DYNAMIC CHANGES OF INORGANIC NITROGEN AND ASTAXANTI—IIN ACCUMULATION IN HAEMATOCOCCUS PLUVIALIS

This study on dynamic changes of culture color,astaxanthin and chlorophylls,inorganic N including N-NO3^-,N-NO2^- and N-NH4^ in batch culture of Haematococcus pluvialis exposed to different additive nitrate concentration showed(1)ast/chl ratio was over 0.8 for brown and red algae,but was usually less than 0.5 for green and yellow algae;(2)N-NO3^-,in general,was unstable and decreased,except for a small unexpected increase in nitrate enriched treatment groups;(3)measurable amounts of N-NO2^- and N-NH4^ were observed respectively with three change modes although no extemal nitrite and ammonia were added into the culture;(4)a non-linear correlation between ast/chl ratio(or color)changes and the levels of N-NO3^-,N-NO2^-,N-NH4^ in H.pluvialis culture;(5)up and down variation of the ast/chl ratio occurred simultaneously with a perceptible color change from yellow to brown(or red)when N-NO3^-,N-NO2^- and N-NH4^ fluctuated around 30,5,5μmol/L respectively;(6)existence of three dynamic modes of N-NO3^-,N-NO2^- and N-NH4^ changes,obviously associated with initial extemal nitrate;(7)the key level of total inorganic N concentration regulating the above physiological changes during indoor cultivation was about 50 μmol/L;and(8)0.5-10mmol/L of nitrate was theoretically conducive to cell growth in batch culture.     

Toxicity and Accumulation of Selenite in Four Microalgae

The toxicity and bioaccumulation of selenite in four microalgae, Spirulina platensis,Dunaliella salina, DunalieUa bardawill and Phaeodactylum tricornutum cultured in the presence of selenite were investigated. Lower concentrations of selenite were generally nontoxic and frequently stimulated algal growth, while higher concentrations of selenite inhibited algal growth. Selenite was more toxic to D. salina and D. bardawill than to S. platensis and P. tricornutum. All algae cultured in selenite were able to incorporate Se to different degrees, which depended on algal species. The distributions of selenite among intracellular macromolecular compounds were different among algal species : most of the selenite was associated with proteins in S. platensis, D. salina and D. bardawill, while most of the selenite was associated with lipids in P. tricornutum, which reflected the physiological differences among the algae. These observations suggest that algae are able to accumulate selenite and bind it with intracell~ar macromolecular compounds when exposed to high concentration of selenite. This may represent a form of storage or detoxification of selenite by the algae.     

The inhibitory degree between Skeletonema costatum and dinoflagllate Prorocentrum donghaiense at different concentrations of phosphate and nitrate/phosphate ratios

Interactions between Skeletonema costatum (S. costatum) and Prorocentrum donghaiense (P. donghaiiense) were inves-tigated using bi-algal cultures at different concentrations of phosphate (PO4-P) and nitrate/phosphate (N/P) ratios. Experiments were conducted under P-limited conditions and the Lotka-Volterra mathematical model was used to simulate the growth of S. costatum and P. donghaiense in the bi-algal cultures. Both of these two species were inhibited significantly in bi-algal culture. The results of the simulation showed that the inhibitory degree of S. costaum by P. donghaiense was high when the concentration of PO4-P was low (0.1μmolL-1/2 d), but that of P. donghaiense by S. costaum was high with increased PO4-P supply (0.6μmolL-1/2 d). At low concen-tration of PO4-P (0.1μmolL-1/2 d), or high concentration of PO4-P (0.6μmolL-1/2 d) with high N/P ratio (160), the interactions be-tween S. costatum and P. donghaiense were dependent on the initial cell densities of both species. At high concentration of PO4-P (0.6μmolL-1/2 d) with low N/P ratio (25 or 80), S. costatum exhibited a survival strategy superior to that of P. donghaiense. The de-gree of inhibition of P. donghaiense by S. costaum increased with elevated N/P ratio when the medium was supplemented with con-centration 0.1μmolL-1/2 d of PO4-P. The degree of inhibition to P. donghaiense by S. costaum increased with elevated N/P ratio at low concentration of PO4-P (0.1 μmolL-1/2 d). This trend was conversed at high concentration of PO4-P (0.6μmolL-1/2 d). However, the degree of inhibition of S. costaum by P. donghaiense increased with the increased N/P ratio at different PO4-P concentrations (0.1μmolL-1/2 d and 0.6μmolL-1/2 d). These results suggested that both phosphate concentration and N/P ratio affected the competition between S. costaum and P. donghaiense: P. donghaiense is more competitive in environments with low phosphate or high N/P ratio and the influence of N/P ratio on the competition was more significant with lower phosphate concentration.     

