Mathematical modeling of PCB bioaccumulation in Perna viridis     

K. N. Yu  P. K. S. Lam  C. C. C. Cheung  C. W. Y. Yip 《Marine pollution bulletin》2002,45(1-12)

In the present work, we built a mathematical model of polychlorinated biphenyl (PCB) bioaccumulation in Perna viridis, namely, a one-compartment model with a time dependent incorporation rate R (μg g⁻¹ lipid per ppb water per day), with positive substrate cooperativity as the underlying physical mechanism. The temporal change of the PCB concentration Q (μg g⁻¹ lipid) in the soft tissues of the mussel depends on the competition of the input rate RW and the output rate kQ, where W is the concentration of PCB in water (ppb water) and k is the elimination rate (per day). From our experimental data, k=0.181±0.017 d⁻¹. The critical concentration in water W_c for positive substrate cooperativity was found to be 2.4 ppb. Below W_c, R is a constant. For a water concentration of 0.5 ppb Aroclor 1254, R=24.0±2.4 μg g⁻¹ lipid ppb⁻¹ d⁻¹. Above W_c, positive substrate cooperativity comes into effect and R becomes a function of time and dependent on the concentration Q in a form R=γQ/(Q+δ). This is the case for a water concentration of 5 ppb Aroclor 1254, where γ=15.1 μg g⁻¹ lipid ppb⁻¹ d¹ and δ≈200 μg g⁻¹ lipid. From this model, the uptake is exponentially increasing when the PCB concentration in the mussel is small compared to 200 μg g⁻¹ lipid, and hyperbolically increasing when the concentration is large compared to 200 μg g⁻¹ lipid, which are consistent with the experimental data. The model is useful for understanding the true processes taking place during the bioaccumulation and for risk assessment with higher confidence. Future experimental data which challenge the present model are anticipated and in fact desirable for improvement and perfection of the model.  相似文献   

The interaction between a manmade lake and groundwater: an example site in the Aurku area,Chiayi County,Taiwan     

Cheh‐Shyh Ting  Jiin‐Shuh Jean  Chien‐Chang Tseng  Ming‐Chee Wu 《水文研究》2007,21(5):647-657

The objectives of this study are (1) to understand the subsurface hydrology in the Aurku area, Chiayi County, southern Taiwan, and (2) to determine the interaction between the manmade lake and groundwater level through the recharge produced by infiltration by on‐site investigation and laboratory sand tank simulation. The manmade lake was selected as the field site for groundwater recharge effect so as to assess the role of infiltration from the aquaculture ponds in this area. These results can be used as reference for future application of constructing a series of manmade lakes. The field experiment was performed to measure the infiltration rate of the manmade lake by using the water balance method and double‐ring infiltration test. The results demonstrated that the manmade lake had helped the recharge of the groundwater. Raising or maintaining a higher water level of the manmade lake can promote higher infiltration. When the groundwater level is equal to or higher than the bottom of the manmade lake, infiltration will slow or cease. The field experiment and laboratory sand tank simulation demonstrated that the infiltration rate increased with the higher storage depth of the manmade lake. The laboratory simulation also indicated that while the groundwater level was lower than the bottom of manmade lake (i.e. the reference level) and the initial water depth (3 cm) was equal to or greater than 50% of the full water storage depth, the infiltration depth increased with time. However, the infiltration depth would be very small or nearly zero when the groundwater level was higher than the bottom of the manmade lake. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Predicting tsunami arrivals: Estimates and policy implications     

Dao Hua Zhang  Tsz Leung Yip  Chiu-On Ng 《Marine Policy》2009

Tsunami is one of a few kinds of natural disasters that leave people some time for escape. This escape time, which is essentially the time for the giant wave to propagate from the epicentre to a coast, has to be estimated without delay upon the occurrence of the incident. With the advancement of water wave theories, much work has been done to model the propagation of tsunamis from deep oceans to shallow water. The authors argue that while much emphasis has been put on the expansion of the high-tech early warning system and the development of complicated tsunami models, a simple-to-use yet accurate predictive model is still wanting. This paper presents a handy linear wave model, which is capable of estimating the arrival time of a tsunami with very good accuracy, as has been verified by comparison with past incidents. With the availability of such a simple model, even local communities without access to a high-tech warning system can readily estimate the time left for emergency evacuation.  相似文献   

