Using recycled calcium sources to solidify sandy soil through microbial induced carbonate precipitation     

Shihua Liang  Juntao Chen  Jiuge Niu  Deluan Feng 《Marine Georesources & Geotechnology》2020,38(4):393-399

Abstract

The use of calcium solutions is a cost-limiting factor for bio-cement production from microbially induced carbonate precipitation (MICP). The aim of this article is to analyse the feasibility of using recycled calcium sources to solidify sand, including oyster shells, scallop shells and eggshells, by comparing the physical and mechanical properties and microstructural characteristics of solidified sand with different recycled calcium sources and chemical calcium nitrate. The results show that oyster shells have the optimal effect on MICP, with values of permeability, dry density, unconfined compressive strength and calcium carbonate precipitation of 1.12?×?10^?4 m s^?1, 2.09?g cm^?3, 1454.6?kPa and 15.28%, respectively. Strength values of bio-cemented sands made from different recycled calcium sources in this article range from 845.1 to 1454.6?kPa. According to the SEM and XRD analysis, calcium carbonates originating from the above recycled calcium sources precipitate as globular vaterite, whereas the precipitation from calcium nitrate is a cluster mixture of vaterite and calcite. Oyster shells, scallop shells and eggshells derived from kitchen waste, which is more economical and environmentally friendly than calcium nitrate, can be applied as recycled calcium solutions in MICP.  相似文献   

高潜水位平原区采煤沉陷防治技术研究进展          下载免费PDF全文

薄怀志 《山东国土资源》2018,34(11)

在高潜水位煤粮复合区,煤炭开采沉陷造成大面积耕地破坏,生态环境恶化,因此,总结采煤沉陷防治技术很有必要。该文介绍了常用的沉陷盆地修复技术和修复模式的研究进展,系统总结了消灾修复技术、工程修复技术、生态修复技术、生物修复技术研究现状和成果。用"矿地一体化"理念统筹资源开发和采煤塌陷地综合治理,"地、环、景、城"四位一体的采煤塌陷地综合治理模式,运用3S、大数据、云平台实现采煤塌陷地动态监测监管,是将来采煤塌陷防治的发展趋势。  相似文献   

一种面向港口溢油监测的小型激光荧光遥测系统     

刘德庆  栾晓宁  郭金家  崔廷伟  金久才  郑荣儿 《海洋科学》2018,42(1):65-69

目前,针对港口溢油巡航监测缺乏行之有效的技术手段。为探索激光诱导荧光光谱技术应用于港口溢油监测的可行性,以微型光纤光谱仪搭建小型激光荧光遥测实验系统,并对其性能进行测试分析。结果发现,在光谱仪曝光时间设为最小(1.11 ms)的情况下,环境光对荧光测量仍会产生影响,利用减背景法可以有效去除溢油荧光信号中环境光的影响;在相同条件下,系统测得不同油质溢油样品的荧光光谱表现出不同的光谱特征,轻质油较重质油的荧光峰蓝移、荧光更强;在上述环境光背景影响和光谱测量分析的基础上,进一步测试了系统的信号探测稳定性,结果显示,系统重复测量的相对标准偏差RSD=2.54%,表明该系统具有较好的信号探测稳定性。综上,基于微型光纤光谱仪的小型溢油激光荧光遥测系统可望在近岸港口溢油巡航监测中发挥重要作用。  相似文献   

Assessing temporal variation of coloured dissolved organic matter in the coastal waters of South Eastern Arabian Sea     

Minu P  Souda V P  Baliarsingh S K  Dwivedi R M  Y Ali null  Ashraf P M 《海洋学报(英文版)》2020,39(1):102-109

