 10–20% to 40–70%). This transition correlated with a marked increase in magnetic susceptibility (150–200×10−8m3Kg−1) at the same depth, which was attributed to elevated levels of detrital magnetic minerals derived from land clearance and soil erosion in the watershed. It was indicated by210Pb dates indicate that there was a gradual onset of eutrophication in the mid-nineteenth century (AD 1850±56) and a more rapid rise in the mid-1940s to late 1950s. The initial increase in eutrophication was due to land clearing, agricultural development and increased nutrient loadings. The major eutrophication increase in the 1950s was from urbanization and storm sewer discharge loaded with high yield chemical fertilizers from lawns and gardens. This high concentration of nutrients has led to an unprecedented level of eutrophication within the wetland.