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1.
U. H. Brockmann 《Aquatic Ecology》1994,28(3-4):371-381
In the low salinity region of the Elbe estuary in March–April 1992 the turbidity zone was characterized by high loads of suspended
matter, 7% of which was organic material (750 μM C) at the surface. Particulate nitrogen, phosphorus and carbohydrates concentrations
reached 55 μM N, 10 μM P and more than 15 μM glc. eq., corresponding to 13% of total C, at the surface and increasing threefold
near the bottom.
In spite of the peaking of particulate organic material levels in the maximum turbidity zone, there were only consistent qualitative
changes in total particulate C, N, P, and carbohydrates along the Elbe estuary. Downstream, both the percentage of particulate
organic material and the turbidity: organic material ratio decreased, indicating decomposition in the upper estuary and dilution
with inorganic suspended matter from the lower estuary.
Diatoms, the dominant phytoplankton group, decreased from the upper reaches towards the turbidity zone by 0.3 (surface) and
1.5 mg C l−1 (bottom). This corresponded to 12 and 60% of the decrease in total particulate carbon. Estimated local input of organic carbon
by primary production (21 μg Cl−1d−1) was almost compensated by calculated minimum grazing (14 μg C l−1d−1). Considering net primary production and grazing, the dissimilation by zooplankton (5 μg C l−1d−1) and heterotrophic bacterial decomposition (48 μg C l−1d−1), when summed over the estimated flushing time (12 days) represented a loss of suspended organic matter of 0.6 mg Cl−1. Since this was only 20% of the observed decrease in particulate carbon, significant dilution processes must be assumed.
Dissolved organic nitrogen decreased from 35 to 10 μM N and dissolvd organic phosphorus from 0.6 to 0.1 μM P towards the sea,
mainly due to dilution. The distribution of phosphate, with highest loads in the turbidity maximum of 2.4 μM, suggested an
interaction with the accumulated load of particulate material. 相似文献
2.
Assessing Nitrification and Denitrification in the Seine River and Estuary Using Chemical and Isotopic Techniques 总被引:4,自引:0,他引:4
Mathieu Sebilo Gilles Billen Bernhard Mayer Daniel Billiou Micheline Grably Josette Garnier André Mariotti 《Ecosystems》2006,9(4):564-577
Downstream from metropolitan Paris (France), a large amount of ammonium is discharged into the Seine River by the effluents
of the wastewater treatment plant at Achères. To assess the extent of nitrification and denitrification in the water column,
concentrations and isotopic compositions of ammonium (δ15N–NH4+) and nitrate (δ15N–NO3−, δ18O–NO3−) were measured during summer low-flow conditions along the lower Seine and its estuary. The results indicated that most of
the ammonium released from the wastewater treatment plant is nitrified in the lower Seine River and its upper estuary, but
there was no evidence for water-column denitrification. In the lower part of the estuary, however, concentration and isotopic
data for nitrate were not consistent with simple mixing between riverine and marine nitrate. A significant departure of the
nitrate isotopic composition from what would be expected from simple mixing of freshwater and marine nitrates suggested coupled
nitrification and denitrification in the water, in spite of the apparent conservative behavior of nitrate. Denitrification
rates of approximately 0.02 mg N/L/h were estimated for this part of the estuary. 相似文献
3.
The food web in the lower part of the Seine estuary: a synthesis of existing knowledge 总被引:1,自引:0,他引:1
The Seine estuary illustrates the alterations to estuaries due to human activities heavy releases of pollutants of various origins and significant morphological changes beginning in the middle of the 19th century. The intertidal mudflat surface has been seriously reduced (< 30km2) since the channels of the Seine River came under management. While the role of the Seine estuary in the dynamics of the eastern English Channel ecosystem is recognized as important, the biological characteristics of the estuary remained relatively unknown until the 1990s. Biological diversity was progressively impoverished from the polyhaline zone to the oligohaline zone. In spite of a heavily contaminated environment, the macrobenthic and planktonic fauna of the Seine estuary remains similar to those of other northeastern Atlantic estuaries. The fauna exhibit clear contrasts between areas with very high abundance and others with very low abundance. The pelagic fauna, especially the copepod Eurytemora affinisand the shrimp Palaemon longirostris, are more abundant in the Seine estuary than in other estuaries. Diversified and abundant, Abra alba-Pectinaria koreni and Macoma balthica benthic communities occur, respectively, in the outer and inner parts of the estuary. In subtidal flats, benthic fauna is especially poor in terms of specific richness, abundance and biomass. Paradoxically, considering the high abundance of prey, fish are particularly scarce. Two food webs have been identified. In the oligohaline zone, where turbidity is maximum, the food web is exclusively planktonic, due to dredging that prevented benthic fauna from settling. In the polyhaline zone, fish populations that feed particularly on benthic fauna benefit from low turbidity and high oxygen concentrations. So, in spite of heavy organic and metallic contamination and human activities, the Seine estuary remains a highly productive ecosystem, which provides a nursery for marine fish and feeding grounds for migratory birds. A global management plan appears to be necessary in order to guarantee that the Seine estuary continues to function as it currently does. 相似文献
4.
