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1.
Human activities have increased anthropogenic CO2 emissions, which are believed to play important roles in global warming. The spatiotemporal variations of CO2 concentration and flux at fine spatial scales in aquaculture ponds remain unclear, particularly in China, the country with the largest aquaculture. In this study, the plot-scale spatiotemporal variations of water CO2 concentration and flux, both within and among ponds, were researched in shrimp ponds in Shanyutan Wetland, Min River Estuary, Southeast China. The average water CO2 concentration and flux across the water–air interface in the shrimp ponds over the shrimp farming period varied from 22.79?±?0.54 to 186.66?±?8.71 μmol L?1 and from ??0.50?±?0.04 to 2.87?±?0.78 mol m?2 day?1, respectively. There was no remarkable difference in CO2 concentration and flux within the ponds, but significantly spatiotemporal differences in CO2 flux were observed between shrimp ponds. Chlorophyll a, pH, salinity, air temperature, and morphometry were the important factors driving the spatiotemporal patterns of CO2 flux in the shrimp ponds. Our findings highlighted the importance and spatiotemporal variations of CO2 flux in the important coastal ecosystems. 相似文献
2.
T-2 toxin (T-2), one of the naturally occurring mycotoxins, often accumulates in aquatic animals from contaminated feed. Shrimp (n?=?30 per group) were fed with different concentrations (0, 0.5, 1.5, 4.5 and 13.5?mg kg ?1) of T-2 for 20?days. Changes in histopathology, fatty acid and water distribution of shrimp muscle were analyzed. Histopathology of shrimp muscle showed dose-dependent marked degenerative and necrotic changes on exposure to dietary T-2. The T-2 significantly ( P?<?0.05) affected the muscle fatty acid composition. ∑SFA, ∑MUFA and ∑PUFA initially decreased and then increased slowly in the high-dosed groups. C16:0, C18:1n-9 and C18:2n-6 were the main saturated fatty acid (SFA), monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA), respectively. Also, T-2 significantly affected water distribution in shrimp muscle. High doses of T-2 reduced free water content, resulting in a reduction in the water holding capacity and hence changes to the shrimp muscle quality. Collectively, these results illustrated that T-2 significantly affects the fatty acid and water distribution, and also muscle histopathology, all of which would result in a reduction in the quality and nutritional value of shrimp. 相似文献
3.
Although research regarding antibiotic resistance genes (ARGs) in aquaculture environments has gained increasing scientific interest, further studies are required to understand the abundances and removal mechanisms of ARGs during the entire rearing period of shrimp aquaculture. Thus, in this study, abundances, distributions and removal rates of ARGs in different environmental compartments of intensive shrimp farms in South China were investigated during the entire rearing period. The results indicated that sul1 and cmlA were the predominant ARGs in the water and sediment samples. Additionally, the total abundance of ARGs was higher in shrimp pond water than in the source water and farm effluent. Moreover, sediment samples indicated significantly higher ARG abundances than water samples from the shrimp ponds ( P?<?0.05). Environmental factors were found to significantly affect the distribution of ARGs in shrimp rearing environments. Furthermore, stable ponds aided the removal of ARGs from shrimp pond water. This study accounted for temporal variations in ARG abundances as well as removal of ARGs in different environmental compartments during the entire shrimp rearing period. However, additional research is required to optimize the water treatment process for removal of ARGs from the aquaculture. 相似文献
4.
Background and purpose Shrimp culture has been expanded rapidly in recent years in coastal wetland zone of Vietnam due to favorable natural conditions.
However, this industry has caused several negative impacts to the environment. One of the critical issues is the excessive
application of antibiotics including human medicines. These chemicals could be released from shrimp ponds and then accumulated
and contaminated of the ecosystem. This review article discusses a whole range of findings that address various aspects of
the usage, occurrence and potentially environmental risks of antibiotics released from shrimp farming, with emphasis on the
South Vietnam coastal wetland. 相似文献
5.
