Production of dimethylsulfide and acrylic acid from dimethylsulfoniopropionate during growth of three marine microalgae

We measured the concentrations of dimethylsulfide （DMS）, acrylic acid （AA）, and dimethylsulfoniopropionate （DMSP） during growth of three microalgae： Prorocentrum micans, Gephyrocapsa oceanica, and Platymonas subcordiformis. The DMSP, AA, and DMS concentrations in culture media varied significantly among algal growth stages, with the highest concentrations in the late stationary growth stage or the senescent stage. In the stationary growth stage, the average DMSP concentration per cell in P. micans （0.066 5 pmol/cell） was 1.3 times that in G. oceanica （0.049 5 pmol/ cell） and 20.2 times that in P. subcordiformis （0.003 29 pmol/cell）. The average concentrations of AA were 0.044 6, 0.026 9, and 0.003 05 pmol/cell in P. micans, G. oceanica, and P. subcordiformis, respectively, higher than the concentrations of DMS （0.272, 0.497, and 0.086 2 fmol/cell, respectively）. There were significant positive correlations between cell density and AA, DMSP, and DMS concentrations. The ratios of DMS/AA and AA/（DMSP＋AA） in the three algae differed significantly over the growth cycle. In all three microalgae, the DMS/AA ratios were less than 25% during the growth period, suggesting that the enzymatic cleavage pathway, which generates DMS, was not the main DMSP degradation pathway. The changes in the DMS/AA ratio indicated that there was a higher rate of enzymatic breakdown of DMSP in the early growth period and a lower rate during senescence. In all three microalgae, the AA/（DMSP＋AA） ratio （degradation ratio of DMSP） decreased during the exponential growth phase, and then increased. The variations in these ratios can approximately indicate the cleavage mechanism of DMSP at different stages of algal growth.     

DMSP and DMS in coastal fast ice and under-ice water of Lützow-Holm Bay, eastern Antarctica

The combined concentration of total dimethylsulfoniopropionate and dimethylsulfide (DMSP+DMS) were measured in Antarctic fast ice on the coast of Lützow-Holm Bay, eastern Antarctica. High bulk-ice DMSP+DMS and chlorophyll a concentrations were found at the bottom of the sea ice, and these concentrations were higher than those in the under-ice water. The bulk-ice DMSP+DMS and chlorophyll a concentrations were highly correlated (r²=0.68, P<0.001), suggesting that the high bulk-ice DMSP+DMS concentrations were caused mainly by the presence of algae assemblages in the ice. The calculated brine DMSP+DMS concentrations were as high as 1100 nM in the bottom ice layer, and the vertical profile patterns of brine DMSP+DMS concentrations were almost the same as for the bulk ice, mainly because of the small amount of variability in the vertical brine volume fraction. DMSP+DMS and chlorophyll a concentrations in the under-ice water increased, whereas the salinity of the under-ice water decreased, during the sampling period. These results reflect the supply of freshwater containing high levels of DMSP+DMS to the water just under the ice as the ice melted. These results suggest that sea-ice melting could be important to sulfur cycling in coastal ice-covered regions of the polar oceans.     

南北半球亚极光区极化流分布特征的统计学研究

利用DMSP卫星粒子数据,对南北半球20 000多个亚极光区极化流(SAPS)事件进行统计学分析,重点研究SAPS的发生率及其发生位置隧季节和世界时的分布,研究表明:(1)SAPS的发生率有明显的季节和世界时依赖性,主要发生在春秋季节,显示出较强的地磁活动依赖性;(2)SAPS在冬至也较多发生,可能与亚暴过程有关;(3...     

