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1.
To investigate regional and interannual variability of the ecosystem in the Southern Ocean, a coupled circumpolar ice–ocean–plankton model has been developed. The ice–ocean component (known as BRIOS-2) is based on a modified version of the s-coordinate primitive equation model (SPEM) coupled to a dynamic–thermodynamic sea-ice model. The biological model (BIMAP) comprises two biogeochemical cycles – silica and nitrogen – and a prognostic iron compartment to include possible effects of micronutrient limitation. Simulations with the coupled ice–ocean–plankton model indicate that the physical–biological interaction is not limited to the effect of a varying surface mixed-layer depth. In the Pacific sector, large anomalies in winter mixed-layer depth cause an increased iron supply and enhance primary production and plankton biomass in the following summer, whereas in the Atlantic sector variability in primary production is caused mainly by fluctuations of oceanic upwelling. Thus, the Antarctic Circumpolar Wave (ACW) induces regional oscillations of phytoplankton biomass in both sectors, but not a propagating signal. Furthermore, interannual variability in plankton biomass and primary production is strong in the Coastal and Continental Shelf Zone and the Seasonal Ice Zone around the Antarctic continent. Interannual variability induced by the ACW has large effects on the regional scale, but the associated variability in biogenic carbon fluxes is small compared to the long-term carbon sequestration of the Southern Ocean.  相似文献   

2.
Primary production in the Northern San Francisco Estuary (SFE) has been declining despite heavy loading of anthropogenic nutrients. The inorganic nitrogen (N) loading comes primarily from municipal wastewater treatment plant (WTP) discharge as ammonium (NH(4)). This study investigated the consequences for river and estuarine phytoplankton of the daily discharge of 15 metric tons NH(4)-N into the Sacramento River that feeds the SFE. Consistent patterns of nutrients and phytoplankton responses were observed during two 150-km transects made in spring 2009. Phytoplankton N productivity shifted from NO(3) use upstream of the WTP to productivity based entirely upon NH(4) downstream. Phytoplankton NH(4) uptake declined downstream of the WTP as NH(4) concentrations increased, suggesting NH(4) inhibition. The reduced total N uptake downstream of the WTP was accompanied by a 60% decline in primary production. These findings indicate that increased anthropogenic NH(4) may decrease estuarine primary production and increase export of NH(4) to the coastal ocean.  相似文献   

3.
The Gulf of Guinea is situated in the narrow protrusion of eastern Equatorial Atlantic between latitudes 2 degrees S and 5 degrees N and longitudes 8 degrees W to 12 degrees E, spanning a coastline length of approximately 130 nautical miles. The dominant feature of this shallow ocean off the coast of countries in Western Africa is the Guinea Current. The distinctive bathymetry, hydrography, productivity and trophodynamics of this shallow ocean qualify it as a large marine ecosystem (LME) and is indeed recognized as the number 28 of the 64 delineated LMEs globally. This area is one of the world's productive marine areas that is rich in fishery resources, oil and gas reserves, precious minerals and an important global reservoir of marine biological diversity. Unfortunately, pollution from residential and industrial sources has affected the waters of the Gulf of Guinea resulting in habitat degradation, loss of biological diversity and productivity, and degenerating human health. In reversing this trend of marine environmental degradation, the countries of the region adopted an integrated and holistic approach using the LME concept to sustainably manage the environmental and living resources of the region. The concept is predicated on the fact that marine environmental pollution and living resources respect no political or geographical boundaries and so require a holistic and regional approach for its management. The Gulf of Guinea countries through the Global Environment facility funded regional/communal project on water pollution control and biodiversity conservation achieved a paradigm shift in living resources and environmental management in the region using the LME concept.  相似文献   

4.
Fresh water resources within the Kingdom of Saudi Arabia are a rare and precious commodity that must be managed within a context of integrated water management. Wadi aquifers contain a high percentage of the naturally occurring fresh groundwater in the Kingdom. This resource is currently overused and has become depleted or contaminated at many locations. One resource that could be used to restore or enhance the fresh water resources within wadi aquifers is treated municipal waste water (reclaimed water). Each year about 80 percent of the country's treated municipal waste water is discharged to waste without any beneficial use. These discharges not only represent a lost water resource, but also create a number of adverse environmental impacts, such as damage to sensitive nearshore marine environments and creation of high-salinity interior surface water areas. An investigation of the hydrogeology of wadi aquifers in Saudi Arabia revealed that these aquifers can be used to develop aquifer recharge and recovery (ARR) systems that will be able to treat the impaired-quality water, store it until needed, and allow recovery of the water for transmittal to areas in demand. Full-engineered ARR systems can be designed at high capacities within wadi aquifer systems that can operate in concert with the natural role of wadis, while providing the required functions of additional treatment, storage and recovery of reclaimed water, while reducing the need to develop additional, energy-intensive desalination to meet new water supply demands.  相似文献   

