• 한국환경과학회지
• /
• 제19권5호
• /
• pp.607-615
• /
• 2010

We investigated the temporal variations of heterotrophic dinoflagellates (hereafter HDNF) and photosynthetic dinoflagellates (hereafter PDNF) from 14 June to 4 September 2003 at a single station in Jangmok Bay. We took water samples 47 times from 2 depths (surface and bottom layers) at hide tide. A total of 63 species were encountered and in general the most abundant genera were Prorocentrum and Protoperidinium. The abundance of PDNF and HDNF was in the range of $0.04{\sim}55.8{\times}10^4$ cells/L and in the range of $0.01{\sim}4.35{\times}10^4$ cells/L, respectively. The mean abundance of PDNF was approximately 7 times higher than that of HDNF, and was higher in the surface layer where has enough irradiance for photosynthesis than in the bottom layer. The total dinoflagellate abundance was higher in the NLP (nitrogen limitation period) than in the SLP (silicate limitation period), and the abundance in the hypoxic conditions was similar to that in the normal conditions. The Shannon-Weaver species diversity index were slightly higher in the bottom layer, the SLP and the hypoxic conditions. The PDNF abundance were correlated with temperature, DO, total inorganic nitrogen and phosphate in the whole water column, and the HDNF abundance was significantly correlated with temperature, salinity and DO. This study shows that the dinoflagellate abundance might be affected by abiotic factors such as irradiance, temperature, salinity, DO and the concentrations of inorganic nutrients, and provides baseline information for further studies on plankton dynamics in Jangmok Bay.

• 생태와환경
• /
• 제37권2호통권107호
• /
• pp.193-204
• /
• 2004

경기도 화성시 서해안 하구역에 조성된 간척 인공호인 화옹호에서 식물플랑크톤의 군집 변화와 종조성, 이에 영향을 미치는 요인을 평가하고자 2002년 6월에서 11월까지 호내 3개 정점과 호외 1개 정점에서 월별 조사 분석을 실시하였다. 조사기간 동안 4개 정점에서 관찰된 식물플랑크톤은 총 5강 8목 26과 63속 192종이었으며, 식물플랑크톤의 총 밀도는 각 정점의 표층에서 24${\sim}$1,882cells $mL^{-1}$로 시기와 정점에 따라 변화의 폭이 컸다. 식물플랑크톤의 총밀도는 염분도, pH, BOD, COD, SS, TN 및 TP등과 유의한 상관관계가 있는 것으로 나타났다. 규조류의 밀도와 관계가 있는 요인은 염분, SS, BOD, COD 및 TN으로 나타났다. 다소 지역적인 차이는 있으나 거리에 따른 농도 구배가 엽록소-a, 총인 및 총질소 모두에서 똑같이 나타남으로써 선행강우로 인한 영양염의 유입이 안정된 시기에 식물플랑크톤의 발달로 나타났다고 추정되었다. 화옹호 태동기의 식물플랑크톤 군집구조는 해양성 조류, 특히 규조류에 의해 좌우되고 있으며, 이들의 시 ${\cdot}$ 공간적 변이에 영향을 미치는 요인으로는 염분도, 강우사상, 영양염 등이 중요한 것으로 나타났다. 본 연구의결과로 판단할 매 화옹호의 현재 환경은 해수의 교환, 희석(강우사상)과 하천으로부터 유입되는 외부기원 영양염에 의해 크게 영향을 받는 상태로 평가된다.

