Daeseok Kang

Relationships among the abundances of plastic debris in different size classes on beaches in South Korea.

Plastic debris on six beaches near the Nakdong River Estuary, South Korea, was sampled in May and September 2012 and classified into three size classes, large microplastics (1-5 mm), mesoplastics (5-25 mm), and macroplastics (>25 mm). The relationships among the abundances of the size classes were then examined. The abundances of each size category in May (before rainy season) and in September (after rainy season) were 8205 and 27,606 particles/m(2) for large microplastics, 238 and 237 particles/m(2) for mesoplastics, and 0.97 and 1.03 particles/m(2) for macroplastics, respectively. Styrofoam was the most abundant item both in microplastic and mesoplastic debris, while intact plastics were most common in macroplastic debris. The abundances of meso- and micro-plastics were the most strongly correlated. There was a higher correlation between the abundances of macro- and meso-plastics than between macro- and micro-plastics.

Impacts of marine debris on wild animals in the coastal area of Korea.

Over the last decade, marine debris has become a major factor affecting the coastal ecosystem of Korea. This study compiled information regarding how marine debris impacts wildlife in Korea. Cases of marine debris impacting wildlife were collected from experts of various fields and from local participants through an open access website from February 2010 to March 2012. A total of 21 species were affected by marine debris: 18 species of birds, 2 species of mammals, and 1 species of crustacean. Five threatened or protected species were identified: black-faced spoonbill, finless porpoise, water deer, whooper swan, and greater painted snipe. Recreational fishing gears were the types of debris that most frequently impacted wildlife, especially birds. Black tailed gulls were the most vulnerable species to recreational fishing hooks and lines. Although it was preliminary, this study revealed that recreational fishing activities should be prioritized when managing marine debris in Korea.

Quantities, composition, and sources of beach debris in Korea from the results of nationwide monitoring

This study assessed the levels of marine debris pollution and identified its main sources in Korea. The surveys were bimonthly conducted by NGO leaders and volunteers on 20 beaches from March 2008 to November 2009. The quantities of marine debris were estimated at 480.9 (±267.7) count⋅100 m(-1) for number, 86.5 (±78.6) kg⋅100 m(-1) for weight, and 0.48 (±0.38) m(3)⋅100 m(-1) for volume. The level of marine debris pollution on the Korean beaches was comparable to that in the coastal areas of the North Atlantic ocean and South Africa. Plastics and styrofoam occupied the majority of debris composition in terms of number (66.7%) and volume (62.3%). The main sources of debris were fishing activities including commercial fisheries and marine aquaculture (51.3%). Especially styrofoam buoy from aquaculture was the biggest contributor to marine debris pollution on these beaches.

Improved water quality in response to pollution control measures at Masan Bay, Korea

The total pollution load management system (TPLMS) was first applied in 2007 to the highly developed Masan Bay watershed, Korea. To evaluate the effect of TPLMS on water quality improvement, we analyzed the water qualities in rivers and bay during 2005-2010, targeting chemical oxygen demand (COD), suspended sediment (SS), total nitrogen (TN), and total phosphorus (TP) loads. Land-based pollutant loading all decreased during this period, with a significant reduction in COD and SS loads (p<0.01). The COD reduction in seawater, following the TPLMS implementation, was also significant (p<0.01). Time-lagged responses in COD and Chl-a supported an estimated seawater residence time of ~1 month. Land-based nutrient loads were also significantly reduced for TN (p<0.01) and TP (p<0.05), however, significant reductions were not observed in the bay, indicating potential alternative nutrient inputs from non-point sources into the bay system.

Effects of humic acid on phytodegradation of petroleum hydrocarbons in soil simultaneously contaminated with heavy metals

The use of humic acid (HA) to enhance the efficiency of phytodegradation of petroleum hydrocarbons in soil contaminated with diesel fuel was evaluated in this study. A sample of soil was artificially contaminated with commercially available diesel fuel to an initial total petroleum hydrocarbons (TPH) concentration of 2300 mg/kg and four heavy metals with concentrations of 400 mg/kg for Pb, 200 mg/kg for Cu, 12 mg/kg for Cd, and 160 mg/kg for Ni. Three plant species, Brassica campestris, Festuca arundinacea, and Helianthus annuus, were selected for the phytodegradation experiment. Percentage degradation of TPH in the soil in a control pot supplemented with HA increased to 45% from 30% without HA. The addition of HA resulted in an increases in the removal of TPH from the soil in pots planted with B. campestris, E arundinacea, and H. annuus, enhancing percentage degradation to 86%, 64%, and 85% from 45%, 54%, and 66%, respectively. The effect of HA was also observed in the degradation of n-alkanes within 30 days. The rates of removal of n-alkanes in soil planted with B. campestris and H. annuus were high for n-alkanes in the range of C11-C28. A dynamic increase in dehydrogenase activity was observed during the last 15 days of a 30-day experimental period in all the pots amended with HA. The enhanced biodegradation performance for TPHs observed might be due to an increase in microbial activities and bioavailable TPH in soils caused by combined effects of plants and HA. The results suggested that HA could act as an enhancing agent for phytodegradation of petroleum hydrocarbons in soil contaminated with diesel fuel and heavy metals.

