Fish,Macroinvertebrate and Epifaunal Communities in Shallow Coastal Lagoons with Varying Seagrass Cover of the Northern Gulf of Mexico     

Rachel B. McDonald  Ryan M. Moody  Ken L. Heck  Just Cebrian 《Estuaries and Coasts》2016,39(3):718-730

Coastal lagoons are ubiquitous along coastlines worldwide. Here, we compare the abundance of epifauna, seagrass-associated macroinvertebrates, and small fish across a gradient of seagrass cover in shallow coastal lagoons of the northern Gulf of Mexico. Two of the lagoons had little or no seagrass cover (0–18.8 %), and four had high cover (83.8–97.5 %). All of the lagoons were partially covered with fringing marsh. We hypothesized that, due to habitat redundancy between seagrass beds and fringing marshes, seagrass-associated fish and macroinvertebrates would not be largely reduced despite the large differences in seagrass cover among the lagoons. Our results support this hypothesis. For most sampling dates, we did not find significant differences in fish and macroinvertebrate abundance among the lagoons and, when we did, several highly vegetated lagoons did not have larger abundances than sparsely vegetated lagoons. The extreme shallowness of the lagoons studied (<1 m) may also provide further protection from large predatory fishes in the absence of seagrasses. Our results also suggest that marsh detritus, by providing habitat for epifauna and helping maintain prey availability, may further temper reductions in seagrass-associated fishes and macroinvertebrates following seagrass decline. The results highlight the importance of marsh-bordered, shallow lagoons as habitat for small fish and macroinvertebrates regardless of seagrass cover. This study contributes to the characterization of habitat redundancy in coastal ecosystems and pinpoints the importance of considering all habitats in concert for the proper understanding and management of coastal ecosystems.  相似文献   

江西德兴铜矿区水系的Cu同位素地球化学特征及其地质意义     

陈丹丹  宋世明  Mathur Ryan  郭坤一  康文凯  李双喜  赵晓丹  张飞 《地质通报》2016,35(1):188-195

江西德兴铜矿水系样的δ65Cu值具有极大的变化范围(-5.8‰~+24.4‰),是迄今为止已报道发现的最大的Cu同位素分馏值。水体中铜的来源可分为黄铜矿源和黄铁矿源,二者具有明显不同的Cu同位素特征。根据水体的Cu同位素值分布特征,圈出了流经矿体(矿体上方)水、矿体外围水和尾矿库水3个源区。水体中的Cu主要以离子态和微粒态存在,二者具有明显不同的65Cu特征,尾矿库中黄铁矿65Cu对水体的Cu同位素组成具有较大的影响作用。Cu同位素在示踪找矿及地质环境监测方面具有良好的应用潜力。  相似文献   

A New Generation Earth Mantle Model from Global Adjoint Tomography     

Youyi Ruan  Wenjie Lei  Matthieu Lefebvre  Ryan Modrak  James Smith  Ridvan Orsvuran  Ebru Bozdag  Judith Hill  Norbert Podhorszki  Dave Pugmire  Jeroen Tromp 《《地质学报》英文版》2018,92(Z1):140-140

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The development of the subduction channel and “turning on” of slab-to-mantle material exchanges at the start of subduction: insights from eruptive serpentinites (IODP Exp 366) from the forearc of the Mariana subduction system     

Jeffrey G. Ryan  Raymond Johnston  P. Fryer  C.G. Wheat  T. Williams 《《地质学报》英文版》2018,92(Z1):167-167

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An analysis of failure mechanism constraints on pre-failure rock block deformation using TLS and roto-translation methods     

Emily Rowe  D. Jean Hutchinson  Ryan A. Kromer 《Landslides》2018,15(3):409-421

Rockfall hazards increase the risk of train derailment along railway corridors in western Canada. In this study, repeated terrestrial laser scanning (TLS) datasets were collected every 2–3 months at three different sites along the Thompson and Fraser River corridors in British Columbia, referred to as the Goldpan, White Canyon, and Mile 109 sites. A total of 207 rockfall events occurring across all three sites between November 11, 2014 and October 18, 2016 were recorded in a database. For each of these rockfalls, pre-failure deformation was measured using a method of three-dimensional roto-translation block tracking. Each rockfall was classified by its deformation behaviour and further categorised based on failure mechanism, volume, lithology, and the roughness condition of the failure plane. Results reveal that detectable levels of deformation were measured in 33% of the total number of rockfall events using the present methods. Rotation deformation was most commonly observed in toppling failures with relatively steep joint orientations. Conversely, planar sliding blocks generally exhibited the least measurable deformation, with the majority not showing any precursory translation or rotation. It is postulated that overhanging rockfall configurations may suppress the expression of deformation in rockfall source blocks, though additional research is required to confirm this.  相似文献   

Flow Characteristics of Cemented Paste Backfill     

Naguleswaran Niroshan  Nagaratnam Sivakugan  Ryan Llewellyn Veenstra 《Geotechnical and Geological Engineering》2018,36(4):2261-2272

