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Assessing uncertainty in models of the ocean carbon cycleScott, Vivian January 2010 (has links)
In this thesis I explore the effect of parameter uncertainty in ocean biogeochemical models on the calculation of carbon uptake by the ocean. The ocean currently absorbs around a quarter of the annual anthropogenic CO2 emissions to the atmosphere [Scholes et al., 2009], slowing the increase in radiative forcing associated with the increasing atmospheric CO2 concentration. Ocean biogeochemical models have been developed to study the role of the ocean ecosystem in this process. Such models consist of a greatly simplified representation of the hugely complex ocean ecosystem. This simplification requires extensive parameterisation of the biological processes that convert inorganic carbon to and from organic carbon in the ocean. The HadOCC ocean biogeochemical model is a Nutrient-Phytoplankton-Zooplankton-Detritus (NPZD) model that is used to represent the role of the ocean ecosystem in the global carbon cycle in the HadCM3 and FAMOUS GCMs. HadOCC uses twenty parameters to control the processes of biological growth, mortality, grazing and detrital sinking that control the uptake and cycling of carbon in the ocean ecosystem. These parameters represent highly complex and in some cases incompletely understood biological processes, and as a result are uncertain in value. A sensitivity analysis is performed to identify the HadOCC parameters that due to uncertainty in value have the greatest possible effect on the exchange of CO2 between the atmosphere and the ocean—the air-sea CO2 flux. These are found to be the parameters that control phytoplankton growth in the well lit surface ocean, the formation of carbonate by marine organisms and the sinking of biological detritus. The uncertainty in these parameters is found to cause changes to the air-sea CO2 flux calculated by the FAMOUS GCM. The initial effect of these changes is equivalent to the order of the error of current estimates of the net annual carbon uptake by the ocean (2.2 ± 0.3 Pg C y−1 [Gruber et al., 2009], 2.2 ± 0.5 Pg C y−1 [Denman et al., 2007]). This indicates that while the effect of ocean biogeochemical parameter uncertainty is non-negligible, it is within the bounds of the uncertainty of the total (inorganic and organic) ocean carbon system, and is considerably less than the uncertainty in the carbon uptake of the terrestrial biosphere [Houghton, 2007]. However, as the ocean plays a crucial role in the global carbon cycle and the regulation of the Earth’s climate, further understanding and better modelling of the role of the ocean ecosystem in the global carbon cycle and its reaction to anthropogenic climate forcing remains important.
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Seasonal and spatial variations in phytoplankton size composition, primary production and copepod production in Tolo Harbour and Tolo Channel.January 2011 (has links)
Wong, Lik Chi. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 96-108). / Abstracts in English and Chinese. / Abstract (in English) --- p.i / Abstract (in Chinese) --- p.iii / Acknowledgements --- p.V / Table of Contents --- p.vi / List of Tables --- p.viii / List of Figures --- p.ix / Chapter Chapter 1. --- General introduction --- p.1 / Chapter Chapter 2. --- "Seasonal and spatial variations of phytoplankton size composition in Tolo Harbour and Tolo Channel, Hong Kong" --- p.3 / Chapter 2.1 --- Literature Review --- p.3 / Chapter 2.2 --- Introduction --- p.6 / Chapter 2.3 --- Materials and methods --- p.8 / Chapter 2.4 --- Results --- p.11 / Chapter 2.5 --- Discussion --- p.32 / Chapter 2.6 --- Conclusion --- p.37 / Chapter Chapter 3. --- "Seasonal and spatial variations of primary production and copepod production in Tolo Harbour and Tolo Channel, Hong Kong" --- p.38 / Chapter 3.1 --- Literature review --- p.38 / Chapter 3.1.1 --- Factors affecting primary production --- p.38 / Chapter 3.1.2 --- Factors