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71.
Aquaculture offers a major opportunity for the economic development of Baja California Sur (BCS), Mexico. The severely limited freshwater supply and the geographic isolation of the state place limits on other productive activities. Despite the aridity, the natural vegetation of BCS is diverse and structurally complex with a high percentage (20%) of endemic species. In this work we compare the environmental impacts produced by two kinds of aquaculture systems: coastal ponds vs. inland ponds. Construction and operation of coastal ponds does not require destruction of the natural vegetation and, as is true for inland ponds. Coastal ponds are also compatible with conservation of mangroves, sea grasses and sensitive habitats for fish and mollusks. To reduce the negative impacts of aquaculture and to protect the vegetation of Baja California Sur, we recommend the use of coastal ponds for shrimp production.  相似文献   
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Recreational beaches are strategic ecosystems for tourism and should be used in a sustainable manner. We studied three beaches in the municipality of Guaymas (NW Mexico), in order to assess their beach quality and identify key management issues. The evaluation was based on the perceptions of users concerning: (1) the user profile; (2) the recreational habits of users; and (3) the biophysical characteristics, infrastructure, services, and cleanliness of each beach. The results showed that the beaches were of different quality. The key management issues identified were the need to design and apply specific management programs for each beach, specifically in regards to improving infrastructure and services, and obtaining certification as a sustainable beach. The evaluation of the beaches as perceived by users suggests that it would be useful to assess beach quality in order to support management goals and be applicable to other beaches, both nationally and internationally.  相似文献   
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Restoration of salt marshes is critical in the context of climate change and eutrophication of coastal waters because their vegetation and sediments may act as carbon and nitrogen sinks. Our primary objectives were to quantify carbon (C) and nitrogen (N) stocks and sequestration rates in restored marshes dominated by Spartina maritima to provide support for restoration and management strategies that may offset negative aspects of eutrophication and climate change in estuarine ecosystems. Sediment C content was between ca. 13 mg C g?1and sediment N content was ca. 1.8 mg N g?1. The highest C content for S. maritima was recorded in leaves and stems (ca. 420 mg C g?1) and the lowest in roots (361?±?4 mg C g?1). S. maritima also concentrated more N in its leaves (31?±?1 mg N g?1) than in other organs. C stock in the restored marshes was 29.6 t C ha?1; ca. 16 % was stored in S. maritima tissues. N stock was 3.6 t N ha?1, with 8.3 % stored in S. maritima. Our results showed that the S. maritima restored marshes, 2.5 years after planting, were sequestering atmospheric C and, therefore, provide some mitigation for global warming. Stands are also capturing nitrogen and reducing eutrophication. The concentrations of C and N contents in sediments, and cordgrass relative cover of 62 %, and low below-ground biomass (BGB) suggest restored marshes can sequester more C and N. S. maritima plantations in low marshes replace bare sediments and invasive populations of exotic Spartina densiflora and increase the C and N sequestration capacity of the marsh by increasing biomass production and accumulation.  相似文献   
74.
The metropolitan area of Rio de Janeiro is one of the twenty biggest urban agglomerations in the world, with 11 million inhabitants in the metropolitan area, and has a high population density, with 1700 hab. km?2. For this aerosol source apportionment study, the atmospheric aerosol sampling was performed at ten sites distributed in different locations of the metropolitan area from September/2003 to December/2005, with sampling during 24 h on a weekly basis. Stacked filter units (SFU) were used to collect fine and coarse aerosol particles with a flow rate of 17 L min?1. In both size fractions trace elements were analyzed by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) as well as water-soluble species by Ion-Chromatography (IC). Also gravimetric analysis and reflectance measurements provided aerosol mass and black carbon concentrations. Very good detection limits for up to 42 species were obtained. Mean annual PM10 mass concentration ranged from 20 to 37 μg m?3, values that are within the Brazilian air quality standards. Receptor models such as principal factor analysis, cluster analysis and absolute principal factor analysis were applied in order to identify and quantify the aerosol sources. For fine and coarse modes, circa of 100% of the measured mass was quantitatively apportioned to relatively few identified aerosol sources. A very similar and consistent source apportionment was obtained for both fine and coarse modes for all 10 sampling sites. Soil dust is an important component, accounting for 22–72% and for 25–48% of the coarse and fine mass respectively. On the other hand, anthropogenic sources as vehicle traffic and oil combustion represent a relatively high contribution (52–75%) of the fine aerosol mass. The joint use of ICP-MS and IC analysis of species in aerosols has proven to be reliable and feasible for the analysis of large amount of samples, and the coupling with receptor models provided an excellent method for quantitative aerosol source apportionment in large urban areas.  相似文献   
75.
