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871.
Antonio C. Allem 《The Environmentalist》1997,17(1):7-10
Roadside habitats in Brazil have been and remain major suppliers of biological diversity and plant genetic resources to society. If the ultimate demise of these habitats is to be avoided, their inclusion in conservation policy planning is mandatory. 相似文献
872.
Lutts S Lefèvre I Delpérée C Kivits S Dechamps C Robledo A Correal E 《Journal of environmental quality》2004,33(4):1271-1279
To identify Cd- and Zn-accumulating plants exhibiting a high growth rate, seeds from the halophyte species Mediterranean saltbush (Atriplex halimus L.) were collected on a heavy-metal-contaminated site in southeastern Spain (Llano del Beal, Cartagena). Seedlings from this ecotype were exposed for 3 wk to 0.1 mM Cd or Zn in a nutrient solution in a fully controlled environment. All plants remained alive and no significant growth inhibition was recorded until the end of the experiment. Mean Cd and Zn accumulation in aerial parts was 830 and 440 mg kg(-1), respectively, and the rate of metal translocation even increased with the duration of stress exposure. Resistance to heavy metals in this species may be partly linked to precipitation of Cd in oxalate crystals in the stems. A Cd-induced decrease in glutathione concentration also suggests that phytochelatins overproduction may occur in these conditions. We conclude that Mediterranean saltbush, which is able to produce up to 5 Mg dry matter ha(-1) yr(-1), may be an effective species for phytoextraction and should be tested for this purpose in field conditions. 相似文献
873.
Depth and area of rooting are important to long-term survival of plants on metal-contaminated, steep-slope soils. We evaluated shoot and root growth and metal uptake of four cool-season grasses grown on a high-Zn soil in a greenhouse. A mixture of biosolids, fly ash, and burnt lime was placed either directly over a Zn-contaminated soil or over a clean, fine-grained topsoil and then the Zn-contaminated soil; the control was the clean topsoil. The grasses were 'Reliant' hard fescue (Festuca brevipila R. Tracey), 'Oahe' intermediate wheatgrass [Elytrigia intermedia (Host) Nevski subsp. intermedia], 'Ruebens' Canada bluegrass (Poa compressa L.), and 'K-31' tall fescue (Festuca arundinacea Schreb.). Root growth in the clean soil and biosolids corresponded to the characteristic rooting ability of each species, while rooting into the Zn-contaminated soil was related to the species' tolerance to Zn. While wheatgrass and tall fescue had the strongest root growth in the surface layers (0-5 cm) of clean soil or biosolids, wheatgrass roots were at least two times more dense than those of the other grasses in the second layer (5-27 cm) of Zn-contaminated soil. When grown over Zn-contaminated soil in the second layer, hard fescue (with 422 mg/kg Zn) was the only species not to have phytotoxic levels of Zn in shoots; tall fescue had the highest Zn uptake (1553 mg/kg). Thus, the best long-term survivors in high-Zn soils should be wheatgrass, due to its ability to root deeply into Zn-contaminated soils, and hard fescue, with its ability to effectively exclude toxic Zn uptake. 相似文献
874.
Balkcom KS Blackmer AM Hansen DJ Morris TF Mallarino AP 《Journal of environmental quality》2003,32(3):1015-1024
High nitrate (NO3-N) concentrations in Iowa rivers have been linked to areas of intensive row crop production, but they have not been experimentally linked to specific management practices used during row crop production. This study demonstrates how the late-spring test for soil NO3-N and the end-of-season test for cornstalk NO3-N can be used to measure N sufficiency levels across many fields and how the results can be used to evaluate management practices within a watershed. More than 3200 soil and cornstalk samples were collected over a 12-yr period from fields planted to corn (Zea mays L.) and already fertilized by farmers using their normal practices. Results showed that early-season rainfall and associated N losses were major factors affecting N concentrations in soils and cornstalks. Evidence for NO3-N movement from fields to rivers was provided by an inverse relationship between annual means for NO3-N concentrations in soils and rivers. Because these losses can be avoided by delaying N applications, the practice of applying N several weeks or months before plants grow was linked to inefficient use of fertilizer and manure N by crops. Results of the study demonstrate how aggregate analyses of soil and cornstalk samples collected across many farms and years make it possible to identify the major factors affecting N management outcomes and, therefore, N management practices that are likely to produce the best outcomes within a watershed or region. This approach seems to have unique potential to interrelate the management practices of farmers, the efficiency of N fertilization, and NO3-N concentrations in rivers. 相似文献
875.
Antonio C. Allem 《The Environmentalist》1991,11(2):131-143
876.