Determination of the spatial and temporal variability of phytoplankton community structure in Daya Bay via HPLC-CHEMTAX pigment analysis

The spatial and temporal variability of the phytoplankton community structure in Daya Bay, South China Sea, were identified by using HPLC-CHEMTAX analytical techniques. The highest chlorophyll a(Chl a) concentrations were observed during summer(with an average value of 0.84 μg/L) and lowest ones during winter(with an average value of 0.33 μg/L). CHEMTAX processing revealed the seasonal succession of phytoplankton species in Daya Bay. During winter, diatoms were the dominant phytoplankton species and contributed 41.5% to total Chl a. Based on Chl a concentration, the average ratio of dinofl agellates to total phytoplankton biomass substantially increased with increasing temperature and nitrogen to phosphorus(N/P) ratio, reaching 52.2% in spring. Nutrient limitation shifted from phosphorus to nitrogen during summer. Moreover, this period was associated with the predominance of diatoms, which accounted for 71.1% of Chl a. Prasinophytes and cryptophytes were the other two dominant groups and particularly dominated during winter. Cyanobacteria became an important group during summer and autumn. Canonical correspondence analysis suggested that chrysophytes, dinofl agellates, and cryptophytes were strongly associated with high nitrate concentration, ammonium, dissolved inorganic nitrogen(DIN), and N/P ratio, and were negatively associated with temperature and phosphate. Diatoms and cyanobacteria were strongly associated with temperature, phosphate, and salinity, and are negatively influenced by nitrate, ammonium, DIN, and N/P ratio. Microscopic observations and pigment HPLC information were in good agreement for diatoms and dinofl agellates in the bay. This study demonstrated the usefulness of pigment analysis in investigating the distribution of phytoplankton groups in a complex physical environment, such as Daya Bay.     

Influence of a Flood Event on Salinity and Nutrients in the Changshan Archipelago Area (Northern Yellow Sea)

River discharge can deliver nutrients to the coastal zone and change the hydrologic properties of the water column. Soon after a flash flood from the Yalu River (Northeast China) in August 2010, we investigated the salinity and nutrient concentrations, as well as other environmental conditions in the Changshan Archipelago area, located approximately 100 km west of the river mouth in the northern Yellow Sea. Diluted water was mainly observed in the upper layers shallower than 15 m, with surface salinity between 18.13 and 30.44 in the eastern study area and between 28.16 and 29.72 in the western area. Surface salinity showed a significant negative correlation with concentrations of dissolved nutrients (P < 0.05), but not with that of Chlorophyll-a (Chl-a), dissolved oxygen (DO), particulate materials or pH. The average concentrations of nitrite, nitrate, and silicic acid decreased from the surface layer to bottom layer and were significantly higher in the east area than in the west area (P < 0.05). In contrast, average ammonium and phosphate concentrations were highest in the bottom layer of both areas, with no significant spatial differences. DO varied between 6.06 and 8.25 mg L-1 in the surface layer, and was significantly higher in the eastern area than in the western area in the surface and middle layers. Chl-a concentration was constantly below 4.09 μg L-1. Our work demonstrated the strong influences of Yalu River on proportions of various nutrient components in the Changshan Archipelago area. Silicic acid and total inorganic nitrogen levels were significantly elevated comparing to phosphate in the eastern area. Such changes can potentially induce phosphate limit to phytoplankton growth.     

Effects of salinity and nutrients on the growth and chlorophyll fluorescence of Caulerpa lentillifera

Caulerpa lentillifera is a green algae that distributes worldwide and is cultivated for food. We assessed vegetative propagation of C. lentillifera by measuring the specific growth rate(SGR) and chlorophyll fluorescence of the green algae cultured at different salinities and nutrient levels. The results indicated that C. lentillifera can survive in salinities ranging from 20 to 50,and can develop at salinities of 30 to 40. The maximum SGR for C. lentillifera occurred at a salinity of 35. Both chlorophyll content and the ratio of variable to maximum fluorescence( Fv / Fm) were also at a maximum at a salinity of 35. Photosynthesis was inhibited in salinities greater than 45 and less than 25. Both the maximum SGR and maximum chlorophyll content were found in algae treated with a concentration of 0.5 mmol/L of NO3-N and 0.1 mmol/L of PO 4-P. The photosynthetic capacity of photosystem II(PSII) was inhibited in cultures of C. lentillifera at high nutrient levels. This occurred when NO3-N concentrations were greater than 1.0 mmol/L and when PO4- P concentrations were at 0.4 mmol/L. As there is strong need for large-scale cultivation of C. lentillifera,these data contribute important information to ensure optimal results.     

