This meta-analysis evaluates the impact of reducing crude protein (CP) levels in growing pig diets on manure nitrogen emissions to identify strategies for maximizing environmental benefits. A systematic search of PubMed, ISI Web of Science, and Scopus (2003 to 2024) yielded 56 observations from 10 studies. We employed random-effects models with restricted maximum-likelihood (REML) estimation and used Hedges’ g to calculate standardized mean differences (SMD). Additionally, meta-regression and broken-line regression analyses were conducted to investigate heterogeneity and emission breakpoints. The results indicate that low-protein diets significantly reduce both urinary nitrogen emissions (SMD = -5.09; p < 0.0001) and fecal nitrogen emissions (SMD = -0.79; p < 0.001). Substantial heterogeneity was observed for both fecal ($I^2$ = 81.6%) and urinary ($I^2$ = 81.7%) nitrogen emissions (p < 0.0001), highlighting the influence of varying study conditions. Broken-line regression analysis identified a significant breakpoint for urinary nitrogen emissions at 18.8% CP (p < 0.01), whereas no significant breakpoint was observed for fecal nitrogen emissions. Meta-regression analysis revealed that every 1% decrease in dietary CP was associated with increased supplementation of synthetic amino acids, including DL-methionine (p < 0.05), DL-tryptophan (p < 0.04), and L-threonine (p < 0.02), with L-lysine showing a tendency to increase (p = 0.10). Furthermore, economic analysis demonstrated that a moderate reduction to 15% CP, supplemented with four essential amino acids, yields a net cost saving of approximately $2.80 USD per metric ton; conversely, a drastic reduction to 13% CP incurs a net cost increase of approximately $14.30 USD per metric ton due to the high cost of valine and isoleucine. In conclusion, reducing dietary crude protein levels serves as an effective strategy for mitigating urinary nitrogen emissions, necessitating the precise supplementation of synthetic amino acids to balance environmental benefits with the nutritional requirements of growing pigs.

Ammonia (NH3) emissions from swine manure are a major contributor to livestock odor and air pollution. In this study, the urease inhibitor Phenyl- Phosphorodiamidate (PPDA) was applied as a preventive control strategy, and its reduction efficiency was evaluated through both chamber simulations and a pilot-scale pig house experiment. The chamber experiment, conducted from March 17 to May 1, 2023, showed that the treatment group receiving both urea and PPDA (P1) exhibited a 53% lower mean NH3 concentration (51.1±15.1 ppm) compared with the urea-only group (U1, 109.0±34.0 ppm; p < 0.001). The maximum concentration was also reduced by 63.8% (245.1 ppm in U1 vs. 88.8 ppm in P1). Dose-dependent tests revealed that reduction efficiency increased with PPDA dosage (1.0 g, 32.3%; 0.5 g, 27.3%; 0.1 g, 21.1%), but gains plateaued beyond 0.5 g, suggesting economic feasibility at intermediate levels. The pilot-scale experiment, conducted in a mechanically ventilated pig house from May 13 to August 2, 2024, confirmed the short-term effectiveness observed in the chamber tests. During the first application period, the treatment group (P5) maintained approximately 50% lower NH3 concentrations than the control group (C2). However, the effect decreased to less than 5% during the second period, and concentrations converged with or exceeded those of the control group during the finishing stage. This decline was attributed to factors such as insufficient slurry mixing, dosage mismatch due to an increase in body weight, and physicochemical changes in the slurry environment. These findings indicate that PPDA effectively suppresses urea hydrolysis and reduces acute NH3 peaks, thereby functioning as a preventive mitigation strategy. Although its long-term efficacy under field-like conditions was limited, optimization of dosage, re-application intervals, and slurry management could enhance performance. Overall, this study demonstrates the potential of PPDA to shift livestock odor management from conventional end-of-pipe approaches toward preventive control strategies, providing a scientific basis for integrated and sustainable odor mitigation.

This study evaluated the effects of dietary cellulose-to-starch ratios on nutrient digestibility, fermentation characteristics, and greenhouse gas emissions in the rumen. For 48 h of in vitro rumen incubation, each substrate (0.3 g) was incubated with rumen fluid mixture (30 mL) in quadruplicate. Six treatments were formulated with different ratios of structural (cellulose-based) and non-structural (starch-based) carbohydrates (10:0, 8:2, 6:4, 4:6, 2:8, and 0:10). After incubation, total gas emission was measured and analyzed for CO2 and CH4. The remaining contents were centrifuged to determine rumen fermentation characteristics and digestibility. The crude protein level of all treatments was maintained at 15% by combining soybean meal and urea. After incubation, in vitro dry matter digestibility (IVDMD) and organic matter digestibility (IVOMD) increased linearly with higher starch content, while ammonia-N and total volatile fatty acid (VFA) concentrations decreased quadratically. In addition, acetate concentration and the acetate to propionate (A:P) ratio increased along with starch content (p<0.05), whereas propionate concentration decreased (p<0.05). As starch content increased, CO2 and CH4 emissions based on DM increased linearly (p<0.05) but decreased (p<0.05) quadratically and linearly based on DMD and OMD, respectively. Therefore, this study concluded that the dietary cellulose-to-starch ratios affected rumen fermentation characteristics and greenhouse gas emissions, particularly methane mitigation by increasing dietary starch content. Further study should be conducted to determine the concentrate-to-forage ratio that reduces greenhouse gas emissions without adverse effects on animal performance.

