Evaluation of toxicity in tributaries of the Mersey estuary using the isopod Asellus aquaticus (L.)     

A. J. O'Neill  T. S. Galloway  M. A. Browne  A. Dissanayake  M. H. Depledge 《Marine environmental research》2004,58(2-5):327

Increasing numbers of industrial, agricultural and natural chemicals are present in sewage effluent and are known to elicit toxic effects in laboratory exposures, but little is known of their combined sub-lethal effect in the field. In this study, a combination of esterase activity and ventilation rate assays was performed to determine the neurological and physiological function of the freshwater crustacean Asellus aquaticus (L.) at sites above and below a sewage treatment works (STW). Cholinesterase and carboxylesterase activities were significantly inhibited (n=8, P<0.05) and ventilation rates increased (n=8, P=0.0001) in A. aquaticus at STW sites compared to those from reference sites, indicating a decrease in neurological and physiological function. The ecological relevance of these findings for the population dynamics of the organisms in the field is discussed.  相似文献   

Adsorption of fluoride on goethite surfaces-implications on dental epidemiology   总被引：1，自引：0，他引：1  

K. B. P. N. Jinadasa  C. B. Dissanayake  S. V. R. Weerasooriya  A. Senaratne 《Environmental Geology》1993,21(4):251-255

Fluoride ion interaction with synthetically prepared goethite has been investigated over a range of pH values (4–9) and F^– concentrations (10^–3–10^–5 M). The amount of F^– retained by goethite suspensions was found to be a function of pH, media ionic strength, F^– concentration, and goethite concentration. The lowest ionic strength (0.001 M KNO₃) gave the highest adsorption medium. Uptake was minimal at pH >7 and increased with decreasing pH. Thermodynamic properties for fluoride adsorption at 298 K and 323 K were investigated. The isosteric heat of adsorption (H _r) was calculated and the heterogeneity and homogeneity of the surface examined for goethite. In view of the importance of fluoride in dental health, the interaction of fluoride on goethite in the physical environment has important implications on dental epidemiology.  相似文献   

Distribution and feeding modes of macrobenthos within three oceanographic feature areas of the KwaZulu-Natal Bight,South Africa     

CB Untiedt 《African Journal of Marine Science》2016,38(1):S91-S104

The composition and distribution of macrobenthic communities was investigated in three areas in the KwaZulu- Natal Bight, a section of shelf off the east coast of South Africa. Areas were pre-selected on the basis of three known oceanographic features, posited to deliver land- or Agulhas Current-derived nutrients onto the shelf and to drive ecosystem functioning in this region. Replicate sediment samples were collected with a 0.2 m² van Veen grab, during two surveys (A, B) corresponding with normal periods of high and low rainfall, respectively. A subset of the full station array was selected across the shelf in an arrangement of increasing depths (inner-, mid- and outer shelf) through each feature area to investigate the spatial distribution and feeding modes of macrobenthic taxa. The two periods showed some differences in abundance and numbers of macrobenthic taxa, but were not statistically different. Total macrobenthic abundance from Survey A was 20 215 individuals from 642 taxa, decreasing to 18 000 individuals from 503 taxa during Survey B. Polychaeta and Crustacea were the dominant taxa sampled; abundance of the latter was attributed largely to a proliferation of Paguristes sp.1 at inner-shelf samples in the midbight (Thukela) region during Survey B. Similarity classification distinguished seven sample groups reflecting differences in feature areas and shelf positions under investigation. The Thukela River midshelf community supported the highest macrobenthic abundance, while the midshelf off the southern bight (Durban region) was most species rich. Findings were attributed to the habitat complexity of the midshelf which includes a palaeo-dune cordon at the 60 m isobath. Functionally, the community was dominated by interface- and deposit-feeding fauna, emphasising the importance of trophic plasticity in an environmentally variable and heterogeneous shelf environment.  相似文献   

南非开普省北部金伯利岩侵位的年代     

Smit.  CB 《国土资源信息化》1989,(1):21-23

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Heavy metal abundances in the Kandy lake—An environmental case study from Sri Lanka     