单元路网长度的DMSP/OLS夜间灯光数据去饱和方法

近年来DMSP/OLS夜间灯光数据被广泛应用到人类活动强度及城市化进程的研究中,但由于OLS传感器的限制导致,在夜间灯光强度过高的城市中心区,NTL数据存在较为明显的饱和现象。这种饱和现象直接掩盖了城市中心区内部的灯光差异、细节,限制了DMSP/OLS数据在城市中心区的应用。目前缓解灯光数据饱和的方法主要分为:辐射定标法和非辐射定标法。其中辐射定标法虽精度较高,但定标算法复杂,干扰因素多,目前只有部分定标产品;非辐射定标法利用辅助数据(包括自然因素指标、社会经济指标)构建函数模型,对饱和区稳定灯光数据进行去饱和处理,具有较好修正效果。本文在总结VANUI(基于NDVI所构建)、EANTLI(基于EVI所构建)等去饱和指数的基础上,利用地理探测器对NDVI、EVI和UNL(单元路网长度)进行因子探测,量化对稳定灯光数据的解释力,提出了UNLI指数。为了验证UNLI、EANTLI及NTL数据之间的差异,通过"饱和区灯光强度细节刻画程度"、"UNLI、EANTLI与辐射定标数据RCNTL相关性分析"、"耗电量及GDP等经济指标回归拟合优度"3个方面进行比对分析,可以看出:(1)UNLI、EANTLI在修正过饱和灯光数据上均有较好的效果,但UNLI对饱和区灯光强度差异的刻画更加准确;(2)UNLI较之VANUI、EANTLI,可以突破空间分辨率的限制,增加灯光强度细节差异;(3)在灯光强度最高的饱和区,UNLI在与RCNTL的相关性最高,但随着灯光强度的减弱,UNLI、EANTLI与RCNTL的线性回归判断系数R~2逐渐接近,UNLI与RCNTL相关性优势正逐渐丧失;(4)在对耗电量、GDP的拟合分析中,引入UNLI指数的"EANTLIUNLI"的分段式修正模型,充分发挥EVI、UNL各自的优势,具有最优的拟合效果(R~2)_(Adj)=0.873)。实验结果表明,本文引入的修正夜间灯光饱和方法,能够有效的缓解城市中心区的灯光数据饱和问题,并在细节刻画和空间分辨率上有较为明显的提升,可以更精确的从灯光强度的角度反映城市结构的特征。     

Modeling the spatiotemporal dynamics of electric power consumption in Mainland China using saturation-corrected DMSP/OLS nighttime stable light data

Obtaining timely and accurate data on the spatiotemporal dynamics of electric power consumption (EPC) is crucial for the effective utilization of electric power in China. The Defense Meteorological Satellite Program's Operational Linescan System (DMSP/OLS) nighttime stable light (NSL) data have good potential for estimating EPC effectively at large scales. However, saturated lighted pixels contained within the NSL data limit the accuracy of EPC estimation. We developed a new method to correct the saturated lighted pixels, using the SPOT VEGETATION (SPOT/VGT) 10-day synthesis product (S10) normalized difference vegetation index (NDVI) data and then modeled the spatiotemporal dynamics of EPC in Mainland China from 2000 to 2008. The results demonstrated the reliability of our approach with an average R value of 0.93 (P<0.001) and an average relative error of ?28.92%. EPC in Mainland China showed an average annual growth rate of 13.46% during the study period from 1198.23 billion kWh in 2000 to 3290.51 billion kWh in 2008. EPC in Mainland China also showed clear regional variation. Northern coastal China and eastern coastal China consumed 37.61% of the total EPC in Mainland China, with only 25.96% of the population and 6.11% of the area.     

Advances in Coccolithophore laboratory culture and their application research

This paper summarizes previous studies of coccolithophores laboratory culture with emphasis on the application of cultured coccolithophores in the ecology, paleoceanography and petroleum. Because of the particular biology and physiology characteristics, coccolithophorid bloom can influence marine and atmosphere environment deeply , play an important roal in global carbon cycle and geological evolution. In the aspect of culture, we introduce the cultural method, the influence of cocolithophores growth by setting different environment parameters, the principle of suitable culture meduim depending on different research purpose. In the aspect of application, firstly, this paper discusses the physiological responses of coccolithophorids about ocean acidification. Then, coccolithophorid is high producer of DMSP(dimethylsulphoniopropionate)which can be divides into gas DMS, which can influence marine and atmosphere environment deeply through some chemical course. Further, another important application is the element geochemistry of coccoliths which is very meaningful in paleoceanography and paleoclimatology study. Finally, this paper also discusses the application of coccolithophores hydrocarbon generation to petroleum geology.     

