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1.
Ola Broberg 《Hydrobiologia》1987,150(1):11-24
The acidified lakes Lake Gårdsjön and Lake Stora Hästevatten the reference lake have been monitored since 1979 and 1980 respectively. The lakes are situated in SW Sweden; in an area severly affected by acid deposition. Lake Gårdsjön was limed in spring 1982. This paper analyses changes in nutrient concentrations upon liming of Lake Gårdsjön. The liming of Lake Gårdsjön was followed by a slight increase in ammonium, nitrate, and dissolved organic nitrogen concentrations. A drastic decrease occurred in particulate nitrogen and particulate carbon, whereas dissolved organic carbon increased. Total phosphorus and particulate phosphorus concentrations were similar to pre-limed conditions. The long-term decrease in phosphorus concentration, exhibited by the reference lake, was not identified in Lake Gårdsjön after liming, but total phosphorus concentration was still less than half compared to Lake Gårdsjön in the early 1970's. Additional measures such as phosphorus fertilization, should in certain cases be considered in addition to liming if the goal is to restore lakes to their pre-acidic conditions. 相似文献
2.
3.
《Biomarkers》2013,18(7):595-600
AbstractContext: Stroke and/or white matter lesions (WMLs) are significant in Fabry disease. Polymorphisms of angiotensinogen (AGT), AGT Promoter and angiotensinogen II receptor type 1 (AGTR1) are correlated with WMLs.Objectives: We compared AGT. AGT Promoter and AGTR1 genotypes to stroke incidence, Fabry-specific [Mainz Severity Score Index (MSSI)] severity score, and neurologic sub-score (n-MSSI).Methods: Sixty-three Fabry patients and 49 matched controls plus historic controls were genotyped. Institutional Review Board approval was received.Results. C and/or CC alleles of AGT Promoter and AGTR1 were significantly correlated with stroke and n-MSSI.Discussion/conclusion: Findings are suggestive of role of AGT Promoter and AGTR1 genotypes in Fabry phenotypes. 相似文献
4.
The fate of15N labeled nitrogen applied to mature citrus trees 总被引:1,自引:0,他引:1
Summary The efficiency and balance of nitrogen from one year's application was studied in a long-term fertigation experiment. Enriched
nitrogen fertilizer, K15NO3, was applied to a 22-year-old Shamouti orange tree with a history of high N applications (N3) and to an N-starved tree (N1). The distribution of N in the different parts of the trees and in the soil was determined after the experimental trees were
excavated.
Similar total recovery of the labeled fertilizer N was found in the trees and soil in both treatments (N1−61.7% N3−56%). However, the distribution between tree and soil was different. The amount of recovered residual fertilizer in the soil
was much larger in the N3 treatment than in N1. The highest percentage of fertilizer N was found in the new organs,i.e. fruits, twigs and leaves. The roots and branches took up only 6–14% from the labeled fertilizer.
Only 20.9% of the leaf N and 23.4% of the fruit N in the N3 tree originated in the labeled fertilizer, indicating translocation of N from older parts of the tree to new growth.
Evidence was found of storage of N in the wooded branches, while the roots contained a surprisingly small part of labeled
fertilizer.
Contribution 1599E. 相似文献
5.
The N2O flux from the surface of grass-covered pots was only significant following grass maturing. Removal of the above-ground plant
material resulted in an immediate and long-lasting increase in N2O production in the soil. The results suggest that easily available organic matter from the roots stimulates the denitrification
when the plants are damaged. Grass cutting might therefore result in a marked nitrogen loss through denitrification. The quantitative
effect was equal in soil with and without succinate added. The size of the anaerobic zone around the roots is therefore sufficient
to allow for denitrification activity mediated by increased organic matter availability because of plant cutting. 相似文献
6.