affecting copepod production --- p.40 / Chapter 3.1.3 --- Marine food chain --- p.42 / Chapter 3.2 --- Introduction --- p.45 / Chapter 3.3 --- Materials and methods --- p.48 / Chapter 3.3.1 --- Primary production --- p.48 / Chapter 3.3.2 --- Copepod production --- p.50 / Chapter 3.3.3 --- Density of Noctiluca scintillans --- p.53 / Chapter 3.4 --- Results --- p.54 / Chapter 3.5 --- Discussion --- p.78 / Chapter 3.5.1 --- Primary production in Tolo Harbour --- p.78 / Chapter 3.5.2 --- Copepod production in Tolo Harbour --- p.82 / Chapter 3.5.3 --- Transfer efficiency in Tolo Harbour --- p.89 / Chapter 3.6 --- Conclusion --- p.92 / Chapter Chapter 4. --- General conclusion --- p.93 / References --- p.96
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Seasonal succession and productivity of phytoplankton populations in two northern Indiana lakesNelson, Craig A. 03 June 2011 (has links)
The seasonal succession and productivity of the phytoplankton populations in Lake Waubee and Lake of the Woods, Indiana, were investigated from November 1980 to August 1981. Algal community dynamics were related to seasonal variations and interactions of several physical, chemical, and biological factors.Algal bianass maxima coincided with increases in light, nutrients, temperature, and turbulence during fall and spring overturn and in early to mid-summer. Growth characteristics and vertical distribution of bianass varied greatly from season to season with shifts in species composition and were indicative of productive lakes.The periodicity and distribution of in situ rates of primary productivity were also characteristic of fertile lakes. Integral photosynthesis ranged from 200 to 300 mg C m2 h-1, indicating mesotrophic to eutrophic conditions.Bioassays for nutrient limitation indicate that algal growth in both lakes is phosphorus-limited during the summer months. Ambient concentrations and loading rates of nitrogen and phosphorus indicate that restoration-management strategies should focus on phosphorus reduction and removal.Ball State UniversityMuncie, IN 47306
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Acclimation to iron limitation in the haptophyte Coccolithus pelagicus : a molecular investigationMoffat, Christopher January 2008 (has links)
Phytoplankton growth is iron limited in at least 20% of the world’s oceans. Iron is an important nutrient required to synthesise enzymes necessary for photosynthesis, respiration, and nitrogen assimilation. Due to its low solubility in seawater, iron limitation of phytoplankton production has been the focus of much recent research. These organisms secrete ligands in order to solubilise the available iron, but not all of the iron dissolved in seawater is biologically available. In this study a molecular based approach was employed to investigate the acclimation of the marine haptophyte Coccolithus pelagicus to iron limitation. Using two dimensional electrophoresis, subtractive cDNA hybridisation, and RT real time PCR, changes in the proteome and in gene expression were examined. Iron limited cells were characterised by slower specific growth rates, lower chlorophyll a concentrations per unit biomass and less extensive calcification relative to iron replete cells. Addition of iron to iron limited cultures resulted in increased specific growth rates and increased chlorophyll a concentration per unit biomass. A subtracted cDNA library revealed seventeen identifiable sequences of which photosystem I protein E (PsaE), a fucoxanthin binding protein transcript, two chlorophyll binding proteins and a predicted membrane protein were shown to be up-regulated in iron-limited cells to varying extents. Two dimensional SDS PAGE revealed 11 differentially expressed proteins in iron limited cells and 1 highly expressed protein exclusive to iron replete cells. The potential utility of each of these as biomarkers of iron-limitation/iron sufficiency for natural populations of coccolithophorids like Coccolithus pelagicus is discussed.
