265 resultados para NH4
Resumo:
A gene-clone-library-based molecular approach was used to study the nirS-encoding bacteria-environment relationship in the sediments of the eutrophic Jiaozhou Bay. Diverse nirS sequences were recovered and most of them were related to the marine cluster I group, ubiquitous in estuarine, coastal, and marine environments. Some NirS sequences were unique to the Jiaozhou Bay, such as the marine subcluster VIIg sequences. Most of the Jiaozhou Bay NirS sequences had their closest matches originally detected in estuarine and marine sediments, especially from the Chesapeake Bay, indicating similarity of the denitrifying bacterial communities in similar coastal environments in spite of geographical distance. Multivariate statistical analyses indicated that the spatial distribution of the nirS-encoding bacterial assemblages is highly correlated with environmental factors, such as sediment silt content, NH4+ concentration, and OrgC/OrgN. The nirS-encoding bacterial assemblages in the most hypernutrified stations could be easily distinguished from that of the least eutrophic station. For the first time, the sedimentological condition was found to influence the structure and distribution of the sediment denitrifying bacterial community.
Resumo:
- NO3--NNH4+-NDINDIPDINNDIPDIP2060NO3--NNO2--NDINDIP80DINDIP-200617.6 Tg20%3.5 Tg1.8 Tg50%/26%25%17%6%9% 2060>30psu22psuDIN: PO43--PSiO3: PO43--P19591985-862003-06SiO3: PO43--PDIN: PO43--PSiO3: DIN2050-601985-8684.6% 2004-0569.8%1985-8699.5%2004-0575.5%0.7%25.4% DODelta SDelta Ta
Resumo:
1321 84 9 DCM 6.41.0108tC/aVGPM250.5 OS5AFMFv/FmFv/Fm Fv/Fm0.37Fv/FmFv/Fm4 Fv/Fm3 Fv/FmFv/Fm Fv/FmFv/FmFv/FmNH4+NO3-PSiFv/Fm1 2 Fv/FmFv/Fm Fv/FmFv/Fm
Resumo:
13TGA 13(C19H15N4)2(NO3)2∙3H2O (3-3)(C19H15N4)2[CdCl4] (3-4)2Ag(tta)∙AgNO3 (3-5)Cu8(tta)15(H2O)Cl (3-6)[Zn(5-CH3-tta)2(isoH)2] (BDC) (3-7)Pb[(PO3)2C(OH) CH3]•H2O (4-1)Ni(C5H4NCOO)2∙4H2O (5-2)Co(C5H4NCOO)2(H2O)2∙2H2O (5-3)[CdCl2(C13H12N2O)2] (5-4){C6H4(COOH)S}2 (5-5)(Deta)(ClO4)NO3 (5-6)(NH4)2[-Mo8O26] (6-1) (NH4)2[Mo4O13] (6-2)3-53-63-73-33-45-25-35-45-55-64-1(5,5)(47•63) (48•62)6-16-2(32•4)(32•53•8)(3•42•54•6•82)(34•43•54•64)
Resumo:
/ 1. /20059.51983-20052.22.0% 2005 97−701 mgC m-2 d-1307 mg C m-2 d-1pH (NH4-N) (PO4-P) Chl aPO4-P11Chl aNH4-N A9B7B8B9C8C9 D9A12005pCO2r=-0.8n=23, p<0.001pCO2pCO2/230 mgC m-2 d-1CO2CO22222106t a-1136916.22.0% 200119832005BacillariophytaPyrrophytaChl a 569.50 mgC m-2 d-1306.83 mgC m-2 d-1 2. DICHCO3- Pco2 (P<0.01) 0.11µmol•L-1<0.5 mol L-1<0.75 mol L-1DICHCO3- PCO2 (P<0.01)DICHCO3- PCO28020mgL-1 5µmol L-120µmol L-1 0.75mol L-1CO2CO2CO2CO2
Resumo:
