Calcification rate and the stable carbon, oxygen, and nitrogen isotopes in the skeleton, host tissue, and zooxanthellae of bleached and recovering Hawaiian corals     

Lisa J. Rodrigues  Andréa G. Grottoli 《Geochimica et cosmochimica acta》2006,70(11):2781-2789

We tested the effectiveness of stable isotopes as recorders of physiological changes that occur during coral bleaching and recovery. Montipora capitata and Porites compressa fragments were bleached in outdoor tanks with seawater temperature raised to 30 °C (treatment corals) for one month. Additional fragments were maintained at 27 °C in separate tanks (control corals). After one month, (0 months recovery), buoyant weight was measured and a subset of fragments was frozen. Remaining fragments were returned to the reef for recovery. After 1.5, 4, and 8 months, fragments were collected, measured for buoyant weight, and frozen. Fragments were analyzed for stable carbon and oxygen isotopic compositions of the skeleton (δ¹³C_s; δ¹⁸O_s) and nitrogen and carbon isotopic compositions of the host tissue (δ¹⁵N_h; δ¹³C_h) and zooxanthellae (δ¹⁵N_z; δ¹³C_z). δ¹³C_s decreased immediately after bleaching in M. capitata, but not in P. compressa. δ¹⁸O_s of both species failed to record the warming event. During the remaining months of recovery, δ¹³C_s and δ¹⁸O_s were more enriched in treatment than control corals due to decreases in calcification and metabolic fractionation during that time. Increased δ¹⁵N_h of treatment P. compressa may be due to expelled zooxanthellae during bleaching and recovery. Increased δ¹⁵N_z at 1.5 months in treatment fragments of both species reflects the increased incorporation of dissolved inorganic nitrogen to facilitate mitotic cell division and/or chl a/cell recovery. Changes in δ¹³C_h and δ¹³C_z at 1.5 months in treatment M. capitata indicated a large increase in heterotrophically acquired carbon relative to photosynthetically fixed carbon. We experimentally show that isotopes in coral skeleton, host tissue and zooxanthellae can be used to verify physiological changes during bleaching and recovery, but their use as a proxy for past bleaching events in the skeletal record is limited.  相似文献   

Improving fluorometry as a source tracking method to detect human fecal contamination     

Peter G. Hartel  Jennifer L. McDonald  Lisa C. Gentit  Sarah N. J. Hemmings  Karen Rodgers  Katy A. Smith  Carolyn N. Belcher  Robin L. Kuntz  Yaritza Rivera-Torres  Ernesto Otero  Eduardo C. Schröder 《Estuaries and Coasts》2007,30(3):551-561

In a continuing effort to develop inexpensive source tracking methods to detect human fecal contamination in environmental waters, targeted sampling was combined with fluorometry. Targeted sampling works by identifying hot spots of fecal contamination through multiple samplings over ever-decreasing distances. Fluorometry identifies human fecal contamination by detecting optical brighteners, primarily from laundry detergents. Because organic matter fluoresces and interferes with fluorometry, two locations were chosen for sampling: waters relatively low in organic matter at Mayagüez Bay, Puerto Rico, and waters relatively high in organic matter at St. Simons Island, Georgia. In Puerto Rico, targeted sampling and fluorometry quickly and easily identified two hot spots of human fecal contamination in the Yagüez River, which flows through the city of Mayagüez. Another source tracking method, detection of theesp gene, confirmed their human origin. On St. Simous Island, targeted sampling and fiuorometry identified two hot spots of potential human fecal contamination. Detection of theesp gene confirmed the human origin of one site but not the other, most likely because background organic matter fluorescence interfered with fhiorometry. A separate experiment showed that adding a 436-um emission filter to the fluorometer reduced this background fluorescence by > 50%. With the 436-nm Filter in place, another sampling was conducted on St. Simons Island, and the second hot spot was identified as fecal contamination from birds. As long as the fluorometer was equipped with a 436-nm filter and organic matter concentrations were considered, targeted sampling combined with fluorometry was a relatively inexpensive method for identifying human fecal contamination in water.  相似文献   

