Modelling nitrogen and phosphorus cycles and dissolved oxygen in the Zhujiang Estuary Ⅰ. Model development

wrmcrloxHuman activities related to the population growth and developrnent of industry and rnwhci-pality have led to the incrouing hadings of various POllutants into estudries during the past fewdecades. These increasing edlutant lOadings have caused declined estuallne hedth which can bemereured by a vdriety of indices. In order to obtain solutions to environrnent problerns, re-sources manageTnnt apencies are supporting a holistic approach to envirorirnental management.An effcient strategy t…     

1988-2018年滇池氮磷比的时空演变特征与原因解析

氮、磷浓度是制约湖泊营养状态和生产力水平的重要环境因子,而氮磷化学计量比是湖泊生态系统的主要指标,因此,判识氮磷比变化趋势及其驱动力对湖泊生态恢复具有重要意义.研究基于19882018年连续观测数据,分析了滇池氮磷浓度和氮磷摩尔比(简称氮磷比)的时空分布演变特征;采用多元线性回归模型分别对滇池草海和外海氮磷比驱动效应进行定量解析,筛选出影响湖体氮磷比变化的潜在驱动因子.结果表明:①19882018年滇池氮磷比呈现显著的线性上升趋势,其中草海和外海氮磷比分别上升1.3和0.7 a^-1.②草海和外海分别在2008年和2004年发生了氮磷比上升突变,突变前上升归因于总氮浓度快速增加,突变后则是由于总磷浓度下降较快.③滇池的氮磷浓度变化主要是受流域氮磷输入负荷、跨流域调水、流域氮磷削减、风速和水位的综合影响,但受控因子在不同区域可能存在差异.④气温是滇池氮磷比变化的主要驱动因子,流域人为氮磷输入差异是滇池氮磷比变化的次要驱动因子.     

Moon-based Earth observation: scientific concept and potential applications

Although Earth’s surface parameters obtained from satellite data have become more and more precise, it is still difficult to guarantee temporal consistency and spatial continuity for large-scale geoscience phenomena. Developing new Earth observation platforms is a feasible way to improve the consistency and continuity of such data. As the planet’s only natural satellite, the Moon has special advantages as a platform for observing Earth, including long lifetime, whole disk view, tectonic stability and unique perspective. After presenting the observation geometry constructed by using the ephemeris, this paper mainly discusses the characteristics of a lunar platform and the proper Moon-based sensors, as well as the scientific objectives of Moon-based Earth observation. Solid Earth dynamics, the energy budget of Earth, Earth’s environmental elements and the Earth-space environment are four potential applications analysed in this paper.     

青藏高原地面-对流层系统的能量收支

利用CCM3中的辐射模式CRM，计算了1月和7月地－气系统、地面－对流层系统和地面辐射能收支，研究了青藏高原地面－对流层系统辐射能收支的冬、夏季节特征及其与地面和地－气系统辐射能收支的关系，并与东部平原地区和高原北侧干旱地区比较。文中还讨论了云和高原冬季地面积雪对辐射能收支的影响，比较了大气辐射加热和地面感热通量对夏季高原对流层大气加热的贡献。     

内蒙古东北部地区一次极端降雪过程的水汽输送特征

利用内蒙古呼伦贝尔市常规观测资料和GDAS、NCEP/NCAR再分析资料,采用欧拉方法分析了2016年春季内蒙古东北部地区一次极端暴雪过程的水汽输送及收支特征,利用HYSPLIT模式和聚类分析模拟计算了此次暴雪天气过程的水汽源地、主要水汽输送通道及其对水汽输送的贡献,并与传统的欧拉方法结果进行对比。结果表明:(1)有3支不同源地的水汽流在内蒙古东北部地区交汇,对呼伦贝尔地区暴雪的发生与维持有重要影响;(2)经向和纬向输送为此次暴雪天气的发生提供了充足的水汽,暴雪区水汽主要源于中高层的南边界和随西风气流的西边界;(3)利用HYSPLIT模式模拟发现,在此次暴雪天气过程中水汽主要来源于新地岛以西洋面、日本海以及巴尔喀什湖,且三者贡献率大致相当。     

The Linkage between Midwinter Suppression of the North Pacific Storm Track and Atmospheric Circulation Features in the Northern Hemisphere