• 아시안잔디학회지
• /
• 제21권2호
• /
• pp.113-126
• /
• 2007

골프장의 한국 잔디에서 Rhizoctonia solani AG2-2에 의해 발생되는 large patch의 근권토양과 건전 잔디의 근귄 토양 샘플을 hole cutter (diameter $10\;cm\;{\times}\;8\;cm$ deep)을 이용하여 샘플을 채취하여 무기성분과 미생물을 조사하였다. Large patch와 건전 잔디의 분산분석 결과 $NO_3$-N(P=0.05), NH4-N(P=0.1) 및 K(P=0.1) 함량에서 중요한 유의차이를 보였다. Large patch가 발생한 토양에 $NO_3$-N 함량은 9.49 mg/kg로 건전한 잔디의 토양 7.02 mg/kg 보다 높았다. 반면, $NH_4$-N의 함량은 large patch 발생한 토양이 12.02 mg/kg으로 건전한 잔디의 근권 토양 14.40 mg/kg 보다 높았다. K 함량은 large patch 토양이 건전한 잔디의 토양보다 낮았다. 근권 토양의 미생물 집락 수를 조사하여 분산 분석한 결과 Pseudomonas spp 집락 수에서 중요한 유의차이(P=0.05)를 보였다. Large patch가 발생한 토양에 미생물의 집락 수가 건전한 잔디의 토양에 비하여 낮았다. 이들 결과는 근권 토양에 과다한 $NO_3$-N, $NH_4$-N 및 K 함량과 토양미생물의 밀도는 large patch 발병과 관련 이 있을 수 있다고 사료된다.

• 한국물환경학회지
• /
• 제31권2호
• /
• pp.181-195
• /
• 2015

Algal blooms in lakes are one of major environmental issues in Korea. A three-dimensional, hydrodynamic and water quality model was developed and tested in Lake Euiam to assess the performance and limitations of numerical modeling with multiple algal groups using field data commonly collected for algal management. In this study, EFDC was adopted as the basic model framework. Simulated vertical profiles of water temperature, dissolved oxygen and nutrients monitored at five water quality monitoring stations from March to October 2013, which are closely related to algal dynamics simulation, showed good agreement with those of observed data. The overall spatio-temporal variations of three algal groups were reasonably simulated against the chlorophyll-a levels of those estimated from the limited monitoring data (chlorophyll-a level and cell numbers of algal species) with the RMSEs ranging from 2.6 to $17.5mg/m^3$. Also, note that $PO_4-P$ level in the water column was a key limiting factor controlling the growth of three algal groups during most of simulation period. However, the algal modeling results were not fully attainable to the levels of observation during short periods of time showing abrupt increase in algae throughout the lake. In particular, the green algae/cyanobacteria and diatom simulations were underestimated in late June to early July and early October, respectively. The results shows that better understanding of internal algal processes, neglected in most algal modeling studies, is necessary to predict the sudden algal blooms more accurately because the concentrations of external $PO_4-P$ and specific algal groups originated from the tributaries (mainly, dam water releases) during the periods were too low to fully capture the sharp rise of internal algal levels. In this respect, this study suggests that future modeling efforts should be focused on the quantification of internal cycling processes including vertical movement of algal species with respect to changes in environmental conditions to enhance the modeling performance on complex algal dynamics.

• 생태와환경
• /
• 제41권4호
• /
• pp.530-540
• /
• 2008

The temporal and spatial variations of size-structured phytoplankton dynamics in Youngsan Lake were investigated to explore potential mechanims controlling the dynamics in the Youngsan Lake. Field data were collected monthly from February to October, 2003 at 6 stations along the axis of Youngsan Lake. In this study, phytoplankton (chlorophyll $\alpha$) were categorized into three size classes: micro-size ($>20{\mu}m$), nano-size ($2{\sim}20{\mu}m$) and pico-size ($<20{\mu}m$). Water temperature, light attenuation coefficients, PAR (photosynthetically active radiation) and suspended solids were measured to analyze relationship between physical-chemical properties and size structure of phytoplankton. Phytoplankton blooms developed during March, July and October in the upper region of the main stem whereas small-scaled spring bloom was observed in the lower region. The scales of phytoplankton blooms were higher in the upper regions than the lower region and blooms were predominated by micro-size class in upper region but predominated by nano-size class in lower region. Growth of size-structured phytoplankton appeared to be controlled by rather light availability than temperature-dependant metabolisms in the system. Phytoplankton growth may be also supported by ambient nutrients available in the water column from analyses of chlorophyll $\alpha$ vs. nutrient concentrations including nitrite+nitrate and orthophosphate. Growth of nano-sized phytoplankton alone appeared to be supported by orthophosphate as well as nitrite+nitrate indicating that response of phytoplankton to nutrient inputs may be size-dependent.

