Dissolved organic matter (DOM) is a key component in the biogeochemical cycling in freshwater ecosystem. However, it has been rarely explored, particularly complex river watershed dominated by natural and anthropogenic sources, such as various effluent facility and livestock. The current research developed a new analytical method for TOC/TN (Total Organic Carbon/Total Nitrogen) stable isotope ratio, and distinguish DOM source using stable isotope value (δ13C-DOC) and spectroscopic indices (fluorescence index [FI] and biological index [BIX]). The TOC/TN-IR/MS analytical system was optimized and precision and accuracy were secured using two international standards (IAEA-600 Caffein, IAEA-CH-6 Sucrose). As a result of controlling the instrumental conditions to enable TOC stable isotope analysis even in low-concentration environmental samples (<1 mgC L-1), the minimum detection limit was improved. The 12 potential DOM source were collected from watershed, which includes top-soils, groundwater, plant group (fallen leaves, riparian plants, suspended algae) and effluent group (pig and cow livestock, agricultural land, urban, industry facility, swine facility and wastewater treatment facilities). As a result of comparing characteristics between 12 sources using spectroscopic indices and δ13C-DOC values, it were divided into four groups according to their characteristics as a respective DOM sources. The current study established the TOC/TN stable isotope analyses system for the first time in Korea, and found that spectroscopic indices and δ13C-DOC are very useful tool to trace the origin of organic matter in the aquatic environments through library database.

We investigated physicochemical properties and isotopic compositions of organic matter (δ13CTOC and δ15NTN) in the old fish farming (OFF) site after the cessation of aquaculture farming. Based on this approach, our objective is to determine the organic matter origin and their relative contributions preserved at sediments of fish farming. Temporal and spatial distribution of particulate and sinking organic matter (OFF sites: 2.0 to 3.3 mg L-1 for particulate matter concentration, 18.8 to 246.6 g m-2 day-1 for sinking organic matter rate, control sites: 2.0 to 3.5 mg L-1 for particulate matter concentration, 25.5 to 129.4 g m-2 day-1 for sinking organic matter rate) between both sites showed significant difference along seasonal precipitations. In contrast to variations of δ13CTOC and δ15NTN values at water columns, these isotopic compositions (OFF sites: -21.5‰ to - 20.4‰ for δ13CTOC, 6.0‰ to 7.6‰ for δ15NTN, control sites: - 21.6‰ to - 21.0‰ for δ13CTOC, 6.6‰ to 8.0‰ for δ15NTN) investigated at sediments have distinctive isotopic patterns (p<0.05) for seawater-derived nitrogen sources, indicating the increased input of aquaculture-derived sources (e.g., fish fecal). With respect to past fish farming activities, representative sources (e.g., fish fecal and algae) between both sites showed significant difference (p<0.05), confirming predominant contribution (55.9±4.6%) of fish fecal within OFF sites. Thus, our results may determine specific controlling factor for sustainable use of fish farming sites by estimating the discriminative contributions of organic matter between both sites.

Here, a novel nitrogen-doped carbon nano-material (N-CGNM) with hierarchically porous structure was prepared from spent coffee ground for efficient adsorption of organic dyes by a simple one-step carbonization process (the uniform mixture consists of spent coffee ground, urea, and CaCl2 with the ratio of 1:1:1, which was heated to 1000 °C with a rate of 10 °C min− 1 and held at 1000 °C for 90 min in N2 atmosphere to carry out carbonization, activation, and N-doping concurrently). The morphology and structure analysis show that the prepared N-CGNM exhibits hierarchical pore structure, high specific surface area (544 m2/ g), and large numbers of positively charged nitrogen-containing groups. This unique structure and chemical composition endow N-CGNM with an excellent adsorption capacity toward anion Congo red (623.12 ± 21.69 mg/g), which is obviously superior to that (216.47 ± 18.43 mg/g) of untreated spent coffee ground-based carbon nano-materials (CGM). Oppositely, the adsorption capacity of N-CGNM towards cation methylene blue is inferior to that of CGM due to the existence of electrostatic repulsion. These findings show a great guidance for the development of low-cost but efficient selective adsorbent.

