Agriculture is a pivotal player in the climate change narrative, contributing to greenhouse gas (GHG) emissions while offering potential mitigation solutions. This study delved into agriculture’s climate impact. It comprehensively analysed emissions from diverse agricultural sources, carbon sequestration possibilities, and the repercussions of agricultural emissions on climate and ecosystems. The study began by contextualising the historical and societal importance of agricultural GHG emissions within the broader climate change discourse. It then discussed into GHG emitted from agricultural activities, examining carbon dioxide, methane, and nitrous oxide emissions individually, including their sources and mitigation strategies. This research extended beyond emissions, scrutinising their effects on climate change and potential feedback loops in agricultural systems. It underscored the importance of considering both the positive and negative implications of emissions reduction policies in agriculture. In addition, the review explored various avenues for mitigating agricultural emissions and categorised them as sustainable agricultural practices, improved livestock management, and precision agriculture. Within each category, different subsections explain innovative methods and technologies that promise emissions reduction while enhancing agricultural sustainability. Furthermore, the study addressed carbon sequestration and removal in agriculture, focussing on soil carbon sequestration, afforestation, and reforestation. It highlighted agriculture’s potential not only to reduce emissions, but also to serve as a carbon reservoir, lowering overall GHG impact. The research also scrutinised the multifaceted nature of agriculture, examining the obstacles hindering mitigation strategies, including socioeconomic constraints and regulatory hurdles. This study emphasises the need for equitable and accessible solutions, especially for smallholder farmers. It envisioned the future of agricultural emissions reduction, emphasising the advancements in measurement, climate-smart agricultural technologies, and cross-sectoral collaboration. It highlighted agriculture’s role in achieving sustainability and resilience amid a warming world, advocating collective efforts and innovative approaches. In summary, this comprehensive analysis recognised agriculture’s capacity to mitigate emissions while safeguarding food security, biodiversity, and sustainable development. It presents a compelling vision of agriculture as a driver of a sustainable and resilient future.

The present study estimated rumen fermentation characteristics and greenhouse gas emissions of different forages. Alfalfa, timothy, tall fescue, Italian ryegrass, and rice straw as the main forage sources for Hanwoo were used in the present study. Crude protein was highest in alfalfa but lowest in rice straw (p<0.05). Ether extract was higher in alfalfa and Italian ryegrass than in the other forages (p<0.05). Crude ash was highest in rice straw but lowest in tall fescue (p<0.05). Neutral detergent fiber was highest in tall fescue but lowest in alfalfa (p<0.05). Acid detergent fiber was highest in Italian ryegrass and rice straw but lowest in alfalfa (p<0.05). In vitro digestibilities of dry matter (DMD) and neutral detergent fiber (NDFD) were highest in timothy but lowest in rice straw (p<0.05). Rumen pH was highest (p<0.05) in alfalfa, while ammonia-N was higher (p<0.05) in alfalfa and Italian ryegrass than in the other forages. Total volatile fatty acid was highest (p<0.05) in timothy, while acetate and propionate were highest (p<0.05) in alfalfa and rice straw, respectively. Acetate to propionate ratio was higher (p<0.05) in alfalfa, timothy, and Italian ryegrass than in rice straw. Rice straw had lowest total gas (mL) (p<0.05) but highest its per DMD and NDFD. Rice straw had higher (p<0.05) CO2 (per DMD and NDFD) compared to alfalfa (per DMD and NDFD), timothy (per DMD and NDFD), tall fescue (per NDFD), and Italian ryegrass (per DMD). Again, rice straw had higher (p<0.05) CH4 (per DMD and NDFD) compared to timothy (per DMD and NDFD) and tall fescue (per NDFD). Therefore, this study indicates that timothy has a higher nutrient digestibility and volatile fatty acid in the rumen leading to a reduction of greenhouse gas emission.

