265 resultados para NH4
Resumo:
,C/N.,5.550.5mg/LNH4+-N,95%.,NH4+-N,R20.9971.16.4mg/L,.16.451.4mg/L,85%,.C/N<1,86.3%,
Resumo:
Cladophora oligoclona(N)(P),.,(TN)10.512 mg/L(TP)0.856 mg/L,NP.12 d,TN(NH4-N)TP(PO4-P)53.13%,44.40%,35.71
Resumo:
5DNARAPD,DNA.:9210150~2 000 bp,93.3%.42,(53),(35).PO43--PTP,NH4+-NTNNO2--N,,COD.,RAPD5
Resumo:
AquaMats,-:TNTPCODMnNH4+-N>AquaMats>>>,TNTPCODMn97.3%77.1%63.3%,22d25cm85cmDO4mg/L-,,
Resumo:
NO3--NNH4+-N(Porphyra haitanensis)(NRA),(N)→(N)N→N,NRA:N→N,NRA;NO3--NNRA,NRA;NH4+-NNO3--NNNRA,NH4+-N,N→N,
Resumo:
,-,9,313469625 mm/d781mm/d,TSSCODC rBOD580.5%~82.9%45.2%~64.2%61.0%~77.0%,NH4+-NNO3--NTN51.5%~67.8%-90.6%~40.0%29.1%~68.6%,TPIP
Resumo:
(N)(P),(),5 d14.36±0.72 g;(TN)(TP)36.97±0.26 m g.L-12.88±0.02 m g.L-11.44±0.09 m g.L-10.07±0.01 m g.L-1,(NH4-N)(NO3-N)95%;(TKN)TP5.75±0.2
Resumo:
,,,MC-LR,,,,(P<0.05),,MC=13.62+5.77×NH4+-0.48×T
Resumo:
,NO3 -NH4+ NH2 CONH2 , (Phaeodactylumtricornutum) , , , , (PUFAs)C18 (C180 ,C182 (n -6) ,C183 (n -6) ) ; (<1 8mmol/L) ,NH4+ ,
Resumo:
Classical cultivation and molecular methods based on the ammonia monooxygenase gene (amoA) were used to study the abundance and diversity of beta-proteobacterial ammonia-oxidizing bacteria (AOB) in lake sediments. The eutrophic and oligotrophic basins of a Chinese shallow lake (Lake Donghu), in terms of ammonium (NH4+) concentrations, were sampled. The AOB number was significantly lower in the oligotrophic basin, but significantly higher in the eutrophic basin. In addition, using restriction fragment length polymorphism targeting the amoA, ten restriction patterns including six unique ones were found in the eutrophic basin, while five patterns were observed in the oligotrophic basin with only one unique restriction group. Phylogenetic analysis for AOB revealed that Nitrosomonas oligotropha- and Nitrosomonas ureae-related AOB and Nitrosospira-affiliated AOB were ubiquitous; the former dominated in the eutrophic basin (87.2%), while the latter dominated in the oligotrophic basin (65.5%). Furthermore, Nitrosomonas communis-related AOB was only detected in the eutrophic basin, at a small proportion (3.2%). These results indicate significant selection and adaptation of sediment AOB in lakes with differing trophic status. (C) 2009 Elsevier Masson SAS. All rights reserved.