Seigen Tsukuda Masahito Sugiyama Yunosuke Harita Kazuo Nishimura 《Biogeochemistry》2006,77(1):117-138
Atmospheric bulk depositions of soluble reactive phosphorus (SRP), soluble unreactive phosphorus (SUP), particulate inorganic
phosphorus (PIP), particulate organic phosphorus (POP), total phosphorus (TP) and some other dissolved and particulate components
were monitored for 3 years in Ashiu, Central Japan. The mean bulk depositions of SRP, SUP, PIP, POP, TP, dissolved components
(Na, Mg, nss-Ca, K, V, Mo, nss-SO4) and particulate components (Al, Fe, Ti, Ca, Mg, Mn, Ba, Sr, Zn) were 175, 76, 136, 397, 783, 156,000, 10,900, 7450, 5470,
10.3, 1.52, 40,100, 13,200, 3590, 2630, 576, 624, 42.3, 30.2, 17.4, 8.2 μmol m−2 year−1, respectively. The value for TP deposition was in the lower range of previous literature. The low P deposition probably reflected
the method applied to reduce the contribution of local particles, including (1) placement of samplers off the ground surface,
(2) installation of multiple samplers, and (3) rejection of contaminated samples. Al data suggested that 15 ± 5% of TP was
brought by lithogenic dust from East Eurasia. Nss-SO4 and Mo data and air-mass backward trajectories suggested that 39 ± 4% of TP was derived from coal combustion in China. It
was speculated that the rest (47 ± 6%) of the TP deposition might be predominantly attributed to the contribution of local
biogenic particles. Net atmospheric TP input (lithogenic dust and fossil fuel combustion) was almost equal to the TP outflow
from Japanese forests on granitic soils. 相似文献
5.
Phosphorus (P) dynamics in the agriculturally-dominated Minnesota River (USA) were examined in the lower 40 mile reach in
relation to hydrology, loading sources, suspended sediment, and chlorophyll to identify potential biotic and abiotic controls
over concentrations of soluble P and the recycling potential of particulate P during transport to the Upper Mississippi River.
Within this reach, wastewater treatment plant (WWTP) contributions as soluble reactive P (SRP) were greatest during very low
discharge and declined with increasing discharge and nonpoint source P loading. Concentrations of SRP declined during low
discharge in conjunction with increases in chlorophyll, suggesting biotic transformation to particulate P via phytoplankton
uptake. During higher discharge periods, SRP was constant at ~0.115 mg l−1 and coincided with an independently measured equilibrium P concentration (EPC) for suspended sediment in the river, suggesting
abiotic control over SRP via phosphate buffering. Particulate P (PP) accounted for 66% of the annual total P load. Redox-sensitive
PP, estimated using extraction procedures, represented 43% of the PP. Recycling potential of this load via diffusive sediment
P flux under anoxic conditions was conservatively estimated as ~17 mg m−2 d−1 using published regression equations. The reactive nature and high P recycling potential of suspended sediment loads in the
Minnesota River has important consequences for eutrophication of the Upper Mississippi River. 相似文献
6.