1NO3-NH4+NO2-PO43- NO3-<188 mol/LNH4+<126 mol/LNO2-<39.5 mol/LDICHCO3- pCO2NDICHCO3-pCO2NH4+>126 mol/LNO2->39.5 mol/LpCO2CO2PO43-19.5mol/LDICpCO2CO2NDICHCO3-pCO2NH4+NO3-NO2-PO43-NNO3-NH4+NO2-71 mol/L49.7 mol/L11.7 mol/LpCO2CO2 DIC=-0.937(PO43-)-0.34(NO3-)-0.46(NH4+)+0.11(NO2-)R2=0.69, n=30Sig.<0.05 HCO3-=-1.357(PO43-)-0.35(NO3-)-0.57(NH4+)-0.013(NO2-)R2=0.76, n=32, Sig.<0.05 CO32-=0.344(PO43-)+0.16(NO3-)+0.18(NH4+)+0.076(NO2-)R2=0.69, n=32, Sig.<0.05 pCO2=-1.321(PO43-)-0.12(NO3-)-0.31(NH4+)-0.032(NO2-)R2=0.84, n=35, Sig.<0.01 2 Chl-aNNH4+<126 mol/LNH4+Chl-aNH4+>126 mol/LChl-aNO2-PO43-39.5 mol/L19.5 mol/LChl-aNO3-PO43-pCO2 PO43-Chl-aNH4+NO3-NO2-PO43-Chl-aChl-apCO2R2=0.75p<0.0001CO2pCO2NH4+NO3-NO2-NNH4+>NO3->NO2-PO43-NH4+NO3-mDICR2=0.64p<0.01HCO3-CO2 3 0.197106t C0.302106t C0.039106t C2.233106t C2006
Resumo:
Azis et al., 2001---- 20075200853~1210 g•m-228200791191.94 kg100.99 kg111.03 kg9~110.49~2.09 g23 0.5-339-111.47-2.09 g28.16 (38.6)%31.29 (31.63)% 92432.1490.06 mg•ind-1•d-1858.99 467.76 mg•gdw-1•d-184.29 mg•m-2•d-141.49 mg•m-2•d-114.34%13.77%14.36%24.72%23.74%24.76%0.27%0.25%0.30%92588.16363.776.991.79 --924.5POM14.30 17.01 mg• h-1•ind-13120.320.18 mg•h-1•ind-17533.66 11.34117.9023.4635.916.2228.083.41 ug NH4-N•gdw-1•h-19654.08 kg164672.75%1204 Scallop Culture Unit, SCU6-943.13-98.94 mg/h74.05 mg/hPOM1279.58SCUPO4-P125.59-1432.23 mol•h-176.2-252.89mol•h-1211.09 83.79 Oyster Culture Unit, OCU5-41.43mol•h-116.54-41.76mol•h-1PO4-P35.56-489.34mol•h-1 9.92-16.68mol•h-1OCUPOM535.68955.5862.37 15.50
Resumo:
12<33 PSUAOU>33 PSUAOU3MoUNi(FeMnCuPbZn)20 NTU4FeMnFeMnMnUUFeUMo5NH4+SiNP15%10%0.1%6
Resumo:
During late spring and early summer of 2005, large-scale (> 15 000 km(2)), mixed dinoflagellate blooms developed along the the coast of the East China Sea. Karenia mikimotoi was the dominant harmful algal bloom species in the first stage of the bloom (late May) and was succeeded by Prorocentrum donghaiense approximately 2 wk later. Samples were collected from different stations along both north-south and west-east transects, from the Changjiang River estuary to the south Zhejiang coast, during 3 cruises of the Chinese Ecology and Oceanography of Harmful Algal Blooms Program, before and during the bloom progression. Nitrogen isotope tracer techniques were used to measure rates of NO3-, NH4+, urea, and glycine uptake during the blooms. High inorganic nitrogen (N), but low phosphorus (P) loading from the Changjiang River led to high dissolved inorganic N:dissolved inorganic P ratios in the sampling area and indicate the development of P limitation. The rates of N-15-uptake experiments enriched with PO43- were enhanced compared to unamended samples, suggesting P limitation of the N-uptake rates. The bloom progression was related to the change in availability of both organic and inorganic N and P. Reduced N forms, especially NH4+, were preferentially taken up during the blooms, but different bloom species had different rates of uptake of organic N substrates. K mikimotoi had higher rates of urea uptake, while P. donghaiense had higher rates of glycine uptake. Changes in the availability of reduced N and the ratios of N:P in inorganic and organic forms were suggested to be important in the bloom succession. Nutrient ratios and specific uptake rates of urea were similar when compared to analogous blooms on the West Florida Shelf.