Fossil fuel combustion during fishing activities is a major contributor to climate changes in the fishing industry. The Tier1 methodology calculation and on-site continuous measurements of the greenhouse gas were carried out through the use of fuel by the coastal and offshore gillnet (blue crabs and yellow croaker) and trap (small octopus and red snow crab) fishing boats in Korea. The emission comparison results showed that the field measurements are similar to or slightly higher than the Tier1 estimates for coastal gillnet and trap. In offshore gillnet and trap fisheries, Tier1 estimate of greenhouse gases was about 1,644-13,875 kg CO2/L, which was more than the field measurement value. The CO2 emissions factor based on the fuel usage was 2.49-3.2 kg CO2/L for coastal fisheries and 1.46-2.24 kg CO2/L for offshore fisheries. Furthermore, GHG emissions per unit catch and the ratio of field measurement and Tier1 emission estimate were investigated. Since the total catch of coastal fish was relatively small, the emission per unit catch in coastal fisheries was four to eight times larger. The results of this study could be used to determine the baseline data for responding to changes in fisheries environment and reducing greenhouse gas emission.

The objective of this study was to determine the effect of various roughage sources on nutrient digestibility and enteric methane (CH4), and carbon dioxide (CO2) production in goats. Four castrated black goats (48.5 ± 0.6 kg) were individually housed in environmentally controlled respiration-metabolism chambers. The experiment design was a 4 × 4 balanced Latin square design with 4 roughage types and 4 periods. Alfalfa, tall fescue, rice straw, and corn silage was used as representative of legume, grass, straw, and silage, respectively. Dry matter digestibility was higher (p < 0.001) in corn silage than in alfalfa hay. Dry matter digestibility of alfalfa hay was higher than those of tall fescue or rice straw (p < 0.001). Neutral detergent fiber digestibility of tall fescue was lower (p < 0.001) than those of alfalfa, rice straw, or corn silage. Daily enteric CH4 production and the daily enteric CH4 production per kilogram of BW0.75, dry matter intake (DMI), organic matter intake (OMI), digested DMI, and digested OMI of rice straw did not differ from those of tall fescue but were higher (p < 0.001) than those of alfalfa or corn silage. Roughage type had no effect on enteric CO2 emission in goats. Straw appeared to generate more enteric CH4 production than legume or silage, but similar to grass.

PURPOSES: To analyze the specific factors of drivers behaviors that amount of cause the greenhouse gas emissions per vehicle. METHODS: Drivers behaviors at intersections are analyzed on the conditions of acceleration and deceleration. RESULTS : First, it is resulted greenhouse gas emissions per vehicle is produced more at intersections than at the main lines of highway. Second, it is resulted that the average speed, the average acceleration rate and the maximum speed are three major factors to produce greenhouse gas per vehicle in acceleration sections. Third, it is resulted that rapid deceleration 20m before entering intersections is the major factor to produce greenhouse gas per vehicle in deceleration sections. CONCLUSIONS: At intersections, sudden acceleration and deceleration is not good for greenhouse gas emissions. Thus, and the average speed, the average acceleration rate and the maximum speed are the chosen as factors to be controlled for drivers' behavior to reduce vehicles' greenhouse gas at intersections.

이 연구는 경안천 토양에서 기후 조건의 차이, 식물의 유무, 질소 농도의 차이에 따른 토양의 생물학적 유기물 분해속도의 변화가 대기 중 온실가스(CH4, CO2) 발생에 미치는 영향을 알아보고자 하였다. 본 연구 결과, 유기물 분해속도와 CH4, CO2 flux 모두 환경 조건이 동시에 변화하는 경우에 영향을 받음을 알 수 있었다. 유기물 분해 속도는 기후 조건의 차이와 질소 농도의 차이, 기후 조건 차이와 식물의 유무가 있는 경우 에 영향을 받음을 알 수 있었다. CH4 flux는 기후 조건 차이와 질소 농도의 차이, 기후 조건 차이와 식물의 유 무, 식물의 유무와 질소 농도의 차이가 있는 경우에 영향 이 있었으며 CO2 flux는 기후 조건 차이와 식물의 유무, 식물의 유무와 질소 농도의 차이가 있는 경우에 영향이 있음을 통해 기후 조건 차이와 식물의 유무, 질소 농도의 차이가 유기물 분해속도에 영향을 주어 대기 중 온실가 스 발생에 영향을 줄 수 있음을 알 수 있었다. 기후 조건 차이는 토양의 분해를 증진시켜 대기로 방 출되는 온실가스 또한 가중시킬 수 있다고 알려져 있으 나, 본 연구를 통해 기후변화가 유기물의 분해와 대기로 의 온실가스 방출을 감소시킬 수 있다는 결과를 도출할 수 있었으며 기후 조건 차이 외의 질소가 유입될 경우, 순영향(positive effect)을 주게 됨을 알 수 있었다. 그러 나 식물의 영향이 작용할 경우 질소의 유입으로 인한 순 영향을 감소시킬 수 있음을 알 수 있었으며, 이에 따른 추가적인 연구가 필요할 것으로 판단된다.

