Okadaic acid, a causative toxin of diarrhetic shellfish poisoning, in green-lipped mussels Perna viridis from Hong Kong fish culture zones: method development and monitoring

Green-lipped mussels (Perna viridis) were collected from seven fish culture zones (FCZs) in Hong Kong and analyzed for okadaic acid (OA). A conventional HPLC method was modified by incorporating a proteinase K digestion step. Results suggest that a higher recovery (2.5 times higher) of OA was obtained from spiked samples after the addition of 1.08 mg proteinase K in comparison with samples incubated without the proteolytic enzyme. For the hepatopancreas (HP) of individual field-collected mussels, the additional digestion step can enhance OA extraction by 3.1 times. Spatial and temporal variations in OA concentrations in the mussels from various FCZs were investigated. The highest concentration of OA in mussel HP samples was 1164.9 ng/g HP wet wt. With respect to OA concentrations in whole mussel tissues from seven sites and four seasonal samplings, the concentrations were between 70.0 and 131.0 ng/g wet wt., which did not exceed the generally recognized international regulatory criteria (>200 ng/g) for OA.     

多层次跟踪预报法在地下流体会商中的应用

本文介绍利用多层次跟踪预报方法之短期预测法在多次福建地下流体资料会商中的应用。水化多层次跟踪预报方法以“水化的多层次跟踪加速前兆图象”为依据进行分析,主要对地震的发震时间进行预测。该图象说明了水化的异常群体随时间的演变趋势与地震活动有关;异常群体的演变与地震之间具有“增长———地震”或“加速———地震”的关系。这种关系,同彭德银等指出的地震总是处于接近或偏离临界状态的演化进程中的理论相适应。     

Investigating the ENSO prediction skills of the Beijing Climate Center climate prediction system version 2

The El Ni?o-Southern Oscillation(ENSO) ensemble prediction skills of the Beijing Climate Center(BCC) climate prediction system version 2(BCC-CPS2) are examined for the period from 1991 to 2018. The upper-limit ENSO predictability of this system is quantified by measuring its “potential” predictability using information-based metrics, whereas the actual prediction skill is evaluated using deterministic and probabilistic skill measures.Results show that:(1) In general, the current operational BCC ...     

2001—2020年三江源地区积雪日数变化及地形分异

基于积雪面积逐日无云遥感产品和气象观测资料,分析了2001—2020年三江源地区积雪日数的水平、垂直分布特征及变化规律,并对积雪日数与气温和降水量进行了相关分析。结果表明：（1） 2001—2020年三江源地区积雪日数呈西高东低,高海拔山脉大于盆地平原的分布格局,高海拔山脉地区积雪日数均值普遍大于200 d,85.48%的区域积雪日数呈波动增加趋势,显著增加区域占比为16.59%,平均增加速率为0.98 d·a^-1。（2） 积雪日数及其变化趋势存在明显的海拔和坡向分异,积雪日数随海拔上升呈指数型增加,较低海拔（<3.0 km）区域积雪日数少、呈减少趋势且减少速率随海拔高度上升而加快;高海拔区域积雪日数较多且呈增多趋势,但海拔大于4.4 km后积雪日数增多速率随海拔上升而减缓,且5.5~6.0 km地区积雪日数呈减少趋势,高海拔地区积雪日数存在一定程度的“海拔依赖性”。积雪日数北坡大于南坡、西坡大于东坡,西北坡积雪日数最多,为78.30 d,不同坡向的积雪日数均呈增多趋势,其中西坡的增多速率最快,达1.04 d·a^-1。（3） 近20 a三江源地区明显的“暖湿化”气候特征是影响积雪日数变化的主要原因,其中降水量是主要驱动因素,积雪日数增多与降水量增加密切相关,且高海拔地区积雪日数对降水量的依赖性更强。     

毛乌素沙地东缘中全新世以来环境变化及其对文明演化的影响初探北大核心CSCD

毛乌素沙地全新世风成沉积为探讨气候变化与文明演化之间的关系提供了可能。本文通过对毛乌素沙地东缘全新世中晚期寨山剖面沉积物的磁学参数、色度、CaCO含量和粒度进行分析,重建了该区域环境变化历史,并初步探讨了环境变化对文明演化的影响。结果表明:该区域6 800-1 500 cal a BP分别经历了一次气候暖湿期(6 800-5 500 cal a BP)、一次气候相对暖干期(5 500-4 000 cal a BP)和一次气候相对暖湿期(4 000-1 500 cal a BP)。毛乌素沙地东缘仰韶文化(6 800-5 500 cal a BP)的大扩张与气候暖湿期具有一致性,遗址数量增加;仰韶晚期和龙山时期(5 500-4 000 cal a BP)气候变化频繁,文化复杂多样,期间经历了仰韶文明的衰落和龙山文化的扩张,遗址数量逐渐增加;青铜铁器时代和秦汉时期(4 000-1 500 cal a BP)各民族文化融合发展,人口活动频繁,经济文化都得到较好的发展,遗址不断增加,且数量较大。研究结果指示文明兴衰受环境演化影响,两者在时间上有较好的一致性,但短时期内文明演化对气候变化的响应有滞后性。     