The midwinter suppression(MWS) of the North Pacific storm track(NPST) has been an active research topic for decades. Based on the daily-mean NCEP/NCAR reanalysis from 1948 to 2018, this study investigates the MWS-related atmospheric circulation characteristics in the Northern Hemisphere by regression analysis with respect to a new MWS index, which may shed more light on this difficult issue. The occurrence frequency of the MWS of the upper-tropospheric NPST is more than 0.8 after the mid-1980 s. The MWS is accompanied by significantly positive sea-level pressure anomalies in Eurasia and negative anomalies over the North Pacific, which correspond to a strengthened East Asian winter monsoon. The intensified East Asian trough and atmospheric blocking in the North Pacific as well as the significantly negative low-level air temperature anomalies, lying upstream of the MNPST, are expected to be distinctly associated with the MWS. However, the relationship between the MWS and low-level atmospheric baroclinicity is somewhat puzzling.From the diagnostics of the eddy energy budget, it is identified that the inefficiency of the barotropic energy conversion related to the barotropic governor mechanism does not favor the occurrence of the MWS. In contrast, weakened baroclinic energy conversion, buoyancy conversion, and generation of eddy available potential energy by diabatic heating are conducive to the occurrence of the MWS. In addition, Ural blocking in the upstream region of the MNPST may be another candidate mechanism associated with the MWS.     

江苏省主要作物农田水分盈亏量的研究

利用江苏省1980～1992年土壤湿度资料,根据土壤水分平衡原理,运用运筹学中的优化技术,结合本省的自然条件和作物生长实际情况,提出有效降水量、下层水分补给量等计算方法,建立了旱地和稻田农田水分盈亏量的计算模式,以便应用实时降水和土壤湿度等资料,计算全省农田水分盈亏量,及时提供农业气象情报服务。     

长江口、杭州湾水域沉积物中磷的化学形态分布特征

污染物进入水体后,其最终的归宿行为与赋存状态是当今环境科学研究的重要方向.沉积物中磷形态的研究对了解磷在污水排放过程中的动态循环以及磷酸盐在水体-沉积物界面的迁移转化都具有十分重要的意义[1,2].目前在长江口、杭州湾水域已建成“上海市合流污水一期工程”、“星火开发区污水排海工程”、“上海市污水治理二期工程”等污水集中外排工程.针对该水域的竹园、白龙港和星火污水排放口附近沉积物中磷的化学形态和分布状况进行了研究.     

基于污染负荷核算的岷江流域总磷污染成因分析及对策

总磷是长江流域水环境污染的首要超标因子,岷江作为长江上游流量最大的支流,总磷污染严重,对长江总磷污染贡献较大。为了解岷江流域总磷污染,采用排污系数法,计算得到2016年岷江流域污染源总磷入河量为1 154 t,以农村生活污染负荷占比最高(51.3%),其次为城镇生活源(28.7%)、农业非点源(8.24%)、工业源(9.57%)、畜禽养殖源(1.21%),城市径流源(0.99%)最低;在空间上岷江流域总磷污染负荷呈中游(64.2%)>下游(32.6%)>上游(3.1%)的特点,与岷江干流总磷浓度变化趋势相符,其中成都市总磷污染负荷最高(51.2%),与区域人口密度高、生产和生活活动密集有关。结合资料收集和现场调查,岷江流域总磷污染成因主要包括农村生活污染治理缺口较大、城镇生活污染处理基础设施建设不足、工业企业密布、部分支流总磷污染严重、水污染治理导向不全面。针对岷江总磷污染负荷分布特征及成因,提出“上游保护优质水体、中游治理重污染水体、下游恢复不达标水体”的分区污染防治对策,统筹流域监管体制机制,强化岷江流域水环境保护和治理。     

Effect of snow and soil frost melting on the concentrations of suspended solids and phosphorus in two rural watersheds in Western Finland

Hydrological processes are known to have a considerable effect on nutrient transport from agricultural land to watercourses. In cold temperate regions peak discharges are caused not only by storm conditions but also by melting of snow and frost. The objective of this work was to investigate the effects of snow and frost melt on concentrations of phosphorus and suspended solids. The samples were taken using flowweighted automatic sampling techniques from two agricultural drainage basins. During the beginning of the snowmelt period the concentration of suspended solids was rather low by comparison with the total phosphorus concentration and the discharge. The different behaviour compared with the relationships found during storm conditions was probably caused by continuous extraction of the soil surface by low ionic concentration melt water, and to some extent by leaching from plant residues. The gradual decrease of total phosphorus concentration during the frost thawing period could be attributed to the gradually increasing proportion of the subsurface and ground water discharge in the runoff.