Gender specific effects on normal and neoplastic liver growth in medaka (Oryzias latipes): a model for environmental modulation of carcinogensis in fish     

Swee J. Teh  David E. Hinton 《Marine environmental research》1996,42(1-4)

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Changes in mobility and speciation of heavy metals in clay-amended incinerator fly ash     

T.?T.?LimEmail author  J.?H.?Tay  L.?C.?Tan  V.?Choa  C.?I.?Teh 《Environmental Geology》2004,47(1):1-10

The generation of municipal solid waste incinerator fly ash (MSWIF) has been increasing significantly over the recent past, and its disposal is problematic and costly due to high concentration of leachable heavy metals present in the material. This study explored a potential stabilization of MSWIF by blending with a natural sorbent material with low permeability, clay, and assessed the potential release of heavy metals from the stabilized mixtures under various simulated subsurface environments. The leachability of heavy metals such as Pb, Cd, Cr, Zn and Cu in the MSWIF-clay mixtures cured for 1 to 360 days was investigated by performing leaching tests and sequential chemical extractions (SCE). Leaching tests were performed at acidic, neutral and alkaline pH values. The leaching test results suggested that the natural clay could turn the MSWIF into non-hazardous material. All the MSWIF-clay mixtures demonstrated leaching behavior different from that of the original MSWIF. SCE results revealed that the acidic and reducing conditions were the most unfavorable to the immobilization of the heavy metals in the stabilized MSWIF-clay matrix. Conversely, the oxidizing and alkaline conditions were not critical to the stabilized MSWIF-clay mixtures. Apparently, clay in the mixtures could function as an adsorptive micro-barrier to retain the heavy metals within the MSWIF-clay matrices.  相似文献   

Environmental and socioeconomic dynamics of the Indian Ocean tsunami in Penang,Malaysia     

Benjamin Horton  Michael Bird  Thomas Birkland  Susan Cowie  Ong Jin Eong  Andrea Hawkes  Gong Wooi Khoon  Lisa Law  Colin Macgregor  Aileen Tan Shau‐Hwai  Teh Tiong Sa  Zulfigar Yasin 《Singapore journal of tropical geography》2008,29(3):307-324

This paper addresses some of the environmental and socioeconomic dimensions of the 2004 Indian Ocean tsunami on Penang, Malaysia. We aim to offer wide access to unique and perishable data, while at the same time providing insight to ongoing debates about hazards, vulnerability and social capital. Our social survey examines some of the dynamics that shaped the tsunami impact, response and recovery process. While in terms of lives lost Penang may not conform to arguments surrounding vulnerable environments, the recovery process is more marked by social disparities in terms of the ability to access resources. Our physical survey records local topography, flow depth and flow direction, and charts the differential impact of the tsunami. Yet measuring hazards is not a straightforward process, and relies on reflexive methodologies and eyewitness accounts.  相似文献   

Determining the sensitive developmental stages of intersex induction in medaka (Oryzias latipes) exposed to 17 beta-estradiol or testosterone.     

C S Koger  S J Teh  D E Hinton 《Marine environmental research》2000,50(1-5):201-206

