Toxicological impact assessment of heavy metal contamination on macrobenthic communities in southern coastal sediments of Korea     

Dhong-il Lim  Jin-Woo Choi  Hyeon Ho Shin  Do Hyun Jeong  Hoi Soo Jung 《Marine pollution bulletin》2013

In the heavily industrialized Masan Bay of southern coast, Korea, the potential harmful effects of heavy metals (Cd, Co, Cu, Ni, Pb, Sn, Zn, and Hg) were evaluated in terms of the pollution load index (PLI) and ecological risk assessment index (ERI) methods, and the results obtained were considered alongside the health of the macrobenthic fauna communities. The results revealed that the bay sediments, especially in the inner bay and the outfall area of a sewage treatment plant, are exposed to moderate to serious levels of metal pollution. Hg and Cd contributed the most to the potential toxicity response indices in sediments recently deposited in the bay. The potential ecological risk assessment of heavy metals in the bay was highlighted by the use of the benthic biological pollution index (BPI), suggesting that the ERI is a useful toxicity response index, which can quantify the overall ecological risk level to a target environment.  相似文献   

Period studies of five neglected Algol-type binaries: RW Cet,BO Gem,DG Lac,SW Oph and WY Per     

A. Erdem  S.S. Doğru  F. Soydugan  C. Çiçek  O. Demircan 《New Astronomy》2010,15(7):628-636

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Electrokinetic Restoration of Sulfate‐Accumulated Saline Greenhouse Soil     

Jung‐Min Cho  Do‐Hyung Kim  Jung‐Seok Yang  Kitae Baek 《洁净——土壤、空气、水》2011,39(12):1036-1040

Electrokinetic (EK) process was performed to restore sulfate‐originated saline soil and to evaluate the effect of treatment duration. Sulfate and potassium were the major ionic salts in the saline soil used in this study. A constant voltage gradient of 1 V/cm was applied for 8, 12, and 16 days. After EK treatment, anions and cations were transported toward anode and cathode, respectively, by electromigration. Chloride was completely removed, and 85.6% of nitrate was removed after 8 days of treatment. The increase of treatment period from 8 to 12 days had a negligible effect on the enhancement in the rate of sulfate removal; however, over 70% was removed after16 days. At the end of experiment, the electrical conductivity (EC) of the soil, an indicator of soil salinity, decreased to 1.93 dS/m from an initial value of 5.3 dS/m, and the distribution of sulfate was similar to that of EC. The operation time of 16 days was sufficient to restore the sulfate‐originated saline soil using the EK process.  相似文献   

Investigations on meteorological conditions for elevated PM2.5 in Fairbanks,Alaska     

Huy N.Q. Tran  Nicole Mölders 《Atmospheric Research》2011,99(1):39-49

The relationships between meteorological conditions (temperature, wind-speed and direction, relative humidity, surface-inversion depth and strength, and stability) and PM_2.5 concentrations in Fairbanks, Alaska were investigated using ten years of observational data. The results show that during wintertime (November through February) PM_2.5 concentrations exceeding the 24 h National Air Quality Standard (35 μg/m³) occurred under calm wind, extremely low temperature (≤20 °C) and moisture (water-vapor pressure < 2 hPa) multiday surface-inversion conditions that trap the pollutants in the breathing level and inhibit transport of polluted air out of Fairbanks. PM_2.5 concentrations tend to be higher under stable than other conditions, but are not sensitive to the degree of stability. The presence of a surface inversion and calm wind are necessary, but in combination with low temperatures and humidity, the conditions are sufficient for high PM_2.5 concentrations. The low temperatures are required because they lead to increased emission rates from domestic heating and power production. During multiday inversions with temperatures above ? 20 °C, high relative humidity (> 75%) partly caused by water-vapor emission reduces PM_2.5 concentrations.  相似文献   

REDD+ Readiness progress across countries: time for reconsideration     

Peter Akong Minang  Meine Van Noordwijk  Lalisa A Duguma  Dieudonne Alemagi  Trong Hoan Do  Florence Bernard 《Climate Policy》2014,14(6):685-708