Abstract This study examined effects of fenoxycarb, a carbamate insecticide, on larvae of the grass shrimp, Palaemonetes pugio. In laboratory experiments, grass shrimp larvae were exposed to fenoxycarb from hatch to postlarval metamorphosis in a chronic, static renewal bio assay. LC50's ranged from 0.92 mg/L at 96 h to 0.35 mg/L at the end of the study (24 days). In assessing sublethal effects of fenoxycarb, postlarval emergence was significantly (p < 0.05) reduced in exposed grass shrimp as compared with controls, and the time to reach postlarval status was significantly (p < 0.05) increased in exposed grass shrimp. Significant differences were not found in other sublethal parameters including postlarval dry weight and intermolt duration. Analysis of fenoxycarb from spiked seawater samples showed concentrations declined by 32 to 42% after 24 h. 相似文献
7.
Development of new economically feasible ecofriendly products from agricultural wastes or byproducts for shrimp farm wastewater treatment is the objective of our continued research. Ammonia is a nitrogenous toxicant, which is commonly found in wastewater from shrimp farms. In the present study, we explored the possibility of the use of simply and inexpensively prepared bagasse products so that this abundant crop byproduct could be used to remove ammonia from shrimp farm wastewater. Bagasse, a natural highly fibrous lignocellulosic byproduct of sugarcane, was converted into five different products. Experimental results have shown that ammonia is efficiently removed from wastewater by four bagasse products with a dose of 1 to 6 g/L within 24 hours. The effect of bagasse products on other water quality parameters and growth kinetics of biofilm bacteria onto bagasse fiber have also been studied. Efficacies of products were compared by using statistical analysis. Products developed from bagasse are useful and economical. 相似文献
8.
This study aims to identify levels of several organochlorine and organophosphorus compounds in shrimp-raising areas of coastal El Salvador, to assess potential impacts on shrimp growth and survival that hamper the sustainability of aquaculture in the region. The paper reports the current levels of γ-HCH, 4,4'-DDT, 4,4'-DDE, 4,4'-DDD, endrin, dieldrin, heptachlor, parathion, methyl parathion, and etoprophos in soils (depth 20 cm), sediments (depth 5 cm), shrimp (Penaeus sp.), and water of three rearing ponds and also in the sediment (depth 5 cm) and water surrounding those ponds in Jiquilisco Bay. Sampling was carried out during the dry (January-March) and rainy (June-August) seasons of 2008. The presence of pesticides in the samples of water, shrimp, and sediment at shrimp ponds was not detected in either season; however, in soil samples (depth 20 cm) taken from these ponds, heptachlor, endrin, dieldrin, 4,4'-DDD, and 4,4'-DDT were identified at concentrations below the method limit of quantification (LOQ), and 4,4'-DDE was found in a concentration falling in the range from 3.85 to 19.61 ng/g. In samples of water taken at the bay water intakes to the rearing ponds, we observed dieldrin concentrations in the range between 0.085 ng/mL and 0.182 ng/mL during the dry season. In the samples of sediments taken in the surrounding areas of shrimp ponds, we found-for both seasons-that in 60 % of the samples, 4,4'-DDE was present in concentrations ranging from 3.75 ng/g to 30.97 ng/g. Additionally, in the rainy season, we observed heptachlor in sediment at concentrations below the method quantification limit. It was concluded that organochlorine compounds from pesticides are still present in Jiquilisco Bay, trapped in deep sediment, even though they have been banned since the 1980s. These were not detected in shrimp tissue, surface water, and shallow sediment in rearing ponds, and hence, we do not believe their presence has any major impact on shrimp production in sampled areas. 相似文献
9.
