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141.
The abundance, structure, and distribution of oribatid communities in high-mountain pine forest biotopes of the Eastern Caucasus are described in dependence on elevation above sea level. The oribatid fauna of high-mountain pine forests proved to be characterized by high abundance, an assortment of dominants, and species richness. It was shown that, as the elevation increases, specific dominants typical of particular altitudinal zones appear in communities, and changes in the mass species occur. These species are stable in terms of their long-term dynamics, and zonal groups (communities) demonstrate a high species diversity.  相似文献   
142.
The abundance and biomass of phytoplankton and zooplankton proved to noticeably decrease after the water passed through the cooling system of the Beloyarsk Nuclear Power Plant: the phytoplankton perished by 38% (65 metric tons per day), and the zooplankton, by 55% (6 t/day). In the period between 1985 and 1991, the concentration of60Co in the plankton of water intake and discharge canals varied from 120 to 1400 Bq/kg dry weight, and that of137Cs, from 150 to 1040 Bq/kg dry weight, which is commensurable with the content of radionuclides in the plants and grounds of the Beloyarsk reservoir. In 1985, it was noted that the plankton passing through the cooling system of the nuclear power plant became enriched with Ca, Fe, Mg, Mn, Co, Cs, Cu, Mo, Ni, Pb, Si, Sn, Ti, V, and W.  相似文献   
143.
河流筑坝后水动力条件发生改变,影响了浮游植物的动态变化,目前对这一过程的研究相对较少。为此,本研究对乌江河流-水库体系浮游植物和流速及相关环境因子进行了季度调查。研究区域水体平均流速为032 m/s,变化范围为001~132 m/s;浮游植物中硅藻、蓝藻、甲藻对水体流速变化最敏感:在流速小于005 m/s时,蓝藻与硅藻占比最大,甲藻次之,其他藻类占比较低;流速在005~010 m/s之间,蓝藻占比下降,硅藻、甲藻及绿藻占比上升,其他藻类占比较低;流速大于010/s时,硅藻占比达到绝对优势。浮游植物细胞丰度随着流速的增加表现出先增加后减小的趋势,两者之间存在单峰关系;不同流速下浮游植物会出现较明显的聚类特征。  相似文献   
144.
开展资源丰度的研究,关键在于找到多种资源综合可比的计算单位和计算方法。本文以中国主要农业资源为例,探讨了一种以净产值为基础估算农牧林渔资源量的方法,并按一个年度的基数值计算了各地区单位面积农业资源的平均丰度。然后,以全国平均丰度值为1,计算出各地区的平均丰度比,再换算为各地区的农业资源有效面积。  相似文献   
145.
微塑料(粒径5 mm)作为一种新型污染物近年来被社会广泛关注.本文以江西省饶河-鄱阳湖入湖段(龙口)典型湿地表层中底泥沉积物为研究对象,分离提取底泥沉积物中微塑料,确定底泥沉积物中微塑料丰度值,利用扫描电子显微镜-能谱仪(SEM-EDS)和傅里叶红外光谱仪分析微塑料表面形貌特征及组成特征.结果表明:(1)底泥沉积物中微塑料丰度为938个·kg-1,主要包括碎片、薄膜、纤维和发泡等4种类型微塑料,其中以碎片类微塑料比例最高,达到66.7%;薄膜类次之,约占比例25%;发泡类及纤维类微塑料相对较少些,二者比例之和仅占8.3%.(2)不同类型微塑料的红外光谱分析表明,碎片类微塑料主要成分为聚乙烯,薄膜类主要成分为聚丙烯,纤维类主要成分为低密度聚乙烯,发泡类主要成分则为聚苯乙烯.(3)微塑料粒径分布特征表明,粒径小于1 mm的微塑料比例占总量的61.3%,且随着粒径增大微塑料数目呈减少趋势.(4)微塑料表面形貌特征表现为沉积物中的微塑料有不同程度的老化痕迹,表面出现裂痕、孔隙并带有撕裂物等特征.  相似文献   
146.
Agricultural intensification, at local and landscape scales, has caused a decrease in plant diversity and changes in species composition in cereal fields. To better understand the role of landscape complexity and farming systems in shaping plant assemblages, it is of interest to focus on functional traits rather than on floristic composition, which may help to highlight trends in vegetation patterns. We analysed the relative abundance of various functional attributes (different life forms, growth forms, wind-pollinated species and wind-dispersed species) at three contrasted field positions (boundary, edge and centre) of 29 organic and 29 conventional cereal fields distributed in 15 agrarian localities of NE Spain. Agricultural intensification affected the biological attributes of the vegetation in dryland Mediterranean cereal fields; local factors (farming system and position) had a more prominent role in affecting plant functional composition than the surrounding landscape. Local factors were important for life form distribution, growth form and pollination type, whereas landscape complexity mainly affected the proportion of wind-dispersed species. Therefore, depending on the objective of the study, it is important to select functional attributes sensitive to the different scales of agricultural intensification, especially because landscape complexity and land-use intensity are commonly related.  相似文献   
147.
