哑铃湾网箱养殖可持续容量研究

在相关养殖容量研究的基础上,提出了养殖环境容量和可持续养殖容量的概念和内涵.以哑铃湾网箱养殖为例,建立了考虑时间累积效应后的养殖环境容量和考虑了社会、经济和环境综合效益后的可持续养殖容量计算模型.估算了在10年时段内哑铃湾网箱养殖环境容量和可持续养殖容量.结果表明,哑铃湾网箱养殖最优环境容量为每年4.11万箱,可持续养殖容量为每年3.45万箱.     

SO2 modeling in İzmit Gulf, Turkey during the winter of 1997: 3 cases

In this study, SO₂ dispersion over İzmit Gulf is simulated by California Puff (CALPUFF) model for three air pollution cases, which occurred on January 28, February 12, and February 26, 1997. These days are generally characterized by dominant high-pressure systems – pressure values reaching 1032 mb, low wind speeds and sometimes calm conditions, and low temperatures with a minimum of 0°C. Hourly simulations during those critical cases were carried out and results revealed very high concentrations of SO₂ transported to the downwind regions of Tüpraş and Gebze, and values sometimes exceeded 1,000 μg/m³. Nighttime and morning simulations associated with inversion produced considerably higher values of SO₂ than the afternoon simulations associated with breeze. Model verification was conducted by comparing the measured daily average values of eight stations with the model predicted values at the same receptor points. Results showed that the model well predicted the values at station Gebze in all three cases. The model sometimes underestimated and sometimes overestimated the concentrations at other receptor stations.     

Phosphate enrichment in the northern Gulf of Aqaba: Regulation by carbonate sediments and impact on nitrogen elevation

The effect of carbonate sediment in regulating phosphate concentrations in sea water was investigated by laboratory incubation experiments using different sediment types. Incubation experiments were made with two types of sediments: uncontaminated sediment from a marine reserve and contaminated sediment with deposited phosphate powders. Fluxes of inorganic nitrogen and phosphate were estimated from linear regressions of solute concentrations over incubation periods. Ammonium and phosphate fluxes were about twofold higher in the uncontaminated sediment that had significantly lower organic carbon and total phosphate concentrations than in the phosphate-contaminated sediment. To test the effect of dissolved phosphate on increasing nitrogen fixation, additional incubation experiments were carried out using treated carbonate and silicate sediments with added dissolved phosphate (20 μM). Incubations were made under sterile conditions with HgCl₂ added to distinguish between biologically enhanced processes and pure physicochemical processes. The adsorption rate of phosphate onto carbonate sediment was about twice that onto silicate sediments. No nitrogen elevation either as ammonium or as nitrate was observed in the soluble phosphate enrichment incubations. In conclusion, this study demonstrates the importance of the regulation of soluble phosphate concentrations in carbonate sediment environments where the carbonate sediment acts as a buffering system keeping soluble phosphate concentrations at certain steady-state levels. The study also demonstrates the lack of evidence on enhancement of nitrogen concentrations due to the increase phosphate concentrations.     

Sound and Fury Signifying Nothing: Using Geoinformatics to Inform Resource Policy in the Gulf of California,Mexico

In this issue of Environmental Management, Glenn and others posit that a previous study had analytical and interpretive errors in analysis of shrimp fishing in the Upper Gulf of California, Mexico. Unfortunately, much of their evidence is too indirect and of insufficient scale to address the central question of salinity in the Upper Gulf. Also, many of their suppositions did not include direct interviews with local officials or a robust understanding of remote sensing literature. This response to their rebuttal presents a set of figures and analysis demonstrating that the Colorado River flows into a closed evaporative basin known as the Laguna Salada and thus cannot flow into the Gulf of California. Readers are asked to examine the images and interpret their meaning for themselves.     

The implications of ecosystem dynamics for fisheries management: a case study of selected fisheries in the Gulf of Paria, Trinidad

It is accepted that if fisheries resources are to remain renewable and able to sustain livelihoods, appropriate management practices must be implemented. Even while fisheries management grapples to resolve single-species issues, the biological and economic interactions among species mandate that to be effective, management techniques must be based on more interactive and aggregate-level analyses. In order to implement these techniques, the actual links, and the potential impact of these links, among the fisheries must be established. Vector autoregression (VAR) analysis has the potential to play an increasingly important role in ecosystem modelling for fisheries management. This study uses VAR analysis to demonstrate the quantitative impact of certain ecosystem changes on the productivity of the carite, honey shrimp and croaker fisheries of the Gulf of Paria, Trinidad, in the particular context of the ecosystem dynamics of trophic linkages, bycatch and multispecies fisheries. Four VAR models are constructed to investigate the extent to which these factors affect the production of the selected fisheries, and to evaluate the management implications of these linkages. The empirical analysis is further evidence that, if sustainable management of fishery resources is to be achieved, management practices based on more multi-species, ecosystem approaches must replace the traditional, single-species management techniques.     

