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101.
Effects of dissolved organic matter on the mobility of copper in a contaminated sandy soil 总被引:1,自引:0,他引:1
E. J. M. TEMMINGHOFF S. E. A. T. M. VAN DER ZEE F. A. M. DE HAAN 《European Journal of Soil Science》1998,49(4):617-628
Changes in land use can result in increased soil organic matter content, and decreases in Ca and pH which will affect the mobility of Cu in soil. We studied how the mobility and coagulation of dissolved organic matter and pH affected the mobility of Cu in contaminated sandy soil by batch and column experiments in the laboratory. The soil, with pH ranging from 3.8 to 5.7, had been polluted with Cu in the range 0.13–1.9 mmol kg?1 more than a decade ago. Calcium and Cu bound by dissolved organic matter (purified humic acid) was determined in the pH range 4–8; Cu2+ concentration ranged from 10?4 to 10?12M and Ca2+ concentration from 10?3 to 10?6M. Binding of Cu by dissolved organic matter as affected by Ca and pH could be predicted well with the non-ideal competitive adsorption (NICA) model. Coagulation of dissolved organic matter was affected by the amount of trivalent (Al3+) and divalent (Ca2+ and Cu2+) cations in solution. There was little effect of pH on coagulation between pH 4 and 6. The concentration of the divalent cations, Ca2+ and Cu2+, at which coagulation of dissolved organic matter appeared could be explained by differences in the binding of Ca and Cu by dissolved organic matter. Binding of Cu by dissolved organic matter as well as by solid organic matter, both affected by Ca and pH, could be described well with the NICA model. We investigated the coagulation and mobility of dissolved organic matter in column experiments and found that they enhanced Cu mobility. Three processes, Cu desorption by soil, dissolved organic matter coagulation and Cu complexation by dissolved organic matter, act simultaneously in the soil columns. All three with counteracting effects on Cu mobility are influenced by Ca and pH and could be adequately represented by the multicomponent NICA model. 相似文献
102.
103.
L.C. DE ALMEIDA I.M. AVILEZ C.A. HONORATO T.S.F. HORI G. MORAES 《Aquaculture Nutrition》2011,17(2):e253-e262
Growth and metabolism were investigated in juvenile tambaqui (Colossoma macropomum) fed with isoenergetic diets in four treatments with protein (P) lipid (L) in g kg?1: P350L49; P301L81; P253L113 and P205L145, respectively. The experiments were carried out in the laboratory facilities. Fish growth, the intermediary metabolites (total sugar, lactate, pyruvate, ammonia, protein, fatty acids, triacylglycerols, amino acids and glycogen), and the enzyme activities of lactate dehydrogenase, malate dehydrogenase, glutamate dehydrogenase, aspartate aminotransferase and alanine aminotransferase were assayed. Fish from treatments P350L49 and P301L81 depicted the best growth. Increase in glycolytic, glycogenolytic and lipolytic activities in liver was observed following dietary lipid increase. In fish fed with high lipid levels, the energetic demand was supplied by enhancement of muscular glycogenesis and lipolysis. The plasma metabolic profile reflected the blood function on metabolites delivery to tissues underlining biochemical adaptations because of changes in the feeding. In conclusion, the increase in dietary lipid plus protein decrease resulted in (i) reduction in fish growth, (ii) augment of liver glycolysis and glycogenolysis (iii) increase in muscular glycogenesis and (iv) predominance of lipolytic metabolism. 相似文献
104.