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Phytoplankton community structure and water quality of Red River, Vietnam / Cấu trúc quần xã thực vật nổi và chất lượng nước sông Hồng, Việt NamDuong, Thi Thuy, Le, Thi Phuong Quynh, Ho, Tu Cuong, Vu, Thi Nguyet, Hoang, Thi Thu Hang, Dang, Dinh Kim, Lu, Xixi 25 August 2015 (has links) (PDF)
This study aimed to describe the distribution and relative abundance of the phytoplankton obtained during the two seasons (rainy and dry seasons) from the Red river system. The water and phytoplankton samples were monthly collected during the year 2012 at four sampling stations along the Red River (Yen Bai, Vu Quang Hoa Binh,and Ha Noi) . Environmental variables (e.g. temperature, dissolved oxygen, pH, suspended solids, conductivity, TDS, NO3-N, NH4-N, PO4-P, Total Phosphorus; and DOC) and phytoplankton (e.g. cell density and relative abundant species) were analyzed. Six phytoplankton classes were identified with the Bacillariophyceae dominating in the phytoplankton community. A distinct seasonal variation in phytoplankton structure was observed with high cells density in dry season and low values in rainy season. PCA (Principal Component Analysis) showed that suspended solid factor that governed the temporal and spatial distribution of phytoplankton structure in the Red River system. / Nghiên cứu này trình bày sự phân bố và độ phong phú tương đối của quần xã thực vật nổi vào mùa mưa và mùa khô trong hệ thống sông Hồng. Các mẫu nước và thực vật nổi được thu hàng tháng trong năm 2012 tại 4 điểm trên sông Hồng (Yên Bái, Vụ Quang, Hòa Bình và Hà Nội). Các thông số môi trường (nhiệt độ, lượng oxy hòa tan, pH, chất rắn lơ lửng, độ dẫn, TDS, NO3-N, NH4-N, PO4-P, T-P và DOC) và thực vật phù du (mật độ tế bào,độ phong phú tương đối ) đã được phân tích. Sáu lớph tảo được được xác định với tảo silíc chiếm ưu thế trong quần xã thực vật phù du. Sinh khối thực vật đạt giá trị cao vào mùa khô trong khi thấp vào mùa mưa. Phân tích hợp phần chính cho thấy yếu tố chất rắn lơ lửng đóng vai trò quan trọng việc xác định biến động thời gian và không gian cấu trúc quần xã thực vật nổi trong hệ thống sông Hồng.
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Estrutura da comunidade fitoplanctônica, em cinco lagos marginais do Rio Turiaçu, (Maranhão, Brasil) e sua relação com o pulso de inundação.Nogueira, Naiza Maria Castro 30 June 2003 (has links)
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Previous issue date: 2003-06-30 / Financiadora de Estudos e Projetos / The phytoplankton communities of five lakes in the floodplain of Turiaçu River (MA) were
analysed for taxonomic composition and evaluated regarding temporal dynamics. Changes on
phytoplankton densities were analysed as well as the variations in physical and chemical water
characteristics along a hydrological cycle, attempting to correlate them to the flood pulse and the
consequent water level fluctuations. Samplings were carried out in lakes Cabeludo, Caboclo,
Arrodiador, Bate Terra and Quebra Pote, five periods of representative phases: dry, water rising,
flooding, water lowing and a second dry. Qualitative samples were taken by horizontal hauls with a
20 µm phytoplankton net, and quantitative samples were taken at the surface and at 20 cm above
the bottom with a Van Dorn bottle. Samples were preserved with in 4% formalin and the
phytoplankton was identified and enumerated in settling chambers under a Zeiss inverted
microscope. Turbulence, rainfall and water level fluctuations were considered the main controlling
factors of the successional dynamics. The lakes are shallow and nutrient rich, being eutrophic
during the dry period and mesotrophic in the other hydrological phases. The phytoplankton
communities of the five lakes are represented by 139 taxa belonging to 9 Classes: 22
Bacillariophyceae, 34 Chlorophyceae, 1 Cryptophyceae, 33 Cyanophyceae, 2 Dinophyceae, 20
Euglenophyceae, 1 Xanthophyceae and 25 Zignematophyceae. Most taxa are new records for
Maranhão State. Cyanophyceae was the numerically dominant group in three periods: water rising
(March), water lowing (August) and dry (December), with relative abundances varying from
23.13% in Lake Caboclo during the water raising period to 65.72% of the total, at the same lake, in
the dry period. Bacillariophyceae were the most abundant organisms in the flooding period (May),
with relative abundances varying from 38,14 % in Lake Bate-Terra to 49,70% in Lake Caboclo.
The most abundant species of Cyanophyceae and Bacillariophyceae were Planktolyngbya
circumcreta and Aulacoseira granulata, respectively. Total phytoplankton densities varied from
1725 ind.mL-1 in Lake Arrodiador, in the flood period, to 8272 ind.mL-1 in Lake Cabeludo, at the
dry period. The highest densities occurred in dry periods, related to the greater nutrient availability
and to the concentration factor resulting from the water level decrease. There was a tendency to
higher species richness, lower dominance, higher equitativity and higher diversity of phytoplankton
during water rising and water lowering. / As comunidades fitoplanctônicas de cinco lagos da planície de inundação do rio Turiaçu (MA)
foram analisadas para a composição taxonômica e avaliadas de acordo com sua dinâmica temporal.