A pilot-scale constructed wetland unit, consisting of free water surface (FWS) and subsurface flow (SF) constructed wetlands arranged in series, was integrated into an outdoor recirculating aquaculture system (RAS) for culturing Pacific white shrimp (Litopenaeus vannamei). This study evaluated the performance of the wetland unit in treating the recirculating wastewater and examined the effect of improvement in water quality of the culture tank on the growth and survival of shrimp postlarvae. During an 80-day culture period, the wetland unit operated at a mean hydraulic loading rate of 0.3 m/day and effectively reduced the influent concentrations of 5-day biochemical oxygen demand (BOD5, 24%), suspended solids (SS, 71%), chlorophyll a (chl-a, 88%), total ammonium (TAN, 57%), nitrite nitrogen (NO2-N, 90%) and nitrate nitrogen (NO3-N, 68%). Phosphate (PO4-P) reduction was the least efficient (5.4%). The concentrations of SS, Chl-a, turbidity and NO3-N in the culture tank water in RAS were significantly (P相似文献
10.
A global perspective on the environmental impacts related to the establishment and operation of shrimp aquaculture is presented. Alternatives to reduce the impacts are considered and research priorities are recommended. 相似文献
11.
Aus Stra?enbau und Stra?enverkehr resultieren erhebliche Auswirkungen auf Landschaft und Naturhaushalt. Infolgedessen k?nnen die heterogenen und durch vielf?ltige
Stoffeintr?ge gekennzeichneten Substrate im Stra?enrandbereich ihre Funktion als Wurzelraum von Pflanzen nur eingeschr?nkt
erfüllen.
Um den Anforderungen nach hoher Verkehrssicherheit auf Schnellverkehrsstra?en gerecht zu werden, setzen Stra?en- und Autobahnmeistereien Auftausalze im Winterdienst ein. Der
Eintrag von Auftausalzen in den Stra?enrandbereich kann jedoch zu Sch?digungen von Geh?lzen und zu ?nderungen von Bodenkenndaten
führen. Zur Minimierung der von Auftausalzen ausgehenden unerwünschten Wirkungen auf Stra?enrandb?den und -vegetation ist
eine Optimierung der Aufwandmenge über eine den Witterungsbedingungen und Verkehrsverh?ltnissen angepa?te Auswahl der Streumittel, d.h. ihre dosierte und gezielte Ausbringung anzustreben. Das Feuchtsalzverfahren (FS 30) mit Ausbringungsmengen von weniger als 10 g Salz/m 2 bietet hierzu einen erfolgversprechenden Weg. Weiterhin k?nnen die sich aus grobk?rnigen und n?hrstoffarmen Substraten ergebenden
ungünstigen N?hrstoffverh?ltnisse in Stra?enrandb?den durch Meliorationsma?nahmen verbessert werden. Ausreichend mit N?hrstoffen versorgte B?den bilden eine wichtige Voraussetzung für ein optimales Pflanzenwachstum
und erh?hen die Widerstandsf?higkeit der Vegetation gegenüber Schadfaktoren. 相似文献
12.
Multiple isoenzymes of the detoxification enzyme family Glutathione S-transferase are expressed in the brine shrimp Artemia. The number of the major ones detected in crude extract by means of chromatofocusing varied between three and four, depending on the age. Two isoenzymes, one alkaline and one neutral (with corresponding isoelectric points of 8.5 and 7.2) appear to be dominant in all three developmental stages studied, (24, 48, and 72 h after hatching). Culturing Artemia for 48 h after hatching, in artificial sea water prepared by municipal wastewater effluent resulted to significant alterations of the isoenzyme profile. In comparison to organisms cultured for the same period of time in artificial sea water prepared by filtered tap water, the expression of the alkaline isoenzyme decreased by 62% while that of the neutral isoenzyme increased by 58%. Furthermore, the enzyme activity of the major isoenzyme of the acidic area increased by more than two folds. It is worth mentioning that although the specific activity of the total enzyme in the whole body homogenate was elevated, no statistically significant alteration of the Km value was observed. These findings suggest that study of the isoenzyme profile of Glutathione S-transferase may offer high sensitivity in detecting environmental pollution and needs to be further investigated. 相似文献
13.