Immigrants and world cities: from the hyper-diverse to the bypassed     

Marie Price  Lisa Benton-Short 《GeoJournal》2007,68(2-3):103-117

A relationship between globalization, cities and immigration is increasingly apparent. Whether one is trying to understand Dubai, Toronto, or London, immigrants are culturally, economically, and spatially changing cities in significant ways. This study compares the roster of world cities with that of major urban immigrant destinations. The number of major urban immigrant destinations is growing due to the acceleration of immigration driven by income differentials, social networks and various state and local policies to recruit skilled and unskilled labor and replenish population. This study will present urban-level data on the foreign-born for 145 metropolitan areas of over 1 million people. It will focus on the world’s 19 metropolitan areas with over 1 million foreign-born residents. Analysis of the data suggests that there is a range of destination types. Although not all world cities are immigrant gateways, many are.  相似文献   

Shallow bias in Neogene palaeomagnetic directions from the Guide Basin, NE Tibet, caused by inclination error     

Maodu Yan  Rob Van der Voo  Lisa Tauxe  Xiaomin Fang  Josep M Parés 《Geophysical Journal International》2005,163(3):944-948

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Upper Yellowstone River Flow and Teleconnections with Pacific Basin Climate Variability during the Past Three Centuries     

Lisa J. Graumlich  Michael F. J. Pisaric  Lindsey A. Waggoner  Jeremy S. Littell  John C. King 《Climatic change》2003,59(1-2):245-262

Climate variability, coupled with increasing demand is raising concerns about the sustainability of water resources in the western United States. Tree-ring reconstructions of stream flow that extend the observational record by several centuries provide critical information on the short-term variability and multi-decadal trends in water resources. In this study, precipitation sensitive Douglas-fir (Pseudotsuga menzeisii) tree ringrecords are used to reconstruct annual flow of the Yellowstone River back to A.D. 1706. Linkages between precipitation in the Greater Yellowstone Region and climate variability in the Pacific basin were incorporated into our model by including indices Pacific Ocean interannual and decadal-scale climatic variability, namely the Pacific Decadal Oscillation and the Southern Oscillation. The reconstruction indicates that 20th century streamflow is not representative of flow during the previous two centuries. With the exception of the 1930s, streamflow during the 20th century exceeded average flows during the previous 200 years. The drought of the 1930s resulted in the lowest flows during the last three centuries, however, this probably does not represent a worst-case scenario for the Yellowstone as other climate reconstructions indicate more extreme droughts prior to the 18th century.  相似文献   

Provenance and tectonic implications of Orán Group foreland basin sediments,Río Iruya canyon,NW Argentina (23° S)          下载免费PDF全文

William H. Amidon  Lisa V. Luna  G. Burch Fisher  Douglas W. Burbank  Andrew R. C. Kylander‐Clark  Ricardo Alonso 《Basin Research》2017,29(Z1):96-112

Foreland basins are important recorders of tectonic and climatic processes in evolving mountain ranges. The Río Iruya canyon of NW Argentina (23° S) exposes ca. 7500 m of Orán Group foreland basin sediments, spanning over 8 Myr of near continuous deposition in the Central Andes. This study presents a record of sedimentary provenance for the Iruya Section in the context of a revised stratigraphic chronology. We use U‐Pb zircon ages from six interbedded ash layers and new magnetostratigraphy to constrain depositional ages in the section between 1.94 and 6.49 Ma, giving an average sedimentation rate of 0.93 ± 0.02 (2σ) km Myr^?1. We then pair U‐Pb detrital zircon dating with quartz trace‐element analysis to track changes in sedimentary provenance from ca. 7.6 to 1.8 Ma. Results suggest that from ca. 7.6 to ca. 6.3 Ma, the Iruya watershed did not tap the Salta Group or Neogene volcanics that are currently exposed in the eastern Cordillera and Puna margin. One explanation is that a long‐lived topographic barrier separated the eastern Puna from the foreland for much of the mid‐late Miocene, and that the arrival of Jurassic‐Neogene zircons records regional tectonic reactivation at ca. 6.3 Ma. A second major provenance shift at ca. 4 Ma is marked by changes in the zircon and quartz populations, which appear to be derived from a restricted source region in Proterozoic‐Ordovician meta‐sediments. Considered in conjunction with the onset of coarse conglomerate deposition, we attribute this shift to accelerated uplift of the Santa Victoria range, which currently defines the catchment's western limit. A third shift at ca. 2.3 Ma records an apparent disconnection of the Iruya with the eastern Puna, perhaps due to defeat of the proto Rio‐Iruya by the rising Santa Victoria range. This study is one of the first applications of quartz trace‐element provenance analysis, which we show to be an effective complement to U‐Pb detrital zircon dating when appropriate statistical methods are applied.  相似文献   