Resumo:
Ecological responses to dam construction are poorly understood, especially for downstream benthic algal communities. We examined the responses of benthic algal communities in downstream reaches of a tributary of the Xiangxi River, China, to the construction of a small run-of-river dam. From February 2003 to August 2006, benthic algae, chemical factors, and habitat characteristics were monitored upstream and downstream of the dam site. This period spanned 6 mo before dam construction and 37 mo after dam construction. Benthic algal sampling yielded 199 taxa in 59 genera that belonged to Bacillariophyta, Chlorophyta, and Cyanophyta. Some physical factors (flow velocity, water depth, and channel width) and 3 algal metrics (diatom species richness, Margalef diversity, and % erect individuals) were significantly affected by the dam construction, whereas chemical factors (e.g., NH4-N, total N, SiO2) were not. Nonmetric multidimensional scaling (NMS) ordinations showed that overall algal assemblage structure downstream of the dam sites was similar to that of upstream control sites before dam construction and for 1 year after dam construction (p > 0.05). However, sites belonging to upstream and downstream reaches were well separated on NMS axis 1 during the 2(nd) and 3(rd) years after dam construction. Our results suggest that impacts of dam construction on benthic algal communities took 2 to 3 y to emerge. Further development of a complete set of indicators is needed to address the impact of small-dam construction. Our observations underscore the need for additional studies that quantify ecological responses to dam construction over longer time spans.
Resumo:
The submersed macrophyte, Vallisneria natans L., was cultured in laboratory with NH (4) (+) -enriched tap water (1 mg L-1 NH4-N) for 2 months and the stressful effects of high ammonium (NH (4) (+) ) concentrations in the water column on this species was evaluated. The plant growth was severely inhibited by the NH (4) (+) supplement in the water column. The plant carbon and nitrogen metabolisms were disturbed by the NH (4) (+) supplement as indicated by the accumulation of free amino acids and the depletion of soluble carbohydrates in the plant tissues. The results suggested that high NH (4) (+) concentrations in the water column may hamper the restoration of submersed vegetation in eutrophic lakes.
Resumo:
Microcystin (MC) problem made more and more care about in China, intercellular MC (Int-MC) and cellular MC (Cel-MC) were important contents to reflect the producing-MC ability by cyanobacteria and by lakes. To study the correlations between Int-MC, Cel-MC concentration and biological and environmental factors, eight cyanobacterial blooming lakes were studied in the middle and lower reaches of the Yangtze River. Microcystin-RR (MC-RR) and Microcystin-LR (MC-LR) were the primary toxin variants in our data. From the linear correlations between MC and environmental factors, cellular-YR had significant correlation with most of chemical factors except total nitrogen (TN) and the ratio of total nitrogen and total phosphorus (TN/TP), most intracellular MC analogues had significant correlations with total dissolved nitrogen (TDN), ammonium (NH4+), nitrite (NO2-), TP, total dissolved phosphorus (TDP), Microcystis. From the canonal correspondence analysis, Int-MC concentrations were closely related with the chemical and biological factors, such as TP, total organic carbon (TOC), chlorophyll a (Chl a), Microcystis biomass, et al. While Cel-MC contents, especially Cel-RR and Cel-LR, were closely related with light environmental in the lakes such as water depth and transparence.
Resumo:
The 16S and 18S rRNA genes of planktonic organisms derived from five stations with nutrient gradients in Lake Donghu, China, were studied by PCR-denaturing gradient gel electrophoresis (DGGE) fingerprinting, and the relationships between the genetic diversity of the plankton community and biotic/abiotic factors are discussed. The concentrations of total nitrogen (TN), total phosphorus (TP), NH4-N and As were found to be significantly related (P < 0.05) to morphological composition of the plankton community. Both chemical and morphological analyses suggested that temporal heterogeneity was comparatively higher than spatial heterogeneity in Lake Donghu. Although the morphological composition was not identical to the DGGE fingerprints in characterizing habitat similarity, the two strongest eutrophic stations (I and II) were always initially grouped into one cluster. Canonical correspondence analysis suggested that the factors strongly correlated with the first two ordination axes were seasonally different. The concentrations of TN and TP and the densities of rotifers and crustaceans were generally the main factors related to the DGGE patterns of the plankton communities. The study suggested that genetic diversity as depicted by metagenomic techniques (such as PCR-DGGE fingerprinting) is a promising tool for ecological study of plankton communities and that such techniques are likely to play an increasingly important role in assessing the environmental conditions of aquatic habitats.