As variações na densidade do fitoplâncton também foram avaliadas, assim como as mudanças nas
características físicas e químicas da água dos lagos, ao longo de um ciclo hidrológico, buscando
correlacioná-las com o pulso de inundação e as conseqüentes variações no nível de água dos lagos.
As amostragens foram realizadas nos lagos Cabeludo, Caboclo, Arrodiador, Bate Terra e Quebra
Pote, em cinco épocas representativas dos períodos: de seca, enchente, cheia, vazante e de um
segundo período de seca, tendo sido realizadas coletas qualitativas, por meio de arrastos
horizontais, com rede de 20 µm de abertura de malha e coletas quantitativas do fitoplâncton total,
na superfície e 20 cm acima do fundo, com Garrafa de Van Dorn. As amostras foram preservadas
em formalina 4% e quantificadas em câmaras de sedimentação, sob microscópio invertido Zeiss. A
turbulência, a precipitação e as variações no nível d água foram consideradas os principais fatores
controladores da dinâmica sucessional. Os lagos são rasos e suas águas ricas em nutrientes, sendo
os lagos eutróficos nos períodos de seca e mesotróficos nos outros períodos hidrológicos. As
comunidades fitoplanctônicas dos cinco lagos estão representadas por 139 táxons, distribuídos em
9 Classes: 22 Bacillariophyceae, 34 Chlorophyceae, 1 Cryptophyceae, 33 Cyanophyceae, 2
Dinophyceae, 20 Euglenophyceae, 1 Xanthophyceae e 25 Zignematophyceae. A maioria dos táxons
são novas ocorrências para o estado do Maranhão. Cyanophyceae foi a classe numericamente mais
abundante em três períodos: enchente (março), vazante (agosto) e seca (dezembro), com
abundâncias relativas que variaram de 23,13% no lago Caboclo no período de enchente, a 65,72%
do total, neste mesmo lago, no período de seca. Bacillariophyceae foi a classe mais abundante no
período de cheia (maio), com abundância relativa variando de 38,14 % no lago Bate-Terra a
49,70% no lago Caboclo. As espécies mais abundantes das classes Cyanophyceae e
Bacillariophyceae foram Planktolyngbya circumcreta e Aulacoseira granulata, respectivamente.
As densidades totais do fitoplâncton variaram de 1.725 ind.mL-1 no lago Arrodiador, no período de
cheia, a 8.272 ind.mL-1 no lago Cabeludo, no período de seca. As maiores densidades ocorreram
nos períodos de seca, relacionadas à maior disponibilidade de nutrientes e ao fator de concentração,
pela redução no nível de água. As comunidades tenderam a uma maior riqueza de espécies, menor
dominância, maior uniformidade e maior diversidade nas fases de enchente e vazante.
