The capacity of marine plankton, macrophytes and particulate matter to adsorb Cu in the presence of Mg     

Carlton D. Hunt  William F. Fitzgerald 《Marine Chemistry》1983,12(4)

A complexometric titration technique was employed to measure the total capacity of a variety of marine organisms to adsorb Cu²⁺. Measured adsorption capacities were 0.22 meq g⁻¹ for phytoplankton, 0.3–1.0 meq g⁻¹ for macrophytes, 1.0–2.5 meq g⁻¹ for zooplankton and 0.3 meq g⁻¹ for suspended particulate matter. The capacity of these materials to adsorb Cu²⁺ was reduced significantly in the presence of Mg²⁺ at seawater concentrations. Competition between Mg^t2+ and Cu²⁺ for adsorption sites at pH 6 is described by an average conditional equilibrium constant of 10^3.7. This constant is such that very little Cu²⁺ may be adsorbed onto particulates and marine phytoplankton in the presence of Mg²⁺. Further, primary productivity data and estimates of the detrital carbon sedimentation in Long Island Sound suggest that the flux of particulate carbon is insufficient to remove significant amounts of Cu from the water column to sediments by adsorption mechanisms.  相似文献   

Dynamics and role of the Durban cyclonic eddy in the KwaZulu-Natal Bight ecosystem     

LA Guastella  MJ Roberts 《African Journal of Marine Science》2016,38(1):S23-S42

The semi-permanent Durban Eddy is a mesoscale, lee-trapped, cold-core cyclonic circulation that occurs off the east coast of South Africa between Durban in the north and Sezela, some 70 km to the south. When present, strong north-eastward countercurrents reaching 100 cm s^–1 are found inshore. It is hypothesised that the cyclone is driven by the strong south-westward flowing Agulhas Current offshore of the regressing shelf edge near Durban. Analysis of ADCP data and satellite imagery shows the eddy to be present off Durban approximately 55% of the time, with an average lifespan of 8.6 days, and inter-eddy periods of 4 to 8 days. After spin-up the eddy breaks loose from its lee position and propagates downstream on the inshore boundary of the Agulhas Current. The eddy is highly variable in occurrence, strength and downstream propagation speeds. There is no detectable seasonal cycle in eddy occurrence, with the Natal Pulse causing more variability than any seasonal signal. A thermistor array deployed in the eddy centre, together with ship CTD data, indicates upward doming of the thermal structure in the eddy core associated with cooler water and nutrients being moved higher in the water column, stimulating primary production. Together with the use of satellite imagery, our findings indicate a second mechanism of upwelling, viz. divergent upwelling in the northern limb of the eddy. Satellite-tracked surface drifters released in the eddy demonstrated the potential for nutrient-rich eddy water to be transported northwards along the inshore regions of the KwaZulu-Natal (KZN) Bight, thus contributing to the functioning of the bight ecosystem, as well as southwards along the KZN and Transkei coasts – both by the eddy migrating downstream and by eddy water being recirculated into the inshore boundary of the Agulhas Current itself.  相似文献   

The sources and composition of mercury in Pacific Ocean rain   总被引：1，自引：0，他引：1  

R. P. Mason  W. F. Fitzgerald  G. M. Vandal 《Journal of Atmospheric Chemistry》1992,14(1-4):489-500

Here we report measurements of total Hg (Hg_T), reactive Hg (Hg_R), and methylmercury (MMHg) in precipitation from the equatorial Pacific Ocean, collected during a cruise in January and February 1990, and from a mid-continental location in the rural temperate lacustrine northcentral Wisconsin environs. The concentrations of Hg_T (14.4±6.5 pM), Hg_R (8.9±4.5 pM) and MMHg (<50 fM) found in equatorial Pacific rain were less than the average concentrations found in Wisconsin. In general, the results indicate that although particulate Hg is a small fraction of the total atmospheric Hg burden, it is the major contributor to Hg in precipitation. Furthermore, deposition could be an important source of Hg_R to the equatorial Pacific Ocean. In contrast, deposition is not a significant source of MMHg to either the equatorial Pacific Ocean or the remote seepage lakes of Wisconsin. This implies that methylated mercury is formedin situ in these systems.  相似文献   

Diet and gill morphology of the East Coast redeye round herring Etrumeus wongratanai off KwaZulu-Natal,South Africa     

LD Vorsatz  CD van der Lingen  MJ Gibbons 《African Journal of Marine Science》2015,37(4):575-581

