Multi-proxy evidence for late Holocene anthropogenic environmental changes at Bongpo marsh on the east coast of Korea

We present a multi-proxy record (pollen, microscopic charcoal, magnetic susceptibility, carbon-isotopic composition, total organic carbon [TOC], carbon/nitrogen [C/N] ratios, and particle size) of the late Holocene environmental change and human activities from Bongpo marsh on the east coast of Korea. Mutual interaction between the environment and humans during the late Holocene has not been properly investigated in Korea due to the lack of undisturbed samples with high sedimentation rates. In this study, the history of human responses to late Holocene environmental changes is clearly reconstructed using a multi-proxy paleoenvironmental approach that has not previously been applied in Korea. The evidence from Bongpo marsh indicates that 1) Bongpo marsh began to develop ca. 650 BC as a coastal lagoon was rapidly filled with organic matter, 2) agricultural disturbance around the study site remained slight until ca. AD 600, 3) full-scale intensive agriculture prevailed and the area of deforestation increased between ca. AD 600 and ca. AD 1870, and 4) the land use changed from lowland rice agriculture to upland cultivation when agricultural productivity declined after AD 1870, probably due to severe deforestation and the consequent heavy influx of clastic sediment on rice fields, as described in various historical documents.     

He+ ion implantation and electron irradiation effects on cathodoluminescence of plagioclase

Cathodoluminescence (CL) spectra of unirradiated, He⁺ ion-implanted and electron-irradiated plagioclase minerals contain the following emission bands: (1) below 300 nm due to Pb²⁺, (2) at ~320 and ~350 nm to Ce³⁺, (3) at 380–420 nm to Eu²⁺, Ti⁴⁺ and/or Al–O^?–Al/Ti defects, (4) at 560–580 nm to Mn²⁺ and (5) at 720–760 nm to Fe³⁺. During the implantation of He⁺ ion, much of their energy may be dissipated by partial destruction and strain of the feldspar framework, resulting in quenching of CL. Deconvolution of CL spectra acquired from albite and oligoclase reveals an emission component at 1.86 eV (666 nm) assigned to a radiation-induced defect center associated with Na⁺ atoms. As its intensity increases with radiation dose, this emission component has potential for geodosimetry and geochronometry. Electron irradiation causes Na⁺ migration in plagioclase, and then a considerable reduction in intensity of emissions assigned to impurity centers, which is responsible for an alteration in the energy state or a decrease in luminescence efficiency following the change of activation energy. Emission intensity at 1.86 eV positively correlates with electron irradiation time for unimplanted and He⁺ ion-implanted albite and oligoclase, but negatively for the implanted albite above 1.07 × 10^?4 C/cm². It implies that radiation halo produced by α-particles should not be measured using CL spectroscopy to estimate β radiation dose on albite in the high radiation level.     

Correlations Between Shear Wave Velocity and In-Situ Penetration Test Results for Korean Soil Deposits

Shear wave velocity (V _S) can be obtained using seismic tests, and is viewed as a fundamental geotechnical characteristic for seismic design and seismic performance evaluation in the field of earthquake engineering. To apply conventional geotechnical site investigation techniques to geotechnical earthquake engineering, standard penetration tests (SPT) and piezocone penetration tests (CPTu) were undertaken together with a variety of borehole seismic tests for a range of sites in Korea. Statistical modeling of the in-situ testing data identified correlations between V _S and geotechnical in-situ penetration data, such as blow counts (N value) from SPT and CPTu data including tip resistance (q _t), sleeve friction (f _s), and pore pressure ratio (B _q). Despite the difference in strain levels between conventional geotechnical penetration tests and borehole seismic tests, it is shown that the suggested correlations in this study is applicable to the preliminary determination of V _S for soil deposits.     

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.     

Application of time-lapse digital imagery for ground-truth verification of satellite indices in the boreal forests of Alaska

Satellite remote sensing studies of snow cover in high-latitude boreal forests require ground-truth verification based on ground observation networks. In this study, we used time-lapse digital images to precisely detect the extent of snow cover at nine locations in the boreal forests of Alaska, and to demonstrate the relationship of these ground-truth measurements to satellite indices of snow cover. Our results show that normalized difference vegetation indices (NDVIs) and normalized difference water indices (NDWIs) show significant variations at the end and beginning periods of continuous snow cover: the NDVIs on the last days of continuous snow cover ranged from 0.12 to 0.37, and those on the first days of continuous snow cover ranged from 0.16 to 0.38. The normalized difference snow indices (NDSIs) were also positive during periods of continuous snow cover and negative during periods of no snow cover. The NDWIs varied significantly from the beginning to the end of periods of continuous snow cover. This study confirms that continuous snow cover is important for accurate phenological studies using NDVIs in the region of the trans-Alaska camera network. Simple cameras can be effectively utilized in ground-based networks, functioning not only as a ground-truth verification tools for calibrating satellite indices, but also as a source of data to fill data gaps in satellite records.     