Coloured dissolved organic matter （CDOM） plays a major role in marine photochemical and biological processes and its optical properties are known to affect the underwater light penetration. This paper highlights in situ optical estimation and satellite retrieval of CDOM in deciphering its temporal variations in coastal waters of the South Eastern Arabian Sea. The study accentuated the source of CDOM as terrigenous origin during monsoon， of in situ productions during pre-monsoon and during post-monsoon of autochthonous-allocthonous origin. The matchup analysis for in situ and MODIS Aqua retrieved A_dg443 exhibited bias which decreased by incorporating the seasonal component. The study also identified degrading bloom of Noctiluca scintillans as the source for exceptionally high CDOM in the area during January and February. The study demands to incorporate seasonal components and phytoplankton abundance while assessing the performance of CDOM algorithms in optically complex coastal waters.  相似文献   

西太平洋秋季130°E断面有色溶解有机物的分布特征及光降解行为研究     

刘可  杨琳  杨桂朋  张婧 《海洋学报》2020,42(10):121-131

对2018年秋季西太平洋130°E断面上层水体有色溶解有机物(CDOM)的光学特性及光降解行为进行了研究。结果表明，西太平洋上层水体CDOM的吸收系数a(320)变化范围为0.025～0.64 m?1，平均值为(0.20±0.08) m?1；a(320)在表层相对较低，主要与表层CDOM的光漂白去除有关；在100～200 m水层较高，主要与次表层的生物活动有关。利用三维荧光光谱?平行因子分析技术，识别出两种荧光组分:类酪氨酸组分C1和海洋类腐殖质组分C2。C1主要源于棉兰老冷涡?上升流所带来的营养物质对浮游植物生产活动和微生物活动的促进作用；C2主要源于黑潮所带来的海洋类腐殖的输入。光化学降解实验发现，CDOM吸收值的损失主要发生在紫外波段；光照60 h后，类酪氨酸组分相较于海洋类腐殖质组分更易发生光降解；且光降解是西太平洋海域CDOM的重要去除途径。  相似文献   

波浪辐射应力对海流模式影响的数值分析     

齐鹏  陈新平 《海洋工程》2018,36(1):55-61

将波浪辐射应力,特别是地转意义下的波浪辐射应力引入海流数值模式POM(princeton ocean model),在渤海海域进行了初步的数值研究。在目前的数值分析中仅考虑了波浪辐射应力的横向分量(也是最重要的分量)。在POM模式中引入非地转和地转意义下的波浪辐射应力两种方案,并与原模式直接运行(即不考虑波浪辐射应力)的结果进行比较。比较显示,波浪辐射应力,特别是地转意义下的波浪辐射应力对海流模式结果的影响不容忽略。在海浪场存在的条件下,由风应力和地转意义下浪致作用力共同作用产生的海流强度应比理论上Ekman漂流的强度大,尤其是在浪致作用力显著的表层,表层流将明显增强,且不会完全符合Ekman漂流理论的转向规律。  相似文献   

棘头梅童鱼的细胞遗传学特征和X1X1X2X2/X1X2Y性染色体系统     

张寿康  郑娇  张静  王志勇  王艺磊  蔡明夷 《海洋学报(英文版)》2018,37(4):34-39

我们通过荧光染色、自身基因组原位杂交（Self-GISH）和多色荧光原位杂交（FISH），首次研究了棘头梅童鱼（Richardson，1844）的核型特征。雌性核型有24对端部着丝粒染色体（2n=48a，NF=48），而雄性核型包含22对端部着丝粒染色体，2条端部着丝粒染色体单体和1条中间着丝粒染色体（2n=1m+46a，NF=48）。雌性和雄性核型之间的差异表明，棘头梅童鱼的性染色体系统为X₁X₁X₂X₂/X₁X₂Y型，其中Y为雄性中特有的中间着丝粒染色体。三色FISH结果显示，5S rDNA和18S rDNA位点定位在最大的端着丝粒染色体（X₁）以及Y染色体的短臂；X₁染色体上有一个特异的臂间端粒信号（ITS），与5S rDNA位点部分重叠。Self-GISH结果显示，在推定的性染色体DNA重复序列聚集。根据实验结果我们提出关于棘头梅童鱼Y染色体起源的假说：Y染色体起源于祖先核型（2n=48a）中的两条端部着丝染色体融合，并且在此过程中伴随着片段缺失。本研究首次在石首鱼科中描述了异形的性染色体，将为其他石首鱼的性染色体研究提供线索。  相似文献   

