东海PN断面透明胞外聚合颗粒物分布特征及来源研究

透明胞外聚合颗粒物（TEP）是凝聚网的重要组成部分甚至核心,在微尺度范围上形成了水环境结构的重要梯度,对于元素地球化学生物循环、碳沉降以及食物网有着举足轻重的作用。本文研究了东海典型断面PN透明胞外聚合颗粒物的分布特征及来源。结果表明:东海典型断面PN透明胞外聚合颗粒物含量介于28~376 μg Xeq./L之间,平均值为（115±67）μg Xeq./L;呈现出明显的夏季 > 冬季 > 秋季 > 春季的季节变化特征以及近岸 > 外海和底层 > 表层的分布趋势。通过对比透明胞外聚合颗粒物分布趋势和硅藻、甲藻分布趋势以及统计分析得出,东海典型断面PN透明胞外聚合颗粒物主要来源于硅藻,甲藻贡献不大;而外海TEP的来源可能主要由超微型浮游植物贡献。     

Cadmium and phosphorus cycling in the water column of the South China Sea: The roles of biotic and abiotic particles

The concentrations of cadmium, phosphorus, and aluminum in size-fractionated phytoplankton, zooplankton, and sinking particles are determined using ICPMS to evaluate the roles of biotic and abiotic particles on the cycling and ratios of Cd and P in the water column. Plankton were collected with a filtration apparatus equipped with 10-, 60-, and 150-μm aperture plankton nets on two occasions (2002 and 2006), and sinking particles were sampled by moored sediment traps deployed at depths of 120, 600, and 3500 m from 2004 to 2005. In contrast to what our previous study revealed, i.e., that most of the other bioactive trace metals in plankton were strongly correlated with abiotic Al and adsorbed on phytoplankton [Ho, T.Y., Wen, L.S., You, C.F., Lee, D.C., 2007. The trace metal composition of size-fractionated plankton in the South China Sea: biotic versus abiotic sources. Limnol Oceanogr 52, 1776–88.], Cd/P ratios, ranging from 0.12 to 0.34 mmol/mol P, did not vary with Al and exhibited fairly consistent values among different sizes of plankton, showing that Cd was mostly incorporated on an intracellular basis. In terms of the sinking particles, fluxes in Cd and P as well as in Cd/P ratios were strongly influenced by both biotic and abiotic particles. Overall, the Cd/P ratios in the sinking particles ranged from 0.03 to 1.2 mmol/mol, with the highest value observed in traps at 120 m during the productive season. The lowest value was observed in deep water during high flux periods for lithogenic particles. At surface depth, flux and Cd/P ratios were elevated during the most productive season in the region. The elevated ratios in the traps at 120 m were most likely related to preferential uptake of Cd for the dominant species (coccolithophores) during the productive period. Relatively, Cd/P ratios sharply decreased with increasing Al flux in deep water and ratios were much lower than the expected Cd/P ratios obtained from the relative portion of lithogenic and biogenic particles, indicating that the adsorption of soluble P into lithogenic particles was significant in the deep water during high lithogenic particle flux periods. Using averaged annual fluxes and standing stock in the water column, the residence time of biogenic Cd and P are 0.10 and 0.20, 250 and 100, and 9100 and 5000 years respectively in the top 120 m, 600 m, and water column as a whole, also showing preferential removal for Cd in the euphotic zone but relatively higher removal rates for P in the deep water. Our study suggests that the shift in microalgal community structure along with input of lithogenic minerals are both potentially important factors in influencing Cd/P ratios in oceanic water on a geological time scale.     

非球形轴对称粒子光散射的散射矩阵元素展开系数的数值计算

扼要地介绍了非球形粒子光散射的散射矩阵元素按广义球函数展开的基本理论,以及球形粒子散射矩阵元素间的关系。在此基础上较详细地阐述了计算展开系数的方法以及在程序研制中所遇到的一些问题。最后,对非球形的Ｃｈｅｂｙｓｈｅｖ粒子光散射的散射矩阵元素的展开系数进行了计算,结果表明数值技术和计算的正确性。     

Correlation Between Total Lightning Activity and Precipitation Particle Characteristics Observed from 34 Thunderstorms

A total of 34 thunderstorms around Shanghai and Wuhan of China are analyzed in order to determine the relationship between total lightning activity and precipitation particle characteristics.Precipitation particle concentration data are obtained from the 2A12 product of TRMM/TMI(Tropical Rainfall Measuring Mission/TRMM Microwave Image) and lightning activity data are from the TRMM/LIS(Lightning Imaging Sensor) and SAFIR3000(Surveillance et Alerte Founder par Interferometric Radioelectirque).On a spatial ...     