Stomach content analyses and measurements of gillraker morphology were used to assess the diet and feeding ecology of the East Coast redeye round herring Etrumeus wongratanai and provide data for comparisons with other small pelagic fishes off South Africa. Samples were collected by jigging from a kayak off Scottburgh, KwaZulu-Natal (KZN), over the period July 2013–May 2014. In total, 66 stomachs (containing 4 407 prey items) and 66 gill arches were examined. Stomach content analyses indicated that East Coast redeye round herring, at the time of sampling, fed on large (1 500–2 500?µm) particles, with ～2 500?µm particles making the greatest contribution to dietary carbon. The species feeds on larger particles than do anchovy Engraulis encrasicolus and sardine Sardinops sagax, but on particles of a similar size to those consumed by West Coast redeye round herring Etrumeus whiteheadi. There were significant differences in mean gillraker gaps between East Coast redeye round herring and both sardine and anchovy, but not between East Coast and West Coast redeye round herring. The differences in gillraker gaps between East Coast redeye round herring, sardine and anchovy are indicative of resource partitioning through differential feeding, based on zooplankton size. The data suggest that there is no resource partitioning between East and West coast redeye round herring, indicating that competition is likely to occur between them. However, such competition is minimised by limited spatial overlap between these two species.  相似文献   

Do people “personally experience” global warming,and if so how,and does it matter?   总被引：1，自引：0，他引：1  

Karen Akerlof  Edward W. Maibach  Dennis Fitzgerald  Andrew Y. Cedeno  Amanda Neuman 《Global Environmental Change》2013,23(1):81-91

For most people, the direct and personally observable signals of climate change should be difficult to detect amid the variability of everyday weather. Yet, previous research has shown that some people believe they have personally experienced global warming. Through four related studies, our paper sheds light on what signals of global warming some people believe they are detecting, why, and whether or not it matters. These studies were conducted using population survey and climatic data from a single county in Michigan. Study 1 found that 27% of the county's adult residents felt that they had personally experienced global warming. Study 2 – based on content analysis of people's open-ended responses – found that the most frequently described personal experiences of global warming were changes in seasons (36%), weather (25%), lake levels (24%), animals and plants (20%), and snowfall (19%). Study 3 – based on NOAA climatic data – found that most, but not all, of these detected signals are borne out in the climatic record. Study 4 – using the survey data – found that personal experience of global warming matters in that it predicts perceptions of local risk of global warming, controlling for demographics, political affiliation, and cultural beliefs about national policy outcomes. We conclude that perceived personal experience of global warming appears to heighten people's perception of the risks, likely through some combination of direct experience, vicarious experience (e.g., news media stories), and social construction.  相似文献   

TIBOOBURRA,A NEW AUSTRALIAN METEORITE FIND,AND OTHER CARBONACEOUS CHONDRITES OF HIGH PETROLOGIC GRADE     

M.J. Fitzgerald  A.L. Jaques 《Meteoritics & planetary science》1982,17(1):9-26

Tibooburra, a new meteorite find from western New South Wales, belongs to the Vigarano subgroup of the carbonaceous chondrites and, on the basis of its opaque mineralogy, appears to be oxidised. Petrological evidence suggests that, like the Allende meteorite, Tibooburra is a CV3 chondrite which has experienced greater metamorphic effects than other CV3 meteorites. Tibooburra has a bulk composition intermediate between the CO and less altered CV chondrites. This transitional nature is exhibited by several elements and is convincingly displayed by the multivariate techniques of cluster analysis and principal component analysis. Tibooburra thus resembles several other CV chondrites, such as Coolidge and Karoonda, which have been strongly metamorphosed. This group of meteorites is believed to have accreted early in the history of the Vigarano parent body and, as a result, contain greater quantities of high temperature Ca-Al-rich inclusions but less low temperature matrix and volatile phases than other CV chondrites. Furthermore, in these meteorites both the matrix and magnesium silicate phases appear to be more iron rich than those in later accreted meteorites. Subsequently, these deeper seated meteorites have undergone more pronounced thermal metamorphism than those located in shallower portions of the parent body.  相似文献   

ADELAIDE AND BENCH CRATER — MEMBERS OF A NEW SUBGROUP OF THE CARBONACEOUS CHONDRITES     

M.J. Fitzgerald  J.B. Jones 《Meteoritics & planetary science》1977,12(4):443-458

The composition and mineralogy of Bench Crater and a new carbonaceous chondrite (Adelaide) are compared. They, Kakangari and possibly certain carbonaceous xenoliths from other meteorites constitute a distinct chemical subgroup of the carbonaceous chondrites characterized primarily by a calcium-to-aluminium ratio (atomic) of about 0.5. It is proposed to call this group the Kakangari (CK) group  相似文献   