Activities of fishermen in the Bay of La Paz, B. C. S. are focused to satisfy the local demand of fish and shellfish by using approximately 300 small outboard crafts equipped with gillnets.Sea lions in this Bay attack the fishes captured damaging both product and gear. We did experimental gillnet throws to determine the frequency and preferences of sea lions in fishing areas. 52 experimental gillnet throws with time averages of 2 hr were performed, rending an average of 30 kg of fish captured and less than 10% of damages to the net.. Traditional fishermen in this Bay usually left the net the whole night, (approximately 7.50 hr, obtaining an average of 50 kg of captured fish, but the damages to the nets is in average of 40%. The cost-benefit balance comparing our alternative fishing method, which includes the use of the gillnets during the afternoon, watching for sea lions and retiring the nets at their arrival, it is more sustainable and profitable than the traditional fishing method currently used by the local fishermen. This paper suggests how to minimize the harmful effects of the sea lions on the fishermen productivity and gear, maximizing the production and reducing the damage. Our alternative method is applicable to other regions where this harmful interaction is taking place. We conclude that the coexistence of sea lions-fisheries is feasible, by applying the simple measures that we propose.  相似文献   
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Solitary median maxillary central incisor (SMMCI) syndrome is a complex disorder consisting of multiple, developmental defects involving midline structures of the head, which includes the cranial bones, the maxilla, and its container dentition (specifically the central incisor tooth germ), together with other midline structures of the body. SMMCI may appear as an isolated trait or in association with other midline developmental anomalies. We describe the case of a patient with SMMCI. He presented with a solitary median maxillary incisor, short stature, corpus callosum anomalies and a microform of holoprosencephaly (HPE), diabetes insipidus, and neurodevelopmental delay. The diagnosis was performed postnatally based on clinical features, radiological imaging, and a comprehensive genetic study. SMMCI can be diagnosed during the prenatal or neonatal periods or during infancy. Evaluation of the superior maxillary bone is important for prenatal diagnosis. Direct evaluation through bidimensional ultrasound or the use of multiplanar ultrasound or tridimensional reconstruction should be performed in cases of brain or face malformations. Early diagnosis can contribute to improved prenatal assessment and postnatal management.  相似文献   
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The Philippines being a locus of tropical cyclones, tsunamis, earthquakes and volcanic eruptions, is a hotbed of disasters. These natural hazards inflict loss of lives and costly damage to property. Situated in a region where climate and geophysical tempest is common, the Philippines will inevitably suffer from calamities similar to those experienced recently. With continued development and population growth in hazard prone areas, it is expected that damage to infrastructure and human losses would persist and even rise unless appropriate measures are immediately implemented by government. In 2012, the Philippines launched a responsive program for disaster prevention and mitigation called the Nationwide Operational Assessment of Hazards (Project NOAH), specifically for government warning agencies to be able to provide a 6 hr lead-time warning to vulnerable communities against impending floods and to use advanced technology to enhance current geo-hazard vulnerability maps. To disseminate such critical information to as wide an audience as possible, a Web-GIS using mashups of freely available source codes and application program interface (APIs) was developed and can be found in the URLs http:// noah.dost.gov.ph and http://noah.up.edu.ph/. This Web-GIS tool is now heavily used by local government units in the Philippines in their disaster prevention and mitigation efforts and can be replicated in countries that have a proactive approach to address the impacts of natural hazards but lack sufficient funds.  相似文献   
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