气溶胶气候效应的一维模式分析

本文首先采用一线辐射对流模式，分析了乡村型、城市型气溶胶和平流层气溶胶含量增加对全球地表气温的直接影响以及硫酸盐粒子含量增加对全球地表气温的间接影响。然后利用考虑了海洋热惯性作用的ＥＢＭ／ＢＤ模式，模拟了近百年来由于大气中硫酸盐粒子含量变化、火山爆发和大气温室气体浓度增加共同引起的全球地表平均气温变化。结果表明：气溶胶的气候效应在地气系统辐射收支和全球气温变化研究中起着非常重要的作用。     

Nitrogen and sulfur species in Antarctic aerosols at Mawson,Palmer Station,and Marsh (King George Island)

High volume bulk aerosol samples were collected continuously at three Antarctic sites: Mawson (67.60° S, 62.50° E) from 20 February 1987 to 6 January 1992; Palmer Station (64.77° S, 64.06° W) from 3 April 1990 to 15 June 1991; and Marsh (62.18° S, 58.30° W) from 28 March 1990, to 1 May 1991. All samples were analyzed for Na⁺, SO ₄ ^2– , NO ₃ ^– , methanesulfonate (MSA), NH ₄ ⁺ ,²¹⁰Pb, and⁷Be. At Mawson for which we have a multiple year data set, the annual mean concentration of each species sometimes vary significantly from one year to the next: Na⁺, 68–151 ng m^–3; NO ₃ ^– , 25–30 ng m^–3; nss SO ₄ ^2– , 81–97 ng m^–3; MSA, 19–28 ng m^–3; NH ₄ ⁺ , 16–21 ng m^–3;²¹⁰Pb, 0.75–0.86 fCi m^–3. Results from multiple variable regression of non-sea-salt (nss) SO ₄ ^2– with MSA and NO ₃ ^– as the independent variables indicates that, at Mawson, the nss SO ₄ ^2– /MSA ratio resulting from the oxidation of dimethylsulfide (DMS) is 2.80±0.13, about 13% lower than our earlier estimate (3.22) that was based on 2.5 years of data. A similar analysis indicates that the ratio at Palmer is about 40% lower, 1.71±0.10, and more comparable to previous results over the southern oceans. These results when combined with previously published data suggest that the differences in the ratio may reflect a more rapid loss of MSA relative to nss SO ₄ ^2– during transport over Antarctica from the oceanic source region. The mean²¹⁰Pb concentrations at Palmer and Marsh and the mean NO ₃ ^– concentration at Palmer are about a factor of two lower than those at Mawson. The²¹⁰Pb distributions are consistent with a²¹⁰Pb minimum in the marine boundary layer in the region of 40°–60° S. These features and the similar seasonalities of NO ₃ ^– and²¹⁰Pb at Mawson support the conclusion that the primary source regions for NO ₃ ^– are continental. In contrast, the mean concentrations of MSA, nss SO ₄ ^2– , and NH ₄ ⁺ at Palmer are all higher than those at Mawson: MSA by a factor of 2; nss SO ₄ ^2– by 10%; and NH ₄ ⁺ by more than 50%. However, the factor differences exhibit substantial seasonal variability; the largest differences generally occur during the austral summer when the concentrations of most of the species are highest. NH ₄ ⁺ /(nss SO ₄ ^2– +MSA) equivalent ratios indicate that NH₃ neutralizes about 60% of the sulfur acids during December at both Mawson and Palmer, but only about 30% at Mawson during February and March.     

SETTLING PROPERTIES OF COHESIVE AND NON-COHESIVE PARTICULATE MIXTURES IN WATER

1. INTRODUCTIONAs a wide range of size distirbution including usually a certain POrtion of cohesive material is thecommon feature of the sediment constituting hyperconcentrated flows. it is desirable to study the settling properties of mixtures of cohesive and non--cohesjve sediment particles at high concentrations.Past studies on the settling of discrete particles in a suspension of fine cohesjve sediment is scarcein the literature. The Sediment Research Laboratory of Tsinghua Universi…     

Arctic hazes in summer over Greenland and the North American Arctic: II. Nature and concentrations of accumulation-mode and giant particles

Airborne measurements made during August 1985 over Greenland and its environs show that both accumulation-mode (0.1 m D2.0 m) and giant (D2 m) particles were present in relatively high concentrations in arctic haze layers and that the accumulation-mode particles dominated light scattering. Particles with diameters (D) between 1 and 4 m consisted predominately of mixed materials, small and dense inclusions, and probably organic compounds containing sulfur. Many of the particles from 0.1 to 1 m in diameter were also of mixed composition, with sulfuric acid, ammonium sulfate and organics probably the dominant constituents.