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Phytoplankton dynamics in two large rivers: / Phytoplanktondynamik in zwei großen Flüssen: Langzeittrends, longitudinale Dynamik und mögliche Auswirkungen des KlimawandelsHardenbicker, Paulin 16 March 2018 (has links) (PDF)
This study addresses the regulation of large river phytoplankton by climate-related drivers with the help of three different approaches, i.e. analyses of long-term data and spatial dynamics (longitudinal samplings) as well as mathematical modeling. The central hypothesis is that discharge has a dominant role among climate-related variables which strongly alters phytoplankton biomass development. A multi-factorial statistical analysis on the basis of long-term data (1990 – 2009; 1994 – 2009) from two measuring stations of the rivers Rhine and Elbe revealed that discharge conditions and light availability were the main driving forces regulating phytoplankton spring bloom dynamics. For the Rhine, a trend towards an earlier occurrence of the spring bloom event and a decrease in seasonal mean phytoplankton biomass could be detected, whereas for the Elbe no shift in the timing of the spring bloom and a tendency towards increasing seasonal mean phytoplankton biomass was found. Longitudinal sampling campaigns served to analyze the spatial plankton development on a short-term scale. River-internal growth and loss processes, as well as import mediated by tributaries were examined. Four longitudinal profiles were realized at different seasons in recent years (2009 – 2011) and it was revealed that tributaries mainly had a diluting impact on plankton densities in the Elbe and provided an additional import of phyto- and zooplankton densities in the Rhine. In the present study, high bivalve abundances were detected in the Rhine, probably leading to river-internal losses of phytoplankton which could compensate phytoplankton production resulting in low phytoplankton concentrations. In the Elbe, low abundances of bivalves and a low benthic grazing pressure prevailed. On the other hand, an unusually low discharge event in spring 2011 in the Rhine demonstrated that loss processes can at times be superimposed by strong phytoplankton production leading to extremely high phytoplankton biomasses and chlorophyll a values. Hence, despite the observed long-term trend of decreasing chlorophyll values in the last two decades, extreme environmental conditions can provoke regime shifts with exceptional phytoplankton mass developments. To assess the potential impacts of future climate change on water quality, the water quality simulation model QSim was used to establish a model for the free-flowing part of the Rhine. The modeling approach was implemented by changing the hydrological and climatologic input data according to different climate projections for the near (2021 – 2050) and the far future (2071 – 2100). The model results indicated a weak response of phytoplankton biomass in the Rhine towards altered climatic conditions, including discharge reductions and water temperature increases. The study suggests that changes in discharge rather than water temperature mediate climate change effects on large river phytoplankton. However, the effects are river specific as a consequence of system specific differences in main control mechanisms (e.g. ‘bottom-up’ versus ‘top-down’). / Anhand von drei verschiedenen Ansätzen analysiert die vorliegende Arbeit die Regulierung von Phytoplankton in großen Flüssen durch klimabedingte Faktoren: Auswertung von Langzeitdaten, räumliche Dynamik (fließzeitkonforme, longitudinale Beprobungen) und mathematische Modellierung. Die zentrale Hypothese ist, dass Abfluss eine dominante Rolle unter den klimabedingten Faktoren spielt und die Phytoplanktonbiomasse stark beeinflusst. Eine multifaktorielle statistische Analyse basierend auf Langzeitdaten (1990 – 2009; 1994 –2009) von zwei Stationen der Flüsse Rhein und Elbe zeigten, dass hauptsächlich Abflussbedingungen und Lichtverfügbarkeit die Antriebskräfte bei der Regulierung der Phytoplanktonfrühjahrsblüte darstellten. Während sich am Rhein ein Trend hin zu einem früheren Auftreten der Frühjahrsblüte und einer Abnahme der mittleren Phytoplankton-biomasse während der Vegetationsperiode zeigte, konnte für die Elbe keine zeitliche Verschiebung der Frühjahrsblüte festgestellt werden und mittlere Phytoplanktonbiomassen zeigten hier eine steigende Tendenz. Longitudinale Fließzeitbeprobungen dienten zur Analyse der kurzfristigen räumlichen Entwicklung des Planktons. Interne Produktions- und Verlustprozesse, sowie der Eintrag durch Zuflüsse wurden untersucht. Vier longitudinale Profile wurden zu unterschiedlichen Jahreszeiten der letzten Jahre (2009 – 2011) realisiert und es wurde gezeigt, dass die Nebenflüsse der Elbe vorwiegend einen Verdünnungseffekt auf die Planktondichten des Hauptstromes hatten, während sie für den Rhein einen wichtigen zusätzlichen Eintrag von Phyto- und