The organotin (OT) compounds tributyltin (TBT) and triphenyltin (TPhT) are potent biocides that have been used ubiquitously in antifouling paints and pesticides since the mid-1970s. These biocides are extremely toxic to marine life, particularly marine gastropod populations. The European Union therefore took measures to reduce the use of TBT-based antifouling paints on ships and ultimately banned these paints in 2003. Despite sufficient data on OT concentrations in marine gastropods, data are scarce for other species such as the North Sea brown shrimp ( Crangon crangon), a dominant crustacean species in North Sea inshore benthic communities. The present study provides the first spatial overview of OT concentrations in North Sea brown shrimp. We have compared these data with historical concentrations in shrimp as well as with sediment concentrations. We have also addressed the effect on the shrimp stock and any human health risks associated with the OT concentrations found. TBT and TPhT in shrimp tail muscle ranged from 4 to 124 and from 1 to 24 μg kg −1 DW, respectively. High levels are accumulated in estuarine areas and are clearly related with sediment concentrations (biota-sediment accumulation factor ∼10). Levels have decreased approximately 10-fold since the ban took effect, coinciding with a recovery of the shrimp stock after 30 years of gradual regression. Furthermore, the OT levels found in brown shrimp no longer present a human health risk. 相似文献
14.
In this study the values of subcooled vapor pressures (log P L) were estimated for 209 trans chloroazobenzenes (C t-ABs) that fill some gaps in analytical and experimental data on these compounds. There are 209 chloro derivatives of trans azobenzenes that are relatively stable and more environmentally relevant than 209 chloro cis congeners. The calculations models were based on the Quantitative Structure-Property Relationship (QSPR) scheme using the semi-empirical method (PM6) in molecular package (MOPAC) software and density functional theory (DFT) method using B3LYP functional and 6-311++G** basis set) in Gaussian 03 software method and the artificial neural networks (ANNs) prediction. The values of log P L predicted by models used varied between ?3.94 to ?2.66 for Mono-; ?4.85 to ?2.97 for Di-; ?5.18 to ?3.17 for Tri-; ?6.02 to ?3.77 for Tetra-; ?6.64 to ?4.64 for Penta-; ?7.36 to ?4.76 for Hexa-; ?7.54 to ?5.79 for Hepta-; ?7.75 to ?6.64 for Octa-; ?7.89 to ?7.44 for Nona-C t-Abs; and ?8.09 and ?8.13 for Deca-C t-AB. Based on these values C t-ABs can be grouped localized among relatively low (log P L ?4 to ?2) and low (log P L < ?4) mobile Persistent Organic Pollutants (POPs). Both the calculation methods employed were characterized by similar prediction ability of subcooled vapor pressure values of C t-ABs, while those of PM6 are much more efficient due to a cheaper hardware used and around 300-fold less time spent on calculations. 相似文献
15.
AbstractCarpobrotus dimidiatus is an indigenous South African medicinal plant species from the Aizoaceae family that bears edible fruit that is consumed for nutritional value. In this study, the elemental distribution in C. dimidiatus fruit and growth soil from fifteen sites in KwaZulu-Natal (South Africa) was determined along with soil pH, soil organic matter and cation exchange capacity, to assess for nutritional value and the effect of soil quality on elemental uptake. The results showed elemental concentrations in fruit to be in decreasing order of Ca (6235–32755?mg kg ?1) > Mg (2250–5262?mg kg ?1) > Fe?>?Mn?>?Zn (20.9–50.6?mg kg ?1) > Cu (3.83–20.6?mg kg ?1) > Pb?>?Cr?>?Cd?>?As?~?Co?~?Ni?~?Se and no potential health risk due to metal toxicity from average consumption. For sites that had high levels of Cd and Pb, bioaccumulation occurred from atmospheric deposition. Concentrations of elements in soil were found to be in decreasing order of Fe (1059–63747?mg kg ?1) > Ca (1048–41475?mg kg ?1) > Mg?>?Mn (9.76–174?mg kg ?1) > Cr (1.55–135?mg kg ?1) > Zn (0.76–58.2?mg kg ?1) > Se?>?Cu?>?Ni?>?Pb?>?Co?>?As?~?Cd with no evidence of heavy metal contamination. This study revealed that the plant inherently controlled uptake of essential elements according to physiological needs and that the concentrations of essential elements in the fruit could contribute positively to the diet. 相似文献
16.