Phytoplankton diversity in a tropical bay,North Borneo,Malaysia as revealed by light microscopy and Next-Generation Sequencing     

Brian Wei Khong Chong  Sandric Chee Yew Leong  Victor S. Kuwahara  Teruaki Yoshida 《海洋学报(英文版)》2022,41(12):142-151

Assessments of phytoplankton diversity in Sabah waters, North Borneo, have primarily relied on morphology-based identification, which has inherent biases and can be time-consuming. Next-Generation Sequencing (NGS) technology has been shown to be capable of overcoming several limitations of morphology-based methods. Samples were collected from the Sepanggar Bay over the course of the year 2018 in different monsoon seasons. Morphology-based identification and NGS sequencing of the V8–V9 region of the 18S LSU rDNA were used to investigate the diversity of the phytoplankton community. Microscopy and NGS showed complementary results with more diatom taxa detected by microscopy whereas NGS detected smaller and rarer taxa. The harmful algal genera in the study site comprised of Skeletonema, Margalefidinium, Pyrodinium, Takayama, and Alexandrium as detected by NGS. This study showed that that an integrative approach of both morphological and molecular techniques could provide more comprehensive information about the phytoplankton community as the approach captured quantitative variability as well as the diversity of phytoplankton species.  相似文献   

Reproductive biology and seasonality of the Indo-Australasian mysid Mesopodopsis orientalis (Crustacea: Mysida) in a tropical mangrove estuary,Malaysia     

Yukio Hanamura  Ryon Siow  Phaik-Ean Chee 《Estuarine, Coastal and Shelf Science》2008

A year-round survey of the tropical shallow-water mysid Mesopodopsis orientalis (Tattersall, 1908) (Crustacea, Mysidacea) was conducted in the Merbok mangrove estuary, northwestern Peninsular Malaysia. The mysid formed dense aggregations at the river's edge close to the mangrove forest during the daytime, but very few were captured elsewhere in the estuary system. The sampled population was found in a wide range of salinities from 16 to 32, demonstrating broad euryhalinity, and the number of the catch at the littoral zone ranged from 11.8 to 2273 ind m⁻². The overall annual mean was 709.2 ind m⁻². Females predominated over males in the entire population, and brooding females were present at every monthly sample, indicating that reproduction is continuous year round. The clutch size positively correlated with female body length. The diameter of eggs (Stage I embryos) was unaffected by the seasonality and independent of the maternal size within an observed size range. The life history pattern of the estuarine population of M. orientalis showed close similarity to that of the coastal counterpart. However, the former was found to produce fewer but larger eggs, and the specimens in this population were larger than those in the coastal population at the embryo, juvenile, and adult stages. This evidence indicates that the life history features of the estuarine population would differ to some degree from those of the coastal counterpart.  相似文献   

Embedding eco-friendly and smart technology features in affordable housing for community happiness in Malaysia     

Mohamad  Zam Zuriyati  Yang  Fong Chee  Charles Ramendran  S. P. R.  Rehman  Mobashar  Nee  Au Yong Hui  Yin  Yip Chee 《GeoJournal》2022,87(1):167-181

GeoJournal - Two phases of study are involved in this research: first, the sales strategies for affordable houses embedded with eco-friendly and smart technology features; and second, the impact of...  相似文献   

A Backus—Gilbert approach to inversion of travel-time data for three-dimensional velocity structure     

Chee W. Chou  John R. Booker 《Geophysical Journal International》1979,59(2):325-344

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SPATIAL VARIATION OF Zn GEOCHEMICAL FRACTIONS IN THE SURFACE SEDIMENTS OF THE STRAITS OF MALACCA: NATURAL OR ANTHROPOGENIC?   总被引：1，自引：1，他引：0  