The Pawcatuck River watershed (764 km2) is a mainly forested drainage basin with a low population density (80 people km−2) that discharges to a shallow estuary, Little Narragansett Bay (RI and CT, USA). In order to quantify the nitrogen (N) and
phosphorus (P) flux to the estuary, we measured all forms of nitrogen and phosphorus, as well as suspended solids at the mouth
of the river above tidal influence, on more than 80 occasions over an annual cycle. The annual export of total nitrogen, total
phosphorus, and total suspended solids amounted to 16.0×106 mol y−1, 0.97×106 mol y−1, and 1.4×106 kg y−1, respectively. Nitrogen export was equally divided between dissolved inorganic (83% NO3−) and organic forms, with particulate nitrogen comprising 17% of the total flux. Phosphorus export was dominated by particulate
forms (67%), with dissolved inorganic phosphate contributing 30% and dissolved organic phosphorus contributing 8% of the annual
flux. Preliminary nutrient budgets for the Pawcatuck watershed suggest that only about 10% of the nitrogen and phosphorus
inputs are exported from the system. Strong regressions between water discharge and TN enabled us to extrapolate the data
collected during the relatively dry study period to a long term average discharge year. Under normal river discharge conditions,
the N flux would be approximately 26.0×106 mol y−1 or about 20% of the nitrogen inputs to the watershed. This value is very close to the N flux predicted by a regression developed
by others from a wide range of larger watersheds. The relatively large size of the Pawcatuck watershed relative to the estuary
(9.6 km2), makes Little Narragansett Bay one of the most intensively nitrogen loaded estuaries on the Atlantic coast in spite of the
dominant forest cover of the watershed. 相似文献
7.
Reversibility of phosphorus sorption by ferruginous nodules 总被引:1,自引:0,他引:1
Ferruginous nodules sorb significant amounts of available soil and fertiliser phosphate. The effect of this sorption on phosphorus
availability of an agricultural soil was tested by sequential extraction and by exhaustive cropping with millet (Pennisetum typhoides) in a greenhouse trial following fertilisation of the original soil containing 70% nodules and of prepared samples containing
various mixes of separated soil fines and nodules. Phosphorus sorption maxima by the soil fines and nodules were 190 mg kg−1 and 380 mg kg−1 respectively. Samples of fines and nodules which had sorbed 110 and 194 mg kg−1 were submitted to 8 successive extractions with 0.01 M KCl, after which P desorption amounted to 117 mg kg−1 and 103 mg kg−1 respectively. Hysteresis between sorption and desorption was negligible for the soil fines and increased with increasing
nodule content of the samples. In the greenhouse experiment, P uptake at the first cropping was highest in the soil fines
at all levels of phosphorus applied. Subsequent croppings, however, showed higher P uptake in the concretionary soils. These
results indicate a higher initial P release from the soil fines with cropping followed by an earlier exhaustion of phosphorus.
At the end of the greenhouse experiment, yields were low in spite of the large quantities of P still remaining in the soils.
Phosphorus fractionation showed that, of the P left in the soil after cropping 20% was in labile, 29% in Fe or Al-associated,
and 51% in low-availability forms. 相似文献
8.
Josette Garnier Aurélie Cébron Gaëlle Tallec Gilles Billen Mathieu Sebilo Anun Martinez 《Biogeochemistry》2006,77(3):305-326
The Seine River estuary (France) is the receptacle of a drainage basin characterised by high population density, heavy industrial
activity and intensive agriculture. Whereas nitrate concentrations are high due to diffuse sources in the upstream drainage
basin, ammonium mainly originates from the effluents of the Achères wastewater treatment plant (WWTP) downstream from Paris
and its suburbs (6.5 million equivalent-inhabitants). Ammonium is mostly nitrified in the tidal freshwater estuary and nitrification
causes a strong summer oxygen deficit. Average longitudinal summer profiles of oxygen and nitrogen concentrations for two
periods, between 1993–1997 and 1998–2003 in dry hydrological conditions (excluding the wet years 2000 and 2001) clearly reflect
the changes due to the improved treatment of wastewater from Paris and its suburbs. On the basis of daily water flux data
and twice monthly nitrogen measurements at the boundaries of the upstream freshwater estuarine section (108 km), we calculated
nitrification and denitrification fluxes, whose annual averages were 43 and 71 × 103 kg N d−1 respectively from 1993 to 2003, with summer values (July–September) representing 73 and 57% of the annual fluxes, respectively.
The degree of denitrification in the upper estuary appears to be closely related to the nitrification, itself more loosely
related to the amount of reduced nitrogen (Kjeldahl) brought by the treated effluents from the Achères WWTP. We estimated
the total N2O emissions to about 40 kg N d−1 (25–60 kg N d−1) in the same sector. 相似文献
9.