Doped porous carbon materials have attracted great interest owing to their excellent electrochemical performance toward energy storage applications. In this report, we described the synthesis of nitrogen-doped porous carbon (N-PC) via carbonization of a triazine-based covalent organic framework (COF) synthesized by Friedel–Crafts reaction. The as-synthesized COF and N-PC were confirmed by X-ray diffraction. The N-PC exhibited many merits including high surface area (711 m2 g−1), porosity, uniform pore size, and surface wettability due to the heteroatom-containing lone pair of electron. The N-PC showed a high specific capacitance of 112 F g−1 at a current density of 1.0 A g−1 and excellent cyclic stability with 10.6% capacitance loss after 5000 cycles at a current density of 2.0 A g−1. These results revealed that the COF materials are desirable for future research on energy storage devices.

본 연구에서는 와편모조류 Alexandrium affine(LIMS-PS-2345)의 생장에 미치는 용존태 무기 및 유기 영양염의 영향을 조사하였 다. 영양염 흡수 동력학 실험에서 A. affine의 최대흡수속도(ρmax)와 반포화상수(Ks)는 질산염에서 77.0 pmol/cell/hr과 17.6 μM, 인산염에서 15.5 pmol/cell/hr과 3.88 μM로 산출되어, 무기영양염에 대하여 높은 요구량 및 낮은 친화성을 가지고 있는 것으로 나타났다. 유기 영양염에 따른 A. affine의 생장속도를 확인한 결과, 유기 질소 urea, glycine와 유기 인 adenosine triphosphate(ATP), glycerol phosphate(Glycerol-P) 첨가구에서 무기 영양염 첨가구의 70 % 이상 생장속도를 보였다. 따라서 낮은 무기 영양염 환경에서 A. affine의 우점화와 종간경쟁에서 우위를 위해서는 용존태 유기 영양염의 이용이 필요할 것으로 생각된다.

동해 남서해역과 같이 용존 무기 질소(dissolved inorganic nitrogen; DIN)가 제한된 환경에서 우점 규조류 Chaetoceros debilis와 Leptocylindrus danicus의 용존 유기 질소(dissolved organic nitrogen; DON)의 이용성을 정량적으로 평가하였다. 질소원으로 DIN은 질산염과 암모늄, DON은 동해에서 중요한 비율을 차지하는 글리신(glycine)과 요소(urea)에 관하여 각각 평가하였다. Monod 식으로부터 유도한 C. debilis의 최대생장속도(μmax)와 반포화상수(Ks)는 질산염에서 1.50 day-1와 1.62 μM, 암모늄에서 1.13 day-1와 6.97 μM, 글리신 1.46 day-1와 3.36 μM, 요소 0.93 day-1와 0.55 μM으로 나타났다. 또한 L. danicus는 질산염에서 1.55 day-1와 5.21 μM, 암모늄에서 1.57 day-1와 4.57 μM, 글리신 1.47 day-1와 3.80 μM, 요소 1.42 day-1와 1.94 μM이었다. 두 종 모두 요소에서 용존 무기 질소보다 상대적으로 높은 친화성이 확인되었으며, 이러한 높은 친화성은 DIN 제한된 상태에서 C. debilis와 L. danicus이 생장을 유지하기 위해 요소를 이용할 것으로 판단되어진다. 따라서 동해 남서해역과 같이 DIN이 제한된 해역의 경우, DON의 효율적인 이용이 식물플랑크톤의 우점화 전략에서 중요한 요인 중 하나로 생각된다.