This study evaluates environmental impact factor emissions generated by three concrete-pavement methods. Specifically, internationally commercialized programs are used to calculate the environmental impact factors of selected domestic concrete-pavement projects, thereby identifying areas requiring improvement. This study quantified the material usage and energy consumption associated with the construction and maintenance of three concrete-pavement methods. Using internationally commercialized software, this study evaluated the emissions of environmental impact factors for jointed concrete, continuously reinforced concrete, and mechanized continuously reinforced concrete pavements under three assumed maintenance scenarios for each method. Analysis of the environmental impact factors over a 30-year period under three maintenance scenarios (Cases A, B, and C) shows that, for the three pavement methods, the construction phase is dominant— constituting 70%–99%—across most impact categories, including global warming, smog formation, acidification, eutrophication, human toxicity, ecological toxicity, and respiratory effects. This study analyzes the environmental impact factors during the construction and maintenance processes of three concrete-pavement types using foreign LCI databases and identifies the environmental impacts of each input material. In the future, if LCI and LCIA databases for domestic road pavement materials are established and analyses are conducted based on the conditions presented in this study, then a foundation can be realized for the development of environmentally friendly materials and methods.

메탄(CH4)은 지구 온난화에 크게 기여하는 온실가스이며, 우리나라 농업 분야에서 벼 재배는 메탄 배출의 주요한 원인으로 알려져 있다. 본 연구는 벼 뿌리의 형태학적 특성과 토양 환경이 메탄 배출 특성에 미치는 영향을 구명하기 위하여 온도 조절이 가능한 인공 유리 온실에서 삼광과 신동진 벼 품종을 대상으로 포트 실험을 수행하였다. 생육 단계별로 챔버를 이용한 메탄 가스 포집과 벼의 생육 특성 및 뿌리의 형태학적 특성을 조사하고 토양의 산화환원전위, 온도, 용존유기탄소를 함께 측정하였다. 두 품종 모두 유수형성기 이후 메탄 배출량이 급격히 증가하여 출수기에 최대 1.7-2.1 mg CH4 m-2 hr-1을 보였으며, 누적 메탄 배출량은 삼광 품종이 다소 높았으나 통계적으로 유의한 차이는 없었다. 벼 뿌리의 형태학적 특성은 두 품종 간 유의한 차이가 없었으나, 주요 생육 시기의 메탄 배출 변화와는 유사하였다. 또한, 토양 산화환원전위는 담수기간이 지속될수록 환원 조건이 더욱 형성되었다. 이는 토양 내 메탄생성균의 기질 공급 등의 유리한 조건을 형성하여 메탄 생성이 활발해졌을 것으로 판단된다. 이러한 결과는 벼 품종 및 재배 관리에 따른 농업 부문의 메탄 저감 전략 마련에 기초 자료로 활용될 수 있을 것으로 판단된다.

The textile tentering process generates exhaust gases characterized by elevated temperature and humidity, accompanied by complex odors, fine particulate matter, and visible white smoke, all of which frequently contribute to public grievances and environmental concerns. This study evaluated a field-installed, multi-stage emissioncontrol system consisting of a scrubber, a wet electrostatic precipitator (WEFC), and a heat exchanger, with emphasis on the effect of routine plate cleaning over a ht ree-month operation. Real-time monitoring at 5-minute intervals measured temperature, humidity, total volatile organic compounds (TVOCs), particulate matter (PM2.5, PM10, TSP), and odor intensity. Odor activity values (OAVs) and odor contributions (OC) were determined from samples collected according to the Korean Odor Measurement Standard. The emission-control system reduced exhaust temperature from 150oC to below 50oC while maintaining stack outlet temperature differences within 5oC, thereby suppressing visible white smoke. The multistage system achieved mean removal efficiencies of 88.6±5.0% for TVOCs and 96.2±6.5% for PM10, with a gravimetric PM10 removal of 99.4%. Weekly cleaning of the electrostatic plates constrained day-to-day variability in odor and PM levels within ±10%, significantly lowering the frequency of white-smoke episodes. Isovaleraldehyde and acetaldehyde accounted for >90% of total OAVs, indicating the need for supplementary treatment targeting aldehydes. These results provide quantitative evidence to guide maintenance scheduling and emission-control policy for the textile processing industry.