Cemented paste backfill (CPB) is primarily used for backfilling underground voids at George Fisher Mine (Mount Isa, Australia). The objective of this paper is to summarise the geotechnical characterisation of the tailings and the rheological properties of the CPB as determined from a laboratory testing program undertaken at James Cook University. Two binders were examined [a General Purpose cement and a slag blend cement] over a range of dosages from 0 to 6% and CPB mix solids content in the range of 72–78%. The slump tests were carried out using the standard cone (ASTM C 143) used for concrete and a cylinder with 110 mm (diameter) × 110 mm (height), whereas the yield stress was measured using a shear vane (Brookfield vane spindle V-73). The index characteristics of the tailings including the grain size distribution, liquid limit, plastic limit, specific gravity were determined as per ASTM standards. This paper will then discuss the interrelationships among the solid content, slump, saturated density and the yield stress of the CPB. It is shown that there is strong correlation between the two different slump test devices used in this study. The smaller cylindrical device appears to have good potential for slurries like mine tailings or dredged mud that have high water content for slump test. There is also strong inter-relationship among solid content, slump, yield stress, and bulk density. Increasing the solid content increases the bulk density and yield stress, but reduces the slump. While there is hardly any difference between the two binder types used in this study in terms of flow parameters, namely the yield stress and slump, the binder dosage has an effect. At any specific solid content, higher binder dosages lead to a drop in the slump and increase in the yield stress. The difference is more pronounced in dense slurries. It is also strongly believed that the trends and relationships developed in this study may be valuable for the other mining operations using CPB.  相似文献   

The origins of marine and non-marine boulder deposits: a brief review     

Dewey  J. F.  Goff  J.  Ryan  P. D. 《Natural Hazards》2021,109(2):1981-2002

Natural Hazards - We identify 14 mechanisms, marine and non-marine, one man made, that result and could result in the formation of boulder deposits after reviewing issues associated with clast...  相似文献   

Reducing wind power curtailment in China: comparing the roles of coal power flexibility and improved dispatch     

Hong Lu  Qionghui Li  Ryan Wiser  Kevin Porter 《Climate Policy》2019,19(5):623-635

Renewable energy curtailment is a critical issue in China, impeding the country’s transition to clean energy and its ability to meet its climate goals. This paper analyzes the impacts of more flexible coal-fired power generation and improved power dispatch towards reducing wind power curtailment. A unit commitment model for power dispatch is used to conduct the analysis, with different scenarios demonstrating the relative impacts of more flexible coal-fired generation and improved power dispatch. Overall, while we find both options are effective in reducing wind power curtailment, we find that improved power dispatch is more effective: (1) the effect of ramping down coal-fired generators to reduce wind power curtailment lessens as the minimum output of coal-fired generation is decreased; and (2) as a result, at higher wind capacity levels, wind curtailment is much more significantly reduced with improved power dispatch than with decreased minimum output of coal-fired generation.

Key policy insights

• China should emphasize both coal power flexibility and dispatch in its policies to minimize renewable power curtailment and promote clean energy transition.

• China should accelerate the process of implementing spot market and marginal cost-based economic dispatch, while making incremental improvements to the existing equal share dispatch in places not ready for spot market.

• A key step in improving of dispatch is incorporating renewable power forecasts into the unit commitment process and updating the daily unit commitment based on the latest forecast result.

• China should expand the coal power flexibility retrofit programme and promote the further development of the ancillary service market to encourage more flexibility from coal-fired generation.

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Layered organization in the coastal ocean: An introduction to planktonic thin layers and the LOCO project     

James M. Sullivan  Margaret A. McManus  Olivia M. Cheriton  Kelly J. Benoit-Bird  Louis Goodman  Zhankun Wang  John P. Ryan  Mark Stacey  D. Van Holliday  Charles Greenlaw  Mark A. Moline  Malcolm McFarland 《Continental Shelf Research》2010,30(1):1-6

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Residence of trace elements in metasomatized spinel lherzolite xenoliths: a proton-microprobe study   总被引：19，自引：0，他引：19  

Suzanne Y. O'Reilly  W. L. Griffin  C. G. Ryan 《Contributions to Mineralogy and Petrology》1991,109(1):98-113

Minerals occurring in dry and modally metasomatized spinel lherzolites from western Victoria have been analysed by proton microprobe for Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, Nb, Ba, Pb, Br, rare-earth elements (REE), Th and U. Mass-balance calculations demonstrate that these trace elements are contained in specific acceptor minerals and do not occur in significant concentrations at clean grain boundaries. The level of particular trace elements in the rock depends on the presence of specific phases: for example high levels of REE, Sr (and U, Th, Br) require apatite, while Ba, Nb and Ta are strongly concentrated in amphibole±mica. Mantle metasomatism in these spinel lherzolites is inferred to result from an open-system process involving infiltration of fluids released by crystallizing silicate melts. This process produces metasomatic zones with different modal mineralogy and hence greatly different trace-element signatures. The data demonstrate that large-ion-lithophile (LIL) and high-field strength (HFS) elements in metasomatized spinel lherzolites are strongly concentrated in non-refractory phases, which will break down easily in heated volumes such as the walls of magma conduits. The heterogeneity observed in trace-element patterns of intraplate alkali basaltic rocks may not reflect source heterogeneity, but may result largely from contamination by metasomatized mantle wall rock. The K_Ds for most trace elements show little temperature dependence except for K_DSr between orthopyroxene and clinopyroxene where K_D decreases with increasing temperature. The generally uniform K_Ds can be used to test for disequilibrium in such assemblages.  相似文献