Mignucci-Giannoni AA Montoya-Ospina RA Jiménez-Marrero NM Rodr&íguez-López MA Williams EH Bonde RK 《Environmental management》2000,25(2):189-198
Trichechus manatus ) in Puerto Rico is mortality due to human activities. We assessed 90 cases of manatee strandings in Puerto Rico based on
historical data and a coordinated carcass salvage effort from 1990 through 1995. We determined patterns of mortality, including
type of event, condition of carcasses, spatial and temporal distribution, gender, size/age class, and the cause of death.
The spatial distribution of stranding events was not uniform, with the north, northeast, and south coasts having the highest
numbers. Six clusters representing the highest incidence included the areas of Fajardo and Ceiba, Bahía de Jobos, Toa Baja,
Guayanilla, Cabo Rojo, and Rio Grande to Luquillo. The number of reported cases has increased at an average rate of 9.6%/yr
since 1990. The seasonality of stranding events showed a bimodal pattern, from February through April and in August and September.
Most identified causes of death were due to human interaction, especially captures and watercraft collisions. Natural causes
usually involved dependent calves. From 1990 through 1995, most deaths were attributed to watercraft collisions. A reduction
in anthropogenic mortality of this endangered species can be accomplished only through education and a proactive management
and conservation plan that includes law enforcement, mortality assessment, scientific research, rescue and rehabilitation,
and inter- and intraagency cooperation. 相似文献
877.
Checa AG Ramírez-Rico J González-Segura A Sánchez-Navas A 《Die Naturwissenschaften》2009,96(1):111-122
Extant monoplacophorans (Tryblidiida, Mollusca) have traditionally been reported as having an internal nacreous layer, thus representing the ancestral molluscan condition. The examination of this layer in three species of Neopilinidae (Rokopella euglypta, Veleropilina zografi, and Micropilina arntzi) reveals that only V. zografi secretes an internal layer of true nacre, which occupies only part of the internal shell surface. The rest of the internal surface of V. zografi and the whole internal surfaces of the other two species examined are covered by a material consisting of lath-like, instead of brick-like, crystals, which are arranged into lamellae. In all cases examined, the crystallographic c-axis in this lamellar material is perpendicular to the surface of laths and the a-axis is parallel to their long dimension. The differences between taxa relate to the frequency of twins, which is much higher in Micropilina. In general, the material is well ordered, particularly towards the margin, where lamellae pile up at a small step size, which is most likely due to processes of crystal competition. Given its morphological resemblance to the foliated calcite of bivalves, we propose the name foliated aragonite for this previously undescribed biomaterial secreted by monoplacophorans. We conclude that the foliated aragonite probably lacks preformed interlamellar membranes and is therefore not a variant of nacre. A review of the existing literature reveals that previous reports of nacre in the group were instead of the aragonitic foliated layer and that our report of nacre in V. zografi is the first undisputed evidence of nacre in monoplacophorans. From the evolutionary viewpoint, the foliated aragonite could easily have been derived from nacre. Assuming that nacre represents the ancestral condition, as in other molluscan classes, it has been replaced by foliated aragonite along the tryblidiidan lineage, although the fossil record does not presently provide evidence as to when this replacement took place. 相似文献
878.
879.
Andressa Cristhy Buch Maria Elizabeth Fernandes Correi Daniel Cabral Teixeir Emmanoel Vieira Silva-Filho 《环境科学学报(英文版)》2015,27(6):217-227
The increasing levels of mercury (Hg) found in the atmosphere arising from anthropogenic sources, have been the object of great concern in the past two decades in industrialized countries. Brazil is the seventh country with the highest rate of mercury in the atmosphere. The major input of Hg to ecosystems is through atmospheric deposition (wet and dry), being transported in the atmosphere over large distances. The forest biomes are of strong importance in the atmosphere/soil cycling of elemental Hg through foliar uptake and subsequent transference to the soil through litter, playing an important role as sink of this element. Soil microarthropods are keys to understanding the soil ecosystem, and for such purpose were characterized by the soil fauna of two Units of Forest Conservation of the state of the Rio de Janeiro, inwhich one of the areas suffer quite interference from petrochemicals and industrial anthropogenic activities and other area almost exempts of these perturbations. The results showed that soil and litter of the Atlantic Forest in Brazil tend to stock high mercury concentrations, which could affect the abundance and richness of soil fauna, endangering its biodiversity and thereby the functioning of ecosystems. 相似文献
880.
Bastiancich Leone Lasagna Manuela Mancini Susanna Falco Mauro De Luca Domenico Antonio 《Environmental geochemistry and health》2022,44(7):1971-1994
Environmental Geochemistry and Health - In the context of global climate change, understanding the relationships between climate and groundwater is increasingly important. This study in the NW Alps... 相似文献