粤港澳大湾区建成区扩张时空特征分析

本文首先基于1992-2019年的夜间灯光数据(DMSP-OLS、NPP-VIIRS),参考粤港澳大湾区建成区面积数据,对比确定灯光阈值,提取出大湾区建成区边界;然后从扩张模式、扩张速度、扩张程度3个方面定量分析了大湾区建成区扩展时空特征;最后结合景观生态学方法分析了大湾区建成区扩展的时空格局特征。研究表明:①粤港澳大湾区城市群重心1992年位于东莞市内,2019年迁移至广州市,形成了以广州市为中心的珠三角地区发展核心区域;②整区扩展区域一体化,蔓延速度有所下降,蔓延程度增强,珠三角地区向周围城市的辐射能力不断增强;③城市扩展主要以珠三角地区为中心沿交通线呈倒"V"发展。     

京沪高铁站点对周边地区的经济带动效应研究——来自DMSP/OLS和NPP/VIIRS卫星灯光数据的证据

随着中国高铁建设的全面铺开,高铁新城正在成为许多城市发展的“新引擎”。本研究以京沪高铁站点为例,分析沿线高铁站点对周边地区的经济带动效应。由于相关社会经济数据的匮乏,文章应用DMSP/OLS和NPP/VIIRS卫星灯光数据结合距离圈层法对京沪高铁站点的经济效应进行评估。研究结果表明,高铁开通后,中等规模城市所在的高铁站点周边地区受益最大,其次是大城市高铁站点的周边地区,而居于小城市的高铁站点对周边地区的带动效果不明显。     

A model of dimethylsulfide dynamics for the subtropical North Atlantic

Dimethylsulfide (DMS) is a volatile sulfur compound produced by the marine biota. The flux of DMS to the atmosphere may act on climate via aerosol formation. It is therefore important to improve our understanding of the processes that regulate sea surface DMS concentrations for eventual inclusion into climate models. In order to simulate the dynamics of DMS concentrations in the mixed layer, a model of DMS production was developed and calibrated against a 1 year time-series of DMS and DMSP (dissolved and particulate) data collected in the Sargasso Sea at Hydrostation ‘S’. The model reproduces the observed divergence between the seasonal cycles of particulate DMSP, the DMS precursor produced by algae, and DMS produced through the microbial loop from the cleavage of dissolved DMSP. DMSP_p (particulate) reaches its maximum in the spring whereas DMSP_d (dissolved) and DMS reach maximum concentrations in summer. Several parameters had to vary seasonally and with depth in order to reproduce the data, pointing out the importance of physiological and structural changes in the plankton food web. These parameters include the intracellular S(DMSp):N ratio, the C:Chl ratio and the sinking rates of phytoplankton and detritus. For the Sargasso Sea, variations in the solar zenithal angle, which co-vary with the seasonal variations in the depth of the mixed layer, proved to be a convenient signal to drive the seasonal variation in the structure and dynamics of the plankton. Variations of the temperature and photosynthetically active radiation also help to reproduce the short-term variability of the annual S cycle. Results from a sensitivity analysis show that variations in DMSP_p are dependent mostly on parameters controlling phytoplankton biomass, whereas DMS is dependent mostly on variables controlling phytoplankton productivity.     

基于DMSP/OLS数据的城市中心城区提取新方法

近年来,DMSP/OLS夜间灯光数据已被广泛应用于城市空间格局和城市化过程、人类活动及效应、经济水平、生态环境影响、电力能源消耗量和灾害分析等领域。本文利用DMSP/OLS的稳定灯光数据产品,首先,以辅助资料的空间对比法确定城市中心城区范围最小阈值,然后,提取DMSP数据中的每个极大值及一定范围内的临近值,作为城市中心城区范围,并将提取的范围与作为辅助资料的MODIS土地覆盖数据中相应的城市中心城区范围作线性回归分析,进而获得估算城市中心城区范围的线性模型。经验证其结果预测吻合度达到82.06%,平均相对误差为8.47%,说明利用该方法提取城市中心城区范围具有一定的可行性,可较准确地提取发展水平不同的城市的中心城区范围。