Zooplankton darstellten. In der vorliegenden Arbeit wurden hohe Muscheldichten im Rhein gefunden, die möglicherweise zu hohen internen Planktonverlusten durch Fraß beigetragen haben, und somit zu niedrigen Phytoplankton-konzentrationen geführt haben könnten. In der Elbe waren die Muscheldichten dagegen gering und somit war auch der benthische Fraßdruck niedriger. Auf der anderen Seite zeigte ein ungewöhnlich niedriges Abflussereignis im Frühjahr 2011 am Rhein, dass diese Verlustprozesse zeitweise von starker Phytoplanktonproduktion überlagert werden können und dadurch extrem hohe Phytoplanktonbiomassen und Chlorophyllwerte entstehen können. Demzufolge können trotz der Beobachtung eines langfristigen abnehmenden Trends in den Chlorophyllgehalten während der letzen zwei Jahrzehnte extreme Umweltbedingungen einen Regime-shift mit außergewöhnlichen Massenentwicklungen des Phytoplanktons hervorrufen. Um den möglichen Einfluss des zukünftigen Klimawandels auf die Gewässergüte abzuschätzen, wurde mithilfe des Gewässergütesimulationsmodells QSim ein Modell für den frei fließenden Abschnitt des Rheins erstellt. Für den Modellierungsansatz wurden die hydrologischen und klimatologischen Eingangsdaten entsprechend der verschiedenen Klimaprojektionen für die nahe (2021 – 2050) und ferne Zukunft (2071 – 2100) verändert. Die Modellergebnisse zeigten, dass sich Änderungen in den klimatischen Bedingungen, einschließlich Abflussreduktion und Wassertemperaturanstieg, nur geringfügig auf die Phytoplankton¬biomasse des Rheins auswirkten. Die vorliegende Arbeit deutet darauf hin, dass Klimawandeleffekte eher durch Änderungen der Abflussverhältnisse auf das Phytoplankton in großen Flüssen wirken als durch Änderungen der Wassertemperatur. Der Effekt ist jedoch flusssystemspezifisch, da die Auswirkungen von systemspezifischen Unterschieden in den Hauptkontrollmechanismen gesteuert werden (z.B. ‚Bottom-up’ versus ‚Top-down’).
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Ecological studies of phytoplankton and harmful algal blooms in Junk Bay, Hong KongLu, Songhui., 呂頌輝. January 2001 (has links)
published_or_final_version / Ecology and Biodiversity / Doctoral / Doctor of Philosophy
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Spatial and Temporal Patterns of Areal and Volumetric Phytoplankton Productivity of Lake TexomaBaugher, Tessy 08 1900 (has links)
Phytoplankton productivity of Lake Texoma was measured for one year from August 1999 to August 2000 for four stations, using the oxygen change method and laboratory incubation. Mean values of the photosynthetic parameters, PBmax and alphaB ranged from 4.86 to 46.39 mg O2.mg Chl-1.hr-1 for PBmax and 20.06 to 98.96 mg O2.mg Chl-1.E-1.m2 for alphaB. These values were in the range to be expected for a highly turbid, temperate reservoir. Estimated gross annual areal productivity ranged from 594 g C.m2.yr-1 (P.Q. = 1.2), at a station in the Washita River Zone to 753 g C.m2.yr-1 at a station in the Red River Zone, of the reservoir. Gross annual areal productivity at Station 17, in the Main Lake Zone, was 708 g C.m2.yr-1. Gross areal and volumetric productivity showed distinct seasonal variation with Photosynthetically Available Radiation (PAR) and temperature. Trophic status estimated on a station-by-station basis, using net productivity values derived from gross productivity and respiration estimates, was mesotrophic for all the stations, though one station approached eutrophy. Net productivity values ranged from 0.74 to 0.91 g C. m-2.d-1. An algal bioassay conducted at two stations in August 2000, revealed that phosphorus was most likely the nutrient limiting photosynthesis at both these stations, although the more turbid riverine station was primarily light-limited.
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The Effects of Pulp and Paper Mill Wastewaters on Phytoplankton Primary Productivity in the Red River, LouisianaHoller, Jeffrey Dee 05 1900 (has links)
Responses of phytoplankton productivity in the Red River to unbleached pulp and paper mill wastewaters were monitored using in situ ^14C incubation. Preoperational studies, conducted prior to the discharge of mill wastewaters varied seasonally, but revealed similar productivity trends when compared with postoperational studies, conducted after mill discharges began entering the Red River. Carbon assimilation rates measured downstream of mill discharge were generally greater than upstream levels in both preoperational and postoperational studies. Selected physical, chemical, and biological parameters varied seasonally, but showed similar upstream-downstream values and preoperational-postoperational values. Total Organic Carbon (TOC), Dissolved Organic Carbon (DOC), and Biochemical Oxygen Demand (BOD_5) were positively correlated with postoperational productivity rates. Apparent color was negatively correlated with productivity rates.
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