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771.
采用氧瓶燃烧处理植物样品,离子色谱法测定吸收液中SO_4~(2-)的方法来确定植物的含硫量,方法简便,分析周期短、重现性和回收率(94.7%~109.2%)均令人满意。 相似文献
772.
Heavy Metal Uptake By Scirpus Littoralis Schrad. From Fly Ash Dosed and Metal Spiked Soils 总被引:1,自引:0,他引:1
Tanushree Bhattacharya D. K. Banerjee Brij Gopal 《Environmental monitoring and assessment》2006,121(1-3):361-378
Scirpus littoralis is a wetland plant commonly found in Yamuna flood plains of Delhi, India. The ability of Scirpus littoralis to take up and translocate five metals- Mn, Ni, Cu, Zn and Pb from fly ash dosed and metal spiked soils were studied under waterlogged and field conditions for 90 days. Scirpus littoralis accumulated Mn, Ni, Cu, Zn and Pb upto a maximum of 494.92, 56.37, 144.98, 207.95 and 93.08 ppm dry wt., respectively in below ground organs (BO) in 90 days time. The metal content ratios BO/soil (B/S) were higher than shoot/soil ratios (T/S) for all the metals, the highest being for Ni. Metal ratios BO/water (B/W) were also higher than shoot/water (T/W) ratios but the B/W ratio was maximum for Zn. The changes in nutrient status (N, P) in soil water and plants were also studied at interval of 30 days. The Pearson's correlation between metal uptake and N, P uptake were calculated. All the metals except Ni showed negative correlation with nitrogen but they were all non-significant. However, P uptake showed positive correlations with all the metals and all were significant at 1% confidence limit. 相似文献
773.
Activity monitoring for nitrifying bacteria by fluorescence in situ hybridization and respirometry 总被引:1,自引:0,他引:1
The activities of two families of nitrifying bacteria weremeasured by applied respirometer and fluorescence insitu hybridization (FISH) for the purpose of monitoring nitrogenremoval. Oxygen uptake rates (OUR) for Nitrosomonas andNitrobacter were separately measured with the dosing ofselective inhibitors during respirometric monitoring. The FISHmethod was applied to analyze microorganism communities. In 5mg NH4
+-N/L solution, the total nitrogen oxygendemand (NOD) was found to be 6,672 mg DO/L-day with ammoniaand nitrite oxidation rate of 4,512 and 2,160 mg DO/L-day,respectively. The oxygen consumption by endogenous oxidationwas 288 mg DO/L-day and the biological oxygen demand 936 mgDO/L-day. Respirometric measurements were well matched by theFISH result, which described the presence and quantity of eachnitrifying bacteria as nitrification proceeded. It was foundthat when coupled with OUR data, FISH could provide valuableinformation about the nitrogen removal process in manypractical wastewater treatment systems. 相似文献
774.
Grazing effects on sustainable semiarid rangeiands in Patagonia: The state and dynamics of the soil seed bank 总被引:4,自引:0,他引:4
Mónica B. Bertiller 《Environmental management》1996,20(1):123-132
The composition of the germinable seed bank was studied in four vegetation states of the Festuca pallescens grasslands in semiarid Patagonia during four years. The aim of this study was to test whether above-ground vegetation states
resulting from grazing exclusion or different combinations of grazing and topography are reflected in different states of
the germinable seed bank. The size of the total and dicot germinable seed bank was positively related to the total cover in
each state. Dicots dominated all germinable seed bank states. Carex patagonica increased its cover as well as its germinable seed bank under grazing disturbance. Grazing did not reduce the germinable seed
bank of perennial grasses in uplands where the grazing pressure is lower as compared with slopes. In slopes the germinable
seed bank of perennial grasses was significantly reduced by grazing. A reduction of the length of the grazing period in late
spring increases the germinable seed bank of perennial grasses both in upland and slope. These results are interpreted in
the frame of a model of management techniques where grazing exclusion during late spring and late summer increases the seed
bank of the perennial grasses and promotes their establishment in uplands. The artificial addition of seeds of perennial grasses
and the manipulation of the soil surface in order to increase "safe sites" appear as management alternatives that deserve
further evaluation to improve plant reestablishment in slopes. 相似文献
775.