Phosphorus (P) is one of main pollution elements of eutrophication. P emissions from different pathways and sources are a
key issue in the protection of water quality and sustainable watershed management practices. We have estimated net anthropogenic
P accumulation (NAPA), as an index of P pollution potential in the Beijing metropolitan region, China. The NAPA estimation
is based on an inventory of P fertilizer use, consumption of human food and animal feed, non-food P, and riverine P net flux.
The overall average NAPA for 1991, 1997, 2003, and 2007 are 777, 943, 1218, and 1084 kg P km−2 y−1, about two times that reported in developed countries. The Urban unit has the largest NAPA (5526 kg P km−2 y−1), whereas Mentougou P was negative, outputting 34 kg P km−2 y−1. P input of fertilizer is the largest source of NAPA, accounting for 40.7% (455 kg P km−2 y−1) of the total P input, followed by non-food P and P in human food and animal feed. NAPA is closely related to land use, on
average 5433 kg P km−2 y−1 in densely populated developed land, 503 kg P km−2 y−1 in agricultural land and 84 kg P km−2 y−1 in forest land. Human population density is the best single predictor of NAPA. Our results provide a basis for understanding
the potential impact of anthropogenic P inputs on environmental problems, such as nation-wide water quality degradation under
the current rapid urban expansion in modern China. 相似文献
10.
Summary A super strain ofBacillus firmus (NCIM-2636) producing a phytohormone, indole-3-acetic acid, in addition to its high ability to solubilize insoluble inorganic
phosphates were applied in acid soils of Nagaland, India. Rice (Oryza sativa L.) variety Jaya and IR-8 were grown in kharif season in two successive years 1980 and 1981. After proper manuring the soils
received single super phosphate (S.S.P.) and Mussoorie Rock phosphate (R.P.) separately at different doses. Yield of crop
in both the years increased significantly due to bacterial inoculation. Maximum grain yield was recorded in Jaya variety under
S.S.P. and R.P. when treatments were at the dose of 43.75 and 17.5 kg P ha−1 respectively while the same in IR-8 variety under S.S.P. and R.P. treatments were at the dose of 35 and 17.5 kg P ha−1 respectively. Maximum straw yield was produced by Jaya variety when 35 and 43.75 kg P ha−1 in the form of S.S.P. and R.P. respectively were applied. Highest straw yield of IR-8 variety was obtained after the application
of 17.5 kg P ha−1 (S.S.P. and R.P.) in combination with phosphate solubilizing bacteria. Bacterial inoculation decreased the phosphorus availability
in 1 st year but increased the same in 2nd year. Phosphorus content in grains was significantly enhanced in both the trials.
Maximum uptake of phosphorus by grains was noted in Jaya variety at the dose of 47.5 kg P ha−1 and in IR-8 variety at the dose of 52.5 kg P ha−1 under S.S.P. treatment, while 8.75 and 35 kg P ha−1 in the form of R.P. yielded similar results in Jaya and IR-8 varieties respectively. Phosphorus at the dose of 35 kg ha−1 was found to cause more P-uptake by straw in both S.S.P. and R.P. treatments. The various data from the experiment conclusively
proved that the bacterium in combination with R.P. produced the desired effect more prominently than when bacterium applied
in combination with S.S.P. 相似文献
11.
F. Andrieux-Loyer X. Philippon G. Bally R. Kérouel A. Youenou J. Le Grand 《Biogeochemistry》2008,88(3):213-231
The macrotidal estuary of Penzé (Brittany, Western part of the Channel, France) has been subjected to recurrent annual toxic
blooms of Alexandrium minutum since 1988. This study aims to specify the phosphorus dynamics and bioavailability in sediments in order to improve our understanding
of Alexandrium occurrences. Sediment-P pools and diffusive phosphate fluxes were studied under similar hydrodynamic conditions, in the intermediate
estuary in May, June and July 2003 and along the salinity gradient from August 2004 to June 2005. The results highlight a
decrease in bioavailable phosphorus (iron and organic bound) from the inner part of the estuary seaward. The ratio of iron-bound
phosphorus to iron-oxyhydroxides is lower in the inner and intermediate estuaries (5–8) than in the outer site (15), suggesting
a saturation of sorption sites and greater phosphorus bioavailability in this area. Pools of bioavailable phosphorus in surficial
sediments are about eight times higher than the annual net-export of P (7 ton year−1). Phosphate releases from sediments are always lower than 5 μmol m−2 d−1 in March. The highest supplies occur in June and August in the intermediate area (up to 400 μmol m−2 d−1) where they represent up to 50% of river loadings. These results further suggest that phosphate pulses coincide with occurrences
of Alexandrium reported in June. 相似文献
12.