Certain environmentally persistent compounds can adversely affect reproduction by acting as steroid hormone agonists or antagonists. The goal of the present study was to determine the developmental stage most susceptible to exogenous hormone (estradiol and testosterone) exposure using a small teleost model. In the first (pilot study) of two experiments, medaka (Oryzias latipes), at varying developmental stages, were bath-exposed to 5 micrograms/l 17 beta-estradiol for 24 h. At 5 months of age, fecundity, fertility and embryo and larval viability (reproductive success) were investigated in control and exposed groups. Fish at 1, 1.5, 2 and 5.5 months of age were also sampled, processed and examined histologically for gonadal alteration. No significant differences in mortality, gonadal morphology, body weight, sex-ratio or time to maturity were seen between control and exposed fish. At 5 months, however, when exposure groups were compared to controls, significant differences were seen in reproductive success and viability of offspring. A second experiment exposed embryo stage 10, and 1-, 7- and 21-day-old larvae for 6 days to 15 micrograms/l 17 beta-estradiol or 100 micrograms/l testosterone. No significant differences were seen at 5 months in mortality, body weight, or time to sexual maturity. However, sex-ratios were significantly biased toward female in the stage 10, 1- and 7-day post-hatch estradiol exposure groups. No significant changes in sex-ratio were associated with testosterone exposure at any developmental stage. Further, intersex gonads were observed in fish from all groups exposed to 15 micrograms/l estradiol. Only those fish exposed as newly hatched fry or at 1 week post-hatch displayed intersex gonads following 100 micrograms/l testosterone exposure. Data from these experiments show that newly hatched fry are that life stage most sensitive to hormone exposure and the most appropriate to use in determining effects of known endocrine-disrupting compounds.  相似文献   

Biological effects of gold mine tailings on the intertidal marine environment in Nova Scotia,Canada   总被引：1，自引：0，他引：1  

K. Doe  R. Mroz  K.-L. Tay  J. Burley  S. Teh  S. Chen 《Marine pollution bulletin》2017,114(1):64-76

From 1861 to the 1940s, gold was produced from 64 mining districts in Nova Scotia, where mercury amalgamation was the dominant method for the extraction of gold from ore until the 1880s. As a result, wastes (tailings) from the milling process were contaminated by mercury and were high in naturally occurring arsenic. In 2004 and 2005, sediments, water and mollusc tissues were collected from 29 sampling stations at nine former gold mining areas along the Atlantic coastline and were analysed for arsenic and mercury. The resulting data were compared with environmental quality guidelines. Samples indicated high potential risk of adverse effects in the intertidal environments of Seal Harbour, Wine Harbour and Harrigan Cove. Arsenic in Seal Harbour was bioavailable, resulting in high concentrations of arsenic in soft-shell clam tissues. Mercury concentrations in tissues were below guidelines. This paper presents results of the sampling programs and implications of these findings.  相似文献   

Biomarker responses in Macoma nasuta (Bivalvia) exposed to sediments from northern San Francisco Bay     

Werner I  Teh SJ  Datta S  Lu X  Young TM 《Marine environmental research》2004,58(2-5):299-304

Our study investigates biomarker responses and survival of Macoma nasuta exposed to sediments collected from six locations in northern San Francisco Bay. Biomarkers analyzed were stress proteins (hsp70) in gill, mantle and digestive gland, lysosomal membrane damage and histopathologic lesions. Sediments and clam tissues were analyzed for a comprehensive suite of heavy metals and trace organic pollutants. Sediment grain size and organic carbon content were determined. Clams accumulated metals, polyaromatic hydrocarbons (PAHs) and organochlorine pesticides (aldrin and p,p(')-DDT and its metabolites p,p(')-DDD and p,p(')-DDE). Pearson and Spearman correlation analysis revealed that mortality, hsp70 in gill and histopathologic lesion scores in gonads, and lysosomal membrane damage were significantly correlated with tissue concentrations of DDT and/or its metabolites. Tissue concentrations of metals, in particular nickel, chromium, and copper, were associated with macrophage aggregates in digestive gland and germ cell necrosis. Cadmium was linked to mortality and lysosomal membrane damage.  相似文献   

Space use by Rhabdosargus holubi in a southern African estuary,with emphasis on fish movements and ecosystem connectivity     

GN Grant  RH Bennett  TS Murray  AK Whitfield 《African Journal of Marine Science》2017,39(2):135-143