Loibl W Bolhàr-Nordenkampf HR Herman F Smidt S 《Environmental science and pollution research international》2004,11(3):171-180
GOAL, SCOPE AND BACKGROUND: Ozone is the most important air pollutant in Europe for forest ecosystems and the increase in the last decades is significant. The ozone impact on forests can be calculated and mapped based on the provisional European Critical Level (AOT40 = accumulated exposure over a threshold of 40 ppb, 10,000 ppb x h for 6 months of one growing season calculated for 24 h day(-1)). For Norway spruce, the Austrian main tree species, the ozone risk was assessed in a basis approach and because the calculations do not reflect the health status of forests in Austria, the AOT40 concept was developed. METHODS: Three approaches were outlined and maps were generated for Norway spruce forests covering the entire area of Austria. The 1st approach modifies the AOT40 due to the assumption that forests have adapted to the pre-industrial levels of ozone, which increase with altitude (AOTalt). The 2nd approach modifies the AOT40 according to the ozone concentration in the sub-stomata cavity. This approach is based on such factors as light intensity and water vapour saturation deficit, which affect stomatal uptake (AOTsto). The 3rd approach combines both approaches and includes the hemeroby. The pre-industrial ozone level approach was applied for autochthonous ('natural') forest areas, the ozone-uptake approach for non-autochthonous ('altered') forest areas. RESULTS AND DISCUSSION: The provisional Critical Level (AOT40) was established to allow a uniform assessment of the ozone risk for forested areas in Europe. In Austria, where ozone risk is assessed with utmost accuracy due to the dense grid of monitoring plots of the Forest Inventory and because the continuously collected data from more than 100 air quality measuring stations, an exceedance up to the five fold of the Critical Level was found. The result could lead to a yield loss of up to 30-40% and to a severe deterioration in the forest health status. However, the data of the Austrian Forest Inventory and the Austrian Forest Damage Monitoring System do not reflect such an ozone impact. Therefore, various approaches were outlined including the tolerance and avoidance mechanisms of Norway spruce against ozone impact. Taking into consideration the adaptation of forests to the pre-industrial background level of ozone, the AOT40 exceedances are markedly reduced (1st approach). Taking into account the stomatal uptake of ozone, unrealistic high amounts of exceedances up to 10,000 ppb x h were found. The modelled risk does not correspond with the health status and the wood increment of the Austrian forests (2nd approach). Consolidating the forgoing two approaches, a final map including the hemeroby was generated. It became clear that the less natural ('altered') forested regions are highly polluted. This means, that more than half of the spruce forests are endangered by ozone impact and AOT40 values of up to 30,000 ppb x h occur (3rd approach). CONCLUSIONS: The approaches revealed that a plausible result concerning the ozone impact on spruce forests in Austria could only be reached by combining pre-industrial ozone levels, ozone flux into the spruce needles and the hemeroby of forests. 相似文献
776.
The aim of this study was to characterize the biological treatment of heavy metal-contaminated water employing Myriophyllum species, namely M. spicatum L. and M. triphyllum. Both species were found to be capable of removing cadmium (Cd) from water; the latter significantly outperformed. Myriophyllum species were treated with 0, 2, 4, 6, 8, 16 mg l−1 cadmium solutions for 24, 48, 72, 96 h, respectively. Cd uptake of both species was the lowest at 2 mg l−1 and the highest at 16 mg l−1. Concentration related cadmium stress on both species exhibit significant difference on pigment levels (8–16 mg l−1). These findings contribute to the fact that submerged aquatic plants can be used for the removal of heavy metals. 相似文献
777.
Effective management of tidal wetlands requires periodic data on the boundaries, extent, and condition of the wetlands. In many states, wetlands are defined wholly, or in combination with other criteria, by the presence of particular emergent halophytic plants. Many important characteristics of the wetlands ecosystem are related directly to the production of emergent plant material or may be inferred from knowledge of the distribution of emergent plant species. Remote-sensing techniques have been applied to mapping of the distribution of wetland vegetation but not to quantitative evaluation of the condition of that vegetation.Recent research in the tidal wetlands of Delaware and elsewhere has shown that spectral canopy reflectance properties can be quantitatively related to the emergent green biomass ofSpartina alterniflora (salt marsh cord grass) throughout the peak growing season (April through September, in Delaware). Periodic measurements of this parameter could be applied to calculations of net aerial primary productivity for large areas ofS. alterniflora marsh in which conventional harvest techniques may be prohibitively time consuming. The method is species specific and, therefore, requires accurate discrimination ofS. alterniflora from other vegetation types. Observed seasonal changes in species spectral signatures are shown to have potential for improving multispectral categorization of tidal wetland vegetation types. 相似文献
778.
M. H. Wong 《Environmental management》1988,12(4):491-499
An ecological survey of the plant and soil characteristics was carried out on three landfill sites near Merseyside, England. It was discovered that bare ground at two of the landfill areas had high levels of methane contained in the soil air (Sefton Meadows landfill: 6–8% at 35 cm and 16–35% at 65 cm below soil surface; Coalgate Lane landfill: 1–24% at 35 cm and 39–45% at 40 cm below soils surface), causing the appearance of dark grey reduced regions in the soil, a phenomenon similar to flooded soil. The wellvegetated areas at the two sites had lower levels of methane (under 7%).In areas relatively free of methane, the concentrations of mineralized N and NO3
– had significant correlations with the dry weights of vegetation (r = 0.71 withp<0.01;r=0.61 withp<0.02 accordingly), indicating the necessity of applying available nitrogen fertilizer. 相似文献
779.
780.
大亚湾核电站运转前及运转后大鹏澳海域水质状况评价 总被引:7,自引:1,他引:7
根据大亚湾核电站运转前及运转后对大亚湾大鹏澳海域的监测资料,选用pH,DO,CODMn,TIN,PO4-P和Chl.a为评价因子,以水质质量综合系数(WQI)为模式,评价了大鹏澳海域水体质量状况。综合评价的结果显示,大鹏澳海域水体质量,在核电站运转前及运转后,冬,夏季节均属清洁水平。 相似文献