SIMPLE SIMULATION OF THE ANNUAL VARIATION OF THE SPECIFIC PHOTOSYNTHESIS RATE IN JIAOZHOU BAY

A simple diagnostic simulation of the annual cycling of the surface specific photosynthesis rate (SPR) in Jiaazhou Bay is described in this paper. Light intensity, temperature and nutrients(nitrate ammonia, phosphate) were considered as main factors controlling photosynthesis of phytoplankton and were introduced into the model by different function equations. The simulated variation ofspecific photosynthesis rate coincided with the measured data. Analysis of the effect of every factor onphotosynthesis indicated that the variation of photosynthesis rate was controlled by all these three factors,while temperature showed good correlation with SPR as measurement showed. This diagnostic simulationyielded the values of some parameter relating with the photosynthesis in Jiaozhou Bay.     

ESTIMATION OF ATMOSPHERIC INPUT OF MERCURY TO SOUTH LAKE AND JINGYUE POOL

Taking South Lake and Jingyue Pool in Changchun as examples,we determined particulate Hg in ambient air and Hg concentration in precipitation.Results indicated that particulate Hg in air and Hg concentration in precipita-tion in both sites in nonheating period were lower than that in heating period,which is influenced by coal combustion.The annual particulate Hg concentrations in precipitation were 0.268μg/L(South Lake)and 0.108μg/L(Jingyue Pool).The high-er particulate Hg concentrations in precipitation were 0.268μg/L(South Lake) and 0.108μg/L(Jingyue Pool).The high-er particulate Hg concentration in air and Hg concentration in precipitation in South Lake than that of Jingyue Pool indicat-ed that mercury deposition was influenced by anthropogenic sources(especially from coas combustion).Hg concentration in precipitation is related with particulate Hg in the atmosphere.Dry deposition fluxes were estimated by using dry deposi-tion model on the base of particulate Hg concentrations in the atmosphere,they were estimated by using dry deposi-tion model on the base of particulate Hg concentrations in the atmosphere,they were 35.5μg/(m^2.a) for South lake and 15.3μg/(m^2.a)for Jingyue Pool.Combined with precipitation amount,wet deposition fluxes were estimated in these two sites,152.2μg(m^2.a)for South Lake and 61.2μg/(m^2.a)for Jingyue Pool.Atmospheric Hg deposition fluxes were 160.2g/a for South Lake and 328.62g/a for Jingyue Pool.e     

Effects of temperature, algae biomass and ambient nutrient on the absorption of dissolved nitrogen and phosphate by Rhodophyte Gracilaria asiatica

Gracilaria asiatica,being highly efficient in nutrient absorption,is cultivated in sea cucumber ponds to remove nutrients such as nitrogen and phosphate.It was cultured in a laboratory simulating field conditions,and its nutrient absorption was measured to evaluate effects of environmental conditions.Ammonia nitrogen(AN),nitrate nitrogen(NN),total inorganic nitrogen(TIN),and soluble reactive phosphorus(SRP) uptake rate and removal efficiency were determined in a 4×2 factorial design experiment in water temperatures(T) at 15℃ and 25℃,algae biomass(AB) at 0.5 g/L and 1.0 g/L,total inorganic nitrogen(TIN) at 30 μmol/L and 60 μmol/L,and soluble reactive phosphorus(SRP) at 3 and 6 μmol/L.AB and ambient TIN or SRP levels significantly affected uptake rate and removal efficiency of AN,NN,TIN,and SRP(P<0.001).G.asiatica in AB of 0.5 g/L showed higher uptake rate and lower removal efficiency relative to that with AB of 1.0 g/L.Nitrogen and phosphorus uptake rate rose with increasing ambient nutrient concentrations;nutrient removal efficiency decreased at higher environmental nutrient concentrations.The algae preferred to absorb AN to NN.Uptake rates of AN,NN,and SRP were significantly affected by temperature(P<0.001);uptake rate was higher for the 25℃ group than for the 15℃ group at the initial experiment stage.Only the removal efficiency of AN and SRP showed a significant difference between the two temperature groups(P<0.01).The four factors had significant interactive effects on absorption of N and P,implying that G.asiatica has great bioremedial potential in sea cucumber culture ponds.     