Competitive Sorption of Antimony with Zinc,Nickel, and Aluminum in a Seaweed Based Fixed‐bed Sorption Column     

Adil Bakir  Peter McLoughlin  Syed A. M. Tofail  Eddy Fitzgerald 《洁净——土壤、空气、水》2009,37(9):712-719

The removal of heavy metals such as Ni(II), Zn(II), Al(III), and Sb(III) from aqueous metal solutions was investigated using novel, cost effective, seaweed derived sorbents. Studies with a laboratory scale fixed‐bed sorption column, using a seaweed waste material (referred to as waste Ascophyllum product (WAP)) from the processing of Ascophyllum nodosum as biosorbent, demonstrated high removal efficiencies (RE) for a variety of heavy metals including Ni(II), Zn(II) and Al(III), with 90, 90 and 74% RE achieved from initial 10 mg/L metal solutions, respectively. The presence of Sb(III) in multi component metal solutions suppressed the removal of Ni(II), Zn(II) and Al(III), reducing the RE to 28, 17 and 24%, respectively. The use of Polysiphonia lanosa as a biosorbent showed a 67% RE for Sb(III), both alone and in combination with other metals. Potentiometric and conductometric titrations, X‐ray photoelectron and mid‐infrared spectroscopic analysis demonstrated that carboxyl, alcohol, sulfonate and ether groups were heavily involved in Sb(III) binding by P. lanosa. Only carboxyl and sulfonate groups were involved in Sb(III) binding by WAP. Furthermore, a greater amount of weak acidic groups (mainly carboxylic functions) were involved in Sb(III) binding by P. lanosa, compared to WAP which involved a greater concentration of strong acidic groups (mainly sulfonates).  相似文献   

Sharks caught in the KwaZulu-Natal bather protection programme,South Africa. 14. The smooth hammerhead shark Sphyrna zygaena (Linnaeus)     

ML Dicken  H Winker  MJ Smale  G Cliff 《African Journal of Marine Science》2018,40(2):157-174

The current study provides long-term catch-rate, biological and feeding data for smooth hammerhead sharks, Sphyrna zygaena, caught in South Africa’s KwaZulu-Natal bather protection programme. In total, 2 512 S. zygaena were caught in net installations between 1978 and 2014, and 72 S. zygaena were caught on drumlines between 2007 and 2014. There was no significant log-linear year trend in the net catch rate over time (slope = 0.0054, t = 1.808, p = 0.07). However, there was a significant temporal increase in mean size of the captured sharks (slope = 0.0012, t = 3.502, p < 0.001). A quasi-Poisson generalised additive mixed model showed that increasing latitude, winter months, colder sea temperatures and the deployment of drumlines all had a significant positive effect on the catch rate of sharks in nets. The size frequency of the catch was unimodal, with significantly more females caught in the nets and more males on the drumlines. The majority (93.1%) of all sharks caught were immature and measured between 80 and 120 cm precaudal length. Teleosts and cephalopods dominated the sharks’ diet in terms of all dietary indices. The prey species consumed indicate that immature S. zygaena are feeding primarily within the pelagic zone of shallow coastal habitats.  相似文献   

How U.S. ocean policy and market power can reform the coral reef wildlife trade     

Brian N. Tissot  Barbara A. Best  Eric H. Borneman  Andrew W. Bruckner  Cara H. Cooper  Heather D’Agnes  Timothy P. Fitzgerald  Amanda Leland  Susan Lieberman  Amy Mathews Amos  Rashid Sumaila  Teresa M. Telecky  Frazer McGilvray  Brian J. Plankis  Andrew L. Rhyne  Glynnis G. Roberts  Benjamin Starkhouse  Todd C. Stevenson 《Marine Policy》2010

As the world’s largest importer of marine ornamental species for the aquaria, curio, home décor, and jewelry industries, the United States has an opportunity to leverage its considerable market power to promote more sustainable trade and reduce the effects of ornamental trade stress on coral reefs worldwide. Evidence indicates that collection of some coral reef animals for these trades has caused virtual elimination of local populations, major changes in age structure, and promotion of collection practices that destroy reef habitats. Management and enforcement of collection activities in major source countries such as Indonesia and the Philippines remain weak. Strengthening US trade laws and enforcement capabilities combined with increasing consumer and industry demand for responsible conservation can create strong incentives for improving management in source countries. This is particularly important in light of the March 2010 failure of the parties to the Convention on International Trade in Endangered Species (CITES) to take action on key groups of corals.  相似文献