5.
Sludge pretreatment prior to anaerobic digestion has been found to reduce sludge production in wastewater treatment. Sludge disintegration using physical, chemical, biological, or mechanical methods can increase biogas production and reduce sludge quantities. Ultrasonication is one of the most effective means of mechanical disintegration. This study aims to investigate ultrasonication as a means for solubilizing waste activated sludge (WAS) to enhance its digestability. Sonication was applied by the use of two different probes providing different powers and energies into the sludge after which the soluble chemical oxygen demand (sCOD) increases were measured. The samples were then digested anaerobically in 250 mL serum bottles for about 50 days. Along with the biogas measurements, the rate of methane production is calculated to be able to quantify the effect of pretreatment and compare the results between different applications. The results showed that with the increase of sonication power and sonication time, sCOD increased. An introduction of higher sonication energy made the sCOD rise sharply, however, this increase was not indefinite; it became gradually lower with the further increase of energy. The results indicated that specific methane production, specific methane yield, and the first order methane generation rate increased with increasing energy input.  相似文献   

6.
Annual phytoplankton productivity in Lake Constance is about 300 g C m−2, a value typical for mesoeutrophic lakes. Seasonal variations in phytoplankton biomass and productivity are exceptionally great because of a sequence of factors controlling the production process. During winter productivity is controlled by low energy inputs and high respiratory losses due to deep water column mixing. Biomass is low and water transparancy high. The spring phytoplankton growth is triggered by the thermal stabilization of the water column. The summer phytoplankton biomass maximum mainly depends on phosphorus availability. However, biomass yields comprise only 15–20% of values to be expected from the Redfield ratio because large proportions of POM are detritus and non-algal biota. Moreover, sedimentation during the second half of the year removes biomass from the euphotic zone. Water transparency and thus vertical distribution of algal photosynthesis is highly dependent on phytoplankton biomass. Self-shading causes considerably smaller seasonal variations in areal biomass and photosynthetic rates than in volume-based values. By light-shade adaptation effects of seasonal fluctuations in mean daily surface radiance fluxes on algal photosynthesis can to a significant extent be compensated for. At any given level of biomass daylength is the major determinant of daily production rates. Dedicated to Professor Elster on his 80th birthday.  相似文献   

7.
A marine secondary producer respires and feeds more in a high CO2 ocean   总被引：1，自引：0，他引：1  
Climate change mediates marine chemical and physical environments and therefore influences marine organisms. While increasing atmospheric CO(2) level and associated ocean acidification has been predicted to stimulate marine primary productivity and may affect community structure, the processes that impact food chain and biological CO(2) pump are less documented. We hypothesized that copepods, as the secondary marine producer, may respond to future changes in seawater carbonate chemistry associated with ocean acidification due to increasing atmospheric CO(2) concentration. Here, we show that the copepod, Centropages tenuiremis, was able to perceive the chemical changes in seawater induced under elevated CO(2) concentration (>1700 μatm, pH<7.60) with avoidance strategy. The copepod's respiration increased at the elevated CO(2) (1000 μatm), associated acidity (pH 7.83) and its feeding rates also increased correspondingly, except for the initial acclimating period, when it fed less. Our results imply that marine secondary producers increase their respiration and feeding rate in response to ocean acidification to balance the energy cost against increased acidity and CO(2) concentration.  相似文献   

8.
Stormwater runoff plumes, municipal wastewater plumes, and natural hydrocarbon seeps are important pollution hazards for the heavily populated Southern California Bight (SCB). Due to their small size, dynamic and episodic nature, these hazards are difficult to sample adequately using traditional in situ oceanographic methods. Complex coastal circulation and persistent cloud cover can further complicate detection and monitoring of these hazards. We use imagery from space-borne synthetic aperture radar (SAR), complemented by field measurements, to examine these hazards in the SCB. The hazards are detectable in SAR imagery because they deposit surfactants on the sea surface, smoothing capillary and small gravity waves to produce areas of reduced backscatter compared with the surrounding ocean. We suggest that high-resolution SAR, which obtains useful data regardless of darkness or cloud cover, could be an important observational tool for assessment and monitoring of coastal marine pollution hazards in the SCB and other urbanized coastal regions.  相似文献   