Measurement of trace nitrate concentrations in seawater by ion chromatography with valve switching

An ion chromatographic method with a valve switching facility was developed to determine trace nitrate concentrations in seawater using two pumps, two different suppressors, and two columns. A carbohydrate membrane desalter was used to reduce the high concentrations of sodium salts in samples. In this method, trace nitrate was eluted from the concentrator column to the analytical columns, while the matrix flowed to waste. Neither chemical pre-treatment nor sample dilution was required. In the optimized separation conditions, the method showed good linearity （R〉0,99） in the 0.05 and 50 mg/L concentration range, and satisfactory repeatability （RSD〈5%, n=6）. The limit of detection for nitrate was 0.02 mg/L. Results showed that the valve switching system was suitable and practical for the determination of trace nitrate in seawater.     

Inhibitory activities of microalgal fucoxanthin againstα-amylase,α-glucosidase,and glucose oxidase in 3T3-L1cells linked to type 2 diabetes

Postprandial hyperglycemia is an early indication of type 2 diabetes and the target of many anti-diabetic and anti-obesity studies. a-Glucosidase and a-amylase are the crucial factors in regulating starch digestion and glucose absorption, making them key targets for many studies to treat postprandial hyperglycemia. We studied the inhibitory activities of microalgal fucoxanthin against rat-intestinal a-glucosidase and pancreatic a-amylase along with the antidiabetic effect to induce differentiation in 3T3-L1 pre-adipocytes using Oil Red-O staining. Fucoxanthin displayed strong hindrance activities toward a-amylase in a concentration-dependent manner, with an IC_(50) value of 0.68 mmol/L, whereas weak inhibitory activity against a-glucosidase, with an IC_(50) value of 4.75 mmol/L. Fucoxanthin also considerably elevated glucose oxidase activity in 3T3-LI cells by 31.3% at 5 μmol/L. During adipocyte differentiation, fucoxanthin showed lipid accumulation in 3T3-L1 cells with no cytotoxicity up to 20 μmol/L. However, fucoxanthin had no inhibitory activity on glucose-6-phosphate dehydrogenase. These results suggest that fucoxanthin might be useful for the prevention of obesity or diabetes by inhibiting carbohydrate-hydrolyzing enzymes and lipid accumulation and be utilized as an ingredient for a functional food or dietary supplement.     

Production of polyhydroxybutyrate by the marine photosynthetic bacterium Rhodovulum sulfidophilum P5

The effects of different NaCl concentrations, nitrogen sources, carbon sources, and carbon to nitrogen molar ratios on biomass accumulation and polyhydroxybutyrate (PHB) production were studied in batch cultures of the marine photosynthetic bacterium Rhodovulum sulfidophilum P5 under aerobic-dark conditions. The results show that the accumulation of PHB in strain P5 is a growth-associated process. Strain P5 had maximum biomass and PHB accumulation at 2%-3% NaCl, suggesting that the bacterium can maintain growth and potentially produce PHB at natural seawater salinity. In the nitrogen source test, the maximum biomass accumulation (8.10±0.09 g/L) and PHB production (1.11±0.13 g/L and 14.62%±2.25% of the cell dry weight) were observed when peptone and ammonium chloride were used as the sole nitrogen source. NH 4 + -N was better for PHB production than other nitrogen sources. In the carbon source test, the maximum biomass concentration (7.65±0.05 g/L) was obtained with malic acid as the sole carbon source, whereas the maximum yield of PHB (5.03±0.18 g/L and 66.93%±1.69% of the cell dry weight) was obtained with sodium pyruvate as the sole carbon source. In the carbon to nitrogen ratios test, sodium pyruvate and ammonium chloride were selected as the carbon and nitrogen sources, respectively. The best carbon to nitrogen molar ratio for biomass accumulation (8.77±0.58 g/L) and PHB production (6.07±0.25 g/L and 69.25%±2.05% of the cell dry weight) was 25. The results provide valuable data on the production of PHB by R. sulfidophilum P5 and further studies are on-going for best cell growth and PHB yield.     

