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881.
手持式X射线荧光光谱仪(XRF)作为快速筛选重金属污染的手段在污染地块调查中广泛使用,但目前国内对XRF现场检测结果指导实验室筛选检测样品的可靠性研究缺乏。本文选择两个实际污染地块调查中的Cu、Pb、As、Ni、Cd和Hg6种重金属的XRF现场检测数据和实验室实测数据,采用一元线性拟合、Pearson相关、差异分析等手段对两种测试结果的一致性进行研究。结果表明,土壤中Cu、Pb、As和Ni4种金属的XRF测定值和实验室实测值具有显著相关性。Hg和Cd的XRF测定值显著高于实验室实测值,Cu、Pb、As和Ni XRF测定值较实验室实测值偏小的样品占比超过50%。6种重金属中Cu和Pb XRF测定值和实验室实测值的相关性及一元线性拟合结果更好(相关系数0.5~0.8,R~2>0.7)。Cu在XRF测定值大于1 000 mg/kg时与实验室实测值的拟合结果更好(R~2>0.7),As和Pb分别为XRF测定值在4.0~10 mg/kg和检出限~80 mg/kg范围时更好(R~2>0.8)。采用重金属筛选值的50%作为筛选实验室样品的标准时,XRF结果预测Cu、Pb和As超标样... 相似文献
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《中国油料作物学报(英文)》2022,7(4):219-224
In the last decade, some disease occurred on our experimental farms that had caused serious losses. They were not caused by fungi, bacteria or viruses. By loop-mediated isothermal amplification (LAMP) technique, the detection results pointed to the possible pathogen as phytoplasma. The investigation results implied that phytoplasmas could cause more than 13 kinds of symptoms in almost all parts of plants in B. napus L., including witches’ broom, multi-stems, aggregate main inflorescences, and flat stems. The incidences of these phytoplasma-associated diseases in our experimental farms rose from 1.61% in 2010 to 6.00% in 2021. Some phytoplasma infected plants died without any growing points. These studies would be helpful for detecting phytoplasmas diseases, selecting disease resistant germplasm and improving varieties with disease resistances in B. napus L. 相似文献
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Diminishing forests as a result of anthropogenic activities continues to impact the persistence of terrestrial species negatively. Raptors are particularly susceptible to human activities because of their low population densities and large home range sizes. In this study, we investigated the occupancy and detection probabilities of the Near-Threatened African crowned eagle (Stephanoaetus coronatus) in Durban, EThekwini Municipality, South Africa. Using point count surveys, we documented the presence/absence of African crowned eagles in 42 sampling sites in the urban mosaic landscape of Durban. We used the presence/absence data to model their occupancy and detection probability in our surveyed sites. The naïve occupancy of African crowned eagles was 0.6, and the estimated occupancy and detection probability were 0.78 + 0.061 and 0.40 + 0.085, respectively. Based on the best models, the occupancy of African crowned eagles was positively influenced by forests (β = 1.24 + 0.69) and negatively influenced by disturbance (β = −1.69 + 0.78) and roads. The detection probability of these eagles was positively influenced by disturbance (β = 0.34 + 0.29) and the presence of exotic tree plantations (β = 0.33 + 0.47) and negatively influenced by the type of surrounding settlements (i.e., urban or rural) (β = −0.59 + 0.43). Based on the averaged models, occupancy is positively influenced by forests (β = 0.15 + 1.48) and negatively influenced by roads (β = −0.05 + 0.34), building density (β = −0.07 + 0.79) and disturbance (β = −0.24 + 3.36). Detection probability is negatively influenced by surrounding settlement (β = −0.12 + 0.41) and positively influenced by disturbance (β = 0.04 + 3.21) and plantations (β = 0.01 + 0.12). Overall, our results showed the persistence of African crowned eagles in the urban mosaic landscape as a consequence of natural and managed green spaces, especially forests. This highlighted the importance of natural forests and exotic tree plantations in ensuring the survival and thriving of African crowned eagles and the key role these green spaces play in species conservation in this urban mosaic landscape. 相似文献
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The urban greenway has been increasingly recognised as an important type of green infrastructure especially for land-scarce, densely-populated cities to efficiently provide their residents with continuous public spaces close to nature for recreation. Nevertheless, empirical studies on urban greenways and their recreational use rarely focus on high-density environment. Moreover, most research endeavours in this field are also largely confined to the subtropical climate, whereas much of the world’s future urban growth is projected to occur in the form of high-density mega-cities in much of tropical South and Southeast Asia. In view of these gaps, this study proposes a new approach that employs Computer Vision tools to examine the effects of the greenway’s physical environment on recreational activities, taking tropical Singapore as the test bed. The semantic segmentation model, PSPNet and the action detection model, ACAM are adapted and applied in conjunction with geographical information system tools to measure the greenway’s physical environment and people’s recreational activity at the human scale, and analyse their relationships. The result reveals a pattern that sees the clustering of different types of recreational activities at different time periods. It also reveals the relationships between recreational activities and specific environmental features, which were observed to have influenced the overall spatial distributions of the recreational activities. The finding also corroborates the design strategies for Singapore’s future urban greenways and offers a reference for engaging community groups to participate in the maintenance of urban greenways. 相似文献
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为获取上海市陈行水库鱼类时空分布特征,分别于2019年4月17日、8月15日和11月13日,采用双频识别声呐(Dual-frequency Identification Sonar,DIDSON)对陈行水库进行鱼类资源探测,利用ECHOVIEW水声数据处理软件构建鱼类目标分析模型,开展鱼类目标的提取与计数,分析并绘制鱼类资源密度的水平和垂直分布图,揭示水库鱼类数量和时空分布特征。结果表明:1)陈行水库中小型鱼类(其体长<0.6 m)居多,占比达80.9 %;2)春季至秋季库区鱼类体长逐渐增加,密度不断增大,数量和总重量也在增加;3)水平空间尺度上,库区鱼类个体主要集聚在水库南部,夏季分布相对集中,秋季相对分散;4)垂直空间尺度上,库区鱼类主要分布在水深2~6 m区间,占比达84.85 %,春季鱼类分布平均水深为3.89 m,夏季为4.34 m,秋季为5.12 m,库区鱼类垂直分布随季节有向底层移动趋势。本文所研究的水声探测方法和鱼类目标分析模型,为类似的鱼类资源调查分析工作提供了有益参考,探测结果为水库采取合理的鱼类资源管理提供了依据。 相似文献
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