9.
The deep ocean piezosphere accounts for a significant part of the global ocean,hosts active and diverse microbial communities which probably play a more important role than hitherto recognized in the global ocean carbon cycle.The conventional biological pump concept and the recently proposed microbial carbon pump mechanism provide a foundation for our understanding of the role of microorganisms in cycling of carbon in the ocean.However,there are significant gaps in our knowledge and a lack of mechanistic understanding of the processes of microbially-mediated production,transformation,degradation,and export of marine dissolved and particulate organic matter(DOM and POM)in the deep ocean and the ecological consequence.Here we propose the POM-DOM piezophilic microorganism continuum(PDPMC)conceptual model,to address these important biogeochemical processes in the deep ocean.We propose that piezophilic microorganisms(bacteria and archaea)play a pivotal role in deep ocean carbon cycle where microbial production of exoenzymes,enzymatic breakdown of DOM and transformation of POM fuels the rapid cycling of marine organic matter,and serve as the primary driver for carbon cycle in the deep ocean.  相似文献   

10.
In 2002, the Helmholtz-Zentrum Geesthacht, Germany, started to use FerryBox-automated monitoring systems on Ships of Opportunity to continuously record standard oceanographic, biological and chemical in situ data in the North Sea. The present study summarises the operational experience gathered since the beginning of this deployment and reflects on the potential and limits of FerryBox systems as a monitoring tool. One part relates to the instrumental performance, constancy of shipping services, and the availability and quality of the recorded in situ data. The other considers integration of the FerryBox observations in scientific applications and routine monitoring campaigns. Examples are presented that highlight the added value of the recorded data for the study of both long- and short-term variability in water mass stability, plankton communities and surface water productivity in the North Sea. Through the assessment of technical and scientific performance, it is evident that FerryBoxes have become a valuable tool in marine research that helps to fill gaps in coastal and open ocean operational observation networks.  相似文献   

11.
Protection of the sea has received much political attention—for example, at successive North Sea Conferences environmental ministers have formulated a stringent policy with the aim of reducing pollution in the north-east Atlantic. In the past this area received many substances from many sources, but gradually intergovernmental action since 1972 in the Oslo and Paris Conventions has succeeded in tracing the major sources and understanding the effects of these inputs on the marine environment. After long discussion, many dumpings and discharges have been ended because they were considered harmful to the marine environment. Dredging activities were included in the discussions but they may be regarded as being a special case compared with many other disposals.

In general, clean dredged material for sea disposal offers no problems, although restrictions may be caused by physical impacts, mainly to habitats for living organisms. However, this material also has positive, often even beneficial uses. In contrast, contaminated material disposal is restricted and the internationally accepted rule is that the material should not create hazards to human health, harm living resources and marine life or damage amenities or interfere with other legitimate uses of the sea. There are in principle three options for dealing with polluted sediments: doing nothing, remedial action in situ, removal of the contaminated material; occasionally treatment is a possibility. The distinction has been made between the disposal of industrial waste, sewage sludge or dredged material. Industrial waste disposal is now prohibited; sewage sludge may be dumped until 31 December 1998, although dredged material may still be stored at sea under certain conditions. The Oslo Convention 1972 decided with regard to dredged material: that pollution has to be tackled at the source; dumping at sea is forbidden, although dredged materials may be excluded from this; land disposal prevails, although in several countries there is a growing resistance to disposal on land; there should be a precautionary approach against marine disposal; a stand-still principle should be followed where the quantities disposed in a certain year should not be exceeded nor should the quality of the receiving water be reduced; marine disposal should be phased out and, where appropriate, time-limits set; and the polluter pays.

Dredged material is regarded as polluted and as a consequence may in general not be disposed of at sea when it contains substances listed in the Annexes of the Convention. Exceptions to this are indicated by the terms ‘a trace contaminant’, ‘rapidly rendered harmless’ or ‘significant amounts’. Therefore, to achieve uniformity in the application of the Convention, guidelines have been prepared by a joint London Dumping Convention/Oslo Commission working group of experts on dredged material. Several characteristics must be considered when choosing a site for marine disposal and interests such as beach recreation, sport and commercial fishing, nature, cultural or historical interests, navigation, military interests and cables and pipelines should be taken into account. Also the capacity of the area to assimilate disposed matter per time unit must not be exceeded, especially in low energy areas. It is considered that in discussions of the environmental aspects of dredging it is important that associations such as PIANC argue for safe and economic navigation.  相似文献   