This study analyzed the emission characteristics of major air pollutants from 97 domestic municipal solid waste incineration facilities using tele-monitoring system (TMS) data collected from 2015 to 2023. Focusing on the effects of the enforcement of enhanced national emission standards in 2019, this research examined changes in emission factors (EFs) of dust and nitrogen oxides (NOX) by facility capacity and aging level. The results showed that the average EFs for dust and NOX significantly decreased by up to 30% after enforcement (p<0.01~0.001), indicating the practical effectiveness of the strengthened standard. This trend was observed consistently across all facility sizes and aging levels, including large-scale and older facilities. In contrast, hydrogen chloride (HCl) and carbon monoxide (CO) did not show clear reductions and remained highly variable, suggesting that emission standards alone may not be sufficient for stable control. These findings demonstrate the need for optimized combustion conditions and improved post-treatment systems for pollutants such as HCl and CO. This study provides empirical evidence highlighting the importance of appropriate facility scale and systematic refurbishment cycles for stable emission reduction in municipal waste incinerators.

This study aims to quantitatively evaluate the life cycle carbon emissions of continuously reinforced concrete pavements on Korean expressways. The analysis focuses on assessing the effect of the changes in pavement design life and maintenance frequency on total carbon emissions to provide a basis for effective carbon reduction strategies. In accordance with ISO 14040 and ISO 14044, carbon emissions were calculated using actual design documents, including bills of quantities and unit price lists. National emission factors were applied to each life cycle stage, including the maintenance stage that was modeled based on the standard maintenance scenarios of the Korea Expressway Corporation. The study also conducted a scenario-based evaluation to examine the impact of extending the pavement design life from 20 to 30 years on maintenance-related emissions. The usage stage accounted for the largest share of total emissions, followed by the material production and maintenance stages. Notably, repeated asphalt overlay maintenance contributed significantly to emissions. Extending the design life reduced the number of high-emission maintenance activities, leading to a significant reduction in the total life cycle emissions. Extending the pavement design life and optimizing maintenance cycles were effective strategies for reducing the life cycle carbon emissions in road infrastructure. Furthermore, applying eco-design principles—such as incorporating recycled aggregates or low-carbon cement during the design stage—could further enhance sustainability. Future research should include various case studies and support the development of standardized national life cycle inventory databases for road infrastructure systems.

The commercial feed additive, native rumen microbes (RC), derived from a diverse microbial community isolated from the rumen of Hanwoo steers is being explored to enhance rumen fermentation and improve ruminant feed utilization. This study evaluated the impact of native rumen microbes supplementation on methane emissions, microbial diversity, and fermentation efficiency on in vitro assessment. Treatments were as follows: CON (basal diet, without RC); T1 (basal diet + 0.1% RC); T2 (basal diet + 0.2% RC). Rumen fermentation parameters, total gas, and methane production were assessed at 12, 24, and 48 h of incubations. The in vitro gas production was carried out using the Ankom RF Gas Production System. Supplementation of RC significantly reduced the total gas production at 12, 24, and 48 hours of incubation (p < 0.05). Volatile fatty acid concentrations were increased, while acetate and propionate were decreased (p < 0.05) at 48 h by the supplementation of RC. Notably, the 0.1% inclusion level of RC significantly reduced methane production by 28.30% and 21.21% at 12 and 24 hours. Furthermore, microbial diversity analysis revealed significant shifts (p < 0.05) in bacterial composition between the control and treatment groups, while supplementation also promoted the growth of bacterial populations, such as Succiniclasticum. These findings suggest that native rumen microbes supplementation, particularly at 0.1% inclusion level, can enhance rumen microbial composition while significantly reducing methane production in vitro.

In this study, comparative combustion was performed in a 3-ton flue tube boiler for emulsified oil manufactured by using 15% water and approximately 1% carbide aqueous solution as an emulsifier in Bunker-C oil, and the characteristics of exhaust emissions were analyzed. As a result of performing comparative combustion under the same ambient environment and external conditions, the exhaust gas temperature decreased by approximately 3.93% from 183.76℃ for bunker-C to 176.52℃ for EM15, and the oxygen concentration increased by approximately 2.96% from 9.72% to 12.68% . Carbon dioxide decreased by approximately 2.3% from 8.49% for bunker-C to 6.19% for EM15, indicating that EM15 has a greenhouse gas reduction effect. When the standard oxygen concentration of 4% was applied, nitrogen oxides decreased by approximately 43.17% from 130.59 ppm for Bunker-C to 74.21 ppm for EM15, and sulfur oxides decreased by approximately 53.05% , confirming the excellent emission reduction characteristics of emulsified fuel oil. Therefore, it is expected that replacing emulsified fuel oil in boilers using Bunker-C oil will enable response to increasingly strengthened emission regulations.

The electric discharge experiment, known as the Miller-Urey experiment, is one of the experiments to understand the origin of life on Earth. The experiment involved simulating the Earth’s early atmosphere by introducing methane(CH4), ammonia(NH3), and nitrogen(N2) gases, and applying energy through electric discharge. Resulting solution was found to contain amino acids such as glycine(C2H5NO2), alanine( C3H7NO2), histidine(C6H9N3O2), proline(C5H9NO2), and valine(C5H11NO2). These amino acids were compared with the results of the recent experiment (Parker et al. 2014). Interestingly, the electric discharge produced C2 swan band and CN emission and it was newly found in gas phase. These two emission bands are commonly observed in comets.