Zusammenfassung Teil 2 dieses übersichtsartikels zur Stadtklimatologie besch?ftigt sich mit der Auspr?gung ausgew?hlter Klimaelemente in urbanen
R?umen, der lufthygienischen Problematik in St?dten sowie mit den human-biometeorologischen Aspekten der Stadtklimatologie.
Es wird zun?chst der Aufbau der Stadtatmosph?re und die st?dtische Strahlungs- und W?rmebilanz dargestellt. Anschlie?end werden
der urbane W?rmeinseleffekt, das bodennahe Windfeld, die urbanen Luftfeuchtigkeitsverh?ltnisse und die Luftqualit?t exemplarisch
erl?utert. Planerische M?glichkeiten zur Verbesserung des Klimas in unseren St?dten werden vorgestellt und ihre Wirksamkeit
abgesch?tzt. Zum Abschluss wird die Rolle des Stadtklimas innerhalb der aktuellen Diskussion rund um die Problematik der globalen
Klimaentwicklung beleuchtet und anhand der Ergebnisse bisheriger Untersuchungen positioniert.
OnlineFirst: 04. August 2004 相似文献
17.
This study investigated the effects of increased temperature and salinity, two potential impacts of global climate change, on the toxicity of two common pesticides to the estuarine grass shrimp, Palaemonetes pugio. Larval and adult grass shrimp were exposed to the fungicide chlorothalonil and the insecticide Scourge® under standard toxicity test conditions, a 10°C increase in temperature, a 10 ppt increase in salinity, and a combined increased temperature and salinity exposure. Toxicity of the fungicide chlorothalonil increased with temperature and salinity. Toxicity of the insecticide Scourge® also increased with temperature; while increased salinity reduced Scourge® toxicity, but only in adult shrimp. These findings suggest that changes in temperature and salinity may alter the toxicity of certain pesticides, and that the nature of the effect will depend on both the organism's life stage and the chemical contaminant. Standard toxicity bioassays may not be predictive of actual pesticide toxicity under variable environmental conditions, and testing under a wider range of exposure conditions could improve the accuracy of chemical risk assessments. 相似文献
18.
AbstractOrganochlorine pesticides (OCPs) are widely used around the world as insecticides, herbicides, fungicides, nematicides, and rodenticides. Despite banned in Brazil, the usage remains occurring in many countries. The persistence and extreme mobility of OCPs contribute to the contamination of the environment and the human body. The OCPs bioaccumulation in adipose tissue triggers the excretion into human milk during breastfeeding. Hence, the present study determined eighteen OCPs residues in the breast milk of mothers from the Western Region of Bahia State, Brazil. Nine different residue species were found, including beta-Hexachlorocyclohexane (9.24?±?0.00?ng g ?1 fat), delta- Hexachlorocyclohexane (22.15?±?10.48?ng g ?1 fat), Heptachlor (58.08?±?74.13?ng g ?1 fat), Aldrin (142.65?±?50.65?ng g ?1 fat), Dieldrin (774.62?±?472.68?ng g ?1 fat), Endosulfan I (408.44?±?245.51?ng g ?1 fat), Dichloro-diphenyl-dichloro-ethylene (29.17?±?22.42?ng g ?1 fat), Dichloro-diphenyl-trichloro-ethane (28.87?±?0.00?ng g ?1 fat) and Methoxychlor (1699.67?±?797.43?ng g ?1 fat). The Methoxychlor presence in all samples may reveal a recent exposure, while Dieldrin and Endosulfan I analyses can point to distant past exposure. 相似文献
19.
