北黄海水体的~(224)Ra

用锰纤维富集-射气法测量了北黄海水体的224Ra,研究了该海域夏季和冬季2个季节224Ra比活度及其垂直分布,并对其进行了比较研究.北黄海夏季224Ra比活度为0.24～3.48Bq/m3,平均值为1.14Bq/m3;冬季224Ra比活度为0.37～6.68Bq/m3,平均值为0.94Bq/m3.北黄海的表层水有3个224Ra高值区,分别位于东北部海域、渤海海峡南部和北黄海中北部海区.30m水深将224Ra比活度的垂直分布分成上层和下层2层.在0～30m水层,夏季,随着水深增加224Ra比活度逐渐增加,比活度变化较小;冬季部分站位由表层向下224Ra比活度逐渐降低.30m水深以下,224Ra比活度随着水深的增加而增加,而且变化幅度较大.由224Ra比活度的垂直分布得出该海域的垂直涡动扩散系数为2.5～43.5cm2/s,夏季北黄海冷水团中心海域底层溶解态化学物质输运补给到上层所经历的时间为9～15d左右.     

北黄海水体的^224 Ra

用锰纤维富集-射气法测量了北黄海水体的^224 Ra,研究了该海域夏季和冬季2个季节^224 Ra比活度及其垂直分布,并对其进行了比较研究．北黄海夏季^224 Ra 比活度为0．24—3．48Bq／m2,平均值为1．14Bq／m2;冬季^224 Ra比活度为0．37～6．68Bq／m2,平均值为0．94Bq／m2．北黄海的表层水有3个^224 Ra 高值区,分别位于东北部海域、渤海海峡南部和北黄海中北部海区．30m水深将^224 Ra比活度的垂直分布分成上层和下层2层．在0～30m水层,夏季,随着水深增加^224 Ra比活度逐渐增加,比活度变化较小;冬季部分站位由表层向下^224 Ra比活度逐渐降低．30m水深以下,^224 Ra比活度随着水深的增加而增加,而且变化幅度较大．由^224 Ra比活度的垂直分布得出该海域的垂直涡动扩散系数为2．5～43．5cm2／s,夏季北黄海冷水团中心海域底层溶解态化学物质输运补给到上层所经历的时间为9～15d左右．     

北黄海水体的226Ra和228Ra

用锰纤维富集-射气法测定了北黄海海水中的镭同位素226Ra和228Ra,研究了该海域水体中镭同位素的含量和分布.研究结果表明北黄海水体夏季226Ra的比活度为1.80～4.35 Bq/m3,平均值为3.06 Bq/m3;冬季226Ra的比活度为2.08～5.20 Bq/m3,平均值为3.28 Bq/m3.北黄海夏季228Ra的比活度为3.85～25.60 Bq/m3,平均值为10.60 Bq/m3;冬季228Ra的比活度为3.14～15.60Bq/m3,平均值为7.66 Bq/m3.该数据范围和中国近海其他海域、孟加拉湾、泰国昭披耶河口、濑户内海等海域相近.北黄海东北部海域,渤海海峡靠近山东半岛的海区和中北部海区表层镭同位素活度较高.C1断面镭同位素的分布特征从镭同位素的方面证实了渤海海峡水交换表现为北进南出特征这一结论的正确性.226Ra和228Ra的垂直分布较为复杂,大部分站位呈现出底层活度变高的趋势,其他少数站位呈现出中间层活度高的分布特征,不同来源的镭同位素输入至该海域形成了这样的分布特征.     