Previous studies suggest that current-driven plant transport in shallow lagoons and estuaries is associated with increased
turbidity. Our hypothesis is therefore that macroalgae erode surface sediment while drifting as bedload. This ballistic effect
of moving plants on surface sediment was tested in a series of controlled annular flume experiments, where simultaneous measurements
of macrophytes transport and turbidity were conducted at increasing current velocities. Sediment erosion always started earlier
in experiments with plants than in control experiments without plants. Turbidity increased immediately when plants started
to move at current velocities of 2–4 cm s−1. From a background concentration of 7–10 mg SPM l−1, turbidity increased to 30–50 mg SPM l−1 for Ceramium sp., Ulva lactuca and Chaetomorpha linum, while the more rigid Gracilaria sp., caused much higher turbidities (50–180 mg SPM l−1). Such plant induced sediment erosion at low current velocity can explain the observed appearance of turbid waters in estuaries
and lagoons in the absence of strong wind and wave action. Based on 3-D hydrodynamic modelling, it was determined that plant
driven erosion occurs during most of the growth season in a shallow eutrophic estuary (Odense Fjord, Denmark). 相似文献
13.
Nodularia spumigena is one of the dominating species during the extensive cyanobacterial blooms in the Baltic Sea. The blooms coincide with strong
light, stable stratification, low ratios of dissolved inorganic nitrogen, and dissolved inorganic phosphorus. The ability
of nitrogen fixation, a high tolerance to phosphorus starvation, and different photo-protective strategies (production of
mycosporine-like amino acids, MAAs) may give N. spumigena a competitive advantage over other phytoplankton during the blooms. To elucidate the interactive effects of ambient UV radiation
and nutrient limitation on the performance of N. spumigena, an outdoor experiment was designed. Two radiation treatments photosynthetic active radiation (PAR) and PAR +UV-A + UV-B
(PAB) and three nutrient treatments were established: nutrient replete (NP), nitrogen limited (−N), and phosphorus limited
(−P). Variables measured were specific growth rate, heterocyst frequency, cell volume, cell concentrations of MAAs, photosynthetic
pigments, particulate carbon (POC), particulate nitrogen (PON), and particulate phosphorus (POP). Ratios of particulate organic
matter were calculated: POC/PON, POC/POP, and PON/POP. There was no interactive effect between radiation and nutrient limitation
on the specific growth rate of N. spumigena, but there was an overall effect of phosphorus limitation on the variables measured. Interaction effects were observed for
some variables; cell size (larger cells in −P PAB compared to other treatments) and the carotenoid canthaxanthin (highest
concentration in −N PAR). In addition, significantly less POC and PON (mol cell−1) were found in −P PAR compared to −P PAB, and the opposite radiation effect was observed in −N. Our study shows that despite
interactive effects on some of the variables studied, N. spumigena tolerate high ambient UVR also under nutrient limiting conditions and maintain positive growth rate even under severe phosphorus
limitation. 相似文献
14.
José Juan Barrera-Alba Sônia Maria Flores Gianesella Gleyci Aparecida Oliveira Moser Flávia Marisa Prado Saldanha-Corrêa 《Hydrobiologia》2008,598(1):229-246
Heterotrophic bacterial and phytoplankton biomass, production, specific growth rates and growth efficiencies were studied
in July 2001 and January 2002 during both spring and neap tides, along a tidal cycle, at three sites in a subtropical estuary.
Major freshwater inputs located in the Northern region led to differences in both phytoplankton and bacterioplankton biomass
and activity along the estuary. While in the Northern region phytoplankton is light-limited, with mean phytoplankton production
(PP) between 1.1 and 1.9 μg C l−1 h−1 and mean specific growth rates (PSG) between 0.14 and 0.16 d−1, the Southern region registered values as high as 24.7 μg C l−1 h−1 for PP and 2.45 d−1 (mean PP between 3.4 and 7.3 μg C l−1 h−1; mean PSG between 0.28 and 0.57 d−1). On the other hand, maximum bacterial production (BP: 63.8 μg C l−1 h−1) and specific growth rate (BSG: 32.26 d−1) were observed in the Northern region (mean BP between 3.4 and 12.8 μg C l−1 h−1; mean BSG between 1.98 and 6.67 day−1). These bacterial activity rates are among the highest recorded rates in estuarine and coastal waters, indicating that this
system can be highly heterotrophic, due to high loads of allochthonous carbon (mainly derived from mangrove forest). Our results
also showed that, despite that BP rates usually exceeded PP, in the Southern region BP may be partially supported (∼45%) by
PP, since a significant regression was observed between BP and PP (r = 0.455, P < 0.001).
