三江平原泥炭沼泽土剖面P、K养分分布特征及影响因素分析

在三江平原湿地植物生长季节 ,选择具有代表性的毛果苔草 -狭叶甜茅 (Carexlasiocarpa Glyceriaspiculosa)湿地发育的泥炭沼泽土为研究对象 ,逐月分层采集土样 ,测定P、K含量 ,同时进行相关环境因子的测量。借助SPSS软件和灰色关联分析技术 ,探讨泥炭沼泽土P、K养分含量特征及影响因子的影响程度。结果表明 :泥炭沼泽土P、K含量在剖面垂直方向具有明显的分层现象 ,P、K含量与土层的二次相关性均较好 ,相关系数除潜育层外均在 0 .94以上。泥炭沼泽土各土层速效P和速效K含量在植物生长季节内均呈明显的动态变化 ,一元三次非线性回归模拟均得到理想的模拟效果。同一环境因子对同一土层全P、全K、速效P或速效K的影响程度各异 ;同一环境因子对不同土层P、K的影响系数也不同 ;因此 ,不同环境因子对同一土层某一对象的影响系数更不相同。     

Identification of sources,characteristics and photochemical transformations of dissolved organic matter with EEM-PARAFAC in the Wei River of China

• The source of DOM in surface water and sediment is inconsistent. • The DOC content changes differently in surface water and sediment. • The content of DOC in the surface water is lower than that in the sediment. • The DOM in the surface water had higher photodegradation potentials than sediment. Dissolved organic matter (DOM) in rivers is a critical regulator of the cycling and toxicity of pollutants and the behavior of DOM is a key indicator for the health of the environment. We investigated the sources and characteristics of DOM in surface water and sediment samples of the Wei River, China. Dissolved organic carbon (DOC) concentration and ultraviolet absorbance at 254 nm (UV₂₅₄) increased in the surface water and were decreased in the sediment downstream, indicating that the source of DOM in the water differed from the sediment. Parallel factor (PARAFAC) analysis of the excitation-emission matrices (EEM) revealed the presence of terrestrial humus-like, microbial humus-like and tryptophan-like proteins in the surface water, whereas the sediment contained UVA humic-like, UVC humic-like and fulvic-like in the sediment. The DOM in the surface water and sediment were mainly derived from microbial metabolic activity and the surrounding soil. Surface water DOM displayed greater photodegradation potential than sediment DOM. PARAFAC analysis indicated that the terrestrial humic-like substance in the water and the fulvic-like component in the sediment decomposed more rapidly. These data describe the characteristics of DOM in the Wei River and are crucial to understanding the fluctuations in environmental patterns.     

Measuring sustainability

An agricultural system is sustainable if productive output is maintained economically over time when assessed in relation to environmental concern. This paper considers ways of statistically evaluating measures of sustainability illustrated by reference to extensive data from the Classical Experiments at Rothamsted.     

基于正交设计的填土高边坡稳定性因素分析

填土高边坡作为一种特殊类型的土质边坡,其力学参数的离散度与施工密切相关。找出各参数对边坡稳定性的依次影响程度,以及在超载和地震作用下它们对稳定性的影响程度所发生的变化,对此类边坡设计和施工控制起着重要的作用。本文以湖北大畈某填土高边坡为依托,采用正交设计法分析了各力学参数对边坡稳定性的影响程度以及超载和地震对稳定因素产生的影响,可为此类边坡的进一步研究提供参考。     

Spatio-temporal variation of near-surface wind speed over Qinghai-Tibet Plateau from 1970 to 2020北大核心CSCD

基于1970-2020年青藏高原区域及其附近154个气象站点的风速风向观测数据,采用线性拟合等方法,分析该地区年平均和季节平均近地面风速的时空分布特征和日变化特征.结果表明:(1)青藏高原区域1970-2020年年均风速在0.6-4.2m/s之间,青藏高原主体年均风速较高,高原周边地区风速较低;(2)青藏高原区域1970-2020年间近地面风速呈极显著下降趋势,2000年以后呈极显著增加趋势;(3)青藏高原区域1970-2020年间近地面风速春季最大,冬、夏次之,秋季最小,不同季节平均风速均是高原主体大于高原周边,4个季节的平均风速均呈极显著降低趋势,春季平均风速降低的速率最大;(4)大气环流驱动力的减弱可能是青藏高原区域地面风速呈减弱趋势的主导性因素.青藏高原近地面风速显著的变化特征可为青藏高原风能资源开发利用、农林生态系统开发与保护等提供科学依据.(图5参46)     

Effects of long-term nutrient addition on meso-micro soil arthropod communities in a Stipa baicalensis grassland北大核心CSCD

