成分数据统计分析的定和问题解决方案

利用成分数据统计分析方法处理数据时,数据的定和问题的处理办法直接影响到统计结果的自然属性和实际意义.本文结合成分因子在估计沉积物端元中的应用,探讨定和问题的两种解决方案,即"剩余变量法"和"平均含量限制法".将这两种方法及传统的端元估计结果与实际端元进行对比,对比结果表明本文方法在端元估计方面比传统方法具有更好的效果.     

中太平洋海山富Co结壳稀土元素及其对成矿环境的指示意义

稀土元素是富结壳中典型的富集元素(Ap-lin和Cronan,1985;Byrse和Kim,1990;Elderfield和Greaves,1982;Suave等,1989),由于其具有地球化学性质相似而成群存在及其在环境改变情况下发生分馏的双重属性,成为研究富钴结壳成矿和古海洋环境演化的有效参数.本文在中太平洋海山CAD-25-1富Co结壳生长年龄和生长世代确定的基础上,通过其壳层稀土元素含量的变化规律研究,揭示中太平洋海山结壳的生长发育与海洋环境演化的关系.     

近140年来广西红树林演变及其对人类活动的响应:有机碳和孢粉联合示踪

Mangrove degradation must reduce carbon sequestration in recent years, thereby aggravating global warming.Thus, short-term impacts of human activity on mangrove ecosystems are cause for concern from local governments and scientists. Mangroves sediments can provide detailed records of mangrove species variation in the last one hundred years, based on detailed 210 Pb data. The study traced the history of mangrove development and its response to environmental change over the last 140 years in two mangrove swamps of Guangxi, Southwest China. Average sedimentation rates were calculated to be 0.48 cm/a and 0.56 cm/a in the Yingluo Bay and the Maowei Sea, respectively. Chemical indicators(δ13Corg and C:N) were utilized to trace the contribution of mangrove-derived organic matter(MOM) using a ternary mixing model. Simultaneous use of mangrove pollen can help to supplement some of these limitations in diagenetic/overlap of isotopic signatures. We found that vertical distribution of MOM was consistent with mangrove pollen, which could provide similar information for tracing mangrove ecosystems. Therefore, mangrove development was reconstructed and divided into three stages: flourishing, degradation and re-flourishing/re-degradation period. The significant degradation, found in the period of 1968–1998 and 1907–2007 in the Yingluo Bay and the Maowei Sea, respectively, corresponding to a rapid increase of reclamation area and seawall length, rather than climate change as recorded in the region.     

冲绳海槽中段火山岩系Sr和Nd同位素地球化学特征及其地质意义

冲绳海槽中段广泛发育基性至酸性火山岩岩石系列 .各类火山岩的平均Sr同位素87Sr/86Sr分别为 0 70 4749,0 70 5 0 6 2 ,0 70 8771,0 70 4840和 0 72 0 30 1;平均Nd同位素比值143 Nd/144 Nd分别为 0 5 12 82 0 ,0 5 12 6 73,0 5 12 413,0 5 12 72 9和0 5 12 0 34 .Sr,Nd同位素比值完全落在MORB岩浆和流纹质岩浆二端员混合的理论双曲线上 .推断冲绳海槽中段不同类型的火山岩是在海槽地壳形成和演化的不同阶段 ,MORB岩浆同化了早已存在的壳源物质而产生的流纹质部分熔体以不同比例与MORB混合而后喷发的产物 ,揭示了冲绳海槽正从大陆裂谷进入海底扩张阶段     

广西钦州湾晚全新世红树林演变及对海平面变化的响应

Mangroves, widely distributed along the coasts of tropical China, are influenced by Asia monsoon, relative sea level change and enhanced human activity. To predict the impacts of future climate change on mangrove ecosystems, it can be understood by reconstructing past mangrove dynamics using proxies preserved in coastal sediments. In this study, we quantitatively partitioned buried organic matter(OM) sources, collected from a vulnerable mangrove swamp in the Qinzhou Bay of northwestern South China Sea, using a ternary end-member mixing model of δ~(13)C and C:N values. Mangrove-derived OM(MOM) contribution was used as a tracer for mangrove development since 2.34 cal ka BP. This information, together with paleoclimate records(i.e.,speleothem δ~(18)O values, sea level change, grain size parameters) and human activity, was used to divide mangrove development into three stages during the late Holocene: relative flourish(2.34–1.13 cal ka BP), relative degradation(1.13–0.15 cal ka BP) and further degradation(0.15–0 cal ka BP). Before 1.13 cal ka BP, mangroves flourished with a high MOM contribution((88.9±10.6)%), corresponding to stable and high sea level under a warm and humid climate. After 1.13 cal ka BP, rapid fall in relative sea level coupled with the strengthening of the Asian winter monsoon, resulted in mangrove degradation and MOM reduction((62.4±18.9)%). Compared with air temperature and precipitation, the relative sea level fall was the main controlling factor in mangrove development before entering the Anthropocene(the time of the Industrial Revolution). After ～150 cal a BP, reclamation of mangrove swamps to shrimp ponds is the main factor causing mangrove degradation and MOM reduction.     