12.
Marine biodiversity in almost all oceans is being threatened at the genetic, species, and ecosystem levels. The marine ecosystem is being degraded and the extinction rate of marine organisms has accelerated. In this paper, the potential causes of fishery resource exhaustion in the East China Sea are analyzed, including the change in the stoichiometric composition of seawater with regard to the concentrations of N and P, toxic effects of marine pollution, marine habitat destruction, increased seawater temperatures caused by climate warming, ocean acidification, pressure from overfishing, and the spread of marine pathogenic bacteria. It is believed that the factors mentioned above have significant impact on the exhaustion of fishery resources in the East China Sea. However, considering the cumulative, synergistic, and superimposed effects as well as the amplification effects resulting from their interactions, the actual risk of ecological extinction of marine organisms might be even more severe than that previously estimated. Hence, ecosystem management and research focused on a single risk factor or influencing factor is not enough to prevent marine ecosystem degradation and fishery resource exhaustion. A comprehensive, systematic, effective, and ecosystem-based management policy is imperative for healthy and sustainable fishery development in the East China Sea.  相似文献   

13.
A model describing macroalgal early life stages and adult dynamics was used to quantify the effects of non-adult forms on the productivity of adult macroalgae in a eutrophic estuary. Predictions indicate that during years with mild winters and low rainfall, spring blooms will occur at the expense of the growth and reproduction of overwintering adults and without the contribution of the spore bank. In these circumstances, there is a positive correlation between the intensity of the blooms and the biomass of overwintering adults until a maximum threshold value. On the contrary, in years with high rainfall and low or inexistent biomass of overwintering adults, the onset of adult’s growth depends on the biomass of viable dormant spores, the growing season occurs later and adult productivity is very limited. Long-term predictions for climate change scenarios suggest that, in general, global warming will have adverse affects on Ulva intestinalis productivity, with the adults being more affected than the early life stages.  相似文献   

14.
Effectiveness of ultrasonication, microwave technologies, and enzyme addition prior to anaerobic digestion is investigated using sludge samples taken from the secondary settling tank of a domestic wastewater treatment plant to improve methane production, enhance dewaterability characteristics of the sludge, and to reduce excess sludge. Microwave pre‐treatment (1500 W, 10 min at 175 °C) results in better extra digester performance (compared to the control reactor) in terms of methane production (25 m3 ton?1 suspended solids (SS)) than ultrasound (no improvement) and enzyme pre‐treatment (11 m3 ton?1 SS). While methane production is not improved as a result of ultrasonication pre‐treatment (15 000 kJ kg?1 SS), a noticeable increase (19%) is observed in the case of microwave pre‐treatment. Higher compactibility values are obtained after ultrasonication and microwave application compared to the control (i.e., from 7.1 to 8.7 and 9.2%, respectively) before anaerobic digestion. Although ultrasonication and microwave application decrease the dewaterability of the raw sludge (capillary suction time (CST) from 827 to 1364 and 2290 s, respectively), similar dewaterability results are obtained at the end of the anaerobic digestion process for all pre‐treated sludge samples. An economic assessment of this study shows that pre‐treatment with microwave results in more than 10‐fold less net cost compared to the enzyme application.  相似文献   

15.
While carbon capture and storage (CCS) is increasingly recognised as technologically possible, recent evidence from deep-sea CCS activities suggests that leakage from reservoirs may result in highly CO2 impacted biological communities. In contrast, shallow marine waters have higher primary productivity which may partially mitigate this leakage. We used natural CO2 seeps in shallow marine waters to assess if increased benthic primary productivity could capture and store CO2 leakage in areas targeted for CCS. We found that the productivity of seagrass communities (in situ, using natural CO2 seeps) and two individual species (ex situ, Cymodocea serrulata and Halophila ovalis) increased with CO2 concentration, but only species with dense belowground biomass increased in abundance (e.g. C. serrulata). Importantly, the ratio of below:above ground biomass of seagrass communities increased fivefold, making seagrass good candidates to partially mitigate CO2 leakage from sub-seabed reservoirs, since they form carbon sinks that can be buried for millennia.  相似文献   

16.
Echinoderms play crucial roles in the structure of marine macrobenthic communities. They are sensitive to excess absorption of CO2 by the ocean, which induces ocean acidification and ocean warming. In the shelf seas of China, the mean sea surface temperature has a faster warming rate compared with the mean rate of the global ocean, and the apparent decrease in pH is due not only to the increased CO2 absorption in seawater, but also eutrophication. However, little is known about the associated changes in the diversity of echinoderms and their roles in macrobenthic communities in the seas of China. In this study, we conducted a meta-analysis of 77 case studies in 51 papers to examine the changes in the contribution of echinoderm species richness to the macrobenthos in the shelf seas of China since the 1980s. The relative species richness (RSR) was considered as the metric to evaluate these changes. Trends analysis revealed significant declines in RSR in the shelf seas of China, the Yellow Sea, and the East China Sea from 1997 to 2009. Compared with the RSR before 1997, no significant changes in mean RSR were found after 1997, except in the Bohai Sea. In addition, relative change in the RSR of echinoderms and species richness of macrobenthos led to more changes (decrease or increase) in their respective biomasses. Our results imply that changes in species richness may alter the macrobenthic productivity of the marine benthic ecosystem.  相似文献   

