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91.
92.
江西省武宁县煤矿多属小型矿山,但小煤矿的开采同样会引起诸多矿山地质灾害问题,如废石乱堆乱放,诱发泥石流;不规范开采,造成区域地下水位下降,引起地面沉降、塌陷和矿井冒顶、突水、瓦斯爆炸等,这些问题需要评估和解决。对上述问题进行成因分析、危害性探讨,并针对每项矿山地质灾害问题提出相应的防治措施,可使该区地质灾害得到有效的控制。 相似文献
93.
平阴县土壤中重金属元素异常成因研究 总被引:1,自引:0,他引:1
通过对平阴县周边及其西部农田区采样调查,平阴县周边元素异常具有异常衬度较高,富集系数大等特征,西部农田区异常具有各元素套合关系好,多数异常衬度不高,富集系数小的特点。结果表明,西部农田区异常是以As,Cd为主要成分的异常,元素含量与SiO2,Al2O3,Fe2O3等常量组分间具有显著的相关性,随SiO2含量的增加而降低,随Al2O3,Fe2O3含量的增加而增加,说明土壤常量组分及其所决定的土壤质地是导致异常形成的主要因素;而平阴城区异常是以S,Hg,As,Zn,Mn等元素为主的异常,是典型的人为综合因素(化工烟尘、工厂污水、生活垃圾)产生的异常。 相似文献
94.
The rocky outcrops irregularly scattered in the sandy‐muddy sea bed of the Northern Adriatic, formed by a base rock and a superimposed concretion of vegetal and animal organisms, are considered an infralittoral coralligenous habitat, according to the most recent definition. In the last four decades, research has mainly concentrated on their geology because of the question of the origin of the base rock – very similar to beachrock – which has only recently been attributed to sedimentary cementation induced by methane seeps. Studies on their macrobenthic assemblages have also been published recently, but true comparisons among them are difficult because they mostly refer only to a few selected phyla or to short‐term observations. Very few papers deal with the whole of the animal and plant communities, including all taxonomic groups and the most important environmental variables. On the basis of the literature data concerning several outcrops in the Gulf of Venice, we suggest that the Adriatic reefs differ slightly from the classic deeper coralligenous assemblages around the Mediterranean coast because they have smaller concretions of algae builders. We also suggest that the Northern Adriatic coralligenous reefs are younger than the other reefs occurring in the Mediterranean Sea. 相似文献
95.
O. Mangoni M. Modigh P. Mozeti
A. Bergamasco P. Rivaro V. Saggiomo 《Estuarine, Coastal and Shelf Science》2008,77(4):633-644
The photosynthetic properties of phytoplankton populations as related to physical–chemical variations on small temporal and spatial scales and to phytoplankton size structure and pigment spectra were investigated in the Northern Adriatic Sea off the Po River delta in late winter 1997. Large diatoms (fucoxanthin) dominated the phytoplankton in the coastal area whereas small phytoflagellates (mainly 19′-hexanoyloxyfucoxanthin, chlorophyll b, 19′-butanoyloxyfucoxanthin) occurred outside the front. The front was defined by the steep gradient in density in the surface layer separating low-salinity coastal waters from the offshore waters.Physical features of the area strongly influenced phytoplankton biomass distributions, composition and size structure. After high volumes of Po River discharge several gyres and meanders occurred in the area off the river delta in February. Decreasing river discharge and the subsequent disappearance of the gyres and the spreading dilution of the river plume was observed in March. The dynamic circulation of February resulted in high photosynthetic capacity of the abundant phytoplankton population (>3.40 mg m−3). In March, the slow circulation and an upper low-salinity water layer, segregated from the deeper layers, resulted in lack of renewal of this water mass. The huge phytoplankton biomass, up to 15.77 mg chl a m−3, became nutrient depleted and showed low photosynthetic capacity. In February, an exceptionally high PmaxB, 20.11 mg C (mg chl a)−1 h−1 was recorded in the Po River plume area and average PmaxB was three-fold in February as compared to the March recordings, 10.50 mg C (mg chl a)−1 h−1 and 3.22 mg C (mg chl a)−1 h−1, respectively.The extreme variability and values of phytoplankton biomass in the innermost plume area was not always reflected in primary production. Modeling of circulation patterns and water mass resilience in the area will help to predict phytoplankton response and biomass distributions. In the frontal area, despite a considerable variability in environmental conditions, our findings have shown that the phytoplankton assemblages will compensate for nutrient depression and hydrographic constraints, by means of size and taxonomic composition and, as a result, the variability in the photosynthetic capacity was much less pronounced than that observed for other parameters. 相似文献
96.