우리나라는 2015년부터 육상 온실가스 다배출 부문을 대상으로 기후변화의 위험성 감소를 위해 온실가스 배출권거래제도 시행을 통하여 온실가스배출 감축을 추진하고 있다. 그러나 해운부문은 선박활동방식의 국제성을 기반으로 국제해사기구(IMO)를 통해 부문별 접근방식으로 전 세계 모든 선박이 일률적인 규제를 통하여 온실가스 배출을 제한하는 제도를 마련하고 있다. 이미 2011년 기술적․운항적 온실가스 규제안을 마련한데 이어 시장기반적 조치에 대하여 선박을 대상으로 논의 중에 있다. 그 중에서도 전통적인 시장기반 조치 중의 하나인 배출권거래제도에 대하여 중요하게 논의되고 있다. 그러나 해운부문은 배출권거래제도 제안문서에서 지목되고 있는 안전경영증서상의 선박운항자가 온실가스관리 업무를 맡기에는 계약구조에 따른 선박의 소유, 점유 및 사용하는 방식의 차이에 따라 일률적으로 적용하기에는 한계가 있다. 육상부문의 배출권거래제도가 점오염원을 대상으로 시행되는 것과는 달리 선박은 비점오염원으로서의 특성이 있어서 관리가 쉽지 않은 실정이다. 또한 해운이 자본집약적 산업임에도 불구하고 글로벌 초대형선사와 중․소형선사간에 인력운용에 따른 수준 격차로 인해 배출권거래제도 편입에 따른 대응문제 등 다양한 문제점이 있다. 이 논문에서는 선박 온실가스배출규제를 위한 배출권거래제도 도입에 있어 앞서 제기한 문제점을 극복하고 국제해사기구의 부문별 접근방식, 전통적인 환경법의 원칙인 오염자 부담의 원칙 이행 및 기후변화협약의 유연성체제 등을 균형 있게 이행할 수 있는 방안에 대해 검토하였다.

Over the past two decades, the options for solid waste management have been changing from land disposal to recycling, waste-to-energy, and incineration due to growing attention for resource and energy recovery. In addition, the reduction of greenhouse gas (GHG) emission has become an issue of concern in the waste sector because such gases often released into the atmosphere during the waste management processes (e.g., biodegradation in landfills and combustion by incineration) can contribute to climate change. In this study, the emission and reduction rates of GHGs by the municipal solid waste (MSW) management options in D city have been studied for the years 1996-2016. The emissions and reduction rates were calculated according to the Intergovernmental Panel on Climate Change guidelines and the EU Prognos method, respectively. A dramatic decrease in the waste landfilled was observed between 1996 and 2004, after which its amount has been relatively constant. Waste recycling and incineration have been increased over the decades, leading to a peak in the GHG emissions from landfills of approximately 63,323 tCO2 eq/yr in 2005, while the lowest value of 35,962 tCO2 eq/ yr was observed in 2016. In 2016, the estimated emission rate of GHGs from incineration was 59,199 tCO2 eq/yr. The reduction rate by material recycling was the highest (-164,487 tCO2 eq/yr) in 2016, followed by the rates by heat recovery with incineration (-59,242 tCO2 eq/yr) and landfill gas recovery (-23,922 tCO2 eq/yr). Moreover, the cumulative GHG reduction rate between 1996 and 2016 was -3.46 MtCO2 eq, implying a very positive impact on future CO2 reduction achieved by waste recycling as well as heat recovery of incineration and landfill gas recovery. This study clearly demonstrates that improved MSW management systems are positive for GHGs reduction and energy savings. These results could help the waste management decision-makers supporting the MSW recycling and energy recovery policies as well as the climate change mitigation efforts at local government level.