Resumo:
The inventories of nutrients in the surface water and large phytoplankton( > 69 pm) were analyzed from the data set of JERS ecological database about a typical coastal waters, the Jiaozhou Bay, China, from 1960s for N, P and from 1980s; for Si. By examining long-term changes of nutrient concentration, calculating stoichiometric balance, and comparing diatom composition, Si limitation of diatom production was found to be more possible. The possibility of Si limitation was from 37% in 1980s to 50% in 1990s. Jiaozhou Bay ecosystem is becoming serious eutrophication, with notable increase of NO2-N, NO3-N and NH4-N from 0.1417 mumol/L, 0.5414 mumol/L, 1.7222 mumol/L in 1960s to 0.9551 mumol/L, 3.001 mumol/L, 8.0359 mumol/L in late 1990s respectively and prominent decrease of Si from 4.2614 mumol/L in 1980s to 1.5861 mumol/L in late 1990s; the nutrient structure is controlled by nitrogen; the main limiting nutrient is probably silicon; because of the Si limitation the phytoplankton community structure has changed drastically.
Resumo:
Due to the influence of human activities, nutrient concentrations, nutrient ratios and phytoplankton composition have notably changed in Jiaozhou Bay, China since the 1960s. From the 1960s to the 1990s, nutrient concentrations have increased 1.4 times for PO4-P, 4.3 times for NO3-N, 4.1 times for NH4-N and 3.9 times for DIN. The atomic ratio of DIN:PO4-P increased very rapidly from 15.9 +/- 6.3 for the 1960s, to 37.8 +/- 22.9 for the 1990s. SiO3-Si concentration has remained at a very low level from the 1980s to the 1990s. The high ratio of DIN: PO4-P and low ratios of SiO3-Si:PO4-P (7.6 +/- 8.9) and SiO3-Si:DIN (0.19 +/- 0.15) showed the nutrient structure of Jiaozhou Bay has changed from more balanced to unbalanced during the last 40 years. The possibility that DIN and/or PO4-P as limiting factors of Jiaozhou Bay phytoplankton has been lessened or eliminated and that of SiO3-Si limiting has been increased. The changes in nutrient structure may have led to the decrease of large diatoms and a shift of phytoplankton species composition. It is likely that there is a trend from large diatoms to smaller cells in Jiaozhou Bay. (C) 2001 Academic Press.
Resumo:
N isotope fractionation (epsilon) was first determined during ambient NO3- depletion in a simulated diatom spring bloom. After 48 h of N-starvation, NH4+ was resupplied to the diatoms in small pulses to simulate grazer-produced N and then epsilon was determined. Large variations in epsilon values were observed: from 2.0-3.6 to 14-0 parts per thousand during NO3- and NH4+ uptake, respectively. This is the first study reporting an epsilon value as low as 0 to 2 parts per thousand for NH4+ uptake and we suggest that greater N demand after N-starvation may have drastically reduced NH3 efflux out of the cells. Thus the N status of the phytoplankton and not the ambient NH4+ concentration may be the important factor controlling epsilon, because, when N-starvation increased, epsilon values for NH4+ uptake decreased within 30 h. This study may thus have important implications for interpreting the delta(15)N of particulate N in nutrient-depleted regimes in temperate coastal oceans.
Resumo:
Sediments and surface water were sampled in a tide flat in the Huiquan Bay, Qingdao, China in January 2004 to simulate the exchange of NH4-N/NO3-N/PO43- between sediments and surface water. A working system was designed with which samples were shaken at 60, 120 and 150 revolutions per minute (r/min). Experiment results show that NH4-N concentration in water at shaking rate of 60 r/min decreased gradually, while at 120 r/min increased gradually. In resuspension, fine-grained sediments contributed most NH4-N to the seawater, followed by medium-grained and coarse-grained sediments. The NO3-N concentration in water had a negative relation, with the shaking rate; the medium-grained sediments contributed more NO3-N to seawater than the coarse- and fine-grained sediments. The PO43- concentration is positively related with the shaking rate, the fine-grained sediments were the main N and P contributor to the seawater, followed by medium- and coarse-grained sediments.
