西港海洋牧场底层海水溶解氧浓度时变特征

利用海底有缆在线观测系统获得的连续实时观测数据,研究了2016年6月2日至10月22日期间威海市西港海洋牧场底层海水溶解氧浓度的时间变化特征,并探讨了其影响机制。结果表明,观测期间底层海水溶解氧浓度整体呈先减小后增大的变化趋势,其变化范围为2.99 mg/L至11.43 mg/L,均值约为6.65 mg/L。进一步分析表明：（1）底层海水饱和溶解氧浓度的变化并不显著,于6月出现过饱和现象;（2）海水温度是底层海水溶解氧浓度日际变化和月变化的主要影响因素;（3）7月至8月中旬,在季节性温跃层抑制垂向混合和水温升高的共同影响下,底层溶解氧浓度总体呈下降趋势;（4）日平均风速与日平均海水溶解氧浓度的相关性并不显著,但大风期间底层海水溶解氧浓度存在先升高后降低的变化特征;（5）底层海水溶解氧浓度的日变化以全日周期为主,可能主要受生物过程、垂向混合扩散和潮流输运等日变化的影响。本研究对于进一步探讨山东半岛海洋牧场区域海水溶解氧的时空分布特征及其影响机制具有重要意义。     

基于快速数字锁相的溶解氧检测优化设计

溶解氧浓度检测在水产养殖和环境监测中具有重要的意义。本文提出了一种基于快速数字锁相的溶解氧检测优化设计,利用快速数字锁相算法与过采样技术,实现了荧光信号和调制信号的快速相位解调,并得到二者相位差,根据Stern-Volmer方程求出溶解氧浓度值。本文分析了调制频率对测量结果的影响,选择合适的调制频率用于测量,并利用最小二乘法对测量结果进行拟合,拟合后的确定系数R-square为0.999 25。实验数据表明,测量结果相对误差（RE）小于±1.5%,相对标准差（RSD）小于4%,稳定时间小于50 s。本文提出的优化设计不仅具有较高的测量精度,还简化了硬件设计,降低了成本。     

Assessment of Landsat atmospheric correction methods for water color applications using global AERONET-OC data

With the longest archive of satellite remote sensing images, the Landsat series of satellites have demonstrated their great potential in aquatic environmental studies. However, although various atmospheric correction (AC) methods have been developed for Landsat observations in water color applications, a comprehensive assessment of their accuracies across different AC methods and instruments has yet to be performed. Using in situ spectral data collected by Aerosol Robotic Network-Ocean Color (AERONET-OC) sites, the performances of five types of AC methods over three different Landsat missions (i.e., Landsat 5/7/8) were evaluated. The Landsat 8 Operational Land Imager (OLI) showed more accurate AC retrievals than the other two instruments, and the results for its green and red bands appeared more reliable than those for the other wavelengths (uncertainty levels of ∼30 %). The iterative NIR algorithm with 2-bands (NIR-SWIR2) model selection embedded in SeaDAS showed the best performances for OLI in two blue bands. Moreover, larger residual errors were found for most Landsat 5/7 bands regardless of the AC methods and spectral bands employed with an uncertainty of >50 %. Interestingly, a simple aerosol subtraction method over the Rayleigh-corrected reflectance (Rrc) outperformed the exponential extrapolation (EXP) algorithms, especially for Landsat 5/7. Neither the image-based AC algorithm nor the surface reflectance (SR) products provided by the United States Geological Survey (USGS) showed acceptable performances over coastal environments. The uncertainties in the various Landsat reflectance products over water surfaces could be associated with a relatively poor signal-to-noise ratio (SNR) in addition to radiometric calibration uncertainties, imperfect aerosol removal methods. Future research is required to collect in situ data across a wider range of water optical properties (particularly more turbid inland waters) to examine the corresponding applicability of Landsat-series observations.     

龟山岛附近海域热液活动流体的来源

台湾东北部龟山岛附近热液活动区流体的来源较为复杂,判断流体来源同时探讨该地区岩浆活动的程度对于龟山岛热液活动研究具有至关重要的意义。通过测定热液流体中的元素浓度和氢氧同位素特征显示:热液流体的微量元素浓度总体上接近海水值,但是通过Mg浓度为0回推得出热液流体的端员组分较为简单,而且有低Cl-浓度的组分(如地下水)加入,所测定热液流体中海水特征是由于取样过程中海水混入所致,氢氧同位素的对应曲线表明热液流体与该地区海水的同位素特征值不一致,并且不是单一龟山岛上地下淡水来源。龟山岛附近热液流体在氢氧同位素值分布特征上与南胡安得富卡洋脊的深水热液活动流体较为一致。可以初步判断龟山岛附近热液活动流体来源主要由两部分组成:深部物质和龟山岛上的大气降水,深部的岩浆物质在上升过程中,发生相分离,分离相在继续上升的过程中遇到下渗的淡水,两者混合构成了热液流体的端员组分。因此龟山岛热液活动的出现是由于深部物质活动造成的,表明目前该地区地壳活动较为活跃。     

The use of selected pseudo-invariant targets for the application of atmospheric correction in multi-temporal studies using satellite remotely sensed imagery

Because atmospheric effects can have a significant impact on the data obtained from multi-spectral satellite remote sensing, it is frequently necessary to make corrections before any other image processing can be started. This paper describes a robust and relatively simple atmospheric correction method that uses pseudo-invariant targets (PITs) in conjunction with the empirical line method. The method is based on the selection of a number of suitable generic PITs, on the basis that they are large, distinctive in shape, and occur in many geographical areas. Whereas the multi-temporal normalization method corrects all images to a selected reference image, in this method images are simultaneously corrected using targets with a range of estimated surface reflectance values. The paper describes some applications of the method for a range of environmental studies involving water quality and air pollution monitoring, and mapping land-cover changes.     