P.F. ALMAIDA‐PAGÁN M.D. HERNÁNDEZ J.A. MADRID J. DE COSTA P. MENDIOLA 《Aquaculture Nutrition》2011,17(2):e48-e55
Fish are able to select a balanced diet according to their nutritional needs by choosing among incomplete feeds or even pure macronutrients. However, the relevance of both the organoleptic properties of diet and the postingestive signals that they produce remains unclear. Thus, sharpsnout seabream were allowed to select between diets containing different edible oils with their organoleptic properties masked by using gelatine capsules. Fish were fed capsules of two different colours so that they could associate the capsule colour with its corresponding postingestive effect. The longitudinal experiment included a first phase during which the fish were adapted to consuming the gelatine capsules. In a second phase, the fish were challenged with two different encapsulated diets: one comprising a complete diet containing fish oil and the other a fat‐free diet. Sharpsnout seabream showed a preference for the fish oil capsules (3.8 ± 1.1 g kg?1 body weight (BW), 66.8% of total intake) over the fat‐free capsules, showing that they were able to associate the colour of the capsule with their nutritional content through postingestive signals. After that, the fish were challenged to select between the capsules containing the fish oil diet and capsules containing a vegetable oil (linseed or soybean), in which case they showed no preference between diets (2.4 ± 0.3: 2.1 ± 0.5 g kg?1 BW of fish oil versus linseed oil capsules and 2.2 ± 0.2: 1.8 ± 0.6 g kg?1 BW of fish oil versus soybean oil capsules), indicating that the fatty acid composition of the different oils was not sufficient to affect dietary selection through postingestive signals. So, in conclusion, when orosensorial information from food is absent, the fish are able to select between diets at a macronutrient level by using postingestive information. However, this information is not sufficient for distinguishing between diets that differ in the type of oil used. 相似文献
105.
Rita de Cassia FLIX ALVAREZ Renato de Mello PRADO Guilherme FELISBERTO Anglica Cristina FERNANDES DEUS Raimundo Leonardo LIMA DE OLIVEIRA 《土壤圈》2018,28(4):597-606
Silicon(Si) has been supplied to plants via application of calcium silicate to soil; however, high doses of calcium silicate are required because of its low solubility. Nanoparticles can reduce Si doses and be applied to seeding furrows. This study investigated the effects of liquid Si sources, i.e., highly soluble silicate(115.2 g L~(-1) Si and 60.5 g L~(-1) Na_2O) and nanosilica( 200 nm), on Si uptake by rice plants, plant lignification, plant C:N:P stoichiometry, plant physiology, and grain yield using an Oxisol under greanhouse condistions. The treatments included the application of nanosilica and soluble silicate to seeding furrows at Si doses of 0, 605, 1 210,and 2 420 g ha~(-1). Plant uptake and treatment effects were evaluated by measuring C and lignin contents, Si, N, and P accumulation,physiological characteristics, and grain yield of rice. The deposition of silica bodies and amorphous silica in the flag leaves was analyzed using scanning electron microscopy. Application of liquid Si increased Si accumulation in rice by 47.3% in relation to the control(0 g ha~(-1) Si), regardless of the Si sources used. Nanosilica application increased leaf lignin content by 112.7% when compared to that in the control. Silicon moderately affected the net C assimilation(increased by 1.83%) and transpiration rates(increased by 48.3%);however, Si influenced neither plant growth nor grain yield of rice. These results are explained by the lack of biotic or abiotic stress in rice plants during the experiment. To the best of our knowledge, in Brazilian agriculture, this is the first report on the use of nanosilica as a Si fertilizer and its effect on plant nutrition. This study provides evidence that rice plants absorb and accumulate nanoparticles;however, further studies are required to investigate the use of nanoparticles in other plant species. 相似文献
106.
大型海藻养殖是一种低成本、高效、环保的水体富营养化生物修复方法,而水流则是影响大型海藻生长的一个重要因素。研究结果表明,水流交换率为200 vol·d-1时,羊栖菜(Sargassum fusiforme)比生长率最高达(4.34±0.11) %·d-1,而水流交换率为100 vol·d-1、中高浓度营养盐条件下石莼(Ulva pertusa)比生长率最大值分别可达(6.31±1.42) %·d-1、(8.00±0.79) %·d-1,营养盐浓度决定了两种大型海藻的生长率,石莼更适宜在高营养盐环境中生长。石莼体内叶绿素a、可溶性蛋白和可溶性碳水化合物在不同应用情境间均存在明显差异,而羊栖菜体内仅可溶性蛋白表现出明显变化。水流交换的增强明显改变了石莼的生长和羊栖菜可溶性碳水化合物含量。陆基中试实验表明,与低水流速度相比,中、高流速条件下羊栖菜的比生长率分别增加80%、14%,石莼则分别增加41.3%、33.3%。 相似文献
107.