北黄海水体的~(226)Ra和~(228)Ra

用锰纤维富集-射气法测定了北黄海海水中的镭同位素226Ra和228Ra,研究了该海域水体中镭同位素的含量和分布.研究结果表明北黄海水体夏季226Ra的比活度为1.80～4.35 Bq/m3,平均值为3.06 Bq/m3;冬季226Ra的比活度为2.08～5.20 Bq/m3,平均值为3.28 Bq/m3.北黄海夏季228Ra的比活度为3.85～25.60 Bq/m3,平均值为10.60 Bq/m3;冬季228Ra的比活度为3.14～15.60Bq/m3,平均值为7.66 Bq/m3.该数据范围和中国近海其他海域、孟加拉湾、泰国昭披耶河口、濑户内海等海域相近.北黄海东北部海域,渤海海峡靠近山东半岛的海区和中北部海区表层镭同位素活度较高.C1断面镭同位素的分布特征从镭同位素的方面证实了渤海海峡水交换表现为北进南出特征这一结论的正确性.226Ra和228Ra的垂直分布较为复杂,大部分站位呈现出底层活度变高的趋势,其他少数站位呈现出中间层活度高的分布特征,不同来源的镭同位素输入至该海域形成了这样的分布特征.     

秋季红沿河核电站海域水龄分布及其对水母丰度分布的影响

本研究调查了秋季红沿河核电站海域镭、氡同位素的活度水平及分布情况,结合镭同位素表观年龄模型计算该海域的水体年龄,进而得出研究区域的水体运移方向,初步探讨了水母丰度分布与水体运移的相关关系。得到结论如下:(1)红沿河核电站海域表层水体中224Ra、226Ra及222Rn的活度水平分别为2.9～62.4 dpm/(100 L),11.9～57.4 dpm/(100 L)及0.1～1.3 dpm/L,镭同位素活度呈现出近岸高、远岸低的分布趋势,氡同位素的分布则更大程度上受水温控制;(2)通过224Ra/226Ra表观年龄模型计算得出红沿河海域表层水体年龄范围介于0～16 d,平均年龄(10.9±3.6) d,水体主体流向为北偏东方向,流速为7.2 cm/s;(3)水母丰度分布与水体流向呈现出较为一致的对应关系,在主体流向方向上,水体年龄较大的海域水母丰度最高。     

苏北浅滩海底地下水排放及其对海域营养盐通量的贡献

海底地下水排放(SGD)是近海海域的一个重要的营养盐来源。本研究借助多种天然镭同位素对春季苏北浅滩海域的SGD及其携带入海的营养盐通量进行量化评估。研究发现:苏北浅滩海域的~(224)Ra、~(223)Ra和~(226)Ra等镭同位素的浓度水平较高,呈现近岸高、远岸低的分布趋势;根据~(224)Ra/~(226)Ra的"表观年龄模型"估算的水龄的分布情况推断,春季该海域表层水体主体流向为东北向,流速约为0.1m/s,这与前人物理海洋数值模拟结果一致;最终利用226Ra质量平衡模型发现海域的SGD通量为(46±29)cm/d,由其携带入海的溶解态无机氮、磷、硅营养盐(DIN、 DIP、 DSi)等的通量分别为(2.6±3.1)×1~09、(3.0±2.5)×10~6和(5.5±4.2)×10~8mol/d。     

中国近岸海域沉积物226Ra的分布特征

本文对中国7个近岸海域沉积物226Ra的分布进行了研究,结果表明珠江口表层沉积物的226Ra含量较高,其余6个近岸海域(黄河口、胶州湾、长江口、杭州湾、厦门湾、大亚湾)的226Ra含量相近。226Ra含量值显示了研究海域沉积物的“亲陆性”,但不同站位226Ra含量受物源区域、水动力作用及其他环境理化诸因素的影响。226Ra在况积物盐酸沥取相的放射性比度及总量均大于残渣相的相应数值,说明陆源物质在风化及向海迁移过程中绝大部分镭进入到水相中。元洪码头附近海域岩心中226Ra的垂直分布表明,镭发生了沉积后的再迁移。所有各相的活度比(238Ra/226U)_a.r、(226Ra/230Th)_a.r.均小于1.0,进一步证明中国近岸沉积物普遍存在226Ra-238U、226Ra-230Th不平衡现象。     

