EXPORT COEFFICIENT MODELING TO ASSESS PHOSPHORUS LOADING IN AN URBAN WATERSHED1

ABSTRACT: An export coefficient modeling approach was used to assess the influence of land use on phosphorus loading to a Southern Ontario stream. A model was constructed for the 1995–1996 water year and calibrated within ± 3 percent of the observed mean concentration of total phosphorus. It was found that runoff from urban areas contributed most to the loading of phosphorus to the stream. When the model was assessed by running it for the 1977–1978 water year, using water quality and land use data collected independently, agreement within ± 7 percent was obtained. The model was then used to forecast the impact of future urban development proposed for the watershed, in terms of phosphorus loading, and to evaluate the reduction in loading resulting from several urban best management practices (BMP). It was determined that phosphorus removal will have to be applied to all the urban runoff from the watershed to appreciably reduce stream phosphorus concentration. Of the BMP designs assessed, an infiltration pond system resulted in the greatest phosphorus load reduction, 50 percent from the 1995–1996 baseline.     

Sustainable Development of Export： Theoretical Meaning, Evaluation Model, and Empirical Research

With the effect of the human trade doctrine in the international trade field, almost all the countries have paid more attention to the sustainable development of international trade. This article chose the export sustainable development as the research object. On the basis of the analysis of the theoretical connotation of the export sustainable development, this article tried to establish an evaluation indices system and set up an evaluation model of the export sustainable development level, and finally made some empirical research on China. The result indicates that the comprehensive level of the export sustainable development in China showed a tendency to rise from 1985 to 2003 and the export sustainable development level of China in these years can be divided into four grades： excellent, good, moderate and poor. In most years, the social economic benefits of export was obtained at the cost of the deterioration of environment and the depletion of resources, and the economic profit of export did not increase with the enlargement of the export scale because of the deterioration of the terms of trade. Therefore, China should be careful about the problem of poverty accompanied by the increase of export.     

Empirical analysis of carbon tariff’s effect on the export structure of China’s manufacturing industry and social welfare based on the GTAP model

In recent years, carbon emissions have gradually evolved from an environment issue into a political and economic one. Carbon tariff has brought about new trade barriers of developed countries, and in order to enhance the industrial competitiveness of developed countries, it will produce unfavorable impact on developing countries. Concentrated on the manufacturing industry, which is the most intensive high-carbon industry in China’s export structure, this article studies the relationship between carbon tariff policy and industry structure of export trade and builds up a relation between climate change and international trade. First, by means of establishing a partial equilibrium model, it applies geometric analysis and mathematical analysis to compute the impact on China’s manufacturing export trade and the consequences of the introduction of the US carbon tariff to China’s manufacturing industry that has already imposed a domestic shipping carbon tax. Furthermore, with the application of the GTAP model, it estimates the overall economic and welfare effects on China’s manufacturing industry if the US and Europe introduce carbon tariff by means of four ways, and then analyzes the influence on China’s manufacturing industry export structure and social welfare as well. The result shows that the introduction of the US carbon import tariff lowers China’s export price and export volume, and the implementation of a domestic carbon tax justifies a higher export price and a lower export volume for China. However, the degree of export reduction is smaller than that under the effect of the US carbon tariff. In the case of developed countries imposing carbon tariff on China’s energy-intensive industries, such as chemical rubber products, oil and coal-processing industry and paper industry, whose export would be reduced, the negative impact on the paper industry is the severest, which will decrease the paper industry’s export ranging from 1.79% to 6.05%, whereas the other industries’ export will increase. Anyhow, it will promote China’s manufacturing industry to adjust the export structure to a certain extent. In addition, it will lead to a decrease in China’s welfare, with a decrease between $2.134 billion and $8.347 billion. Finally, this paper provides information on international coordination, export structure adjustment and green manufacturing adjustment as a reference for the development of China’s manufacturing industry.     

长江颗粒(类)金属元素分布、来源和向海输送

基于对长江干流与主要支流丰水期的调查和下游一个水文年的综合观测,结合多元数理统计手段和历史观测数据,对悬浮颗粒物中元素的时空变化、控制因素和来源等进行了解析,探讨了流域自然和人为因素对元素输送的影响.结果表明,大多颗粒物携带的元素在涪陵至宜昌河段存在下降趋势,这和三峡水库对颗粒物的滞留有关.多个元素在人口活动密集的下游地区出现高值,为人类活动和流域地质背景共同作用的结果.统计表明,硼（B）、钪（Sc）、镓（Ga）、锶（Sr）、钛（Ti）、锆（Zr）和铌（Nb）元素主要来源于岩石风化和土壤侵蚀等自然过程;锰（Mn）、铜（Cu）、锌（Zn）、镍（Ni）、钴（Co）、铅（Pb）、镉（Cd）和铬（Cr）元素主要受人类活动影响.尽管颗粒物中各元素入海通量差异大,但大多在丰水期的输送通量占全年的比例最高,且颗粒态元素的输送通量远高于溶解态.长江悬浮颗粒物中重金属元素含量在全球河流处于中等浓度水平.长江输沙量因筑坝发生了较大的变化,悬浮颗粒物中金属元素的输送源汇格局因此正在发生改变,并可能对河流和河口环境产生深远的影响.     