Handling editor: P. Viaroli 相似文献
15.
Ionic content as a factor influencing turbidity in two floodplain lakes after a flood 总被引:1,自引:1,他引:0
The relationship between ionic content, measured as electrical conductivity, and turbidity resulting from inorganic suspensoids
was investigated experimentally on the Ponogolo river floodplain. Turbid floodwaters were mixed in various proportions with
clear lake water of high conductivity and settling rates determined. For the conductivity range 215–1084 μS cm−1 there was an increase in the maximum settling rate from 3.3–20.6% h−1. These data were compared with observations made, in a turbid lake of low conductivity and a clear water lake of high conductivity,
during and after a flood. The importance of lake morphology, flushing and conductivity as determinants of turbidity and light
attenuation in the floodplain lakes is discussed. The relevance of these observations to the understanding of turbidity in
other systems is considered. 相似文献
16.
The biogeochemical controls on particulate phosphorus distribution in the Humber estuary have been investigated with regard
to salinity and season. Surveys of the Humber were conducted in August 1991 and January, March and June 1992. Samples were
collected for particulate phosphorus, dissolved phosphorus, suspended load and salinity analysis. Particulate phosphorus forms
16 to 93% of the total phosphorus present in the water column of the Humber estuary. Total particulate phosphorus concentrations
in the Humber ranged from 1 to 45 μmol l−1. This range is comparable to that observed in similar sized industrialized estuaries of the U.S.A. and northern Europe. Flocculation
at low salinities was found to be a major influence on particulate phosphorus concentrations. Highest concentrations of particulate
phosphorus were found in reaches below a salinity of 5 and may result in phosphorus being trapped in the sediments of the
estuary. There is evidence that this phosphorus may be released as oxygen concentrations decrease during the summer. Suspended
load, adsorption/desorption equilibrium and external inputs were also found to influence the particulate phosphorus concentrations. 相似文献
17.
Instability of the turbidity maximum in the macrotidal Geum River estuary, western Korea 总被引:2,自引:0,他引:2
In the low-salinity area of many macrotidal estuaries, through the combination of tidal pumping and estuarine circulation,
an estuarine turbidity maximum (ETM) develops providing favorable conditions for various organisms. To investigate ecological
roles of the ETM in East Asian estuaries, we conducted seasonal observations in the Geum (or Keum) River estuary, one of the
representative macrotidal estuaries flowing into the Yellow Sea, from 2007 to 2008. The estuary was frequently filled with
high-salinity (>10 PSU) and low-turbidity (<100 NTU) water under small or no freshwater discharge from a dam (ca. 8 km upstream
from the river mouth). Brackish water was, however, completely pushed out of the estuary within a few hours after an intensive
discharge in summer. Chlorophyll a (up to 50 μg l−1) and pheophytin (up to 80 μg l−1) were concentrated in a low-salinity (<1 PSU) and high-turbidity (up to 1000 NTU) area, indicating that the intensive discharge
transported both living phytoplankton and resuspended detritus into the area. In contrast, a phytoplankton bloom (chlorophyll
a, up to 100 μg l−1) was observed at low salinities under little discharge in winter. The present study demonstrated an absence of the ETM suitable
for estuarine-dependent organisms from the present Geum River estuary, indicating potential importance of adequate control
of freshwater discharge for the formation and maintenance of the ETM. 相似文献
18.