224,223Ra和137Cs在吕宋海峡及周边海域的分布以及其对“彩虹”台风的响应

本文报道2015年9月和2016年5月期间天然放射性核素²²⁴Ra和²²³Ra在吕宋海峡及周边海域表层和垂向水体的分布特征。为理解日本福岛核事故的影响,本文亦分析研究区域内人工放射性核素¹³⁷Cs的分布特征。结果表明,^224,223Ra和¹³⁷Cs比活度水平均处于我国南海海洋天然放射性本底变化范围之内。²²⁴Ra在吕宋海峡以西南海北部海域比活度较高,在吕宋海峡以东菲律宾海域比活度较低。¹³⁷Cs没有明显的分布趋势。基于三站位（LS3,LS5和LS8）²²⁴Ra、¹³⁷Cs以及温盐的垂向分布特征,本文揭示²²⁴Ra和¹³⁷Cs在热带表层水、次表层水和中-深层水中比活度水平和梯度变化的差异特征。彩虹台风事件扭转了整个吕宋海峡及周边海域的海流循环过程。大量以低水平²²⁴Ra为特征的西太平洋海水涌入南海,降低水体²²⁴Ra比活度水平。但是,西太平洋和南海北部海域水体¹³⁷Cs比活度水平没有明显差异,台风导致的海流变化对水体¹³⁷Cs比活度没有明显影响。     

九龙江河口区水体中224Ra的分布及其应用

研究了九龙江河口区表层水体中224Ra的分布,发现同世界其他河口一样,224Ra在九龙江河口区呈非保守行为;同时发现224Ra-Ss关系受季节变化的影响显着;与世界其他河口相比,九龙江河口表层水体中224Ra含量偏高;用九龙江河口区海端溶解态224Ra估算九龙江河口水流向外海的流速在夏季为2.5cm/s,冬季为0.91cm/s.     

南极普里兹湾及其邻近海域表层水镭同位素的分布及应用

中国第27次南极科学考察期间(2010年12月30日至2011年1月16日),对普里兹湾及其邻近海域表层海水进行了226Ra和228Ra的分析,结果表明:226Ra和228Ra比活度的变化范围分别为1.47—2.43Bq/m3和0.17—0.45Bq/m3,平均值分别为2.13Bq/m3和0.29Bq/m3,228Ra/226Ra)A.R.(228Ra与226Ra的活度比)的变化范围为0.08—0.20,平均值为0.14。根据盐度和226Ra的质量平衡方程,计算出研究海域表层水中冰融水、南极夏季表层水和普里兹湾中深层水的份额。研究海域表层水中温度、盐度、226Ra、228Ra、228Ra/226Ra)A.R.和冰融水份额的空间分布显示,在埃默里冰架前沿海域,西侧海域较东侧海域具有低温、高盐、高226Ra、低228Ra、低228Ra/226Ra)A.R.、低冰融水份额的特征,证实埃默里冰架下水体东进西出的运动规律。根据埃默里冰架前沿东、西侧水体228Ra/226Ra)A.R.的差异,估算出埃默里冰架下表层水体东进西出所经历的时间为1.85a。此外,在普里兹湾湾口中部海域(66.5—67.5°S,72°—74°E),观察到次表层水的上升通风作用,该区域较高的228Ra含量和228Ra/226Ra)A.R.证明这些表层水体并非来自湾外绕极深层水的上涌,而可能来自湾内埃默里冰架输出水体。     

A 2—D section of 228Ra and 226Ra in the Northeast Pacific

Seawater samples collected in the northeast Pacific from 112° 50′W to 126° 36′W along a latitudinal band (21–25° N) have been analysed for ²²⁸RA and ²²⁶Ra. Both nuclides exhibit their characteristic distributions. In the surface water, the exponential-like decrease of ²²⁸ Ra away from Baja California can be interpreted by horizontal water mixing with eddy diffusion coefficients (K_x) of 1 × 10⁶ cm² s⁻¹ and 5 × 10⁷ cm² S⁻¹ for scale lengths of 200 km and 1000 km, respectively. In the bottom waters, the decrease of ²²⁸Ra away from bottom sediments can be modeled by vertical eddy diffusivities (K_z) of 15–30 cm² s⁻¹ except at one station (24° 16.9′ N, 115° 8.9′ W) where a value of 120 cm² s⁻¹ is obtained. The ²²⁸Ra-derived diffusivities were used to compute the mass balance of ²²⁶Ra using a two-box model. The model results show a mean mixing coefficient of 3.8 cm² s⁻¹ for the thermocline and a mean upwelling velocity of 7.7 m y⁻¹ in the study area, both are about two or three times higher than those generally quoted for the Pacific.     