Based on the comprehensive collection of the field observed salinity of the Bohai Sea (BHS) and the northern Huanghai Sea (NHS) from the 1950s to the present,the patterns of 10-years-averaged salinity at the different layers in the recent five decades (the 1950s,the 1960s,the 1970s,the 1980s and the 1990s) are obtained by the spatial-temporal interpolation technique with the scrupulous data quality control in this study.Then,by combining the spatial-temporal interpolation technique with successive correction method,the annual distributions of salinity both in the BHS and in the NHS are obtained as well.The data analyses indicate that the overall salinity in the BHS and the NHS increases from the 1960s till the present,with the increase of annual mean salinity of 0.04 psu from the 1950s,and the maximum increase rate of salinity is about 0.14 psu/a in the Bohai Bay.The high salinity tongue extended significantly from the NHS into the BHS.The intensified eastern wind field is related to the western intrusion of the NHS warm current,which probably leads to the moving forward of the high salinity water mass into the BHS.However,it is rather different from the salinity distribution characteristics between the 1950s and the 1960s.The extensive precipitation in the 1960s could lead to an increase in the discharge of the Huanghe River,which might result in the decrease of salinity in the BHS.But the salinity isoline of 32 in the NHS still extended significantly into the BHS in the 1960s.Since the 1980s,the patterns of salinity distribution have changed thoroughly.The salinity in the central area of the BHS was low,while the salinity in the Bohai Bay and the Liaodong Bay was higher than the other regions with its horizontal salinity gradient decreasing in the 1980s.The Empirical Orthogonal Function Analysis (EOF) is also conducted to study the interannual salinity variability of the BHS and the NHS.The correlation coefficient between the time coefficient series of the main mode and the Huanghe River discharge can reach -64.57%.It can be concluded that salinity variation of the BHS and the NHS has strong negative correlation with the Huanghe River discharge. 相似文献
97.
Conservation and management of coastal lagoons envisage direct human intervention. To prevent siltation and to preserve the hydrodynamics features of the lagoon system, the inner channels undergo regular maintenance dredging. 相似文献
98.
A putative tetrasporophyte-specific gene, designated as SSH466 (GenBank accession No. DQ019223), was one of the genes identified in this work using suppression subtractive hybridization (SSH) method in Gracilaria lemaneiformis. The full length of the gene was obtained using SMART RACE strategy. Sequence analysis revealed that the gene had 1 019 nucleotides, including an open reading frame of 498 nucleotides encoding 166 amino acid residues, 158 nucleotides of 5' untranslated region and 363 nucleo- tides of 3' non-coding region. Protein motif and secondary structure prediction showed that there existed a transmembrane domain with a unique β-sheet. Thus, SSH466 protein might be a cross-membrane protein. Sequence homology search in the public GenBank databases did not reveal any significant match with SSH466. Virtual Northern blot analysis confirmed that it was a tetrasporo- phyte-specific gene. 相似文献
99.
Method for evaluating the degrees of land use sustainability of mountainous county and its application in Yunnan Province,China 总被引:4,自引:1,他引:3
The evaluation of sustainable land use is the key issue in the field of studying the sustainable land utilization. In general analysis, the sustainable land use is evaluated respectively from its ecological sustainability, economic sustainability and social sustainability in China and other countries in recent years. Although this evaluation is an important work, it seems insufficient and hard to comprehensively reflect the whole degree of land use sustainability. Thus, to make up this deficiency, this paper brings forward the evaluation indexes, which make it possible to quantitatively reflect the whole degree of land use sustainability, namely, the concept of "degrees of overall land use sustainability" (Dos), and research and measurement development of the method of and calculation in Dos. Taking the evaluation of the degree of land use sustainability in county regions of Yunnan Province as the actual example for analysis, results are basically as follows:
1) The degree of land use sustainability (Dos) is the ration index to organically and systematically integrate the degree of ecological friendliness (DeF), the degree of economic viability (Dev) and the degree of social acceptability (Dsa), able to comprehensively reflect the whole sustainability degree of regional land use
2) Based on the value of Dos, the grading system and standard for the sustainability of land use may be established and totally divided into five grades, namely, the high-degree sustainability, middle-degree sustainability, low-degree sustainability, conditional sustainability and non-sustainability. Meanwhile, the standard for distinguishing sustainability grades has also been confirmed so as to determine the nature of sustainability degrees in different grades. This makes the possibility for the combination of nature determination with ration in research result and provides with the scientific guideline and decision-making gist for better implementation of sustainable land use strategy.
3) The pract 相似文献
1) The degree of land use sustainability (Dos) is the ration index to organically and systematically integrate the degree of ecological friendliness (DeF), the degree of economic viability (Dev) and the degree of social acceptability (Dsa), able to comprehensively reflect the whole sustainability degree of regional land use
2) Based on the value of Dos, the grading system and standard for the sustainability of land use may be established and totally divided into five grades, namely, the high-degree sustainability, middle-degree sustainability, low-degree sustainability, conditional sustainability and non-sustainability. Meanwhile, the standard for distinguishing sustainability grades has also been confirmed so as to determine the nature of sustainability degrees in different grades. This makes the possibility for the combination of nature determination with ration in research result and provides with the scientific guideline and decision-making gist for better implementation of sustainable land use strategy.
3) The pract 相似文献
100.