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

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.     

Geochemistry of Quaternary sediments of the Jeongokri archaeological site,Korea: implications for provenance and palaeoenvironments during the Late Pleistocene

The geochemical characteristics of an approximately 6‐m‐long sediment core collected from the Jeongokri archaeological site (Hantan River, Korea) were examined to determine the provenance of the sediments and to reconstruct the palaeoenvironment of the study area during the Late Pleistocene (200–127 ka). The core sediments were subdivided into two parts based on grain size: an upper (0–380 cm depth) and lower part (>380 cm depth). The lower part was deposited primarily by fluvial processes during an interglacial period [marine isotope stage (MIS) 7] with warm and humid conditions. Conversely, the upper part was mainly deposited by aeolian processes during a cold and dry glacial period (MIS 6). Geochemical characteristics, represented by major, trace and rare earth element (REE) compositions, and textures of the Jeongokri core sediments show distinct differences between the upper and lower parts. The mineralogy and major, trace and REE compositions indicate that the influence of felsic source rocks (e.g. granite) was dominant in the lower sediments, which were derived from the Hantan River. In contrast, increased quartz content and the very fine and homogeneous grain size in the upper sediments indicate an aeolian origin. REE ratios and distribution patterns, and geochemical signatures indicate that these sediments were derived predominantly from Chinese loess deposits and partially from local sediments from the Korean Peninsula; the possible source area of the upper sediments is the northern part of the Yellow Sea basin. The Yellow Sea basin, having mixed geochemical signatures between Chinese loess and Korean‐derived sediments, was exposed because of low sea levels during MIS 6. The exposed Yellow Sea basin was located in the path of winter‐monsoon winds, which may have carried a great deal of airborne sediments from the basin to the Jeongokri area. Copyright © 2011 John Wiley & Sons, Ltd.     

Multi‐site calibration using a grid‐based event rainfall–runoff model: a case study of the upstream areas of the Nakdong River basin in Korea

Most runoff analyses using a grid‐based distributed model use one parameter group calibrated at the outlet of a watershed, instead of dividing the watershed into subwatersheds. Significant differences between the observed value and the simulation result of the subwatersheds can occur if just one parameter group is used in all subwatersheds that have different hydrological characteristics from each other. Therefore, to improve the simulation results of the subwatersheds within a watershed, a model calibrated at every subwatershed needs to be used to reflect the characteristics of each subwatershed. In this study, different parameter groups were set up for one or two sites using a distributed model, the GRM (Grid based Rainfall‐runoff Model), and the evaluations were based on the results of rainfall–runoff analysis, which uses a multi‐site calibration (MSC) technique to calibrate the model at the outlet of each site. The Hyangseok watershed in Naeseong River, which is a tributary of Nakdong River in Korea, was chosen as the study area. The watershed was divided into five subwatersheds each with a subwatershed outlet that was applied to the calibration sites . The MSC was applied for five cases. When a site was added for calibration in a watershed, the runoff simulation showed better results than the calibration of only one site at the most downstream area of the watershed. The MSC approach could improve the simulation results on the calibrated sites and even on the non‐calibrated sites, and the effect of MSC was improved when the calibrated site was closer to the runoff site. Copyright © 2014 John Wiley & Sons, Ltd.     

Numerical simulation of vertical ground heat exchangers: Intermittent operation in unsaturated soil conditions

The effect of varying the thermal properties of inhomogeneous unsaturated soil on the intermittent operation of a vertical ground heat exchanger (GHE) was simulated by a conjugate heat transfer simulation using a transient conductive heat transfer model. A three-phase soil model was used to introduce soil properties that vary with depth. The performance during the first few hours was significantly different from that of an analytical infinite line source model that assumes steady-state borehole conditions, although relatively good agreement was obtained thereafter. Unsaturated soil conditions afforded a 40% lower mean heat exchange rate than saturated conditions. This demonstrates the importance of considering unsaturated conditions in the design and performance evaluation of GHEs.     

Approximated solution on the properties of the scavenging gap during precipitation using harmonic mean method

Wet deposition refers to both natural and artificial processes where particles are scavenged by atmospheric hydrometeors. Below-cloud atmospheric particles are removed by raindrops via Brownian diffusion, interception, and impaction. The overall scavenging coefficient has a broad and distinctive minimum for aerosol penetration between 0.1 and several micrometers in diameter. In this study, the approximated analytical solution for most penetrating particle size during precipitation was obtained. Brownian diffusion and interception were considered under the assumption of the inertial impaction can be neglected in this study conditions. Both the minimum collection efficiency and minimum scavenging coefficient particle size were estimated using the harmonic mean type approximation, with the solution compared to the numerically calculated results. The approximated results were comparable with the numerical solutions. The results showed that collection efficiency diameter is a function of terminal velocity and the collection mechanisms included. When considering Brownian diffusion and interception, most penetrating particle size increases as drop diameter increases, which shows a contrary to the study of Wang (1978) and this shows that most penetrating particle size depends on collection efficiency mechanism, flow velocity and collector diameter. Consequently, this study analytically approximated general type-solutions for scavenging gap particle size and minimum collection efficiency during precipitation.     