17.
In the production of a special artificial leather (BAREX) in the CSSR wastewaters containing dimethylformamide (DMF) and dimethylamine (DMA) are produced. Investigations have shown that cultures of algae (Scenedesmus quadricauda) are able to use the two substances as a nitrogen nutrient source after a time of adaptation. In the course of the reactions of decomposition the pH-value plays an important part, since at increased values ammonia is released, which has a temporarily inhibitory effect on the production of algae masses and daughter cells. This detrimental effect can be considerably reduced by aeration with carbondioxide containing (3%) air. Since the production of algal biomass is restricted by a phosphorus deficiency, too, a combined treatment with municipal sewage is very advantageous, according to the results from investigations.  相似文献   

18.
Phthalates are considered priority pollutants because of their potential adverse effects on ecosystems and human health. The objectives of this study were to determine the occurrence of five phthalates (DMP, DEP, DBP, BBP, and DEHP) in sewage sludge and to determine the seasonal variability of these contaminants at three (Bahçe?ehir, Pa?aköy, and Tuzla) full‐scale municipal and domestic wastewater treatment plants (WWTP) in Istanbul, Turkey. Mass balance was also calculated for DEHP at Tuzla WWTP sludge treatment units. DMP, DEP, DBP, BBP, and DEHP concentrations in sewage sludge ranged from 1.4 to 2.7 mg/kg dry weight (dw), 1.1 to 2.8, 0.6 to 4.6, 2.8 to 6.2, 18 to 490 mg/kg dw, respectively. Phthalate concentrations from the Bahçe?ehir and Pa?aköy WWTPs met the limit (100 mg/kg dw) of Turkey national sludge regulation and the Europe Union draft of sludge directive for land application, whereas phthalate concentrations from Tuzla WWTP exceeded the maximum permissible concentration. Phthalate concentrations did not show seasonal variations for Bahçe?ehir and Pa?aköy WWTPs, which receive mainly household wastewater while some fluctuations were observed DEP, DBP, and DEHP at Tuzla WWTP which has a lot of industrial wastewater contribution. The mass balance showed that approximately 17% of DEHP in the primary and secondary sludge was removed by anaerobic digestion, while 43% returned back to the beginning of the WWTP and 40% remained in the dewatered sludge. This study suggests that phthalates in sludge from WWTPs with industrial wastewater contribution may limit the use of sludge for land application.  相似文献   

19.
Archaeal and bacterial glycerol dialkyl glycerol tetraethers (GDGTs) play a unique role in discerning the biogeochemical processes and climate change in terrestrial (e.g. soil, peat, stalagmites, lakes, rivers, hot springs) and marine environments. Organic proxies based on GDGTs (e.g. TEX86, MBT/CBT and BIT) have made impressive applications in the open ocean and terrestrial environments. However, the applicability of these proxies in marginal seas has not been thoroughly evaluated, which is necessary given the complexity and dynamics of these systems, such as organic matter (OM) flux, hydrodynamic conditions, and human impact. This review aims to summarize recent studies of GDGTs and GDGT-based proxies in the Chinese marginal seas (CMS), which are characterized by diverse gradient in terrigenous supplies and ocean productivity and hold rich information on climate and sea level changes, ocean current dynamics, sedimentary evolution and biogeochemical processes.  相似文献   

20.
We examine effects of high river particulate flux and municipal wastewater effluent on heterotrophic organic carbon cycling in coastal subtidal sediments. Heterotrophic production was a predictable (r2 = 0.95) proportion (56%) of oxidized OC flux and strongly correlated with organic/inorganic flux. Consistent growth efficiencies (36%) occurred at all stations. Organic biomass was correlated with total, OC and buried OC fluxes, but not oxidized OC flux. Near the river, production was modest and biomass high, resulting in low P/B. Outfall deposition resulted in depleted biomass and high bacterial production, resulting in the highest P/B. These patterns explain why this region is production “saturated”. The δ15N in outfall effluent, sediments and dominant taxa provided insight into where, and which types of organisms feed directly on fresh outfall particulates, on older, refractory material buried in sediments, or utilize chemosynthetic symbiotic bacteria. Results are discussed in the context of declining bottom oxygen conditions along the coast.  相似文献   

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