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基于遥感数据和XGBoost算法的31个城市NO_(2)、CO_(2)浓度比率变化特征 被引量:2
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作者 陈玉敏 魏阳 +8 位作者 常政威 张凌浩 刘洪利 刘雪原 曾文 赵子翔 李春圆 米潭 詹宇 《地球科学与环境学报》 CAS 北大核心 2023年第6期1355-1367,共13页
研究城市二氧化氮(NO_(2))与二氧化碳(CO_(2))的共同排放水平对于实现城市减污降碳协同增效具有重要意义。NO_(2)与CO_(2)的人为排放具有同源性,二者的浓度比率可以体现城市的大气污染物和碳排放综合水平。基于XGBoost算法,利用对流层... 研究城市二氧化氮(NO_(2))与二氧化碳(CO_(2))的共同排放水平对于实现城市减污降碳协同增效具有重要意义。NO_(2)与CO_(2)的人为排放具有同源性,二者的浓度比率可以体现城市的大气污染物和碳排放综合水平。基于XGBoost算法,利用对流层星载监测仪(TROPOMI)、轨道碳观测2号(OCO-2)和3号(OCO-3)卫星的遥感数据以及相关环境协变量,重构全国2019~2020年NO_(2)垂直柱浓度(X NO_(2))和CO_(2)垂直柱浓度(X CO_(2))的高分辨率数据集,并分析31个城市的X NO_(2)年均值与ΔX CO_(2)(X CO_(2)观测值与背景值之差)的比率(X NO_(2)/ΔX CO_(2))变化情况。结果表明:X NO_(2)及X CO_(2)重构模型的验证决定系数(R 2)分别为0.90和0.96;城市X NO_(2)和ΔX CO_(2)值成正相关关系(相关系数为0.66);发展水平较高的城市相对发展水平一般的城市具有更高的X NO_(2)/ΔX CO_(2)值;受城市能源利用水平的差异影响,发展水平较高的城市X NO_(2)/ΔX CO_(2)值与城市GDP、常住人口数量及空气污染水平成负相关关系(相关系数分别为-0.35、-0.38、-0.10),而发展水平一般的城市则成正相关关系(相关系数分别为0.37、0.32、0.47)。X NO_(2)/ΔX CO_(2)值与城市污染治理和能源利用水平相关,研究结果可为城市控制空气污染提供数据支撑。 展开更多
关键词 二氧化氮 二氧化碳 浓度比率 遥感 机器学习 时空分布 减污降碳 城市
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The Inhibitory Degree Between Skeletonema costatum and Dinoflagllate Prorocentrum donghaiense at Different Concentrations of Phosphate and Nitrate/Phosphate Ratios 被引量:1
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作者 CAO Jing WANG Jiangtao 《Journal of Ocean University of China》 SCIE CAS 2012年第2期153-158,共6页
Interactions between Skeletonema costatum (S. costatum) and Prorocentrum donghaiense (P. donghaiiense) were inves-tigated using bi-algal cultures at different concentrations of phosphate (PO4-P) and nitrate/phosphate ... Interactions between Skeletonema costatum (S. costatum) and Prorocentrum donghaiense (P. donghaiiense) were inves-tigated using bi-algal cultures at different concentrations of phosphate (PO4-P) and nitrate/phosphate (N/P) ratios. Experiments were conducted under P-limited conditions and the Lotka-Volterra mathematical model was used to simulate the growth of S. costatum and P. donghaiense in the bi-algal cultures. Both of these two species were inhibited significantly in bi-algal culture. The results of the simulation showed that the inhibitory degree of S. costaum by P. donghaiense was high when the concentration of PO4-P was low (0.1μmolL-1/2 d), but that of P. donghaiense by S. costaum was high with increased PO4-P supply (0.6μmolL-1/2 d). At low concen-tration of PO4-P (0.1μmolL-1/2 d), or high concentration of PO4-P (0.6μmolL-1/2 d) with high N/P ratio (160), the interactions be-tween S. costatum and P. donghaiense were dependent on the initial cell densities of both species. At high concentration of PO4-P (0.6μmolL-1/2 d) with low N/P ratio (25 or 80), S. costatum exhibited a survival strategy superior to that of P. donghaiense. The de-gree of inhibition of P. donghaiense by S. costaum increased with elevated N/P ratio when the medium was supplemented with con-centration 0.1μmolL-1/2 d of PO4-P. The degree of inhibition to P. donghaiense by S. costaum increased with elevated N/P ratio at low concentration of PO4-P (0.1 μmolL-1/2 d). This trend was conversed at high concentration of PO4-P (0.6μmolL-1/2 d). However, the degree of inhibition of S. costaum by P. donghaiense increased with the increased N/P ratio at different PO4-P concentrations (0.1μmolL-1/2 d and 0.6μmolL-1/2 d). These results suggested that both phosphate concentration and N/P ratio affected the competition between S. costaum and P. donghaiense: P. donghaiense is more competitive in environments with low phosphate or high N/P ratio and the influence of N/P ratio on the competition was more significant with lower phosphate concentration. 展开更多