국제연합식량농업기구(FAO, United Nations Food and Agriculture Organization)의 보고서에 따르면 21세기 전 세계의 인구는 2050년 약 90억에 달할 것으로 예측되며, 이러한 인구팽창으로 인한 식량부족 및 사료공급의 문제는 생산 시 야기되는 자원고갈 및 환경영향에 대한 우려와 함께 전 세계의 큰 관심사로 화두되었다. 이렇듯 현대사회가 직면한 복합적인 문제점을 해결하기 위해 전 세계적으로 새로운 미래자원에 대한 탐색이 이루어졌으며, 곤충이 하나의 유망자원으로서 새롭게 각광받기 시작하였다. 특히 목질을 섭식하는 흰개미의 경우 난분해성 물질인 리그닌과 셀룰로오스의 분해능력으로 인해 해외에서는 이미 오래전부터 흰개미의 장내 미생물을 이용하여 목질계 바이오매스로부터 바이오에탄올을 생산하는 방법에 대해 연구가 진행되어왔다. 하지만 국내에서는 흰개미를 목조 문화재를 가해하는 해충으로 분류하여 흰개미의 방제에 초점을 맞추어 연구가 많이 진행되어왔을 뿐 유용자원으로서의 흰개미의 잠재성에 대한 관심과 연구가 미흡한 실정이다. 또한, 흰개미는 우수한 단백질 공급원으로서 일부 국가에서는 식용 및 사료로서 활용하고 있지만 이에 따른 환경영향 및 효율에 관한 연구 역시 미흡하다. 따라서 본 연구는 국내에 분포하는 일본흰개미(Reticulitermes speratus kyushuensis Morimoto)를 대상으로 흰개미가 주로 섭식하는 폐목재를 먹이로 주어 사육하였을 때, 생산되는 식용과 사료의 온실가스 발생량(LCA, Life cycle assessment)과 질소의 순환효율(ROI, Return on Investment)을 정량화하여 환경적･경제적 이점을 도출하고자 하였다.정량화된 온실가스 발생량과 질소의 순환효율은 식용으로 활용할 경우 기존의 단백질원인 한우, 양돈, 육계, 대두와 비교하고, 사료의 경우 대두박과 비교하였다. 그 결과 흰개미를 식용과 사료로 이용할 경우 온실가스 발생량 측면에서 비교적 높은 값을 나타내었으며, 질소의 순환효율에서는 상대적으로 우수한 결과를 나타내었다. 미래 유망자원으로서 보다 다양한 곤충에 대한 탐색이 이루어질 필요성이 있으며, 곤충활용에 따른 환경적⋅경제적 이점의 정량화는 향후 곤충산업의 발전방향을 제시하고 활성화하는데 이바지할 수 있을 것으로 예상한다.

국제연합식량농업기구(FAO, United Nations Food and Agriculture Organization)의 보고서에 따르면 21세기 전 세계의 인구는 2050년 약 90억에 달할 것으로 예측되며, 이러한 인구팽창으로 인한 식량부족 및 사료공급의 문제는 생산 시 야기되는 탄소, 질소의 손실로 인한 자원고갈 및 환경영향에 대한 우려와 함께 전 세계의 큰 관심사로 화두되었다. 또한, 대두, 유채, 팜을 이용한 식물성 바이오오일의 생산은 식량작물을 에너지작물로 활용함에 따라 개발도상국의 식량부족 문제를 심화시키는 악효과를 야기했다. 이렇듯 현대사회가 직면한 복합적인 문제점을 해결하기 위해 전 세계적으로 새로운 미래자원에 대한 탐색이 이루어졌으며, 곤충이 하나의 유망자원으로서 새롭게 각광받기 시작하였다. 다양한 곤충 중 흰개미의 경우, 분류계통상 고등 및 하등 흰개미로 분류되는데 종류에 따라 섭식대상이 다양하며 소화기작에서도 약간의 차이를 보인다. 특히 목질을 섭식하는 흰개미는 난분해성 물질인 리그닌과 셀룰로오스의 분해능력으로 인해 해외에서는 이미 오래전부터 흰개미의 장내 미생물을 이용하여 목질계 바이오매스로부터 바이오에탄올을 생산하는 방법에 대해 연구가 진행되어왔다. 하지만 국내에서는 흰개미를 목조 문화재를 가해하는 해충으로 분류하여 흰개미의 방제에 초점을 맞추어 연구가 많이 진행되어왔을 뿐 유용자원으로서의 흰개미의 잠재성에 대한 관심과 연구가 미흡한 실정이다. 또한, 흰개미는 우수한 단백질 공급원으로서 일부 국가에서는 식용 및 사료로서 활용을 하고 있지만 이에 따른 환경영향 및 효율에 관한 연구 역시 미흡하다. 따라서 본 연구는 국내에 분포하는 흰개미 중 일본흰개미(Reticulitermes speratus kyushuensis Morimoto)를 대상으로 흰개미가 주로 섭식하는 폐목재를 먹이로 주어 사육하였을 때, 생산되는 오일과 식용의 온실가스 발생량과 탄소와 질소의 순환효율을 정량화하여 흰개미를 산업용으로서 활용하는 것에 대한 타당성과 전체 탄소와 질소의 물질흐름에 있어서 환경적･경제적 이점을 정량화하고자 하였다.