C. B. Dissanayake  A. M. Rohana Bandara  S. V. R. Weerasooriya 《Environmental Geology》1987,10(2):81-88

The Kandy lake, situated in the heart of Sri Lanka's second largest city with a population of nearly 120,000, has been monitored to probe the extent of heavy metal pollution. Although the lake is a source of drinking water to the city, a large number of effluent canals drain into the lake carrying a continuous flow of industrial and domestic waste matter. A total of 66 surface water samples were analyzed for their Fe²⁺, total Fe, total V, SO ₄ ²⁻ , Cd²⁺, and Pb²⁺ contents. Pb and Cd were found in high concentrations averaging 150 μg/l and 77 μg/l, respectively, and exhibit a marked positive correlation with each other (r=+0.94). Vehicular emissions and industrial waste matter contribute largely to the Pb and Cd contents of the lake, the anthropogenic influence outweighing the contributions made by geological materials. All field observations and laboratory experiments indicate a tendency of the Kandy Lake towards eutrophicity.  相似文献   

The relationship between soil geochemistry and die back of montane forests in Sri Lanka: a case study   总被引：1，自引：1，他引：0  

P. N. Ranasinghe  C. B. Dissanayake  D. V. N. Samarasinghe  R. Galappatti 《Environmental Geology》2007,51(6):1077-1088

Tropical montane forests of Sri Lanka form a unique ecosystem with more than 50% of endemic plant species. It has been noted that trees, belonging to different size and age classes of these forest, have been dying due to a yet unknown factor. This phenomenon was first observed in the Horton Plains National Park, which is a high plateau, composed of tropical montane forests. Later dying of forests were observed at several areas including Hakgala montane forest. Physical parameters trace nutrients as well as toxic element concentrations in soils, were studied in order to identify the possible geochemical factors behind the forest die back. Systematic soil sampling was carried out covering the entire Horton Plains National Park and random samples were collected from Hakgala montane forest. Samples were analyzed for available Fe, Mn, Zn, Cu, Ni, Cd, Al and Pb using standard colorimetric and atomic absorption spectrometric procedures. Physical parameters such as pH, moisture content, and conductivity of the samples were also measured. Among extractable micro-nutrients Cu and Zn, and Ni show no deficiency or excess levels. However, the recorded available high concentrations of Fe, Mn and Al can be toxic to certain montane plant species. Acidic moist soil of the area may enhance the toxic effects of these elements. Possible source of these elements should be the underground lithology of the area. According to the results obtained, there is a relationship between forest die back and high Pb concentrations. The same phenomenon was also observed in the Hakgala forest. The distribution pattern of Pb in the Horton Plains coincides well with the die back distribution pattern. The observed Pb values at Horton Plains and Hakgala are almost similar to values observed at Pannipitiya and Dombagaskanda locations, which are located close to main roads carrying heavy traffic. It is quite possible therefore, that Pb toxicity may be a significant factor behind the forest die back even though other factors should not be completely ruled out at this juncture. Strong monsoon winds, bringing Pb from the polluted southwestern part of the country, can be the most possible source of soil Pb. Further studies however are indeed necessary to confirm the conclusion.  相似文献   

The ECOMAN project: A novel approach to defining sustainable ecosystem function     

Galloway TS  Brown RJ  Browne MA  Dissanayake A  Lowe D  Depledge MH  Jones MB 《Marine pollution bulletin》2006,53(1-4):186-194

The ECOMAN was initiated in 2001 by the University of Plymouth, UK, Plymouth Marine Laboratory and the Department of the Environment, Fisheries and Rural Affairs (DEFRA) to address the need for more pragmatic assessment techniques linking environmental degradation with its causes. The primary aim of the project was to develop an evidence-based approach in which suites of easy-to-use, cost-effective and environmentally valid biological responses (biomarkers) could be used together to assess the health of coastal systems through the general condition of individuals. A range of sub-lethal endpoints, chosen to reflect successive levels of biological organisation (molecular, cellular, physiological), was evaluated in common coastal organisms showing different feeding types (filter feeding, grazing, predation) and habitat requirements (estuary, rocky shore). Initially, the suite of biomarkers was used in laboratory studies to determine the relative sensitivities of key species within different functional groups to common contaminants. These results were then validated in field studies performed in a range of ecosystems exhibiting different degrees/signatures of contamination. Here, an example is provided of a field study in the Humber Estuary, UK, which illustrates how multivariate statistical analysis can be used to identify patterns of response to discriminate between contaminated and clean sites. The use of a holistic, integrated approach of this kind is advocated as a practical means of assessing the impact of chemical contamination on organismal health and of ranking the status of marine ecosystems.  相似文献   