Nitrogen deposition and its spatial pattern in main forest ecosystems along north-south transect of eastern China

A continuous three-year observation(from May 2008 to April 2011)was conducted to characterize the spatial variation of dissolved inorganic nitrogen(DIN)deposition at eight main forest ecosystems along the north-south transect of eastern China(NSTEC).The results show that both throughfall DIN deposition and bulk DIN deposition increase from north to south along the NSTEC.Throughfall DIN deposition varies greatly from 2.7 kg N/(ha·yr)to 33.0 kg N/(ha·yr),with an average of 10.6 kg N/(ha·yr),and bulk DIN deposition ranges from 4.1 kg N/(ha·yr)to 25.4 kg N/(ha·yr),with an average of 9.8 kg N/(ha·yr).NH4+-N is the dominant form of DIN deposition at most sampling sites.Additionally,the spatial variation of DIN deposition is controlled mainly by precipitation.Moreover,in the northern part of the NSTEC,bulk DIN deposition is 17%higher than throughfall DIN deposition,whereas the trend is opposite in the southern part of the NSTEC.The results demonstrate that DIN deposition would likely threaten the forest ecosystems along the NSTEC,compared with the critical loads(CL)of N deposition,and DIN deposition in this region is mostly controlled by agricultural activities rather than industrial activities or transportation.     

汶川地震反应谱特征周期统计分析

反应谱特征周期反映了地震动频谱特性,也是抗震设计中重要的特征参数.为了研究汶川特大地震反应谱特征周期的特性,本文以汶川地震中173个有详细地勘场地上的强震动记录为基础,统计分析了不同场地类别和断层距的反应谱特征周期,并与我国现行抗震设计规范中特征周期的规定值进行比较.本文研究结果显示随着场地变软,特征周期平均值有增大趋势;与汶川特大地震中反应谱特征周期的统计结果相比,我国抗震设计规范规定的远场反应谱特征周期值偏小.     

Geological Characteristics and Ore‐forming Time of the Dexing Porphyry Copper Ore Mine in Jiangxi Province

The Dexing porphyry copper ore mine is located in the Qin-Hang metallogenic belt between the Yangtze block and the Cathaysia block. It is a giant porphyry copper mine in China, including 3 ore districts: Tongchang, Fujiawu and Zhushahong. Our analyses of Re in molybdenite indicate that the ore-forming material of the copper ore deposits in Dexing should be mainly mantle-derived. Our study fills in a gap in the study of formation time of the Dexing copper mine, and further proves that the copper ore deposits in the three ore districts should be formed simultaneously, about 170 Ma, belonging to the early Yanshan period, and that the formation time of the copper ore deposits should be consistent with the formation time of granodiorite porphyry in which the copper ore deposits are hosted. Promising areas for seeking porphyry copper ore deposits is predicated to be the west or southwest of Dexing.     

Phosphorus adsorption characteristics at the sediment–water interface and relationship with sediment properties in FUSHI reservoir, China

This study was designed to survey the reservoir sediment properties, assess the phosphorus (P) sorption isotherm, and analyze the relationship between sediment properties and sorption parameters. Physicochemical analysis indicated that sediment from the FUSHI reservoir in Zhejiang Province, China, has similar physical and chemical properties and has been contaminated by P. Sorption isotherm experiments showed that the sorption process could be described by Langmuir and Freundlich models. The parameters of Q _max (Phosphorus sorption maximum) and K (Freundlich adsorption isotherm constant) ranged from 618.98 to 825.70?mg?kg^?1 and 114.18 to 170.74?l?kg^?1, respectively. EPC₀ (zero P equilibrium concentration) ranged from 0.14 to 0.24?mg?l^?1, more than the total P concentration in the water of the reservoir. Thus, the reservoir sediment releases P into the water and acts as a ??P resource??. The clay, Fe_o, Al_t, and Fe_t?+?Al_t content were the main active components in P sorption. Q _max had a highly significant positive relationship with some properties and could be estimated by a combination of these.     

夏季南海西部中尺度物理过程对营养盐和叶绿素a分布特征的影响

通过对2014年8月31日-9月26日国家自然科学基金委南海西部综合航次的调查结果分析,发现在中南半岛沿岸海域存在具有低温高盐的冷涡和位于其东南部海域具有高温低盐的暖涡。相对于暖涡和其他海域,冷涡水团含有更高的营养盐,并在50 m、75 m和100 m层增加明显,DIP分别高0.21 μmol/L、0.39 μmol/L和0.23 μmol/L,DIN分别高4.94 μmol/L、7.56 μmol/L和3.76 μmol/L,DSi分别高2.55 μmol/L、5.25 μmol/L和3.46 μmol/L,说明冷涡对提高初级生产力具有明显的营养优势条件和巨大潜力;叶绿素a最大值均出现在50 m层,其中以海南岛近岸海域最大,冷涡在25 m层提高初级生产力明显,主要是受营养盐影响显著;而在75 m、100 m层可能受到冷涡带来的低温环境而导致叶绿素a含量不高。