Resumo:
Red tides (high biomass phytoplankton blooms) have frequently occurred in Hong Kong waters, but most red tides occurred in waters which are not very eutrophic. For example, Port Shelter, a semi-enclosed bay in the northeast of Hong Kong, is one of hot spots for red tides. Concentrations of ambient inorganic nutrients (e.g. N, P), are not high enough to form the high biomass of chlorophyll a (chl a) in a red tide when chl a is converted to its particulate organic nutrient (N) (which should equal the inorganic nutrient, N). When a red tide of the dinoflagellate Scrippsiella trochoidea occurred in the bay, we found that the red tide patch along the shore had a high cell density of 15,000 cells ml(-1), and high chl a (56 mu g l(-1)), and pH reached 8.6 at the surface (8.2 at the bottom), indicating active photosynthesis in situ. Ambient inorganic nutrients (NO3, PO4, SiO4, and NH4) were all low in the waters and deep waters surrounding the red tide patch, suggesting that the nutrients were not high enough to support the high chl a >50 mu g l(-1) in the red tide. Nutrient addition experiments showed that the addition of all of the inorganic nutrients to a non-red-tide water sample containing low concentrations of Scrippsiella trochoidea did not produce cell density of Scrippsiella trochoidea as high as in the red tide patch, suggesting that nutrients were not an initializing factor for this red tide. During the incubation of the red tide water sample without any nutrient addition, the phytoplankton biomass decreased gradually over 9 days. However, with a N addition, the phytoplankton biomass increased steadily until day 7, which suggested that nitrogen addition was able to sustain the high biomass of the red tide for a week with and without nutrients. In contrast, the red tide in the bay disappeared on the sampling day when the wind direction changed. These results indicated that initiation, maintenance and disappearance of the dinoflagellate Scrippsiella trochoidea red tide in the bay were not directly driven by changes in nutrients. Therefore, how nutrients are linked to the formation of red tides in coastal waters need to be further examined, particularly in relation to dissolved organic nutrients. (C) 2008 Elsevier B.V. All rights reserved.
Resumo:
Eutrophication has become increasingly serious and noxious algal blooms have been of more frequent occurrence in the Yangtze River Estuary and in the adjacent East China Sea. In 2003 and 2004, four cruises were undertaken in three zones in the estuary and in the adjacent sea to investigate nitrate (NO3-N), ammonium (NH4-N), nitrite (NO2-N), soluble reactive phosphorus (SRP), dissolved reactive silica (DRSi), dissolved oxygen (DO), phytoplankton chlorophyll a (Chl a) and suspended particulate matter (SPM). The highest concentrations of DIN (NO3-N+NH4-N+NO2-N), SRP and DRSi were 131.6, 1.2 and 155.6 mu M, respectively. The maximum Chl a concentration was 19.5 mg m(-3) in spring. An analysis of historical and recent data revealed that in the last 40 years, nitrate and SRP concentrations increased from 11 to 97 mu M and from 0.4 to 0.95 mu M, respectively. From 1963 to 2004, N:P ratios also increased from 30-40 up to 150. In parallel with the N and P enrichment, a significant increase of Chl a was detected, Chl a maximum being 20 mg m(-3), nearly four times higher than in the 1980s. In 2004, the mean DO concentration in bottom waters was 4.35 mg l(-1), much lower than in the 1980s. In comparison with other estuaries, the Yangtze River Estuary was characterized by high DIN and DRSi concentrations, with low SRP concentrations. Despite the higher nutrient concentrations, Chl a concentrations were lower in the inner estuary (Zones 1 and 2) than in the adjacent sea (Zone 3). Based on nutrient availability, SPM and hydrodynamics, we assumed that in Zones 1 and 2 phytoplankton growth was suppressed by high turbidity, large tidal amplitude and short residence time. Furthermore, in Zone 3 water stratification was also an important factor that resulted in a greater phytoplankton biomass and lower DO concentrations. Due to hydrodynamics and turbidity, the open sea was unexpectedly more sensitive to nutrient enrichment and related eutrophication processes.