长江口及毗邻海域底栖生物丰度和生物量研究   总被引:3,自引:0,他引:3  
2005年夏季对长江口及毗邻海域(长江口、杭州湾和舟山海域)的40个站位进行了底栖生物的分类、组成、丰度、生物量以及多样性的研究.底栖生物共监测到86种,其中以长江口底栖生物种类最多(62种),其次为舟山海区(44种),杭州湾最少(5种);全海域底栖生物生物量平均9.55g/m2,其中以舟山海区最高(12.45 g/m2),长江口次之(8.52 g/m2),最低为杭州湾(0.53 g/m2);栖息密度平均为86个/m2,其中以长江口最高(138个/m2),舟山海区次之(33个/m2),杭州湾最少(4个/m2);各海区底栖生物多样性指数以舟山海区最高(1.28),长江口和杭州湾多样性指数均小于1,尤其是杭州湾仅为0.33;底栖生物的沙漠化程度较重,长江口、杭州湾及舟山海区生物量为零的站位分别占了31.2%、33.3%、13.3%.将以上结果与近十年来的积累调查资料比较显示,底栖生物生存环境仍较恶劣,长江口和杭州湾海域仍有三分之一的区域呈现沙漠化,但这种恶化趋势已得到初步遏制.  相似文献   
148.
给水厂废弃铁铝泥(Ferric and aluminum residuals,FARs)可用于控制湖泊沉积物磷释放.因此,在实际应用之前对FARs的风险进行评估非常重要.本研究通过室内富集实验,考察FARs对沉积物中氨氧化菌(ammonia-oxidizing bacteria,AOB)活性、丰度和多样性的影响.结果表明:投加FARs后,沉积物对氨氮的去除能力微弱提高.富集后沉积物中AOB丰度增加,投加FARs的沉积物中AOB丰度达到1.32×108copies·g-1,而未投加FARs的沉积物中AOB丰度为1.14×108copies·g-1.此外,amo A基因的系统发育分析表明富集前后沉积物中的AOB均附属于Nitrosospira和Nitrosomonas两个种属,并且投加FARs沉积物中AOB的多样性略高于未投加的.综上结果表明,FARs回用于湖泊富营养化控制的同时,将有益于沉积物中好氧氨氧化作用的进行.  相似文献   
149.
博斯腾湖浮游动物的调查研究   总被引:1,自引:0,他引:1  
通过1987年7月至1989年9月的野外调查和实验室测试,对新疆博斯腾湖大湖区域五个小区浮游动物种群结构、数量和优势种进行了研究.查明浮游动物58属103种,以原生动物和轮虫占优势,年平均数量 776个/ L.博斯腾湖可列为中营养湖泊.  相似文献   
150.
The European Union's Natura 2000 (N2000) is among the largest international networks of protected areas. One of its aims is to secure the status of a predetermined set of (targeted) bird and butterfly species. However, nontarget species may also benefit from N2000. We evaluated how the terrestrial component of this network affects the abundance of nontargeted, more common bird and butterfly species based on data from long-term volunteer-based monitoring programs in 9602 sites for birds and 2001 sites for butterflies. In almost half of the 155 bird species assessed, and particularly among woodland specialists, abundance increased (slope estimates ranged from 0.101 [SD 0.042] to 3.51 [SD 1.30]) as the proportion of landscape covered by N2000 sites increased. This positive relationship existed for 27 of the 104 butterfly species (estimates ranged from 0.382 [SD 0.163] to 4.28 [SD 0.768]), although most butterflies were generalists. For most species, when land-cover covariates were accounted for these positive relationships were not evident, meaning land cover may be a determinant of positive effects of the N2000 network. The increase in abundance as N2000 coverage increased correlated with the specialization index for birds, but not for butterflies. Although the N2000 network supports high abundance of a large spectrum of species, the low number of specialist butterflies with a positive association with the N2000 network shows the need to improve the habitat quality of N2000 sites that could harbor open-land butterfly specialists. For a better understanding of the processes involved, we advocate for standardized collection of data at N2000 sites.  相似文献   
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