Carbon sink potential of eutrophic lake sediments: a reconstruction of the potntial in lakes Nakaumi and Shinji during the last about four hundred years

利用表层沉积物和沉积物柱样研究了近百年和近百年来中海湖和新治湖富营养化湖泊沉积物的碳汇潜力。在1cm的表层沉积物中，中海的腐泥含量较高，约占3.6~4.0%。这些值自AD 1997以来保持不变。L.所有样品的TOC含量。新寺也表现为腐泥型，除东部外，含量均较高，约3.5~4.3%。这些TOC值以L.在过去的5年里，真嗣没有改变。根据C/N比值（7-9）和Py-GC-MS分析结果，认为两个湖泊有机质的来源均以浮游植物为主。沉积物柱样显示，在AD 1800和1900之间，两个L. Nakaumi和Shinji和TOC含量在AD 1900后从1%急剧增加到4%。通过对AD 2003数据的初步分析表明，表层沉积物中TOC含量超过3.5%的沉积物具有较好的正相关性， ...更多信息 H2S（ppm）= 13.9 * TOC（%）- 52.1（TOC>3.5%）。中海东北部的大气CO2浓度较低，平均约360 ppm（2013年4月至5月），这可能取决于春季浮游植物的盛开。白天和夜间的二氧化碳浓度差异高达80 ppm。L. Nakaumi和Shinji分别为7.0 mgC/cm 2/y和4.0 mgC/cm 2/y，基于Kanai等人报道的沉降速率，(1998，2002年）。因此，L. Nakaumi和Shinji的潜在碳汇分别约为6，000 tonC/y和3，200 tonC/y。低TOC沉积物的OCAR值较低，L. Nakaumi在50-25 cm（1770-1890），TOC约为0.7%。在30- 20厘米（1830-1890），即小冰期，Shinji分别建议2，000吨C/年和1，300吨C/年。这些在凉爽气候期间的低值约为目前潜力的三分之一。这些咸水湖的特点是对气候变化的快速反应碳汇。少

Carbon sink potential of eutrophic lake sediments from lakes Nakaumi and Shinji was studied for recent and several hundred years environments using surface sediments and sediment cores.TOC (total organic carbon) contents of southern and central L. Nakaumi showed high sapropelic about 3.6~4.0% in the 1cm surface sediments. These values are constant from AD1997. TOC contents of all samples from L. Shinji showed also sapropelic and high about 3.5~4.3% except for eastern part. These TOC values in L. Shinji are not changed during the last 5 years. According to the result of C/N ratio (7-9) and py-GC-MS, origin of organic matter in both lakes is supposed to be predominant phyto-plankton. Sediment cores showed low TOC contents about 1% between AD1800 and 1900 in both L. Nakaumi and Shinji and TOC contents drastically increased from 1% to 4% after AD1900. Analysis of AD2003 data by our preliminary research indicates that TOC contents over 3.5% of surface sediments have a good positive correlat … More ion with H2S (ppm), showing an equation: H2S (ppm) = 13.9 * TOC (%) - 52.1 (TOC>3.5%). Atmospheric CO2 concentration on the northeastern Nakaumi was low about 360 ppm in average (April to May, 2013), which could depend on spring blooming of phyto-plankton. Impressive difference of the CO2 concentration between daytime and nighttime was up to 80 ppm. Average OCARs in the surface sediments of L. Nakaumi and Shinji are 7.0 mgC/cm2/y and 4.0 mgC/cm2/y，respectively based on the sedimentation rate reported by Kanai et al., (1998, 2002). As a result, L. Nakaumi and Shinji have a potential carbon sink of about 6,000 tonC/y and 3,200 tonC/y, respectively. Low OCARs of the cored sediments with low TOC about 1% in L. Nakaumi during 50-25 cm (1770-1890) and TOC about 0.7% in L. Shinji during 30-20cm (1830-1890), i.e. Little Ice Age, suggested 2,000 tonC/y and 1,300 tonC/y, respectively. These low values during cool climate are about one - third of the present potential. These brackish lakes are characterized as a quick response carbon sink for climate change. Less