Sulfide oxidation and distribution of metals near abandoned copper mines in coastal environments,Prince William Sound,Alaska, USA     

Randolph A. Koski  LeeAnn Munk  Andrea L. Foster  Wayne C. Shanks III  Lisa L. Stillings 《Applied Geochemistry》2008

The oxidation of sulfide-rich rocks, mostly leftover debris from Cu mining in the early 20th century, is contributing to metal contamination of local coastal environments in Prince William Sound, Alaska. Analyses of sulfide, water, sediment, precipitate and biological samples from the Beatson, Ellamar, and Threeman mine sites show that acidic surface waters generated from sulfide weathering are pathways for redistribution of environmentally important elements into and beyond the intertidal zone at each site. Volcanogenic massive sulfide deposits composed of pyrrhotite and (or) pyrite + chalcopyrite + sphalerite with subordinate galena, arsenopyrite, and cobaltite represent potent sources of Cu, Zn, Pb, As, Co, Cd, and Hg. The resistance to oxidation among the major sulfides increases in the order pyrrhotite ? sphalerite < chalcopyrite ? pyrite; thus, pyrrhotite-rich rocks are typically more oxidized than those dominated by pyrite. The pervasive alteration of pyrrhotite begins with rim replacement by marcasite followed by replacement of the core by sulfur, Fe sulfate, and Fe–Al sulfate. The oxi dation of chalcopyrite and pyrite involves an encroachment by colloform Fe oxyhydroxides at grain margins and along crosscutting cracks that gradually consumes the entire grain. The complete oxidation of sulfide-rich samples results in a porous aggregate of goethite, lepidocrocite and amorphous Fe-oxyhydroxide enclosing hydrothermal and sedimentary silicates. An inverse correlation between pH and metal concentrations is evident in water data from all three sites. Among all waters sampled, pore waters from Ellamar beach gravels have the lowest pH (∼3) and highest concentrations of base metals (to ∼25,000 μg/L), which result from oxidation of abundant sulfide-rich debris in the sediment. High levels of dissolved Hg (to 4100 ng/L) in the pore waters probably result from oxidation of sphalerite-rich rocks. The low-pH and high concentrations of dissolved Fe, Al, and SO₄ are conducive to precipitation of interstitial jarosite in the intertidal gravels. Although pore waters from the intertidal zone at the Threeman mine site have circumneutral pH values, small amounts of dissolved Fe²⁺ in the pore waters are oxidized during mixing with seawater, resulting in precipitation of Fe-oxyhydroxide flocs along the beach–seawater interface. At the Beatson site, surface waters funneled through the underground mine workings and discharged across the waste dumps have near-neutral pH (6.7–7.3) and a relatively small base-metal load; however, these streams probably play a role in the physical transport of metalliferous particulates into intertidal and offshore areas during storm events. Somewhat more acidic fluids, to pH 5.3, occur in stagnant seeps and small streams emerging from the Beatson waste dumps. Amorphous Fe precipitates in stagnant waters at Beatson have high Cu (5.2 wt%) and Zn (2.3 wt%) concentrations that probably reflect adsorption onto the extremely high surface area of colloidal particles. Conversely, crystalline precipitates composed of ferrihydrite and schwertmannite that formed in the active flow of small streams have lower metal contents, which are attributed to their smaller surface area and, therefore, fewer reactive sorption sites. Seeps containing precipitates with high metal contents may contribute contaminants to the marine environment during storm-induced periods of high runoff. Preliminary chemical data for mussels (Mytilus edulis) collected from Beatson, Ellamar, and Threeman indicate that bioaccumulation of base metals is occurring in the marine environment at all three sites.  相似文献   