2014년 9월 동해 남서해역의 용존 영양염 분포 및 식물플랑크톤 군집구조와 우점종의 질소 화합물에 대한 이용성을 파악하였다. 용존 무기 질소(dissolved inorganic nitrogen; DIN)와 용존 무기 인(dissolved inorganic phosphorus; DIP)은 표층에서 낮고, 수심이 깊어짐에 따라 증가하였다. 반면에 용존 유기 질소(dissolved organic nitrogen; DON)와 용존 유기 인의 경우 무기태 영양염과 상반되는 분포를 보였다. DIN:DIP 비는 전체 수괴에서 약 20으로 Redfield ratio (16)보다 다소 높게 나타났지만, 혼합층의 경우 2로 식물플랑크톤의 생장에 대해 무기질소가 제한요인으로 작용할 수 있는 것으로 보였다. 특히, 무기 질소가 제한된 혼합층에서 DON은 용존 총 질소(dissolved total nitrogen; DTN) 중 88 %를 차지하였다. 우점종 Chaetoceros debilis와 Prorocentrum minimum은 DIN 이외에 요소와 아미노산과 같은 다양한 DON을 이용하여 생장하였다. 따라서 식물플랑크톤의 DON 이용능력은 DIN이 제한된 동해에서 중요한 생존전략으로 작용할 것이다.

고도정수처리를 위한 관형 세라믹 정밀여과와 이산화티타늄(TiO2) 광촉매 첨가 PES (polyethersulfone) 구의 혼성공정에서 유기물질의 영향 및 정밀여과(MF), PES 구 흡착, 광산화의 역할을 막오염에 의한 저항(Rf) 및 투과선속(J), 총여과부피(VT)를 통해서 비교 및 고찰하였다. 휴믹산의 농도가 증가함에 따라 급격한 막오염으로 인해 Rf 는 증가하고 J는 감소하였으며, VT는 휴믹산의 농도가 2 mg/L인 조건에서 가장 높았다. 광산화와 흡착의 영향을 알아보기 위해 휴믹산의 농도 4 mg/L와 6 mg/L에서의 결과를 비교하였다. 두 가지 조건에서 공통적으로 정밀여과(MF)만의 단독공정에서 막오염이 급격하게 진행되어 Rf값이 가장 높게 나타났고, 총여과부피(VT)는 광촉매와 자외선의 혼성공정(MF + TiO2 + UV)에서 가장 높은 값을 나타내었다. 탁도와 유기물질의 평균처리효율은 MF + TiO2 + UV 공정에서 가장 높은 값을 나타내었다.

정수처리용 알루미나 정밀여과 및 광촉매의 혼성공정에서 주기적 질소 역세척 시 휴믹산 농도의 영향을 알아보고, 막오염에 의한 저항 (Rf) 및 투과선속 (J), 총여과부피 (VT) 측면에서 정밀여과의 물 역세척 또는 한외여과의 질소 역세척한 기존 결과와 비교 고찰하였다. 그 결과, 휴믹산 농도의 영향으로 막오염이 진행되는 경향은 질소 또는 물 역세척에 따라, 동일한 재질이라도 한외여과 또는 정밀여과에 따라 차이를 보였다. 또한 동일한 재질의 분리막의 경우 한외여과 보다 정밀여과에서 질소 역세척이 막오염 억제에 효과적이고, 동일한 정밀여과인 경우 물 역세척보다 질소 역세척이 효과적이었다. 탁도 처리효율은 휴믹산 농도와 무관하게 거의 일정하였으나, 휴믹산 처리효율은 휴믹산 10 mg/L에서 최대였다. 이러한 결과로부터 정밀여과막의 질소 역세척시 휴믹산의 농도가 증가할수록 처리수의 휴믹산 농도도 높아지지만, 휴믹산 농도 10 mg/L에서 광촉매 구의 흡착과 광산화로 휴믹산이 최대 효율로 제거된다는 것을 알 수 있었다.