Effects of Environmental Cadmium on Cadmium Accumulation,Oxidative Response,and Microelements Regulation in the Liver and Kidney of Hexagrammos otakii

The effects of cadmium(Cd)on metal accumulation,microelements contents,and antioxidant responses in Hexagram-mos otakii were studied.The fish were exposed to 0.2,2.5,or 10μg L?1 Cd for 12 or 24 days.Then,the concentration of Cd and mi-croelements(Ca,Fe,Zn,and Se)were determined in the liver and kidney.Moreover,the activities of antioxidant enzymes including superoxide dismutase(SOD),catalase(CAT),and glutathione-S-transferase(GST),and the content of malondialdehyde(MDA)in the liver and kidney were also measured.A continuous accumulation of Cd was observed throughout the experimental period.Cd accumulation was higher in liver than that in the kidney,while Ca and Fe contents were lower in liver than those in the kidney.Cd exposure resulted in a decrease of Ca and Fe concentrations in the kidney,while there was no effect on the liver.Zn and Se remained unaffected with exposure to Cd.Cd exposure induced severe oxidative stress in H.otakii,as indicated by significant induction of the activities of SOD,CAT,and GST,and a simultaneous increase of MDA content.These data show that antioxidant enzymes and mi-croelements contents can be used as potential biomarkers to monitor environmental health in fish.     

NUTRIENTS IN SEAWATER AND INTERSTITIAL WATER OF THE SEDIMENTS IN THE HUANGHE RIVER ESTUARINE AREA (NOVEMBER)

The investigation shows that the concentrations of nutrients are high in estuarine and coastal waters and low in offshore waters. The concentration of nitrate in estuaries is controlled through a physical mixing process and is also affected by hiotic activity. The annual transport of total inorganic nitrogen and dissolved phosphate-phosphorus from the Huanghe River water to the sea is about 8.45×104 and 1.45×103 tons respectively. The distributions of inorganic nitrogen and silicate in interstitial water of surface sediments are similar to those in surface and bottom sea water. Their contents in interstitial water are227 552μmol/l (average 375) for ammonia, 0.31 -9.0μmol/l (average 1.6) for nitrite, 0 41μmol/1 (average 6.0) for nitrate, and 41 139μmol/l (average 77) for silicate. The average concentrations of phosphate in the surveyed area are 0.64μmol/l for seawater and 1.2μmol/l for interstitial water. A cycle of phosphate in the estuary is also suggested in this paper.     

Toxicity of single-walled carbon nanotubes on green microalga Chromochloris zofingiensis

Nanoparticles,or particles in size of 1-100 nm,are extensively used in the world in different applications.For instance,single-walled carbon nanotubes(SWCNTs) are commonly used in consumer products,such as biosensors,drug and vaccine delivery transporters,and novel biomaterials.Although nanoparticles do not cause safety concerns to consumers who use nanoparticle-containing products,these small particles are potentially harmful for workers who produce them in factories or in cases of discharge to aquatic ecosystems.SWCNTs do not have a natural analogue,so the effects on health of their disposal remain largely unknown.In this study,we evaluated the effects of SWCNTs on a population of the green microalga Chromochloris zofingiensis and the profile and production of pigments and fatty acids.The alga was incubated with SWCNTs for 6 days in 0(control),40,80,160,or 320 mg/L concentrations.SWCNTs showed both positive and negative effects on the growth of C.zofingiensis,with a biomass enhancement at low levels(40-160 mg/L) but inhibition at high levels(320 mg/L).By contrast,a decreased accumulation of fatty acids and pigments of C.zofingiensis was observed over the range of the tested concentrations.These results indicate that the markers on the inhibitive toxicity of SWCNTs are increasingly sensitive in the following order:biomass and fatty acids < primary carotenoids < chlorophylls < secondary carotenoids.C.zofingiensis is a suitable microalga for evaluating the ecotoxicological hazards of SWCNTs,especially in terms of pigmentation response.     

STUDY ON KINETICS OF GLUCOSE UPTAKE BY SOME SPECIES OF PLANKTON

The. rates of glucose uptake by some species of plankton were determined by 3H-glucose tracer method. Experimental results indicated that the observed glucose uptake at natural sea water concentrations by Platymonas subcordiformis and Brachionus plicatilis was principally a metabolic process fitted with the Michaelis-Menten equation in the range of adaptive temperatures. Heterotrophic uptake by Platymonas subcordiformis was mainly dependent on diffusion at high glucose levels. The uptake by Brachionus plicatilis showed active transport even at high glucose levels, indicating its high heterotrophic activity. The uptake rate by Anemia salina was lower, and its Vm/K ratio was lower than those of the other two species of plankton.     