• Journal of Ecology and Environment
• /
• 제30권3호
• /
• pp.209-223
• /
• 2007

Twenty-four wetlands located in Higashi-Hiroshima City in West Japan were selected for this study in order to investigate both the relationship between aquatic plant composition and environmental conditions; and the relationship between changing land use patterns in the catchments and the concentration of different forms of nitrogen in the wetlands. The dominant and subdominant species which comprised the principal vegetation were determined based on a vegetation census conducted in each wetland during the growing season from June to August, 2006. The seasonal variations of water quality factors (pH, electrical conductivity, turbidity, dissolved oxygen, total dissolved solid, and temperature) and different forms of nitrogen such as nitrite, nitrate, ammonium, total nitrogen, dissolved organic nitrogen and dissolved inorganic nitrogen concentrations were analyzed as important indicators of water quality for the surface water of the wetlands. The surveyed wetlands were classified into three types (non-disturbed wetlands, moderately-disturbed wetlands and highly-disturbed wetlands), based on the degree of human disturbance to their catchment areas. An analysis of variance indicated that there was a significant difference among the wetland groups in the annual mean values of electrical conductivity, total dissolved solids, total nitrogen, nitrite, dissolved inorganic nitrogen and dissolved organic nitrogen. Classification of the wetlands into three groups has revealed a pattern of changes in the composition of plant species in the wetlands and a pattern of changes in nitrogen concentrations. A majority of the non-disturbed wetlands were characterized by Brasenia schrebi and Trapa bispinosa as dominant; with Potamogeton fryeri and Iris pesudacorus as sub-dominant species. For most of the moderately-disturbed wetlands, Brasenia schrebi were shown to be a dominant species; Elocheriss kuriguwai and Phragmites australis were observed as sub-dominant species. For a majority of the highly-disturbed wetlands, Typha latifolia and T. angustifolia were observed as dominant species, and Nymphea tetragona as the sub-dominant species in the study area. An analysis of land use and water quality factors indicated that forest area played a considerable role in reducing the concentration of nutrients, and can act as a sink for surface/subsurface nutrient inputs flowing into wetland water, anchor the soil, and lower erosion rates into wetlands.

• 한국환경복원기술학회지
• /
• 제14권4호
• /
• pp.11-23
• /
• 2011

Mountain streams, which are major components of an entire river network, play an important role as the source of water, sediment, coarse and fine organic matter, and nutrients for lowland rivers. Therefore, dynamics and downstream linkages of each compartment of the mountain stream can be essential for watershed management in catchment scale. The dynamics and downstream linkages are understood as a development of step-pool sequences along a river course. Recently, stream restoration after flooding event often employ the development of step-pool sequences in the world. In this paper, we 1) examined the geomorphic characteristics and the role of step-pool sequences in steep mountain streams by reviewing the results of past studies, and 2) introduced the case studies of stream restoration using step-pool sequences, and finally 3) addressed design methods considering geometry and stability of artificial step-pool sequences for stream restoration. Step-pool sequences play an important role not only as roughness with energy dissipation but also as heterogeneity of stream feature for aquatic habitat. Step-pool sequences, even if they are constructed artificially along a stream, may be effective for small stream restoration considering eco-friendly torrent controls. So far the artificial step-pool sequences were employed for mountainous streams, but those would be applied to urban stream.

• Journal of the korean society of oceanography
• /
• 제38권2호
• /
• pp.68-79
• /
• 2003

Although seagrasses are relatively abundant, few studies have been conducted on seagrass physiology and ecology in Korea. Zostera marina is the most abundant seagrass species, widely distributed throughout all coastal areas of the Korean peninsula. To examine seasonal dynamics and spatial variations of eelgrass, Zostera marina distributed on the coast of Korea, morphological characteristics, biomass, tissue nutrient constituents, leaf productivity and environmental factors were monitored monthly from the eelgrass beds in Kabae Bay and Kosung Bay on the south coast of the Korean peninsula from June 2001 to June 2002. Eelgrass density, biomass, morphological characteristics, leaf productivities, and tissue nutrient constituents exhibited clear seasonal variations, and these seasonal trends reflected seasonal changes in water temperature. Eelgrass shoot density and biomass at Kabae Bay site showed more obvious seasonal trends than Kosung Bay. No strong seasonality in Kosung Bay site appeared to be caused by high water temperature ($>30{\circ}C$) during summer months at this site. Despite differences in nutrient availabilities between two study sites, eelgrass biomass and leaf productivities were not significantly different between study sites, and this lack of spatial variations implies that the ambient nutrient availabilities at the present study sites are in excess of seagrass nutrient demand. Eelgrass tissue N content and sediment pore water DIN concentrations exhibited reverse relationship at the present study. This reverse relationship suggests in situ nutrient concentrations are not good indicator of nutrient availabilities, and regeneration and turnover rates of sediment nutrients are also important factors to determine nutrient availabilities at the site.