To analyze the effect of nutrient addition on small- and medium-sized soil arthropod communities in a Stipa Baikal meadow grassland, a nitrogen (N) and phosphorus (P) addition experiment was designed in the Stipa Baikal meadow grassland at Ewenki Banner, Hulunbeier City, Inner Mongolia, China in 2010. Changes in the structure and diversity of soil arthropod communities and their relationship with environmental factors were studied. Soil arthropod samples were collected during the forage greening (May), growth (August), and yellowing (end of September) periods in 2019. The results showed that: (1) compared to the control sample, N-added and NP-added samples had higher number of soil arthropods by 1.38 and 1.15 times, respectively, and an increase of 28.57% and 21.43% in the number of soil arthropod groups. The numbers of individual as well as groups of soil arthropods tended to increase with P addition; however, this response did not reach a significant level. (2) The water and heat conditions during the vegetation growth period in the test area were more suitable for the development of soil fauna communities. (3) The redundancy analysis (RDA) results further indicated that the community composition of soil fauna is mainly regulated by pH and plant evenness, and soil pH is particularly important in mediating changes in small- and medium-sized soil fauna communities. This study suggests that long-term nutrient addition has a positive impact on small- and medium-sized soil arthropod communities by changing plant evenness and soil pH, and the contribution of soil pH is greater than that of plant evenness. © 2022 Authors. All rights reserved.     

鄱阳湖出流水质2004~2014年变化及其对水位变化的响应:对水质监测频率的启示

通过对鄱阳湖湖口2004~2014年以周为单位的水质指标,包括溶解氧（DO）,氨氮（NH₄⁺-N）和高锰酸盐指数（COD_Mn）的变化特征及其与水位响应关系进行分析,并对合理的监测频率进行了探讨。结果表明：（1）就DO,NH₄⁺-N和COD_Mn而言,鄱阳湖出湖水质在2004~2014年没有显著恶化的趋势,然而在年内呈现明显的周期性变化,其浓度与湖泊水位波动有较显著的负相关性（p<0.01）,相关系数分别达到-0.63,-0.67和-0.36;（2）考虑水质指标在湖相状态与河相状态存在显著的差异（p<0.01）,概率密度分布曲线进一步表明,在鄱阳湖呈湖相时,湖口NH₄⁺-N浓度小于0.25 mg/L的概率为93%,而在河相时仅为32.8%。DO与COD_Mn浓度在河湖相的特征与NH₄⁺-N相似。因此,在湖相状态下,鄱阳湖出流水质良好的概率更大,而高水位下的稀释作用可能是影响湖泊年内变化的主要控制因素;（3）时间序列分析表明DO,NH₄⁺-N和COD_Mn存在明显的自相关性,1~2月一次的监测频率基本能够准确的描述NH₄⁺-N和DO的动态变化特征,而COD_Mn仍需要1~2周一次的监测,从而避免过多的损失动态信息。能够为将来更深入的研究湖泊水情与水质定量关系提供基础和思路,从而为湖泊水环境管理和调控提供对策和建议。     

基于GIS和RUSLE模型的万州区土壤保持服务功能空间分布特征

土壤保持服务是重要的生态系统服务之一,代表生态系统对土壤侵蚀所起到的削减和改善作用。以万州为研究区,基于GIS平台和修正通用土壤流失方程(RUSLE),运用降雨、DEM等数据建模,探讨万州区土壤保持服务功能的空间分布特征并分析其影响因素。结果显示:(1)万州区土壤保持总量为1 435.84×10~5t/a,单位面积年均土壤保持量为417.91 t/(hm~2·a),具有较高的土壤保持服务功能重要性;(2)土壤保持服务空间分布受地形和人类活动等的显著影响,东南部山地区域较高,而铁峰山与方斗山之间的长江河谷较低,其空间分布特征与土壤侵蚀的分布状况大致相反;(3)坡度角度,15°~25°坡度区产沙量最大占全区的41.56%,8°~15°区域次之,这两个坡度区人地矛盾最为集中;土地利用类型中,旱地侵蚀最为强烈,而林地侵蚀微弱并表现出很高的土壤保持服务功能。研究结果对万州乃至整个三峡库区的水土保持工作有借鉴意义。     

近50 a长江流域暴雨日数时空变化分析

利用1961~2010年长江流域逐日降水资料和DEM数据,结合Mann-Kendall趋势法、变差系数法以及GIS空间分析等方法,分析了近50 a长江流域年均暴雨日数时空变化特征。结果表明:长江流域年均暴雨日数基本呈自东向西递减的规律,且随着海拔升高,年均暴雨日数逐渐减少,两者呈显著负相关关系;长江流域上游高原气候影响区年均暴雨日数小于1 d;而中上游中亚热带湿润气候影响区大于2 d;随着纬度的增加,暴雨开始时间推迟,结束时间提前,持续时间减少;年暴雨日数的变差系数与年均暴雨日数满足幂指数关系,相关系数达0.97,为显著相关。表现为年均暴雨日数大(小)的地方,变差系数小(大);除长江中下游中部和四川盆地及其周边地区年暴雨日数为减少趋势外,其它地方均表现为不同程度的增加趋势。鄱阳湖水系、四川(雅安市、峨眉山市、万源市)、湖南(安化县、南岳区)、湖北(洪湖市、英山县)年暴雨日数多且变差系数小,洪水、泥石流等灾害压力巨大;为有关部门了解长江流域洪水等灾害的发生机制、提高灾害预测预报能力、制定防灾减灾政策等提供科学依据。