INTERACTIONS BETWEEN AMMONIUM UPTAKE AND NITRATE UPTAKE BY NATURAL PHYTOPLANKTONASSEMBLAGES

Measurements of ammonium and nitrate uptakes by natural phytoplankton assemblages from Jiaozhou Bay at various combinations of ammonium and nitrate concentrations with 15N trace techniques showed that uptake rate of either nitrogen was influenced by the presence of the other but that the influence of ammonium on nitrate uptake was much greater than, that of nitrate on ammonium uptake. The influence mechanism of ammonium on nitrate uptake manifested as competition at lower concentrations and as inhibition at higher concentrations (ammonium concentration >0.6 umol/L), but no total inhibition appeared within the concentration.range of the experiments (0-10umol/L). The influence of nitrate on ammonium uptake seems to be a result of competition for uptake sites on the cell surface. In view of the in situ nutrient concentration in the given marine . environment, it is believed that both nitrogen sources are utilized by phytoplankton. Nitrate uptake in the presence of ammonium and ammonium uptake in the presen     

THE IN VITRO EFFECTS OF STEROIDS, HUMAN CHORIONIC GONADOTROPIN AND CYANOKETONE ON GERMINAL BREAKDOWN OF STRIPED MULLET (MUGIL CEPHALUS L.)OOCYTES

The in vitro effects of steroids, human chorionic gonadotropin (HCG) and cyanoketone on germinal vesicle breakdown (GVBD) of striped mullet (Mugil cephalus L.) oocytes were investigated. All concentrations of HCG (5,10,50 I.U./ml), progesterone and pregnenolone at the highest concentrations(lug/ml) were moderately effective in inducing GVBD, whereas 17B-estrodiol, cortisol, testosterone, 11B-hydroxyandrostenedione and 11-ketotestosterone did not stimulate GVBD. 17a, 20Bdihydroxy-4-pregnen-3-one (17a, 20BdiOHprog) and deoxycorticosterone (DOC) were the most potent steroids in stimulating final oocyte maturation. The results indicate that C21 hydroxylated steroids are potent inducers of final maturation in mullet. Further, co-incubations with 17B-eslradiol, cortisol and testosterone did not alter the maturation-inducing effects of HCG or 17a,200diOHprog. Cyanoketone, a blocker of 3BHSD activity, was only partially effective in blocking GVBD induced by HCG. This suggests that A5 (pregnenolone derived) and     

EFFECT OF CYTOKININS AND AUXINS ON THE GROWTH OF FREE-LIVING CONCHOCELIS OF PORPHYRA YEZOENSIS

IAA 3-Indolylaceic acid, NAA a-Naphthylacetic acid and Cytokinins in PESI culture mediumwere used in a study on the effects of plant hormones on the growth of free-living conchocelis ofPorphyra yezoensis which showed that its growth in medium with cytokinins, IAA and NAA was morerapid than that in medium with non-phytohormones, that the optimal concentrations for promotinggrowth were 10μg/L for IAA and ZA (Zeatin), and 0.1 μg/L for BA 6-Benzyl amino purine and KIN6-Furfurylamino- purine. Mix use of NAA, IAA and cytokinins, NAA/ZA 1-1000/1μg/L, NAA/BA10/1-1000μg/L, NAA/KIN 1/1-1000μg/L promoted growth. IAA/ZA 0.1 - 1/0.1 - 1 μg/L, IAA/BA0.1 - 1/0.1 - 10 μg/L IAA/KIN 1/0.1 - 1000μg/L also promoted growth.     

FLUXES OF SEAWATER AND SOME DISSOLVED CHEMICALS IN THE BASHI STRAIT

An Acoustic Doppler Current Profiler (ADCP) was used in Nov. 1990 measure the seawaterfluxes in a southeast-northwest cross-section in the Bashi Strait to a depth of 400 m. Measuredconcentrations of dissolved oxygen (DO), phosphate (PO_4), nitrate (NO_3), silicate (SiO_2), total alkalinity(TA) and calculated total CO_2, (TCO_2) and the current speed were used to estimate the flux densities(concentration times current speed) of seawater and chemicals.The fluxes of nutrients were near zero near surface and increased with depth. For oxygen andcarbonates, the distributions of flux had structures similar to that of the curmt speed field.