Für die Biosph?renreservate (BR) Schorfheide-Chorin und Spreewald (Land Brandenburg) wurde ein handlungsorientiertes, kostengünstiges,
arbeitsteiliges Konzept für die ?kosystemare Umweltbeobachtung (?UB) entwickelt, dessen methodische Entwicklung auch auf andere
Schutzgebiete übertragbar ist. Hierzu werden neben statistischen Auswertungen fl?chenhaft vorliegender Informationen auch
weitere Kriterien wie Naturn?he, Seltenheit und Ma?nahmenbezug durch das Einbringen von Expertenwissen systematisch genutzt,
um so die Besonderheiten und Eigenarten der beiden behandelten Gro?schutzgebiete zu erfassen und in gewissem Umfang zu wichten
und so gezielt auch Fragestellungen naturschutzfachlicher Relevanz nachzugehen. Nach einer Inventarisierung der vorhandenen
?kosysteme wurden auf der Basis der Auswahlkriterien
I) |
Dominanz |
II) |
Seltenheit |
III) |
Naturn?be bei fl?chenhafter Verbreitung sowie |
IV) |
ma?nahmen- und prozessorientierte Beobachtung die zu beobachtenden ?kosysteme aus den ?kosystemgruppen W?lder/Forsten, Moore,
Seen, Flie?gew?sser, Grünland und Acker ausgew?hlt und mit den jeweils relevanten Nutzungen zu ?kosystem-Nutzungskomplexen
zusammengefasst. Diese spiegeln sowohl die natürliche Ausstattung der BR als auch die jeweiligen Nutzungsgradienten wider.
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Der vorliegende Artikel stellt diese Fl?chenauswahl detailliert dar, Für beide Biosph?renreservate wurden so insgesamt 32
?kosystem-Nutzungskomplexe in W?ldern und Forsten, 32 in Mooren, 53 in Seen, 7 in Flie?gew?ssern, 23 auf mineralischem Grünland
sowie 20 auf Acker bzw. Gartenland ausgew?hlt, die die Biosph?renreservate repr?sentieren. 相似文献
20.
In this overview two definitions of climate are presented, from the meteorological point of view and from the climate system’s
point of view. The origin of climate change is discussed, i.e., externally forced variability and free, or internal variability
that is caused without external trigger by internal instabilities of the system. Both, forced and free variability can appear
as periodic, randomly quasi-periodic, and abrupt climate change. Finally, various possibilities of climate forecast are considered.
Klima?nderungen: M?gliche Ursachen in Vergangenheit und Zukunft
Zusammenfassung In diesem übersichtsartikel werden zwei Klimadefinitionen, die meteorologische und die systemanalytische, vorgestellt. Verschiedene
Ursachen für Klima?nderungen werden vergleichend diskutiert: die extern angetriebene Klimavariabilit?t und die ohne ?u?eren
Ansto?, aufgrund von internen Instabilit?ten im System ausgel?ste, freie oder interne Klimavariabilit?t. Sowohl die angetriebene
als auch die freie Klimavariabilit?t kann sich durch periodische, zuf?llig periodische und abrupte Klima?nderungen bemerkbar
machen. Abschlie?end werden die verschiedenen M?glichkeiten der Klimavorhersage betrachtet.
Professor Dr. Martin Claussen ist amtierender Direktor des Potsdam-Instituts für Klimafolgenforschung und Vorsitzender der Deutschen Meteorologischen Gesellschaft
(Amtsperiode 2003–2005). Sein aktuelles Forschungsgebiet umfasst die Klimasystemmodellierung einschlie?lich der Pal?oklimamodellierung,
wobei die Wechselwirkung zwischen dem physikalischen Klimasystem und der Biosph?re im Vordergrund der Forschung steht. Professor
Claussen ist ausgebildeter Meteorologe und lehrt zurzeit Klimaphysik an der Universit?t Potsdam. 相似文献
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