질산태 질소의 공급수준이 알팔파의 영양생장기 동안의 질소동화와 성장 및 재생기간 동안의 뿌리조직내 전분과 질소 축적에 미치는 영향을 규명하고자 0.2, 1.0 및 3.0 mM KN 하에서 10주 동안의 영양생장 후 건물 및 질소 화합물의 식물조직내의 분포를 분석하고, 24일간 1차 및 2차 재생을 각각 시킨 후 뿌리조직에 축적된 전분과 질소 함량을 분석하였다. 10간의 영양생장 후 건물과 질소화합물의 함량을 1.0 mM 처리구를 기준으로 비교한 결과,

The objective of this study is to obtain the basic data for investigating the effects of organic reserves on winter survial or regrowth yield. Forage rape (Brussicu napus L.) was sown at 10 day> interval from Sep. I to Nov. 1. Field-grown palnts were samp

The objective of this study is to obtain the basic data for investigating the effects of organic reserves on winter survial or regrowth yield. Forage rape(Brassica napus L.) was sown on Sep. 1, 1994. Experimental plots were divided into three replicates u

The objective of this study is to obtain the basic data for investigating the effects of organic reserves on winter survival or regrowth yield. Forage rape (Brassica napus L.) was sown by three seeding densities of 5, 15 and 25cm interval among plants on

To restore reclaimed land, it needs to be supplemented with organic matter; this is especially true for Korea, where organic matter constitutes only one-tenth of conventional agricultural soils. The giant Miscanthus, a perennial grass known for its extensive biomass, shows signs of being an excellent source of organic matter for restoring reclaimed land. Therefore, the objectives of this study were to (i) evaluate the feasibility of using the giant miscanthus as an organic resource within the context of re-using reclaimed land for agricultural purposes (i.e., potato cultivation), and (ii) determine the optimum fertilization rate for the potatoes while the giant miscanthus is being used as an organic resource. Our results show that after 180 days, giant miscanthus lost 23–47% of its original dry weight, with the extent of the loss dependent on soil salinity. Nutrient concentrations (Mg2+, Na+) continued to increase until the end of the study period. In contrast, potassium (K+) and the ratio of carbon to nitrogen (C/N) decreased until the end of the study period. Specifically, after 180 days, low salinity topsoil treatments had the lowest C/N ratio. In the first year, 150 % of standard N rates were required for the potatoes to achieve maximum productivity; however in the 2nd year, standard rates were sufficient to achieve maximum productivity. Overall, this implies that even though the application of giant miscanthus did eventually improve soil quality, increasing crop yields, N fertilization is still necessary for the best outcomes.

This study was conducted to evaluate the effects of green manures and complemental fertilization with oil cake or liquid fertilizer on growth and nitrogen use efficiency of Chinese cabbage cultivated in organi systems. Field experiments were carried out at the National Institute of Agricultural Science in Suwon, South Korea from 2012 to 2014. Two green manure crops, Crotalaria and Hairy vetch, was cultivated in summer and in winter, respectively. The application methods of the green manure consisted of three tillage systems (overall tillage, partial tillage and no tillage). Oil cake and liquid fertilizer were used as complemental fertilizer. The results showed that when used as covering material in the upland soil without tillage, green manure fertilization was more effective in increasing growth and yield of Chinese cabbage than when incorporated into soil. It was possible to grow and harvest Chinese cabbage in the spring season by the application of hairy vetch as winter green manure. The higher yield of Chinese cabbage with green manure application was caused by the lower incidence rate of soft rot and tip-burn. The yield of the Chines cabbage that received green manure applications over two consecutive seasons followed by the supplemental fertilization with oil cake was similar to that of the conventional chemical fertilization. Following a single season green manure application in summer, however, the yield of cabbage was only about 70% of the conventional treatment. Green manure cultivation with additional liquid fertilization produced a yield similar to the conventional fertilization treat-ment, soil inorganic nitrogen concentration remained stable and the nitrogen use efficiency increased in the green manure applied soil. In conclusion, the organic cultivation of Chinese cabbage in the autumn season could be outperformed in the upland soil receiving two seasons (winter and summer) of green manure fertilization followed by the supplemental fertilization with liquid fertilizer.