• 생태와환경
• /
• 제35권1호통권97호
• /
• pp.1-9
• /
• 2002

팔당호 지류인 경안천의 입자태 및 무기 영양염의 동태와 이들이 식물플랑크톤의 군집구조의 천이에 미치는 영향을 규명하기 위하여 1993년 8월 18일부터 11월 13일까지 주 1회의 조사를 14주 동안에 걸쳐서 수행하였다. 질산성 질산염은 조사기간 중 항상 풍부하였고 인산염과 규산염은 갈수기에 급격히 감소하는 경향을 보였다. Chlorophyll a의 값은 1993년 8월 21일 $90.6\;{\mu}g/l$로 최대 값이 관찰되었으며 10월 중순 이후부터는 $15{\sim}16\;{\mu}g/l$을 유지하였다. 입자태 유기탄소와 입자태　유기질소는 매우 풍부한데 비해, 입자태 유기인의 농도는 최저$0.3\;{\mu}g\; atm/l$의 낮은 능도 분포를 보였으며, 입자태 유기탄소 및 유기질소의 변화양상은 chlorophyll a의 변차양상과 잘 일치하였으며, 이것은 입자태 유기탄소 및 질소는 식물플랑크톤의 성장에 의한 내생적 공급에 의함을 의미한다. 이와는 반대로 경안천의 인의 공급은 외부로부터 공급되고 있으며, 항상 인산염이 식물플랑크톤의 제한인자로 작용하지만, 때때로 낮은 Si/P ratio을 나타내어 규산염의 고갈 현상이 관찰되었다. 이 결과는 때로는 식물플랑크톤의 성장에 인산염 보다는 규산염이 제한 인자로 작용한다는 것을 암시한다. 인산염이 제한 인자로 작용하는 시기에는 규조류가 우점하고 있었으며, 규산염이 제한인자로 작용하는 시기 (9월 $11{\sim}18$일, 10월 $2{\sim}16$일)에는　남조류와 녹조류가 우점 하였다. 특히,　남조류 중에서 Anabaena, Microcystis및 Oscillatoria가 우점종으로 출현하였다.

• 한국산학기술학회논문지
• /
• 제15권5호
• /
• pp.3345-3350
• /
• 2014

춘계 진해만에서 식물플랑크톤의 분포특성에 영향을 미치는 영양염 농도 및 거동을 파악하기 위해서 총 23개 정점에서 2010과 2011년에 현장조사를 수행하였고, 지리지형학 특성과 오염물 부하를 고려하여 4개의 구역으로 구분하여 평가하였다. 진해만 광역해역에서 해역별 영양염 제한은 해수 순환이 원활한 중앙해역인 구역 II에서 80% 이상으로 가장 높게, 다음으로 서남해역의 구역 III과 IV에서는 17%-83%의 중간정도로 나타났으며, 마산만 인근의 반폐쇄적인 구역 I에서는 35% 이하로 낮게 관찰되었다. 연도별 영양염 공급원으로는 2010년에는 오 폐수 등에 의한 질소기원 영양염의 유입이 높은 비중을 차지하였고, 2011년에는 강우에 의한 담수유입에 의하여 해역의 저염분화와 더불어 질소, 규소, 인 계열의 영양염이 동시에 유입되었다. 특히 2010년에는 질소계열의 영양염과 규조류(Pseudo-nitzchia spp.)의 높은 상관성을 보였고, 2011년에는 모든 영양염과 규조류 (Leptocylindrus danicus)와 높은 관련성이 있었다. 결과적으로 춘계 진해만에 유입되는 질소 계열의 영양염은 규조류의 성장에 중요한 영향을 미쳤으며, 그들의 빠른 영양염 섭취(uptake)로 인하여 해역에 따라서 영양염 절대농도 뿐 만 아니라, 영양염 구성성분비의 제한을 일으킬 수 있다는 것을 파악하였다.