印尼爪哇上升流海域次表层叶绿素最大值层的浮游植物色素分布特征     

高春蕾  傅明珠  宋洪军  王磊  韦钦胜  孙萍  刘琳  张学雷 《海洋学报(英文版)》2018,37(12):97-106

Upwelling occurs on the coast of Java between June and October, forced by local alongshore winds associated with the southeasterly monsoon. This causes variations in phytoplankton community composition in the upwelling zone compared with the surrounding offshore area. Based on pigments analysis with subsequent calculations of group contributions to total chlorophyll a(Chl a) using CHEMTAX, we studied the distribution and composition of phytoplankton assemblages in the subsurface chlorophyll maximum along the south coast of Java and the influence of upwelling. Nineteen phytoplankton pigments were identified using high-performance liquid chromatography, and CHEMTAX analysis associated these to ten major phytoplankton groups. The phytoplankton community in the coastal area influenced by upwelling was characterized by high Chl a and fucoxanthin concentrations, indicating the dominance of diatoms. In contrast, in the offshore area, the Chl a and fucoxanthin concentrations declined to very low levels and the community was dominated by haptophytes represented by 19′-Hexanoyloxyfucoxanthin. Accordingly, microphytoplankton was found to be the major size class in the coastal area influenced by upwelling, while nanophytoplankton was most abundant in the offshore area. Low concentrations of other accessory pigments indicated less contribution from dinoflagellates,prasinophytes, chlorophytes and cryptophytes. Photo-pigment indices revealed that photosynthetic carotenoids(PSCs) were the largest component of the pigment pool, exceeding the proportion of Chl a, with the average PSCTP up to 0.62. These distribution trends can mainly be explained by phytoplankton adaption strategies to upwelling and subsurface conditions by changing species composition and adjusting the pigment pool.  相似文献   

水口水库区地震活动特征分析     

陈光 《大地测量与地球动力学》2010,30(Z1)

基于水口水库区历史地震活动特征,探讨水口水库地震的序列特征;对库区短水准地形变资料及震源机制解结果的分析认为,水口水库区的地震活动前期主要为水的诱发作用,后期与构造应力场作用加强有关。  相似文献   

Satellite-derived variability of the Aegean Sea ecohydrodynamics     

N. Skliris  A. MantziafouS. Sofianos  A. Gkanasos 《Continental Shelf Research》2010

Eight years of AVHRR-derived sea surface temperature (SST) and SeaWiFS-derived surface chlorophyll (Chl) data (1998–2005) are used to investigate key processes affecting the spatial and temporal variability of the two parameters in the Aegean Sea. Seasonal mean SST and Chl maps are constructed using daily data to study seasonal dynamics whereas empirical orthogonal function (EOF) and correlational analysis is applied to the 8-day composite SST and Chl anomaly time-series in order to study the variability and co-variability of the two parameters from subseasonal to interannual time-scales. The seasonal mean fields show that Black Sea cold and chlorophyll-rich waters enter through the Dardanelles Strait and they are accumulated in the north-eastern part of the Aegean Sea, steered by the Samothraki anticyclone. Large chlorophyll concentrations are encountered in the hydrological front off the Dardanelles Strait as well as in coastal areas affected by large riverine/anthropogenic nutrient loads. The SST seasonal mean patterns reveal strong cooling that is associated with upwelling along the eastern boundary of the basin during summer due to strong northerly winds, a process which is not present in the surface chlorophyll climatology. The Chl dataset presents much stronger sub-seasonal variability than SST, with large variations in the phase and strength of the phytoplankton seasonal cycles. EOF analysis of the anomaly time-series shows that SST non-seasonal variability is controlled by synoptic weather variations and anomalies in the north–south wind-stress component regulating the summer coastal upwelling regime. Mean SST and Chl patterns, and their associated variations, are not closely linked implying that Black Sea and riverine inputs mainly control the intra-annual and interannual variability of the surface chlorophyll in the Aegean Sea rather than mixing and/or upwelling processes.  相似文献