Efforts towards Reducing Emissions from Deforestation and Forest Degradation plus conservation, sustainable management of forests and enhancement of carbon stocks (REDD+) have grown in importance in developing countries following negotiations within the United Nations Framework Convention on Climate Change (UNFCCC). This has favoured investments in processes to prepare countries for REDD+ at the national level (a process referred to as REDD+ Readiness). Yet, little attention has been given to how Readiness can be assessed and potentially improved. This article presents a framework for Readiness assessment and compares progress in REDD+ Readiness across four countries, namely Cameroon, Indonesia, Peru, and Vietnam. The Readiness assessment framework comprises six functions, namely planning and coordination; policy, laws, and institutions; measurement, reporting, verification (MRV), and audits; benefit sharing; financing; and demonstrations and pilots. We found the framework credible and consistent in measuring progress and eliciting insight into Readiness processes at the country level. Country performance for various functions was mixed. Progress was evident on planning and coordination, and demonstration and pilots. However, MRV and audits; financing; benefit sharing; and policies, laws and institutions face major challenges. The results suggest that the way national forest governance has been shaped by historical circumstances (showing path dependency) is a critical factor for progress in Readiness processes. There is need for a rethink of the current REDD+ Readiness infrastructure given the serious gaps observed in addressing drivers of deforestation and forest degradation, linking REDD+ to broader national strategies and systematic capacity building.  相似文献   

Forecast of wave run-up on coastal structure using offshore wave forecast data     

Sung Joon Na  Ki Deok Do  Kyung-Duck Suh 《Coastal Engineering》2011

In this paper, first we introduce the wave run-up scale which describes the degree of wave run-up based on observed sea conditions near and on a coastal structure. Then, we introduce a simple method which can be used for daily forecast of wave run-up on a coastal structure. The method derives a multiple linear regression equation between wave run-up scale and offshore wind and wave parameters using long-term photographical observation of wave run-up and offshore wave forecasting model results. The derived regression equation then can be used for forecasting the run-up scale using the offshore wave forecasting model results. To test the implementation of the method, wave run-up scales were observed at four breakwaters in the East Coast of Korea for 9 consecutive months in 2008. The data for the first 6 months were used to derive multiple linear regression equations, which were then validated using the run-up scale data for the remaining 3 months and the corresponding offshore wave forecasting model results. A comparison with an engineering formula for wave run-up is also made. It is found that this method can be used for daily forecast and warning of wave run-up on a coastal structure with reasonable accuracy.  相似文献   

Temporal occurrence patterns and habitat use of fish in the Mangyeong estuary on the western coast of Korea in 2003, before dike enclosure     

Sun Wan Hwang  Tae Won Lee  Hak Bin Hwang  Sun Do Hwang 《Ocean Science Journal》2011,46(4):307-314

We documented the temporal occurrence patterns and habitat use of fish in the Mangyeong River estuary on the western coast of Korea from February to December 2003 based on monthly samples collected with a stow net. A total of 46 fish species were collected during the study period. Chelon haematocheilus, Konosirus punctatus, Neosalanx jordani, Sardinella zunasi, Synechogobius hasta, and Thryssa kammalensis were the predominate species, accounting for 84.4% of the collected fish. We classified the fish as brackish water (BF), coastal migratory (CMF), diadromous (DF), or freshwater (FF) fish. BF such as C. haematocheilus, S. hasta, and Coilia nasus were the most abundant and were collected almost year-round. As water temperatures increased in spring, adult CMF, such as K. punctatus, S. zunasi, T. kammalensis, T. adelae, Johnius grypotus, Miichthys miiuy, and Larimichthys polyactis, entered the estuary. In summer, large numbers of their juvenile offspring were caught, indicating a peak in fish abundance. The juveniles grew in the estuary before moving out to deeper waters for overwintering. Diadromous juveniles, such as those of Anguilla japonica (commonly known as glass eel), were collected in the spring during their upstream migration. FF, such as Carassius cuvieri and Acheilognathus rhombeus, were collected during the rainy season. In terms of the number of species, the number of individuals, and the biomass, the ratio of BF to all other fish type classifications in the Mangyeong Estuary (without a dam) was higher than that in the Geum River estuary (with a dam). The fish assemblage in the Mangyeong Estuary still maintained estuarine characteristics before dike enclosure, providing habitats for BF, nursery grounds for CMF, and migratory pathways for DF.  相似文献   

