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981.
982.
Short-term uptake experiments and long-term semicontinuous culture experiments were performed under the condition of phosphorus
(P) limitation to estimate and compare the P uptake and growth kinetics of the microalga Tetraselmis subcordiformis and the macroalga Ulva pertusa. Two new parameters, the maximum specific uptake rate (V
m
sp
) and the maximal growth efficiency (β), are introduced to achieve uniformity for the comparison of nutrient uptake and growth
efficiency between microalgae and macroalgae. T. subcordiformis possesses 3 times lower half saturation uptake constant, 4 times higher maximal growth rate and 20 times higher maximum specific
uptake rate than U. pertusa, while U. pertusa possesses 4 times higher maximal growth efficiency than T. subcordiformis. 相似文献
983.
984.
Sediment samples were cored from 3 locations representing the inner bay, the outer bay and the bay mouth of Jiaozhou Bay in September 2003 to study the source and biogeochemical characteristics of nitrogen and phosphorus in the bay. The content and vertical distributions of total nitrogen (TN), total phosphorus (TP), organic nitrogen (ON), organic phosphorus (OP), inorganic nitrogen (IN), inorganic phosphorus (IP), the ratio of organic carbon and total nitrogen (OC/TN), and the ratio of total nitrogen and total phosphorus (TN/TP) in the sediments were analyzed. The results show that both TN and TP in surface sediments decrease from the inner bay to the outer bay. In general, ON occupies 50%-70% of TN and IP accounts for more than 60% of TP. In ratio of OC:TN, the nitrogen accumulated in the sediments from the inner bay and the bay mouth came mainly from terrestrial sources, and the portion of autogenetic nitrogen was 28.9% and 13.1%, respectively. However, in the outer bay, nitrogen was mainly autogenetic, accounting for 62.1% of TN, whereas phosphorus was mainly land-derived. The sedimentation fluxes of nitrogen and phosphorus varied spatially. The overall diagenesis rate of nitrogen was higher than that of phosphorus. Specifically, the diagenesis rate of OP was higher than that of IP. However, the diagenesis rate of ON was not always higher than that of IN. In species, the diagenesis rate of IN is sometimes much higher than that of the OC. In various environments, the diagenesis rate is, to some degree, affected by OC, pH, Eh, and Es. 相似文献
985.
BIOGEOCHEMICAL PROCESSES OF PHOSPHORUS AND SILICON IN SOUTHERN BOHAI SEA SURFACE SEDIMENTS 总被引:3,自引:0,他引:3
Based on the author’s previously obtained results on P and Si forms in southern Bohai Sea surface sediments,this study maindy foucusing on the controlling factors,existence forms,and biogeo-chemical processes of P and Si showed that the transferable forms of phosphorus in sediments were mainly controlled by the mineralization of organic matters and the reduction of high-valence iron;whereas the transferable forms of silicon were possibly controlled by the dissolution and precipitation as well as bio-chemical processes of living organisms. 相似文献
986.
Iron and phosphorus limitation and their combined effects on the growth and development of Prorocentrum micans Ehrenberg (Dinophyceae) and Cryptomonas sp. (Cryptophyceae) have been studied. The growth status of these algae at different Fe and P levels is quantitatively analyzed
through lab-culture experiments. Results show that Fe starvation can misalign chloroplast lamellas, and metamorphose and twist
thylakoid, leading to a retarded growth rate. The combined effects of Fe and P can accelerate their growth, and an optimum
culture condition to maintain the maximum growth rate is a combination of 0.05 μM Fe and 50 μM P. Algal uptake of Fe and P
are synergistic. Their cellular concentrations bear significant correlations (r = 0.9979 for Cryptomonas sp. and 0.9938 for P. micans; P < 0.01) and correspondingly the molar P:Fe ratios are ∼160:1 and ∼356:1, respectively. These findings will provide novel
insights for revealing the crucial factors controlling the occurrence of algal blooms. 相似文献
987.
基于GIS技术的农用地非点源磷污染危险性评价——以长江流域为例 总被引:1,自引:0,他引:1
识别磷素流失的关键源区,对合理实施养分资源管理、指导平衡施肥、有目的治理来源于农业养分造成的污染和农业的可持续发展有着重要的意义,本文以地理信息系统(GIS)的空间分析功能和养分平衡计算等方法为依托,参照国际常用的磷指数法对长江流域主要农用地进行了农业非点源磷污染风险评价,得到以下结论:磷非点源污染危险性指数高和极高的农用地,分别占到了流域农用地的24.40%和0.49%;风险低和中区域分别占到了11.16%和63.95%。长江流域为农用地磷污染风险中等的流域。 相似文献
988.
利用电感耦合等离子体发射光谱测定磷矿中的有效五氧化二磷,样品采用柠檬酸浸提处理,干过滤,滤液引入电感耦合等离子体发射光谱测定。这种方法与传统分光光度法测定有效五氧化二磷相比较,能很好的测定磷矿中有效五氧化二磷,相对标准偏差较低,结果准确。 相似文献
989.
UM Scharler MJ Ayers AM de Lecea M Pretorius ST Fennessy JA Huggett 《African Journal of Marine Science》2016,38(1):S193-S203
Riverine influences on nearshore oceanic habitats often have detrimental consequences leading to algal blooms and hypoxia. In oligo- to mesotrophic systems, however, nutrient delivery via rivers may stimulate production and even be a vital source of nutrients, as may nutrient supplements from upwelling. We investigated the nutrient content (C, N, P) and stoichiometry of sediment, and several pelagic, benthopelagic and benthic species in the KwaZulu-Natal (KZN) Bight, a narrow shelf area on the south-east coast of South Africa, bordering the Agulhas Current. Three suggested nutrient sources to the bight are the Thukela River in the central region of the bight, upwelling in the northern part and a semi-permanent eddy (Durban Eddy) in the southern part. Elemental content of the various groups studied showed significantly higher values for most groups at the site near the Thukela River. C:P and N:P were highest in the southern part of the bight, and lowest near the Thukela Mouth or at Richards Bay in the north, indicating the latter were the P-richer sites. Sediment organic matter showed lowest elemental content, as expected, and zooplankton stoichiometry was highest compared to all other biotic groups. Environmental heterogeneity played a greater role in organismal C, N and P content and stoichiometry compared to phylogeny, with the exception of the differences in C:P and N:P of zooplankton. From this bight-wide study, the higher elemental content and lower ratios at the Thukela Mouth site supported previous findings of the importance of coastal nutrient sources to the bight ecosystem. Reductions in river flow for water use in the catchment areas may therefore have negative consequences for the productivity of the entire ecosystem. 相似文献
990.