Distinct metamorphic evolution of alternating silica-saturated and silica-deficient microdomains within garnet in ultrahigh-temperature granulites: An example from Sri Lanka     

P.L. Dharmapriya  Sanjeewa P.K. Malaviarachchi  Leo M. Kriegsman  K. Sajeev  Andrea Galli  Y. Osanai  N.D. Subasinghe  C.B. Dissanayake 《地学前缘(英文版)》2017,8(5):1115-1133

Here we report the occurrence of garnet porphyroblasts that have overgrown alternating silica-saturated and silica deficient microdomains via different mineral reactions. The samples were collected from ultrahigh-temperature (UHT) metapelites in the Highland Complex, Sri Lanka. In some of the metapelites, garnet crystals have cores formed via a dehydration reaction, which had taken place at silica-saturated microdomains and mantle to rim areas formed via a dehydration reaction at silica-deficient microdomains. In contrast, some other garnets in the same rock cores had formed via a dehydration reaction which occurred at silica-deficient microdomains while mantle to rim areas formed via a dehydration reaction at silica-saturated microdomains. Based on the textural observations, we conclude that the studied garnets have grown across different effective bulk compositional microdomains during the prograde evolution. These microdomains could represent heterogeneous compositional layers (paleobedding/laminations) in the precursor sediments or differentiated crenulation cleavages that existed during prograde metamorphism. UHT metamorphism associated with strong ductile deformation, metamorphic differentiation and crystallization of locally produced melt may have obliterated the evidence for such microdomains in the matrix. The lack of significant compositional zoning in garnet probably due to self-diffusion during UHT metamorphism had left mineral inclusions as the sole evidence for earlier microdomains with contrasting chemistry.  相似文献   

The Stream Sediment Geochemistry of the Walawe Ganga Basin of Sri Lanka - Implications for Gondwana Mineralization     

Rohana Chandrajith  C.B. Dissanayake  H.J. Tobschall 《Gondwana Research》2000,3(2)

A regional geochemical and mineralogical study aimed at investigating the mineralization in the western-part of the Walawe Ganga (river) Basin in Sri Lanka is represented in this paper. The river basin is the 3^rd largest in the country and has within it a boundary zone between two geologically different crustal blocks, which are marked by granulitic grade rocks and amphibolite grade rocks. Size fractions of stream sediments (< 63 μm; 63–125 μm; 125–177 μm and 177–250 μm) developed on the granulite-grade metamorphic terrain have been analysed at their source for their mineralogical and selected element compositions. Thirty-eight (38) sediment samples and 15 representative probable parent rock samples were chemically analysed giving special emphasis to the High Field Strength trace Elements (HFSE) including the Rare Earth Elements (REE). The granulite grade rocks in the study area is geochemically similar to that of post Archean upper crust. However the stream sediments developed from the high-grade rocks during the intense weathering, are markedly enriched with HFSE and REE. The enrichment of HFSE and LREE is accounted for by the presence of HFSE- and REE- rich accessory mineral phases such as zircon, monazite, apatite, garnet and rutile in the sediments. In some samples, the content of heavy minerals contributes as much as 50 wt. %. These minerals act as a source of elements in the sediments. However, extreme hydraulic sorting of HFSE- and REE-bearing minerals during the sediment deposition cannot be expected within a short distance from near the sources except from a mineralized occurrence. Therefore, the higher enrichment of these elements presumably indicates occurrences of scattered mineral sources such as highly differentiated granites and associated pegmatites within the Walawe Ganga drainage basin. These granitic pegmatites are probably intruded during or soon after the main granulite-facies metamorphic event and similar events are seen in other terrains of East-Gondwana.  相似文献   

Activity of IGCP-368 During 2000     

M. Yoshida  M. Santosh  C.B. Dissanayake 《Gondwana Research》2001,4(2):249

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