Theoretical connections between optimization algorithms based on an approximate gradient   总被引：1，自引：0，他引：1  

Sy T. Do  Albert C. Reynolds 《Computational Geosciences》2013,17(6):959-973

Performing a line search method in the direction given by the simplex gradient is a well-known method in the mathematical optimization community. For reservoir engineering optimization problems, both a modification of the simultaneous perturbation stochastic approximation (SPSA) and ensemble-based optimization (EnOpt) have recently been applied for estimating optimal well controls in the production optimization step of closed-loop reservoir management. The modified SPSA algorithm has also been applied to assisted history-matching problems. A recent comparison of the performance of EnOpt and a SPSA-type algorithm (G-SPSA) for a set of production optimization test problems showed that the two algorithms resulted in similar estimates of the optimal net-present-value and required roughly the same amount of computational time to achieve these estimates. Here, we show that, theoretically, this result is not surprising. In fact, we show that both the simplex, preconditioned simplex, and EnOpt algorithms can be derived directly from a modified SPSA-type algorithm where the preconditioned simplex algorithm is presented for the first time in this paper. We also show that the expectation of all these preconditioned stochastic gradients is a first-order approximation of the preconditioning covariance matrix times the true gradient or a covariance matrix squared times the true gradient.  相似文献   

Formation of the Upper Pleistocene terraces of Lake Van (Turkey)     

Catherine Kuzucuoğlu  Aurélien Christol  Damase Mouralis  Ali‐Fuat Doğu  Ebru Akköprü  Monique Fort  Daniel Brunstein  Halil Zorer  Michel Fontugne  Mustafa Karabiyikoğlu  Stéphane Scaillet  Jean‐Louis Reyss  Hervé Guillou 《第四纪科学杂志》2010,25(7):1124-1137

Sedimentological and geomorphological studies of terraces around Lake Van (1647 m) provided a preliminary framework for lake‐level variations. The elevations of terraces and past lake level were measured with a differential global positioning system. A chronology is developed using ²³⁴U/²³⁰Th dating of travertines, ³⁹Ar/⁴⁰Ar dating of pyroclastites and ¹⁴C dating of organic matter. Facies and stratigraphic correlations identify four transgressions (C1′, C1″, C2′ and C2″), each followed by a regression which ended with low lake levels that caused river incision and terrace formation. Evidence of the oldest transgression (C1′) is found in the uppermost reaches of valleys up to 1755 m, an altitude higher than the present lake threshold (1736 m). This C1′ transgression may be related to pyroclastic flows which dammed an outlet located in the western part of the lake basin and which is dated to before 105 ka. After 100 ka, a second transgression (C1″) reached 1730/1735 m, possibly related to a younger ignimbrite flow, in association with high water inflow (warm and/or wetter conditions). The two younger transgressions reached 1700–1705 m. The first one (C2′) is dated to 26–24.5 cal. ka BP and the second one (C2″) to 21–20 cal. ka BP. Available data suggest that the long‐term lake‐level changes responded mainly to climate oscillations. Additional events such as river captures caused by volcanic falls filling valleys, tectonism, erosion and karstic diversion may have impacted these long‐term lake‐level changes. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Valuing direct use values of wetlands: A case study of Tam Giang–Cau Hai lagoon wetland in Vietnam     

Tran Huu Tuan  Mai Van Xuan  Do Nam  Stale Navrud 《Ocean & Coastal Management》2009,52(2):102-112

Tam Giang–Cau Hai lagoon wetland directly or indirectly provides the likelihoods for about 300,000 persons living around as well as on the lagoon. Due to expansion of aquacultures, intensive fishing, and lack of an appropriate management scheme, the biological resources in the lagoon are degraded. This study provides information on the direct use values of the lagoon wetland, using market price approach. This information on economic values can be used for designing new policies and making trade-offs among alternative management options for the lagoon wetland.  相似文献