Jang K. Kim George P. Kraemer Christopher D. Neefus Ik Kyo Chung Charles Yarish 《Journal of applied phycology》2007,19(5):431-440
Porphyra is one of the world’s most valued maricultured seaweeds and has been cultivated for several hundred years in Asia. The objective
of this study was to produce critical information as a guide for the selection of an appropriate Porphyra species from coastal New England for the development of a land-based aquaculture system. Four Northwest Atlantic Porphyra species: P. leucosticta,
P. amplissima, P. linearis and P. umbilicalis, were cultivated for 1 and 2 weeks at saturated light intensities (100–150 μmol photons m−2s−1) and six combinations of ammonium (25 and 250 μmoles L−1) and temperature (10, 15 and 20°C). Specific growth rate (SGR) increased with decreasing temperature in P. leucosticta, P. linearis and P. umbilicalis and increased with increasing temperature in P. amplissima. The SGR of all species was greater at the higher ammonium concentration. Porphyra linearis had the highest SGR, increasing in biomass by approximately 16% day−1. Phycoerythrin (PE) content was higher at 10°C and 250 μmoles L−1 in all species except P. amplissima. The PE content, measured as fresh weight (FW), of P. linearis (29 mg g−1 FW−1) and P. umbilicalis (26 mg g−1 FW−1) was significantly higher than the other two species. Tissue nitrogen content of all species measured in dry weight was on
average 1.45% higher at 250 μmoles L−1 than at 25 μmoles L−1 ammonium concentration. Porphyra umbilicalis had the highest tissue nitrogen contents (6.76%) at 10°C and 250 μmoles L−1 ammonium. Based on these results, P. linearis and P. umbilicalis should be considered as potential candidates for bioremediation with finfish and shellfish mariculture. 相似文献
19.
Comparative effects of salt-stress and alkali-stress on the growth,photosynthesis, solute accumulation,and ion balance of barley plants 总被引:7,自引:0,他引:7
We compared the effects of salt-stresses (SS, 1: 1 molar ratio of NaCl to Na2SO4) and alkali-stresses (AS, 1: 1 molar ratio of NaHCO3 to Na2CO3) on the growth, photosynthesis, solute accumulation, and ion balance of barley seedlings, to elucidate the mechanism of AS
(high-pH) damage to plants and the physiological adaptive mechanism of plants to AS. The effects of SS on the water content,
root system activity, membrane permeability, and the content of photosynthetic pigments were much less than those of AS. However,
AS damaged root function, photosynthetic pigments, and the membrane system, led to the severe reductions in water content,
root system activity, content of photosynthetic pigments, and net photosynthetic rate, and a sharp increase in electrolyte
leakage rate. Moreover, with salinity higher than 60 mM, Na+ content increased slowly under SS and sharply under AS. This indicates that high-pH caused by AS might interfere with control
of Na+ uptake in roots and increase intracellular Na+ to a toxic level, which may be the main cause of some damage emerging under higher AS. Under SS, barley accumulated organic
acids, Cl−, SO4
2−, and NO3
− to balance the massive influx of cations, the contribution of inorganic ions to ion balance was greater than that of organic
acids. However, AS might inhibit absorptions of NO3
− and Cl−, enhance organic acid synthesis, and SO4
2− absorption to maintain intracellular ion balance and stable pH. 相似文献
20.
Temporal and spatial trends in nitrogen and phosphorus inputs to the watershed of the Altamaha River,Georgia, USA 总被引:4,自引:0,他引:4
The watershed of the Altamaha River, Georgia, is one of the largest in the southeastern U.S., draining 36,718 km2 (including parts of metro Atlanta). We calculated both nitrogen (fertilizer, net food and feed import, atmospheric deposition,
and biological N fixation in agricultural and forest lands) and phosphorus (fertilizer and net food and feed import) inputs
to the watershed for 6 time points between 1954 and 2002. Total nitrogen inputs rose from 1,952 kg N km−2 yr−1 in 1954 to a peak of 3,593 kg N km−2 yr−1 in 1982 and then declined to 2,582 kg N km−2 yr−1 by 2002. Phosphorus inputs rose from 409 kg P km−2 yr−1 in 1954 to 532 kg P km−2 yr−1 in 1974 before declining to 412 kg P km−2 yr−1 in 2002. Fertilizer tended to be the most important input of both N and P to the watershed, although net food and feed import
increased in importance over time and was the dominant source of N input by 2002. When considered on an individual basis,
fertilizer input tended to be highest in the middle portions of the watershed (Little and Lower Ocmulgee and Lower Oconee
sub-watersheds) whereas net food and feed imports were highest in the upper reaches (Upper Oconee and Upper Ocmulgee sub-watersheds).
Although the overall trend in recent years has been towards decreases in both N and P inputs, these trends may be offset due
to continuing increases in animal and human populations. 相似文献