在青藏高原三江源区草地上,以开顶式温棚模拟增温,在其内部施用不同形态氮素(硝态氮和氨态氮)比例的氮肥,对重齿风毛菊(Saussurea katochaete)的光合速率、叶绿素荧光及其群落总生物量进行研究,旨在为人工管理草场施肥提供指导。结果表明:重齿风毛菊的光合速率随硝态氮比例增加而下降,气孔导度则增加。其他气体交换参数没有规律性变化。光系统II(PSII)光化学量子产量(ΦPSII)在硝态氮比例为0%时最大,非光化学瘁灭(NPQ)则随硝态氮比例增大而增大。重齿风毛菊所在群落的总生物量在硝态氮和氨态氮比例平衡时达到最大。结果表明不同比例氮素施肥会对青藏高原草甸植物的净光合速率和群落总生物量产生影响。 相似文献
108.
J Schön S Neumann DE Wildt BS Pukazhenthi K Jewgenow 《Reproduction in domestic animals》2009,44(S2):294-301
Oestrogens are involved in regulation of spermatogenesis and sperm maturation and are essential for male fertility. To study the role of oestrogens on epididymal function in the domestic cat, we analyzed the localization patterns of oestrogen receptors (ERs) within the epididymis of juvenile, pubertal and adults using immunohistochemistry. Cat epididymal tissues obtained during routine castrations were fixed in chilled Bouin's solution and processed for immunohistochemistry with ER-specific antibodies. For a certain receptor type, ER localization was influenced by donor age. In the juvenile epididymis, ERα was localized in the nuclei of epithelial cells of efferent ducts and undifferentiated epithelium of the ductus epididymis. During puberty, ERα localization in the undifferentiated epithelium of the epididymis shifted from the nuclei to the cytoplasm and plasma membrane. Oestrogen receptor-α level was highest in the pubertal and adult epididymis, especially within the cytoplasm and in plasma membranes of caput epithelial cells. This finding was suggestive of a role in fluid reabsorption within the efferent ducts and the epididymis. In corpus and cauda regions, ERα was less abundant, suggesting a minor role for oestrogens in sperm storage areas. Interestingly, localization of ERβ was neither influenced by age nor location within the epididymis and was ubiquitous throughout. Results demonstrate that oestrogen actions within the epididymis may be predominantly mediated through ERα during sexual maturation in the domestic cat. 相似文献
109.
110.
P. CRAMP F. J. DERKSEN J. A. STICK H. DE FEIJTER‐RUPP N. G. ELVIN J. HAUPTMAN N. E. ROBINSON 《Equine veterinary journal》2009,41(4):328-333
Reasons for performing study: The nerve‐muscle pedicle graft technique is a treatment for recurrent laryngeal neuropathy (RLN), but the optimal placement of the pedicles within the cricoarytenoideus dorsalis (CAD) muscle is unknown. Hypothesis: The magnitude and direction of force placed on the muscular process of the left arytenoid cartilage affects the magnitude of laryngeal abduction. Methods: Five larynges were harvested from cadavers. Using increments of 0.98 N, a dead‐weight force generator applied a force of 0–14.7 N for 1 min each to the left muscular process at 0, 10, 20, 30, 40, 50, 60 and 70° angles. The rima glottis was photographed digitally 1 min after each force had been applied. Distances between biomarkers (Lines 1–4) and right to left angle quotient (RLQ) were used to assess the degree of left arytenoid abduction. Results: Increasing force from 0–14.7 N progressively and significantly increased the length of all lines and RLQ, indicating abduction. Furthermore, there was a significant interaction between force and angles. Applying forces of 7.84 N or greater (Lines 2–4 and RLQ) or 11.76 N or greater (Line 1) at angles 0, 10, 20 and 30° resulted in significantly greater abduction than applying the same forces at 40, 50, 60 and 70°. Angles of 0–30° correspond with the direction of pull exerted by the lateral compartment of the CAD muscle. Conclusion: In RLN, nerve‐muscle pedicle grafts should be placed preferentially in the lateral rather than in the medial compartment of the CAD muscle. Potential relevance: The information presented can be used to assist surgeons in the planning and application of the nerve‐muscle pedicle graft procedure. 相似文献