Nation building and resource management: The politics of ‘nature’ in Timor Leste     

Lisa Palmer  Demetrio do Amaral de Carvalho 《Geoforum》2008,39(3):1321-1332

This paper examines the role of custom and tradition in the process of nation building and resource management in post-independence Timor Leste (East Timor). While customary land tenure is alluded to but not explicitly recognized under the Timorese Constitution, it is clearly stated that all natural resources are owned by the State. However, this paper argues that rather than waiting for the government to create land and resource management related laws, local people in Timor Leste are making and remaking their own laws, mobilizing their customary practices and, increasingly, ‘performing’ their traditions in public demonstrations of their extant capacities. In part, this process can be read as a way of enticing in outsiders, making them a party to the law making process, a witness to its legitimacy. Often critical to such processes, is the ability of local level leaders to draw in outsiders through their engagements with the idea of ‘nature’ – a concept which allows diverse interests to come together in conversation and build relationships despite what is often a dissonance in the meanings and priorities attributed to the concept (see Tsing, A.L., 2005. Friction: An Ethnography of Global Connection. Princeton University Press, Princeton and Oxford). The paper focuses on a view from the margins – Tutuala in the far east of the country – and ways in which this community is attempting to both resist and embrace the developmental hegemony of a centrist state. This, it is argued, is a case which demonstrates the power of the local (both ritually and politically) to shape and intervene in the national development process and the associated discourses of nature preservation.  相似文献   

Winter Flounder Larval Genetic Population Structure in Narragansett Bay,RI: Recruitment to Juvenile Young-of-the-Year     

Larry Buckley  Jeremy Collie  Lisa A. E. Kaplan  Joseph Crivello 《Estuaries and Coasts》2008,31(4):745-754

The genetic population structure of winter flounder larvae was examined in Narragansett Bay, RI. Winter flounder larvae collected from 20 stations within Narragansett Bay and one station outside of the Bay were analyzed for six microsatellite loci. When analyzed by geographic collection sites, there were 16 distinct genetic populations of winter flounder larvae (R _ST values from 0.1 to 0.6). The presence of distinct genetic populations was supported by assignment of individual larvae to populations by Bayesian analysis. Bayesian analysis resulted in 14 distinct genetic populations that overlapped with the geographically distributed populations (R _ST values from 0.1 to 0.6). Young-of-the-year juveniles collected in the same year as the larvae were also analyzed at the same six microsatellite loci. Juveniles were assigned to larvae populations by both a Bayesian approach and a neural network approach. Juveniles collected from within Narragansett Bay were found to arise from geographically adjacent Narragansett Bay winter flounder larval populations (>99%), suggesting no widespread movement of juveniles away from spawning grounds. These results are discussed in the context of winter flounder population biology in Narragansett Bay, RI.  相似文献   

A Time-Sensitive Framework for Including Geographic Information Systems (GIS) in Professional Development Activities for Classroom Teachers     

Lisa Tabor Millsaps  John A. Harrington 《The Journal of geography》2017,116(4):152-164

This work shares a time-sensitive framework for teaching GIS to educators of all levels and disciplines. Existing relationships with teachers enabled the addition of GIS content in professional development activities. The amount of time devoted to GIS-related content varied depending on time made available for interaction with the audience. Content audiences included geography, history, social studies, science, agriculture, religion, and math teachers. The framework was developed, tested, and refined over a period of six years, during thirty-six trainings, and with 580 educators. Use of this framework emphasizes that not one size fits all in GIS education and that GIS can work for any teacher, their content, their classroom, and their time availability.  相似文献