关键词 Skeletonema costatum Prorocentrum donghaiense inhibitory effect PHOSPHATE species competition N/P ratio
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雾霾颗粒在绝缘子表面积污规律的研究 被引量:2
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作者 罗俊杰 袁竹林 +1 位作者 高嵩 黄亚继 《热能动力工程》 CAS CSCD 北大核心 2018年第7期106-113,共8页
为了研究雾霾天气下,颗粒在绝缘子表面上的积污规律,本文设计搭建了绝缘子人工雾霾试验平台,并且利用此平台对0~10μm的细颗粒在不同风速下的沉积进行试验研究。研究结果表明:2.5~10μm范围内的颗粒浓度降低幅度最大;0.6~2.5μm范... 为了研究雾霾天气下,颗粒在绝缘子表面上的积污规律,本文设计搭建了绝缘子人工雾霾试验平台,并且利用此平台对0~10μm的细颗粒在不同风速下的沉积进行试验研究。研究结果表明:2.5~10μm范围内的颗粒浓度降低幅度最大;0.6~2.5μm范围内的颗粒浓度降低幅度次之;0~0.6μm范围内的颗粒浓度降低幅度很小,相对于前两者,可以忽略其沉积量;0~10μm的颗粒在低风速(v≤1.5m/s)下的浓度降低比率近似相等,在高风速(v≥2.5 m/s)下的浓度降低比率也近似相等,二者遵循不同的积污规律。 展开更多
关键词 绝缘子 雾霾颗粒 浓度降低比率 积污规律
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Effects of leaf age,elevation and light conditions on photosynthesis and leaf traits in saplings of two evergreen conifers,Abies veitchii and A.mariesii 被引量:1
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作者 Rina Suzuki Koichi Takahashi 《Journal of Plant Ecology》 SCIE CSCD 2020年第4期460-469,共10页
Aims Subalpine coniferous species are distributed over a wide range of elevations in which they must contend with stressful conditions,such as high elevations and extended periods of darkness.Two evergreen coniferous ... Aims Subalpine coniferous species are distributed over a wide range of elevations in which they must contend with stressful conditions,such as high elevations and extended periods of darkness.Two evergreen coniferous species,Abies veitchii and Abies mariesii,dominate at low and high elevations,respectively,in the subalpine zone,central Japan.The aim of this study is to examine the effects of leaf age,elevation and light conditions on photosynthetic rates through changes in morphological and physiological leaf traits in the two species.Methods We here examined effects of leaf age,elevation and light conditions on photosynthesis,and leaf traits in A.veitchii and A.mariesii.Saplings of the two conifers were sampled in the understory and canopy gaps at their lower(1600 m)and upper(2300 m)distribution limits.Important Findings The two species showed similar responses to leaf age and different responses to elevation and light conditions in photosynthesis and leaf traits.The maximum photosynthetic rate of A.veitchii is correlated negatively with leaf mass per area(LMA)and non-structural carbohydrate(NSC)concentration.LMA increased at high elevations in the two species,whereas NSC concentrations increased only in A.veitchii.Therefore,the maximum photosynthetic rate of A.veitchii decreased at high elevations.Furthermore,maximum photosynthetic rates correlate positively with nitrogen concentration in both species.In the understory,leaf nitrogen concentrations decreased and increased in A.veitchii and A.mariesii,respectively.LMA decreased and the chlorophyll-to-nitrogen ratio increased in understory conditions only for A.mariesii,suggesting it has a higher light-capture efficiency in dark conditions than does A.veitchii.This study concluded that A.mariesii has more shade-tolerant photosynthetic and leaf traits and its photosynthetic rate is less affected by elevation compared with A.veitchii,allowing A.mariesii to survive in the understory and to dominate at high elevations. 展开更多
关键词 leaf chlorophyll leaf mass per area leaf nitrogen non-structural carbohydrate concentration stable carbon–isotope ratio
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