Integrative assessment of organotin contamination in a southern European estuarine system (Ria de Aveiro, NW Portugal): tracking temporal trends in order to evaluate the effectiveness of the EU ban

Organotin (OT) compounds have been used as biocide agents in antifouling paints since the mid 1960s and are now ubiquitous in the marine environment. Due to their high toxicity to non-target species they were banned from antifouling paints in the European Union in 2003 (2002/62/EC directive). The aim of the present work is to assess any obvious decline of the OT environmental levels at Ria de Aveiro (NW Portugal) after the ban. The organotins - monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT), monophenyltin (MPT), diphenyltin (DPT), triphenyltin (TPT), monoctyltin (MOT), dioctyltin (DOT) and trioctyltin (TOT) - were quantified in the gastropod Nassarius reticulatus, in the mussel Mytilus galloprovincialis and in sediments. Imposex (imposition of male characters on females of gonochorist gastropods) in N. reticulatus was additionally used as a biomarker of TBT pollution. Time comparisons show a slight decrease of imposex between 2003 and 2005 probably as a consequence of the EU ban, though in some cases this trend seems to have started earlier since 2000. The fraction of TBT relatively to its metabolites has been decreasing over the last years but still remains high suggesting that there are still recent inputs of this compound into the study area.     

Isomer specific determination of hexabromocyclododecanes (HBCDs) in small cetaceans from the South China Sea--Levels and temporal variation

A diastereoisomer (alpha, beta, and gamma) specific analytical method for measuring hexabromocyclododecanes (HBCDs) was developed using liquid chromatography-tandem mass spectrometry (LC-MS-MS). The method developed was applied to analyze blubber of small cetaceans to divulge the distribution and temporal variation of HBCDs in the Asian marine environment. HBCDs were detected in all the blubber samples of finless porpoises (Neophocaena phocaenoides) and Indo-Pacific humpback dolphins (Sousa chinensis) collected from the South China Sea during 1990-2001. Concentrations of HBCDs were higher in humpback dolphins (31-380 ng/g lipid) than in finless porpoises (4.7-55 ng/g lipid), which can be attributed to habitat differences. Average concentrations of alpha-HBCD in finless porpoises increased from 9.5 ng/g lipid in 1990 to 35 ng/g lipid in 2000/01. alpha-HBCD was predominant among the three isomers with some exceptions in finless porpoises collected in 1990. This is the first report on HBCDs contamination in marine mammals from Southeast Asia.     

Contamination status and spatial distribution of organochlorine compounds in fishes from Nansei Islands, Japan

Two species of fishes (n=52; tilapia and mullet) from industrialized and urbanized areas of Okinawa Island (Manko-Noha river, Hija river and Shikaza river) and from a remote area of Ishigaki Island (Anparu mudflat), Japan were collected between August 2005 and July 2006, and analyzed for five organochlorine compounds (OCs), viz., DDTs, PCBs, CHLs, HCHs and HCB. Concentrations and the contamination patterns of OCs in fishes varied between locations. Considerable residue levels of OCs, especially CHLs and DDTs were found in both fishes from the main Okinawa Island. These levels were relatively higher than the reported values for seafood from Japanese coasts, indicating that even now pollution sources of these contaminants still exist in this region. On the other hand, lower concentrations of OCs were detected in fishes from Ishigaki Island waters than those of other Japanese coastal waters, suggesting that this region is less contaminated by OC contaminants.     

The combined effects of oxygen availability and salinity on physiological responses and scope for growth in the green-lipped mussel Perna viridis

Mussels were maintained for 4 weeks under different combinations of dissolved oxygen concentration (1.5, 3.0 and 6.0 mg O2 l(-1)) and salinity (15, 20, 25 and 30) in a 3×4 factorial design experiment. Clearance rate (CR), absorption efficiency (AE), respiration rate (RR) and scope for growth (SFG) decreased with decreasing salinity and dissolved oxygen concentration (DO), while excretion rate (ER) increased with decreasing salinity and increasing DO. The O:N ratio was <10 at salinities of 15 and 20, irrespective of DO levels. SFG was negative in most of the treatments, except for those under 6.0 mg O2 l(-1) or at a salinity of 30 when DO was lower. The results may help explain the distribution pattern of Perna viridis in Hong Kong waters and provide guidelines for mussel culture site selection.