Twenty-one juvenile Cape stumpnose Rhabdosargus holubi (140–190 mm fork length) were tagged with internal acoustic transmitters in the lower, middle and upper reaches of the Kowie Estuary, South Africa. The movements of each fish were continually monitored from October 2014 to February 2015 using 22 stationary data-logging acoustic receivers situated at approximately equidistant intervals along the length of the estuary (21 km). Juvenile R. holubi spent the greatest proportion of time within the estuarine environment (83%), with the sea (16%) and riverine (1%) environments used to a much lesser extent. Within the estuarine environment, tagged individuals showed high levels of residency and fidelity to their capture and release sites; however, the degree of residency was dependent on the position of the release site, with batches in the upper and lower reaches exhibiting different space-use patterns. When larger juvenile R. holubi migrated back to the sea for the next phase of their life cycle, they generally did not return to the estuarine environment, thus indicating a permanent ontogenetic shift in habitat use with the onset of sexual maturity. This contribution to our understanding of the ecology of a ubiquitous estuarine fish further highlights the importance of estuarine habitats as nursery areas that require effective management.  相似文献   

DETERMINATION OF SEDIMENTARY RATE IN ESTUARY AND COAST BY ~(228)Th TECHNIQUE     

康兴伦  顾德隆  张经  朱校斌  施伟  康建海  秦晓光 《中国海洋湖沼学报》2001,(4)

ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅＨｕａｎｇｈｅＲｉｖｅｒｗｅｌｌｋｎｏｗｎｗｏｒｌｄｗｉｄｅｆｏｒｉｔｓｈｉｇｈｓｅｄｉｍｅｎｔｄｉｓｃｈａｒｇｅｉｓＣｈｉｎａ’ｓｓｅｃｏｎｄｌａｒｇｅｓｔｒｉｖｅｒ,ｗｈｏｓｅｒｕｎｏｆｆｉｓｍａｉｎｌｙｓｕｐｐｌｉｅｄｂｙｐｒｅｃｉｐｉｔａｔｉｏｎｏｖｅｒｔｈｅｕｐｐｅｒｒｅａｃｈｅｓ.Ｈｏｗｅｖｅｒ,ｔｈｅｍａｔｅｒｉａｌｆｒｏｍｓｏｉｌｅｒｏｓｉｏｎｉｎｔｈｅＬｏｅｓｓＰｌａｔｅａｕｉｎｔｈｅｍｉｄｄｌｅｒｅａｃｈｅｓｉｓａｍａｊｏｒｃｏｎｔｒｉｂｕｔｏｒｔ…  相似文献   

The outermost ob associations in M33     

G. R. Ivanov  TS. B. Georgiev  P. Z. Kunchev 《Astrophysics and Space Science》1989,159(1):103-107

The blink survey ofUBVR plates of the Tautenburg Schmidt telescope reveals about 20 new stellar associations. A few suspected associations are located at 8 kpc from the center of M33. The new associations fit well into the spiral structure of the galaxy.  相似文献   

Geopolymer formation and its unique properties   总被引：3，自引：0，他引：3  

Daeik Kim  Hsuan-Ting Lai  George V. Chilingar  Teh Fu Yen 《Environmental Geology》2006,51(1):103-111

The characteristic property of naturally-occurring geopolymers is a high content of humic materials that are recognized by the nitrogen function. Through a simulated geopolymerization, biopolymers with non-nitrogen function, such as xanthan gum, were found to have the characteristics of humic acid by means of UV–Vis spectrometry. This fact ascertains that any kind of biopolymer may naturally transform to a geopolymer. A geopolymer is a type of crosslinked long-chain compound, built in three-dimensional structures whose property is immune to microbial degradation. A crosslinked biopolymer was shown to have the same characterization as a geopolymer that has a long life due to its crosslinking capacity and anti-microbial properties. In this study, the formation of petroleum-based geopolymers (e.g., kerogen) was introduced. This study may elucidate the structure of geomacromolecules and the mechanism of their formation, closely related with crosslink reaction between inorganic and organic molecules. This will further change the conventional definition of geopolymer that involves only the inorganic geopolymer.  相似文献