CheeKongYap AhmadIsmail SoonGuanTan 《湿地科学》2005,3(2):94-103

1INTRODUCTION Studiesonheavymetalcontaminationinsedi mentshavealwaysbeenfocusedonthecoastalandin tertidalareas(Sivalingam,etal.,1980;Ismail,1993;Ismail,etal.,1993;IsmailandRosniza,1997;Yap,etal.,2002a,2002b).Theheavymet alconcentrationsfoundinthesediments…  相似文献   

泗滨砭石冲泡水的微量元素成分特征     

谢先德  江洁慈  刘颖  涂湘林 《地球化学》2013,(1):1-10

泗滨砭石是一种产于山东古泗水流域的结构致密、含CaCO3高达96%的微晶灰岩,本文分别用超纯开水和加入多元素等离子体标准溶液的开水,对泗滨砭石碎块进行冲泡实验,在不同时段用ICP-AES和ICP-MS分别测定冲泡液中微量元素的含量,以了解饮用砭石泡水的水质状况。实验取得了如下结果:(1)超纯开水的冲泡液不含对人体有害的Cd、Cr、Cu、Pb和Zn等重金属元素,但含有很微量的Ca、Mg、Sr、Na、K和Si等常见元素,其含量随着冲泡时间的延长呈现上升的趋势,但都大大低于国家对生活用水质量标准的指标,且冲泡液的pH值稳定在8.1~8.2之间,呈弱碱性,口感较好。(2)在加入标准溶液的冲泡液中,主要常见元素的含量,均随着冲泡时间的延长和pH值的上升呈连续增高趋势,但稀土元素和对人体有害重金属元素,以及绝大多数金属离子的含量都呈连续下降的趋势。(3)CaCO3的溶解、金属离子碳酸盐沉淀和金属离子与CaCO3表面之间的吸附,是导致冲泡液中绝大多数金属离子浓度呈连续下降趋势的三个主要因素。(4)砭石冲泡的水虽无毒无害,口感较好,并具有降低冲泡用水中有害重金属元素浓度和对人体适当补充Ca和K的功能,但由于各种离子的浓度都比较低,饮用砭石冲泡水与饮用一般的弱碱性瓶装水的差别并不很大。  相似文献   

Criteria of Acceptance for Constant Rate of Strain Consolidation Test for Tropical Cohesive Soil     

Khairul Anuar Kassim  Ahmad Safuan A. Rashid  Ahmad Beng Hong Kueh  Chong Siaw Yah  Lam Chee Siang 《Geotechnical and Geological Engineering》2016,34(4):931-947

In this study, the rapid consolidation equipment (RACE) was developed as an alternative device to the conventional consolidation test using Oedometer, consuming merely a few hours for the whole precedure to determine the consolidation characteristics of cohesive soil. RACE operates based on the constant rate of strain (CRS) consolidation theory, which is a continuous loading method of testing, requiring a good estimation of the loading rate such that it is ideal for the achievement of steady state condition during testing. The steady state condition is achieved when the c _v values from drained and undrained face of CRS converged with the c_v from Oedometer test. A slightly modification has been made on the normal constant rate of strain (CRS) test by proposing a direct back pressure system to the specimen using a tube to saturate the soil sample. This research has produced a set of criteria for determining the suitable rate for the rapid consolidation test based on the ratio of normalized strain rate, β, and proposed a new coefficient in terms of a ratio of β to clay fraction (CF), as a part of new criteria for testing a fine soil. Four types of sample were tested with different rates of strain using the RACE and their results were compared with those conducted using the Oedometer on the same soil type, from which fairly good agreements were evident in many specimens. It was found from the study that the minimum value of normalized strain rate, β, for the CRS test is 0.005 and for the u _a /σ _v ratio is suggested as 0.01. Also, the maximum β/CF for soils with clay friction lower and higher than 50 % are 0.008 and 0.001, respectively. The minimum β/CF value for both conditions is 0.0001.  相似文献