Biosorption and growth inhibition of wetland plants in water contaminated with a mixture of arsenic and heavy metals

The potential of wetland plants as an onsite biosorbent and a biomonitor for combined pollution of arsenic and four heavy metals from non‐point sources was investigated in this study. Ceratophyllum demersum, Hydrilla verticillata, Hydrocharis dubia, and Salvinia natans were exposed to a water containing mixture of As, Cr, Cu, Pb, and Zn. Growth inhibition and biosorption potential of the wetland plants in artificially contaminated conditions were studied. These contaminants significantly reduced the growth of the plants. The tested wetland plants accumulated appreciable amounts of the contaminants in the following order: Pb>Cr>Cu>Zn>As. H. verticillata showed distinct visual change and a high biosorption factor (BSF) rank for As and heavy metals among the plants used in the study. As an unspecific collector of contaminants, it might be useful as a biomonitor and biosorbent in the As and heavy metal‐contaminated aquatic system.

Prediction of macrozoobenthic species distribution in the Korean Saemangeum tidal flat based on a logistic regression model of environmental parameters

This study aims to contribute to the development of heuristic statistical models, which are able to predict benthic macrofaunal responses to environmental gradients in coastal areas, such as tidal flats. Ecological response surfaces were derived for 15 intertidal macrobenthic species, using logistic regression based on three separate environmental parameters (shore level, mud content, and organic content) measured on the tidal flats of the Saemangeum estuary, Korea. The presence/absence of the 15 intertidal macrofauna was accurately predicted from each separate environmental factor in the environmental models, with a prediction accuracy of ~65–92%. Subsequently, geographical comparison was made between the mapped probability surfaces and maps of observed species occurrence. The results indicated that the models developed for different species exhibited a wide variety of functional forms, highlighting potential variability in species response to changes in habitat conditions, even for closely associated species with a similar trophic type. Our modeling approach was capable of predicting macrobenthic species distributions with a relatively high degree of accuracy, although the ecological processes controlling intertidal macrobenthic distribution could not be fully determined. Overall, good agreement between modeling results and field observations, with relatively high concordance regardless of target species, emphasized that such an approach would be of practical use in terms of ecosystem approach to tidal flat management.

Emergy Evaluation of the Korean Economy and Environment: Implications for the Valuation of Marine Ecosystem Services

− Several emergy researches have been carried out to estimate the value of marine ecosystem services in Korea over the last decade. Their results cannot be compared mainly due to inconsistency in emergy-money ratios used to convert emergy unit into monetary unit. This study aimed at providing a standardized format for the emergy evaluation of the Korean economy and environment for different emergy evaluations to be compatible. Even though the area of the continental shelf increased in this study compared to those of previous studies, areaweighted average tidal range for the entire continental shelf of Korea resulted in smaller tidal range, decreasing the final emergy input from tide. However, emergy inputs from nonrenewable resources and purchased goods and services increased with new categorization and use of more detailed data, combined with updated unit emergy values. This led to higher emergy-money ratio for the Korean economy, indicating that previous emergy valuations might have overestimated the contributions of marine ecosystem to the real wealth of the Korean society. The base year for gross domestic product used in the emergy evaluation needs to be clearly indicated due to its impact on the calculation of the emergy-money ratio. A standardized emergy table for the Korean economy will contribute to ensuring consistency among future emergy researches on the valuation of marine ecosystem services.

Emergy evaluation of management measures for derelict fishing gears in Korea

Derelict fishing gears (DFGs) have been recognized as an important marine debris issue that requires urgent action in Korea. This study used the emergy methodology to evaluate the cost efficiency of three DFG management measures of Korea from a biophysical perspective. Selected measures were the cleanup-using-ships (CL) program, the buyback (BB) program, and the floating reception barge (FB) program that ranged from more preventive approaches to curative ones in the management spectrum of DFGs. Among three measures, the CL program was the costliest one to implement both in emergy and monetary terms. The FB program that is closest to the preventive side of the spectrum required the least emergy input and monetary cost. The emergy requirements per ton of DFGs collected for the CL and BB programs were 4.4 and 3.6 times that of the FB program, respectively. The CL and BB program also required more inputs in monetary terms - 8.6 and 6.8 times higher, respectively, than the FB program did. The closer a measure is to the preventive side of the management spectrum, the less costly its implementation. This suggests that in terms of cost to implement, the current DFG management policy needs to be reorganized so that preventive measures can play a larger role in dealing with DFG issues in Korea.

The Honolulu Strategy and Its Implication to Marine Debris Management in Korea

The Honolulu Strategy is a framework document to address marine debris issue globally. The Fifth International Marine Debris Conference held in March 2011 and organized by NOAA and UNEP catalyzed the development of the Holonulu Strategy. Goals of the Strategy are to reduce the amount and impact of land-based, sea-based, and accumulated marine debris. A set of strategies for each goal were provided for education and awareness, legislation, and alternative technologies. The Strategy also lists indicators that could be used to evaluate outcomes of strategies. The adoption of the Honolulu Strategy by the international community has led the international organizations such as GPA, IMO, and CBD to strengthen their responses to the marine debris issue. UN has also set up specific actions that will be implemented until 2025 through its resolutions on marine debris. Recent global developments related to the marine debris issue might lead to a change in the character of the international marine debris management from the current soft law regime to a mandatory one. The Honolulu Strategy could provide a guideline when the Korean government formulates the Second Basic Plan for Marine Debris Management, especially with its prevention-oriented approaches, utilization of scientific policy development tools, and adoption of evaluation system using performance indicators.