Promises and Perils of Decentralized Forest Governance: The Case of Indonesia's Forest Management Units in Reducing Emission from Deforestation and Forest Degradation (REDD+)

Indonesia's forest management unit (Kesatuan Pengelolaan Hutan or KPH) system can be a promising mechanism for balancing international and national interests for global carbon mitigation initiatives with local interests in project implementation. We discuss the potential role of the KPH system in implementing REDD+ (Reducing Emission from Deforestation and Forest Degradation) projects and improving decentralized forest governance. Substantial financial gains from international initiatives like REDD+ and others can provide appropriate motivation for the central government to ensure successful decentralization of forest management. Development and implementation of REDD+ activities can also support the KPHs in performing their basic functions: conducting forest inventory, developing and implementing forest management plans, and strengthening communication and coordination with local communities. However, engaging indigenous peoples and local communities, which is a legal mandate for the system, will require building some measure of democratic process that can hold the KPHs accountable to local people.     

Veterinary antibiotics contamination in water, sediment, and soil near a swine manure composting facility

Antibiotics have been commonly used to prevent animal diseases and promote livestock productivity. However, its release into the surrounding environments leads to ecological disturbance and risks to human health. This study was conducted to monitor the occurrence and seasonal variations of antibiotics in water, sediment, and soil close to a swine manure composting facility, Korea. Various types of antibiotics such as tetracyclines (TCs) including tetracycline, chlortetracycline, and oxytetracycline, and sulfonamides (SAs) including sulfamethazine, sulfamethoxazole, and sulfathiazole were measured by the high-performance liquid chromatography-tandem mass spectrometry via a solid-phase extraction. In the results it was identified that the variations of measured antibiotics’ concentrations in water, sediment, and soil are depending on the season. The observed concentration levels of TCs were higher in winter than in summer season, indicating that the low temperature is a parameter attributing to interruption of its degradation in water, sediment, and soil. The concentration levels of SAs were significantly higher than those of TCs and in general, all measured antibiotics’ concentrations were also in general higher in Korea when compared to those in other countries. The long-term monitoring of antibiotics’ residues in aquatic and terrestrial environments is necessary.     

Determination of Trace Elements in Geological Reference Materials G‐3, GSP‐2 and SGD‐1a by Low‐Dilution Glass Bead Digestion and ICP‐MS

We present a revised alkali fusion method for the determination of trace elements in geological samples. Our procedure is based on simple acid digestion of powdered low‐dilution (flux : sample ≈ 2 : 1) glass beads where large sample dilution demanded by high total dissolved solids, a main drawback of conventional alkali fusion, could be circumvented. Three geological reference materials (G‐3 granite, GSP‐2 granodiorite and SGD‐1a gabbro) decomposed by this technique and routine tabletop acid digestion were analysed for thirty trace elements using a quadrupole ICP‐MS. Results by conventional acid digestion distinctly showed poor recoveries of Zr, Hf and rare earth elements due to incomplete dissolution of resistant minerals. On the other hand, results obtained by our method were in reasonable agreement with reference data for most analytes, indicating that refractory minerals were efficiently dissolved and volatile loss was insignificant.     

Changes of biochemical properties and heavy metal bioavailability in soil treated with natural liming materials

This study evaluated the efficiency of naturally occurring lime-based waste materials (oyster shells, eggshells, and mussel shells) on immobilization of selected heavy metals (Cd and Pb) and a metalloid (As) in a contaminated agricultural soil. A 30-day incubation experiment was performed using soil mixture with natural liming materials or calcite (CaCO₃) at 0, 1, 3, 5, and 10 wt %. Soil biochemical properties including pH, electrical conductivity (EC), exchangeable cations, organic matter (OM), total nitrogen (TN), microbial populations, and enzyme activities were determined to ensure the changes in soil quality during incubation. The results showed that the application of natural liming materials led to an increase in soil pH similar to that of CaCO₃. Soil concentrations of Cd, Pb, and As extracted with 0.1 or 1 M HCl, and diethylene triamine pentacetic acid (DTPA) were decreased significantly after adding liming materials, accompanied by increased microbial population and enzyme activities of dehydrogenase, phosphatase, β-glucosidase, and arylsulfatase. Additionally, eggshells and mussel shells induced significant increases in OM and TN in the soil. Application of natural liming materials offers a cost-effective way to immobilize heavy metals and metalloids in soils.