甘肃省森林碳储量现状与固碳速率

针对森林碳平衡再评估的重要性和区域尺度森林生态系统碳库量化分配的不确定性, 该研究依据全国森林资源连续清查结果中甘肃省各森林类型分布的面积与蓄积比重以及林龄和起源等要素, 在甘肃省布设212个样地, 经野外调查与采样、室内分析, 并对典型样地信息按照面积权重进行尺度扩展, 估算了甘肃省森林生态系统碳储量及其分布特征。结果表明: 甘肃省森林生态系统总碳储量为612.43 Tg C, 其中植被生物量碳为179.04 Tg C, 土壤碳为433.39 Tg C。天然林是甘肃省碳储量的主要贡献者, 其值为501.42 Tg C, 是人工林的4.52倍。天然林和人工林的植被碳密度均表现为随林龄的增加而增加的趋势, 同一龄组天然林植被碳密度高于人工林。天然林土壤碳密度从幼龄林到过熟林逐渐增加, 但人工林土壤碳密度最大值主要为近熟林。全省森林植被碳密度均值为72.43 Mg C&middot;hm~(-2), 天然林和人工林分别为90.52和33.79 Mg C&middot;hm~(-2)。基于森林清查资料和标准样地实测数据, 估算出全省天然林和人工林在1996年的植被碳储量为132.47和12.81 Tg C, 2011年分别为152.41和26.63 Tg C, 平均固碳速率分别为1.33和0.92 Tg C&middot;a~(-1)。甘肃省幼、中龄林面积比重较大, 占全省的62.28%, 根据碳密度随林龄的动态变化特征, 预测这些低龄林将发挥巨大的碳汇潜力。</p

市售牛油果油和葡萄籽油品质研究Quality analysis of commercially available avocado oil and grapeseed oil

为了全面分析我国市售牛油果油和葡萄籽油的品质，为食用油产品开发提供指导，采集了市售牛油果油、葡萄籽油主流产品各9种，全面分析其理化品质、危害物风险和营养素水平，并与常见大宗食用油营养素水平进行对比。结果表明：在理化品质上，两种植物油的不同产品存在一定差异，但均符合国家标准；两种植物油苯并$$a$$芘、塑化剂含量均符合国家标准，88.9%的产品反式脂肪酸含量控制在1%以内，但国际前沿关注的3-氯丙醇酯和缩水甘油酯存在超标风险；牛油果油的主要营养素为油酸、角鲨烯、植物甾醇、维生素E，葡萄籽油的主要营养素为亚油酸、植物甾醇、维生素E、谷维素。 In order to comprehensively investigate the product quality of avocado oil and grapeseed oil in Chinese market, and provide guidance for the development of edible oil products，9 different products of each kind of oil were collected. Their physicochemical quality, risk of hazards, and nutrient level were fully analyzed, and their nutrient level was compared with the common bulk edible oil. The results showed that in terms of physicochemical quality, there were certain differences between different products of the two vegetable oils, but both met the national standards. The content of benzo$$a$$pyrene and plasticizer in the two vegetable oils met the national standards, and the content of trans fatty acid in 88.9% of the products was controlled within 1%, but the 3-chloropropanol ester and glycidyl ester, which were concerned by the international frontier, had the risk of exceeding the standard. The primary nutrients in avocado oil were oleic acid, squalene, phytosterol and vitamin E, and in grapeseed oil were linoleic acid, phytosterol, vitamin E and glutathione, respectively

基于古地磁与~(230)Th定年的西沙西科1井乐东组生物礁沉积年代的初步研究

生物礁是重要的自然资源,在全球气候变化与碳循环中扮演了重要角色.磁性地层学是建立年代框架的有效手段,但是,由于生物礁沉积物中天然剩磁强度弱,南海地区生物礁的磁性地层学研究尚未很好展开.为此,本文利用西沙群岛西科1井乐东组生物礁沉积样品进行了详细的岩石磁学和磁性地层学研究.结果显示,西沙群岛乐东组记录了布容正极性时、奥杜维尔正极性时和松山负极性时.通过对比已有的钻孔资料,本文认为应基于岩石地层特征这一标准将西沙地区的乐东组埋深予以统一.在此基础上,综合磁性地层与~(230)Th定年结果,本文将乐东组的底界限定在~2.0 Ma.</p