中国特有针叶树种对气候变化的敏感性研究

About 214 trees in 9 sampling sites, representing 5 endemic conifer species, were collected from the western Sichuan Province and eastern Qinghai Province, China. In this study, structure we try to investigate tree-ring sensitivity to climate in order to obtain primary information of reconstructing past climate from the trees in this region. All the 5 species present distinct ring boundaries ^ few ABS(absent rings) and available for cross-dating,which are all past the test by program COFECHA. Statistics for all the 8 tree-ring width residual chronologies present significant inter-correlation between series and high values of mean sensitivity. As well as the maximum latewood density of Picea crassifolia Kom and Pinus densata Mast. These results indicate usefulness of these chronologies for dendrochronological studies. Pearson correlation analyses were applied to provide a basic estimate of the causal relationships between tree-ring width and climate factors. We found some significant relationships between tree-ring width> maximum density and temperature as well as precipitation. Especially, there is high correlation between the maximum density of the Picea crassifolia Kom and the index of moisture, the ratio of precipitation and temperature, which can indicate well the climate; however the higher correlation can be see between the maximum density of Pinus densata Mast and the total temperature from June to September. Regardless of tree species, chronologies in our study region presented accordant variations of which may reveal strong common climate signal. Thus these chronologies are shown to be dependable for building tree-ring network in the nearly future. However, there are limitations in this study, only monthly mean of temperature and precipitation were available. Also, for this typical subtropical mountain system, meteorological stations are usually located in valley and biased to represent moisture conditions on the slopes. Thus the estimation of precipitation both in temporal and spatial domain was rather restricted. Further study, such as wood anatomy, physiology and densitometry, are needed for better understanding the environmental and climatic history in this area.

氟代谢平衡及其在地方性氟中毒防治中的应用研究

本文通过氟代谢平衡法，研究了大鼠在不同氟摄入量条件下以及食物高钙、高蛋白质、酸性饮水、碱性饮水，大鼠氟的摄入、排泄和蓄积的特征；并对氟代谢的指标之一，尿氟含量在地方性氟中毒防治中的应用进行了分析；同时，以大鼠氟代谢作为低氟玉米样品氟富集的载体，采用生物富集方法，探索性测定了测定超低氟含量玉米样品。通过实验观察，得到以下几点主要认识： 1. 氟的蓄积量从高到低的次序是：常规食料组＞碱性饮水组＞酸性饮水组＞富蛋白饲料组＞富钙饲料组。高钙和高蛋白饮食减少了大鼠的饮水量和摄食量，使高氟含量的饮水和食物进入机体的量减少，从而减少了摄氟量。高钙食物和高蛋白质食物，促使尿氟浓度显著增高，骨氟浓度减低，降低了大鼠的氟蓄积。高钙食物使粪排氟量比例增加，高蛋白食物使尿排氟量比例增加。 2. 大鼠生长过程中，一般在3个月时代谢旺盛，摄氟量、蓄积量和排氟量大幅增加。 3. 大鼠摄入过量氟导致骨形态学改变。随着实验时间加长，大鼠摄氟量增加，电镜下骨细胞出现凋亡和坏死数量增多，有的成骨细胞出现细胞器变性，骨基质发育不良；骺板仅见软骨细胞减少，未见细胞器变性，软骨基质未见异常。 4. 人群群体尿氟，对于氟中毒评价病情、环境氟暴露有重要意义，在地方性氟中毒防治工作中是一个可用于实际工作的指标。判定病区与非病区表准的人群尿氟几何均数为：成人1.6mg/L，儿童1.4mg/L。 5. 利用大鼠氟代谢平衡法测得新鲜玉米氟含量为：0.35mg/kg，其范围可能在0.01~0.69mg/kg之间，此方面还需进一步研究。

地方性燃煤型砷中毒的生物化学研究

目的　研究燃煤型砷中毒疾病发生发展的生物化学机制和卟啉作为早期燃煤型砷暴露生物标志的可能性。 方法　主要进行两方面的研究，一是根据内蒙古前期研究中建立的方法，采用砷负荷评估方法－二巯基丁二酸(DMSA)试验，测定贵州燃煤型砷中毒区患者和对照体内砷负荷（形态和数量），通过病例对照研究，了解燃煤型砷中毒患者体内砷负荷的特点、砷代谢的机制，同时通过对比内蒙古饮水型砷中毒区的研究数据，了解二型砷中毒患者体内砷负荷的差别及成因。二是通过暴露对照、不同年龄和性别分层对比系统研究燃煤型砷暴露对卟啉排泄的影响。 结果 1. 在国内外首次建立了采用DMSA(二巯基丁二酸)试验评估砷中毒人群砷负荷的方法，并在燃煤型砷中毒区予以实施。 2. 利用DMSA能够络合移除体内的砷，特别是MMA，显示具有用于评估体内砷负荷和健康风险的潜在可能性； 3. 工作中发现一些砷中毒区病人在停用高砷煤很长时间后（>30y）体内砷负荷仍然很高； 4. 研究表明DMSA能够促进MMA3+排出，移除体内贮存的砷，从而降低砷对人体的远期致癌风险。 5. 首次在尿中检测出与DMSA结合的两种砷复合物，这一发现此前还未有过报道，该发现对进一步了解巯基类药物的排砷机制提供了重要信息，具有重要的意义； 6. 在砷暴露对卟啉影响研究方面，发现低龄组（<20y）尿卟啉Ⅲ和粪卟啉Ⅲ比对照显著增高，此外，砷暴露组尿液中砷与总粪卟啉和总卟啉呈正相关，这说明卟啉具有作为早期燃煤型砷暴露生物标志潜在价值。