山东莱芜黄羊山晚寒武世牙形石组合及寒武系与奥陶系界线的确定

通过实测莱芜黄羊山晚寒武世地层剖面,利用牙形石确定了寒武系与奥陶系的界线;对长山阶的碳氧同位素曲线特征进行了分析,并与我国华南及哈萨克斯坦等国的寒武系芙蓉统底部的碳同位素曲线进行对比,建立了莱芜地区上寒武统与华南以及国外上寒武统的对比关系。     

Benthic remineralization at the land–ocean interface: A case study of the Rhône River (NW Mediterranean Sea)

Biogeochemical processes in sediments under the influence of the Rhône River plume were studied using both in situ microelectrodes and ex situ sediment core incubations. Organic carbon (OC) and total nitrogen (TN) content as well as stable carbon isotopic composition of OC (δ¹³C_OC) were analysed in 19 surface sediments to determine the distribution and sources of organic matter in the Rhône delta system. Large spatial variations were observed in both the total O₂ uptake (5.2 to 29.3 mmol m⁻² d⁻¹) and NH₄⁺ release (−0.1 to −3.5 mmol m⁻² d⁻¹) rates at the sediment–water interface. The highest fluxes were measured near the Rhône River mouth where sedimentary OC and TN contents reached 1.81% and 0.23% respectively. Values of δ¹³C_OC ranged from −26.83‰ to −23.88‰ with a significant seawards enrichment tracing the dispersal of terrestrial organic matter on the continental shelf. The amount of terrestrial-derived OC reaches 85% in sediments close to the Rhône mouth decreasing down to 25% in continental shelf sediments. On the prodelta, high terrestrial OC accumulation rates support high oxygen uptake rates and thus indicating that a significant fraction of terrestrial OC is remineralized. A particulate organic carbon (POC) mass balance indicates that only 3% of the deposited POC is remineralized in prodelta sediments while 96% is recycled on the continental shelf. It was calculated that a large proportion of the Rhône POC input is either buried (52%) or remineralized (8%), mostly on the prodelta area. The remaining fraction (40%) is either mineralized in the water or exported outside the Rhône delta system in dissolved or particulate forms.     

Petrographic and geochemical characterization of seep carbonate from Bush Hill (GC 185) gas vent and hydrate site of the Gulf of Mexico

Authigenic carbonates are common at cold seep sites as a result of microbial oxidation of hydrocarbons. Seep carbonate samples were collected from the surface of the Bush Hill (Green Canyon Block 185, Gulf of Mexico), a mound containing gas hydrate. The carbonates consisted of oily, porous limestone slabs and blocks containing bioclasts and matrix. Analysis by X-ray diffraction shows that aragonite is the dominant mineral (89–99 wt% with an average of 94 wt%) in the matrix of seep carbonate. This cement occurs in microcrystalline, microspar, and sparite forms. The moderate ¹³C depletion of the seep carbonate (the most depleted one has δ¹³C value of −29.4‰, and 26 of 38 subsamples have δ¹³C values >−20.0‰) indicates that the non-methane hydrocarbons was incorporated during seep carbonate precipitation. Relative enrichment of ¹⁸O may be related to localized destabilization of gas hydrate or derived from ¹⁸O-enriched pore water originated from smectite–illite transition in the deep sediments. The total content of rare earth elements (REE) of the 5% HNO₃-treated solution of the carbonates is from 0.40 ppm to 30.9 ppm. The shale-normalized REE patterns show varied Ce anomalies from significantly negative, slightly negative, and no to positive Ce anomalies. Variable content of trace elements, total REE, and Ce anomalies in different samples and even in the different carbonate mineral forms (microcrystalline, microspar and sparite) of the same sample suggest that the formation condition of the Bush Hill seep carbonate is variable and complex, which is possibly controlled by the rate of fluid flux.     

海洋卡盾藻的致毒机制研究进展

海洋卡盾藻 ( Chattonella marina ) 引起的赤潮近年来在中国频繁爆发,对水产养殖业及海洋生态系统造成了严重危害.海洋卡盾藻产生的神经毒素、溶血毒素、游离脂肪酸和活性氧等次生代谢物可能是造成鱼类大范围死亡的重要原因.对此进行综述,以期为阐明海洋卡盾藻赤潮的致毒机制与危害方式提供参考,为正确认识和评价卡盾藻赤潮的危害提供依据.     

羌塘盆地雁石坪地区中-晚侏罗世碳、氧同位素特征与沉积环境分析

通过对雁石坪地区中-上侏罗统碳酸盐岩的碳、氧同位素组成特征分析,认为其原始组分保存良好。在垂向上,碳、氧同位素的变化与沉积相演化和海平面曲线相吻合,说明它们与沉积环境的演化密切相关。结合碳、氧同位素的环境效应分析,认为中侏罗世雀莫错期沉积水体主要以陆源淡水作用为主,沉积环境属陆缘近海湖;布曲期为广海碳酸盐台地环境;夏里期为三角洲-淡化泻湖-潮坪环境。晚侏罗世索瓦早期为高盐度、高水温,相对局限浅海碳酸盐台地环境。中侏罗世至晚侏罗世早期经历了一次完整的海侵-海退旋回和一次海侵过程。