中国西南广西英罗湾红树林近130年来演化指标——沉积物中的红树叶片亚化石

Located in the intertidal zone of the tropical and subtropical coasts, mangrove forests are an important ecosystem in the global carbon cycle and serve as a protector of local seashores. Under the double impacts of climate change,especially sea-level rise, and human activity, mangrove forests around the world have faced degradation, against which the reconstruction of the historical development of mangrove forests using an effective indicator has been regarded as a necessary strategy for designing a predictable model. As the primary product of mangrove forest, it is reasonable that the content of leaf fragments of mangrove(CLFM) buried in sediments in the form of sub-fossils potentially has the same indicative function for the development of mangrove forests as that of widely-used mangrove pollen. In this study, the leaf fragments of mangrove in two sediment cores(YLW02 and YLW03) drilled in the Yingluo Bay in Guangxi, Southwest China were picked out and weighted for calculation of CLFM, which was used as an indicator of mangrove development after examination of parallelism and a statistical correlation of the CLFM with the concentration of mangrove pollen. The results clearly show that the vertical distribution of the CLFM for the core taken from the landward margin of mangrove forests(YLW03) only parallels that of the local mangrove species(Rhizophora. stylosa) with a significantly positive correlation(R=0.56, P=0.05), while the vertical distribution of the CLFM for the core taken from the interface between seaward margin of mangrove forest and the trunk of tidal creeks of the bay(YLW02) parallels the summed concentration of mangrove pollen(SCMP) with a more positive correlation than that of YLW03(R=0.85, P=0.01), indicating that the trunk outlet of tidal creeks must have been the site where mangrove production gathered from the overall forest rather than from local production. The variations in the CLFM of both cores indicate that overall the mangrove forests in the Yingluo Bay have increasingly flourished over the last 130 years except for the interval of 1940–1950 AD in response to an increase in air temperature and decrease in rainfall, which would have resulted in an increase in seawater salinity;while the coupled extreme increases in air temperature and in rainfall in summer, which would have resulted in extreme decreases in seawater salinity, would be responsible for the relative degradation of mangrove forests in the interval of 1940–1950 AD.     

广西北海潮间带沉积物中重金属的污染状况及其潜在生态危害

利用广西北海段潮间带表层沉积物样品的实验数据,对其沉积物中重金属（Hg,Cd,Pb,Zn,Cu,As）含量的空间分布特征进行了初步分析;并采用海洋沉积物重金属质量国家一类标准和Hakanson沉积物重金属潜在生态危害系数（Eir）与危害指数（RI）方法评价了该海域重金属污染程度和潜在生态危害。结果表明：北海段重金属的平均质量分数（mg/kg）为：Zn（69.81）〉Pb（16.58）〉Cu（12.76）〉As（9.08）〉Cd（0.22）〉Hg（0.07）;其中,廉州湾和英罗湾的重金属质量分数相对较高,而铁山湾和银滩段的相对较低。此外,绝大多数观测站点的沉积物尚保持清洁状态,且其潜在生态危害较轻,多属轻微生态危害。     

龙门岛潮间带沉积化学及百年演变特征

通过对龙门岛潮间带典型沉积化学剖面调查与柱状取样分析,结果表明:该岛潮间带沉积物中含较多的黏土,有利于有机碳、油类、总氮、总磷和重金属元素的富集,同时对海岛及周边海域污染状况反映敏感;该岛北部LM01剖面表现出油类、铜、铅、锌的污染特征,XC剖面亦有总磷(TP)、铜、总氮(TN)污染的迹象;LM01柱上部30 cm段油类、TP和重金属向上呈明显的递增趋势,反映出20世纪70年代末至今,随着龙门岛及周边大陆和海洋的开发利用,入海污染物质逐年增加,潮间带底质环境随之恶化.