基于223Ra和224Ra的桑沟湾海底地下水排放通量

海底地下水排放（SGD）是陆地向海洋输送水量和营养物质的重要通道之一,对沿海物质通量及其生物地球化学循环有重要的影响,对生态环境起着不可忽视的作用。本文运用天然放射性同位素223Ra和224Ra示踪估算了我国北方典型养殖基地桑沟湾的海底地下水排放通量。结果表明,海底地下水样尤其是间隙水中Ra活度[224Ra=（968±31）dpm/（100 L）,223Ra=（31.4±4.9）dpm/（100 L）,n=9]远高于表层海水[224Ra=（38.7±2.0）dpm/（100 L）,223Ra=（1.70±0.50）dpm/（100 L）, n=21]。假设稳态条件下,考虑Ra的各源、汇项,利用Ra平衡模型,估算出桑沟湾SGD排放通量为（0.23~1.03）×107 m3/d。潮周期内的观测结果显示,涨潮时,水力梯度较小,SGD排放变弱,落潮时,水力梯度较大,导致了相对较多的SGD排放。在一个潮周期间,基于223Ra和224Ra得到的SGD排放通量平均为0.39×107 m3/d。潮汐动力下的SGD排放平均占总SGD排放的61%,因此桑沟湾沿岸的地下水排放主要受潮汐动力的影响,并对海水组成及海陆间物质交换有显著贡献。     

Holocene stratigraphy and depositional architecture of eastern Pozzuoli Bay (eastern Tyrrhenian Sea margin,Italy): the influence of tectonics and wave-induced currents

Pozzuoli Bay is located in the eastern Tyrrhenian Sea and is an area characterized by active tectonics and volcanism. On the basis of high-resolution seismic reflection profiles, it was possible to reconstruct the stratigraphy and three-dimensional stratal architecture of the Holocene succession. Two volcanic units and three sedimentary ones were recognized. The basal unit NC consists of volcanic deposits and dates at 10.0-8.0 ka B.P. It is followed by unit D, deposited between 8.0 and 5.5 ka B.P., which displays a backstepping configuration in the central area and a forestepping configuration in the northern area. Unit D is covered by the progradational unit B which is elongated in a SE-NW direction. Unit C is interbedded between unit B and is interpreted as the volcanic products of the Agnano-Monte Spina eruption which occurred 4.4 B.P. Unit A, the youngest unit, shows a progradational configuration and is elongated in a E-W direction. The sedimentary units record the transgressive and highstand of the eustatic sea level. They show vertical and lateral variations in the depositional architecture. Changes in the stacking pattern record variations in tectonic subsidence and hydrodynamic regimes.     

Vertical transport in a stratified oceanic medium

On the basis of the analysis of the data of hydrological observations, we construct an empirical dependence of the vertical heat fluxQ on the temperature gradientT _z . The integral advective-diffusive transfer is taken into account by the method of Kolesnikov. We obtain a generalized dependence of the coefficient of vertical thermal diffusivityK _z onT _z and note that the well-known Rossby-Montgomery relation and Kolesnikov formula are its special cases. We analyze the possibility of application of this dependence to linear and nonlinear problems of thermal conductivity and diffusion in the ocean. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

厦门湾有色溶解有机物的光吸收特性研究

研究了厦门湾九龙江河口区、西海域、同安湾及东侧水道海水中有色溶解有机物(CDOM)的光吸收特性,分析了CDOM的河口行为,并讨论了CDOM光吸收特性与其荧光性质之间的关系。结果表明,厦门湾表层海水CDOM光吸收系数a(355)的水平分布表现为河口区最高、东侧水道最低、西海域和同安湾介于两者之间,底层水a(355)的分布与表层基本相似,表明陆源河流输入是厦门湾CDOM的主要来源;a(355)的垂直分布为表层高于底层,主要受水文和生物因素控制。厦门湾表层水CDOM光谱斜率S的平均值介于0.014—0.018nm-1,但河口低盐度区S值较小,反映陆源腐殖质的影响。a(355)在河口混合中呈保守行为,表明CDOM具有良好的保守性质。CDOM的吸收系数a(355)与其荧光强度之间表现为较好的相关关系,指示可以用灵敏度更高的荧光方法来研究CDOM的分布和行为。     