The organic content of the surficial sediment: a method for the study of ecosystems development in abandoned river channels 总被引:1,自引:0,他引:1
To characterise different abandoned river channels, a simple index of the surface sediment was developed i.e. the content of organic matter (expressed as C × N) plotted in relation to that of CaCO3. The age of the channels studied ranges from 20 to 300 years. Some of them still contain water; others are silted up. Two types are distinguished. The ecosystems of the first one are closed and show a slow rate of development governed by autogenous processes. Those of the second type are more open and show a fast rate of development mainly controlled by allogenous processes. These distinctions are used in a diagrammatic model of the dynamics of Rhône River alluvial plain to be used in fundamental or applied future research. 相似文献
7.
The effects of defoliation treatments on plant growth in sunflower (Helianthus annuus) were studied in the field. Four defoliation treatments, 0 (control), 37.4, 56.1 and 93.4% of the total leaf dry weight,
were applied to plants that had small third leaves. Decreased leaf weight/whole plant weight (F/W) ratios in defoliated plants
rapidly recovered to almost the same ratio as that observed in the control within 12 to 16 days after defoliation according
to the degree of defoliation. The mechanism involved in the recovery of the F/W ratio in defoliated plants mainly consisted
of three parameters: enhancement of (1) carbon distribution ratios in the leaves, (2) photosynthetic activity in the remaining
leaves, and (3) retranslocation of carbon from the stem and/or roots to leaves.
Inhibitive effects of defoliation on relative growth rate and net assimilation rate were seen at an early stage, but subsequently
both rates became larger in defoliated plants than in controls. Defoliated plants tended to show rapid development and expansion
of new leaves, and to show increased specific leaf area and protein synthesis in individual leaves. The sugar content of leaves
in defoliated plants was higher than that in controls, while the content in both stem and roots was lower. These responses
seem to be advantageous for development of the photosynthetic system. Heights of defoliated plants were clearly depressed
according to the degree of defoliation, and this was attributed largely to differences in the elongation rates of the internodes
resulting from defoliation. 相似文献
8.
M. W. A. Verstegen A. Siegerink W. Van der Hel R. Geers C. Brandsma 《Journal of thermal biology》1987,12(4):257-261
The aim of the experiments was to investigate the effect of air velocity on the temperature preferred by growing pigs 12–14 weeks old. Pigs displayed a temperature preference by means of operant supplemental heating. They pushed a button connected to heating lamps. Six experiments of three weeks each and with two treatments with a group of 8 pigs each were made. Animals were housed in groups and weighed 14–20 kg at the start of the experiments. Air velocity was 0.08, 0.25 and 0.40 m/s. At each air velocity four replicates were made. Mean temperatures preferred were 17.9°C at 0.08 m/s, 20.5°C at 0.25 m/s and 21.7°C at 0.40 m/s. Within a day temperature preference fluctuated with 5.7 K at 0.08 m/s, 4.3 K at 0.25 m/s and 4.2 K at 0.4 m/s. Temperatures preferred were highest during day time. 相似文献
9.
Kyriacos Athanasiou Iordanis Arzimanoglou Colette Piccoli Hiroshi Yamasaki 《Cell biology and toxicology》1987,3(3):251-261
Airborne particulates were collected over a period of twelve months by the use of Hi-Vol samplers in the basin of Athens, Greece. N-Hexane extracts were tested in a battery ofin vitro tests for their ability to induce mutation in bacteria as well as mutation, sister chromatid exchange and morphological transformation in cultured mammalian cells. Positive results were found for mutagenicity withSalmonella strain TA98 in the Ames assay, for sister chromatid exchange induction in CHO cells and for transformation in BALB/c 3T3 cells in culture. They also showed weak non-doserelated induction of ouabain resistance in BALB/c 3T3 cells. The contribution of oxidizing and nitrating agents found in the Athens atmosphere, together with sunlight UV irradiation in the formation of direct acting mutagens and potential carcinogens from ambient polycyclic aromatic hydrocarbons, is suggested.Abbreviations FCS
fetal calf serum
- FPG
fluorescent-plus-Giemsa technique
- ouaR
ouabain resistant
- PAH
polycyclic aromatic hydrocarbon
- SCE
sister chromatid exchange
- TSP
total suspended particulate 相似文献
10.