Sulfate produced during anaerobic reduction limits the activity of methanogens but it is not reflected in the Intergovernmental Panel on Climate Change (IPCC) methodology for estimating CH4 emissions. In this study, CH4 emissions from the Sudokwon landfill site were estimated by adopting a methane correction factor, which was determined through the relationship between the COD/sulfate ratio and CH4 generation. Although the gas originating from the Sudokwon landfill site has not produced any environmental problems in recent years due to gas collection and soil cover maintenance activities, CH4 emissions estimated by the IPCC methodology indicated that only 60% of the CH4 was recovered and the remainder was emitted into the atmosphere, suggesting a potential environmental problem. Accordingly, CH4 estimates determined according to IPCC methodology must be modified by adopting the methane correction factor and considering the effect of sulfate concentration.

This study presents detailed emission of greenhouse gases of using Clean Energy Agriculture System according to a cradle-to-gate life-cycle assessment, including emission from energy use and leak of Biogas. Calculations were done with the PASS software and the covered gases are CH4, N2O and CO2, Total GHG fluxes of amount to 1719.03 kgCO2/day, 39.63 kgCO2/day (2.31%) are from facility house process, 0.19 kgCO2/day (0.01%) are from transport process, 696.72 kgCO2/day (40.53%) are from Anaerobic digestion process, 846.61 kgCO2/day (49.25%) are from Heating and cooling system, 135.88 kgCO2/day (7.90%) are from Fertigation production process. The results suggest that for effective reduction of GHG emissions from Facility house using clean energy. Reduction targets should address both the production process as defined by IPCC sectors and the consumption process. An LCA assessment as presented here could be a basis for such efforts.

산업혁명 이후 연료의 사용이 늘어 CO2 배출량이 급증하여 지구온난화로 인한 다양한 환경변화를 야기해 전 세계가 기후 변화의 위협에 직면해 있다. 국내 온실가스 총 배출량 중 건설 분야 비중은 약 42%로 높은 비중을 차지하고 있으며, 이 중 도로 분야는 약 16%의 비중을 차지하고 있다. 건설재료 및 자재는 제조 시 대부분 화석연료를 사용하므로 CO2 발생량이 매우 많다. 이와 같은 상황을 고려하여 도로 분야에서도 점차적으로 환경 친화적 건설에 대한 중요성이 부각되고 있다. 최근 국내에서는 도로건설로 인하여 발생되는 환경문제를 해소하기 위한 방안으로 친환경 도로건설을 이루기 위하여 다양한 포장 공법이 개발되고 있으나 소음저감, 미끄럼저항 증대 또는 내구성 강화 등의 기능성 측면만을 고려하여 연구가 진행되어졌을 뿐 도로 이용자 측면에서의 친환경성을 확보하고자 오염물질의 저감 및 화석자원의 고갈 등에 대한 근본적인 환경문제의 해결은 미비한 실정이다. 본 연구에서는 친환경 도로포장의 재료로 슬래그 골재를 사용하였고, 슬래그 골재의 입도 및 기초물성 측정, 혼합물 제작을 수행하였다. 슬래그 골재는 다공성 재질로 일반 골재의 흡수율 기준보다 높게 측정되었고, 혼합물 제작 시 조건을 다르게 하여 평가를 진행하였다. 슬래그의 밀도 차이로 동일 중량임에도 두께 얇고 일반 골재와 혼합시 두 재료의 밀도가 다르기 때문에 통과중량백분율 적용이 어려운 것으로 확인되었다. 밀도가 다른 두 재료의 혼합을 위해 체적 단위로 환산한 배합비를 적용하여 배합설계를 수행하였다. 두 종류로 제작된 혼합물의 비교를 통해 슬래그 골재 사용의 극대화 한 재활용 포장 기술의 적용 및 고부가가치화 목적을 두어 연구를 진행하였다.