Sources and Delivery of Nutrients to the Northwestern Gulf of Mexico from Streams in the South‐Central United States1

Rebich, Richard A., Natalie A. Houston, Scott V. Mize, Daniel K. Pearson, Patricia B. Ging, and C. Evan Hornig, 2011. Sources and Delivery of Nutrients to the Northwestern Gulf of Mexico From Streams in the South‐Central United States. Journal of the American Water Resources Association (JAWRA) 47(5):1061‐1086. DOI: 10.1111/j.1752‐1688.2011.00583.x Abstract: SPAtially Referenced Regressions On Watershed attributes (SPARROW) models were developed to estimate nutrient inputs [total nitrogen (TN) and total phosphorus (TP)] to the northwestern part of the Gulf of Mexico from streams in the South‐Central United States (U.S.). This area included drainages of the Lower Mississippi, Arkansas‐White‐Red, and Texas‐Gulf hydrologic regions. The models were standardized to reflect nutrient sources and stream conditions during 2002. Model predictions of nutrient loads (mass per time) and yields (mass per area per time) generally were greatest in streams in the eastern part of the region and along reaches near the Texas and Louisiana shoreline. The Mississippi River and Atchafalaya River watersheds, which drain nearly two‐thirds of the conterminous U.S., delivered the largest nutrient loads to the Gulf of Mexico, as expected. However, the three largest delivered TN yields were from the Trinity River/Galveston Bay, Calcasieu River, and Aransas River watersheds, while the three largest delivered TP yields were from the Calcasieu River, Mermentau River, and Trinity River/Galveston Bay watersheds. Model output indicated that the three largest sources of nitrogen from the region were atmospheric deposition (42%), commercial fertilizer (20%), and livestock manure (unconfined, 17%). The three largest sources of phosphorus were commercial fertilizer (28%), urban runoff (23%), and livestock manure (confined and unconfined, 23%).     

廉洲湾赤潮自动监测结果与分析

根据2009年7月广西廉洲湾海域三个自动监测站的实时监测数据,对赤潮发生的过程进行分析,发现此次赤潮过程中,溶解氧、pH值、叶绿素存在明显的昼夜变化规律,且出现同步升高回落现象。通过现场采样分析与比对,表明自动监测站可实现对赤潮的预警预报。     

中国北部湾地区夏季大气碳气溶胶的空间分布特征

于2009年8月在北部湾地区的南宁、钦州、防城港、北海、湛江、茂名、海口、洋浦、东方等9个城市的城区和郊区同步采集PM2.5样品,采用热光反射碳分析仪分析得到有机碳(organic carbon,OC)、元素碳(elemental carbon,EC)的质量浓度,对OC、EC浓度水平、空间分布及其可能的来源进行分析.结果表明,观测期间北部湾9个城市PM2.5、OC和EC的浓度均值分别为(38.4±17.7)、(9.2±2.6)和(1.9±1.1)μg·m-3,总碳气溶胶(total carbonaceous aerosol,TCA)占PM2.5质量的56.8%.北部湾地区夏季OC主要来源于生物质燃烧和二次生成的有机碳(secondary organic carbon,SOC),EC主要来源于机动车和工业排放.     

Vertical and spatial distribution of biogenic silica in the sediment of the gulf of Riga,Baltic Sea

The vertical and spatial concentration trends of biogenic silica (BSi) were investigated in a variety of sediment types from the Gulf of Riga. These trends were compared with the concentration of organic carbon to examine how variations in the mass sedimentation and the dissolution rate of BSi versus bacterially mediated oxidation of organic matter affect the distribution of BSi in different environments. The effects of important physical and biogeochemical factors on the distribution of BSi have also been examined.

The concentration of BSi in the surface sediment at accumulation bottoms ranges between 0.8–1.5 mmol/g with an average concentration of 1.1 mmol/g. This is about two times the concentration that has been reported in similar sediments in the open Baltic proper. Much lower concentrations were measured in erosion and transitional areas; on average around 0.2 and 0.6 mmol/g, respectively.

A comparison between recent sedimentation rate measurements (²¹⁰Pb) and concentrations of BSi within different accumulation bottoms suggests an approximate inverse relationship with each other. The importance of variation in the sedimentation rate on the surface BSi concentration is supported by the fact that higher C_org/BSi ratios are found in periphery accumulation zones close to transition areas (larger supply of carbon rich allochthonous material that dilutes settled amounts of BSi) than at accumulation bottoms in the central part of the Gulf. The C_org/BSi ratio in the sediment is always lower than in living siliceous algae which shows that the microbial degradation of organic carbon is always greater than the inorganic dissolution of BSi, irrespective of the assemblage of silica and non‐silica species.

The general vertical concentration pattern at accumulation sites showed a decreased concentration with increased depth down to 2–6 cm below seafloor where the concentration gradually equalizes. The concentration in the equalizing zone is on average about 20% lower than in the uppermost centimeter. This implies that the main part of the BSi entering the accumulation bottoms is permanently buried and that a great amount of silica already has been released during halmyrolysis. The spatial and vertical BSi trends at sites in transitional and erosional areas reflects prevailing sedimentation conditions with a low concentration in sections with a dominance of sand and gravel (no deposition of fine material) and a higher concentration in the sections containing stiff glacial clay (former accumulation area).

The average annual burial amount of BSi in the Gulf has been estimated to be around 50 000 tons of which most is buried in accumulation bottoms outside the central muddy part of the Gulf. The buried amount is about 60% of the annual river load of silica.     

Total petroleum hydrocarbon burden in fish tissues from the Arabian Gulf

The levels of total petroleum hydrocarbons (TPH) and lipid contents have been reported for eight commercially important fish species from the Arabian Gulf. GC-FID has been used as quantification technique. Out of the species analyzed, Scarus ghabon showed the highest level of TPH (7.4 ± 3.2 µg g^?1) in the muscle tissue followed by Epinephelus tauvina (6.8 ± 3.6 µg g^?1). Except for E. microdon (4.8 ± 2.1 µg g^?1), all other fish species showed a similar level of TPH concentration. Significant correlations were obtained between lipid contents and TPH levels in the muscles of the fish. Body weight of the fish was also found to be strongly correlated with TPH concentration in the muscle tissue. There is a tendency of accumulating higher TPH in the winter season as compared to in the summer season.