Adsorption–desorption reactions and bioturbation transport of Ra in marine sediments: a one-dimensional model with applications

The distribution of trace metals in sediments and their exchange between sediments and overlying water is governed by multiple processes including molecular diffusion, bioturbation (porewater advection, porewater mixing, and particle mixing), chemical reactions and adsorption–desorption. To understand these processes and their relative contributions, a one-dimensional model was built, which includes bioturbation and adsorption–desorption processes, to describe the transport of ²²⁴Ra. Because ²²⁴Ra is adsorbed on MnO₂, ²²⁴Ra may serve as a proxy for trace metal transport. Three sites were sampled and both dissolved and adsorbed ²²⁴Ra were analyzed and modeled to understand the transport and exchange processes. It was found that particle transport of adsorbed ²²⁴Ra followed by desorption at the sediment/water interface typically represents the dominant flux. We have further been able to define conditions where the porewater transport for adsorption reactive metals like ²²⁴Ra (and other metals) may be out of the sediments whereas the active scavenging of ²²⁴Ra from the water column at the sediment water interface via adsorption reactions can result in a flux of ²²⁴Ra into the sediment. These processes are both predicted by the model and observed in sediment samples.     

Adsorption–desorption reactions and bioturbation transport of 224Ra in marine sediments: a one-dimensional model with applications

The distribution of trace metals in sediments and their exchange between sediments and overlying water is governed by multiple processes including molecular diffusion, bioturbation (porewater advection, porewater mixing, and particle mixing), chemical reactions and adsorption–desorption. To understand these processes and their relative contributions, a one-dimensional model was built, which includes bioturbation and adsorption–desorption processes, to describe the transport of ²²⁴Ra. Because ²²⁴Ra is adsorbed on MnO₂, ²²⁴Ra may serve as a proxy for trace metal transport. Three sites were sampled and both dissolved and adsorbed ²²⁴Ra were analyzed and modeled to understand the transport and exchange processes. It was found that particle transport of adsorbed ²²⁴Ra followed by desorption at the sediment/water interface typically represents the dominant flux. We have further been able to define conditions where the porewater transport for adsorption reactive metals like ²²⁴Ra (and other metals) may be out of the sediments whereas the active scavenging of ²²⁴Ra from the water column at the sediment water interface via adsorption reactions can result in a flux of ²²⁴Ra into the sediment. These processes are both predicted by the model and observed in sediment samples.     

Vertical distribution of the hydrogen sulphide sources in the Black Sea

Data on the diffusion coefficientK _zand the concentration of H₂S in the Black Sea are used to compute the depth distribution of the vertical flux, and the intensity of the H₂S sources and sinks. On average, the total production of H₂S in the Black Sea reaches 37×10⁶ t/year. The main bulk of H₂S is produced not at the bottom, but in the layer of 450–1300 m. Destruction of H₂S prevails above the 400 m layer. Dissolved oxygen penetrating the H₂S zone can oxidize only half of the hydrogen sulphide produced in the sea.Translated by Mikhail M. Trufanov.     

Formation of the vertical salinity profile in the Black Sea

The vertical distribution of salts brought by the Bosphorus undercurrent is numerically evaluated. By multiplying the average vertical salinity gradient by the diffusion coefficient,K _z , and the cross-section of the sea at the appropriate depth, we can determine the total vertical salt flux,Q(z). The derivative ofQ with respect toz depicts the salt source intensity distribution over depth. The highest intensity, Q/z, matches the 200 m depth level, i.e. the shelf edge. Below 1500 m, Q/z equals merely 0.1% of the value observed at a depth of 200 m. Above 37 m, salts are noted to sink, which corresponds to their outflow with the Bosphorus current. The distribution of Q/z and the respective values of mineral phosphorus and hydrogen sulphide are matched up.Translated by Vladimir A. Puchkin.