The IPCC methodology for estimating methane emissions from a solid waste landfill is based on the first order decay (FOD) method. One emission factor in the model is the methane generation potential (L0) that is estimated from the amount of decomposable degradable organic carbon (DOC) in a solid waste landfill. L0 is estimated based on the fraction of DOC in the waste, the fraction of the degradable organic carbon that decomposes under anaerobic conditions (DOCf), methane correction factor (MCF), and the fraction of methane in generated landfill gas (F). The other emission factor is the methane generation rate constant (k). The IPCC recommended that every country needs to develop country-specific key parameters (DOC, DOCf, k) more appropriate for its circumstances and characteristics. The objective of this research was to investigate the greenhouse gas emission factor (k) and parameters (DOC, DOCf) for wood wastes in a solid waste landfill. To investigate DOC, DOCf, and k for wood wastes, the biodegradable rate of wood wastes was determined by comparing the composition of excavated samples (L-1, L-2) with their fresh ones (F-1, F-2). The DOC values were found to be 48.36% and 45.27% for F-1 and F-2, respectively. It showed that the IPCC default value of DOC for wood wastes is appropriate for estimating methane emission. The maximum DOCf (0.17 and 0.18) or each wood waste excavated from G landfill was found to be lower compared with those for IPCC. The IPCC provided that default values of DOCf 0.5. The k values were found to be 0.0055 and 0.0058 year−1 for F-1 and F-2, respectively. The result confirmed that the biodegradation rate of wood wastes was very slow due to its lignin.

Analysis and evaluation of uncertainty is adopting the advanced methodology among the methods for greenhouse gas emission assessment that was defined in GPS2000 (Good practice guideline 2000) and GPG-LULUCF (GPG Land Use, Land-Use Change and Forestry). In 2006 IPCC guideline, two approaches are suggested to explain the uncertainty for each section with a national net emission and a prediction value on uncertainty as follows; 1) Spread sheet calculation based on the error propagation algorithm that was simplified with some assumptions, and 2) Monte carlo simulation that can be utilized in general purposes. There are few researches on the agricultural field including greenhouse gas emission that is generated from livestock and cultivation lands due to lack of information for statistic data, emission coefficient, and complicated emission formula. The main objective of this study is to suggest an evaluation method for the uncertainty of greenhouse gas emission in agricultural field by means of intercomparison of the prediction value on uncertainties which were estimated by spread sheet calculation and monte carlo simulation. A statistic analysis for probability density function for uncertainty of emission rate was carried out by targeting livestock intestinal fermentation, excrements treatment, and direct/indirect emission from agricultural lands and rice cultivation. It was suggested to minimize uncertainty by means of extraction of emission coefficient according to each targeting section.

Quantifying greenhouse gas (GHG) emission is important for evaluating various reduction measures for greenhouse gas, which causes significant negative impacts on earth. To estimate GHG emission from waste sector over the period of between 2000 and 2009 in Daejeon Metropolitan City, the 2006 IPCC (Intergovernmental Panel on Climate Change) and Korean GHG Inventory for local government guidelines and methodologies were employed. Four different waste treatment methods (landfill, incineration, biological treatment, and Sewage wastewater treatment) were evaluated to estimate GHG emission by following the guidelines. The trends of GHG emission rate by direct emission increased between 2000 and 2009 as a result of increased incineration rate. The solid waste sector was directly responsible for 307,700 tonCO2eq/yr in 2009. Incineration contributed approximately 57% of the GHG emission, while landfill disposal was responsible for about 30% of the GHG. Approximately 464,400 tonCO2eq/yr in 2009 was emitted by indirect emission from the waste sector. Based on the results, a variety of measures are needed to reduce the GHG emission from waste sector in Daejeon Metropolitan City along with implementing effective waste source reduction and recycling policy. More specifically, this evaluation proposed that among the possible reduction options, further source separation of recyclables as well as improved diversion of recyclable materials at proposed Daejeon resource recycling complex in 2014 would have the greater benefits for reducing GHG emissions in Daejeon Metropolitan City's waste sector.