千岛湖地区上梧溪流域地表径流非点源氮污染分类识别

非点源污染的准确定量是流域非点源污染控制和治理的基本前提和重要保障.在综合考虑基流非点源污染的前提下,对传统输出系数模型(ECM)进行优化和改进,建立以周为时间步长的输出系数模型(IECM),实现上梧溪流域不同土地利用类型地表径流非点源总氮(TN)污染更加准确的定量识别.结果表明,IECM可以有效实现该流域TN负荷的模拟定量,校准期与验证期的纳什系数(NSE)分别为0.82和0.77,R²分别为0.87和0.84.基于IECM得到的上梧溪流域2020年11月至2021年10月地表径流和基流的TN输出强度分别为5.74 kg·(hm²·a)^-1和9.85 kg·(hm²·a)^-1,分别占总径流负荷的36.80%和63.20%.相较于IECM,ECM由于未考虑基流对非点源污染的贡献,其估算的地表径流TN负荷量较IECM高54.21%.显然,直接将基流非点源污染归结于地表径流将导致地表径流负荷输出强度的严重高估.基于IECM计算得到的上梧溪流域水田、草地、林地、旱地和人居地的以地表径...     

云蒙湖流域土地利用变化对非点源氮污染负荷的影响

以临沂市水源地云蒙湖流域为研究区域,利用人工模拟降雨实验,结合输出系数模型获取流域内各土地利用类型氮素输出系数,在GIS和RS支持下,分析近25年来土地利用变化对非点源污染氮素负荷时空变化的影响.结果表明,1986、1995与2010年非点源污染氮素负荷分别为3.77×103、4.45×103、5.5×103t,呈上升趋势;从土地利用类型来看,耕地非点源污染TN逐年增加,其贡献率也逐年增加,贡献率由1986年的80.11%,1995年82.60%上升至2010年85.59%,林地、草地TN变化较小,贡献率呈减小趋势,居民用地TN增加幅度大,但由于面积较小,其贡献率较小;就子流域而言,耕地面积比例高的子流域,氮素污染负荷增加程度较大;流域耕地与氮素负荷呈显著正相关,对氮产出负荷起＂源＂作用,林地、草地与氮素负荷量呈负相关,对氮产出负荷起＂汇＂作用.因而,可通过调整土地利用结构以减少和控制流域氮流失对水体环境的污染.     

西苕溪典型小流域土地利用对氮素输出的影响

在太湖地区的西苕溪流域不同地理位置选择了11个小流域,于2004年分3次野外监测氮素输出浓度.利用多年降雨径流关系估算径流量,用于计算各小流域氮素输出负荷与强度,结合2000年TM遥感影像获得的各小流域土地利用数据,综合分析了土地利用对流域氮素输出的影响.结果表明,流域土地利用结构对氮素输出具有重要影响,流域耕地面积比例与氮素输出水平呈正比,而林地比例与氮素输出水平呈反比;各小流域面积的大小与氮素输出负荷呈正相关,而小尺度流域面积对氮素输出浓度和单位面积氮素输出强度无关.     

云南哀牢山大气降雨过程中养分输入及输出变化的初步研究

本文以滇西南中山湿性常绿阔叶林为研究对象,分析了大气降雨对该森林生态系统养分输入和输出的影响。结果表明,该地区在大气降雨过程中养分输入：Ｎ以大气降雨为主；Ｐ、Ｋ、Ｍｇ以穿透雨为主,它们分别占总输入量的６９．８５％、７７．３３％、９８．１９％和８０．４０％；Ｃａ养分输入,大气降雨和穿透雨约各占总输入量的一半,分别是４５．３５％和５４．３８％。养分输出以地下土壤渗漏为主,Ｎ、Ｐ、Ｋ、Ｃａ、Ｍｇ分别占总输出量的９６．５２％、８６．７９％、６９．１３％、９８．１７％和９７．２１％。在养分循环中Ｎ、Ｐ、Ｋ、Ｃａ分别增加了１５．９４１ｋｇ／ｈａ．ａ、０．３５３ｋｇ／ｈａ,ａ、３．８３ｋｇ／ｈａ．ａ和１．２６４ｋｇ／ｈａ．ａ．,而Ｍｇ则减少了０．６５４ｋｇ／ｈａ．ａ。     

洱海沉水植物残体风浪输移量及其时空分布

为研究洱海沉水植物残体风浪输移特征,掌握由此而引起的N、P变动情况,通过为期1a的野外定点调查,研究了风浪对洱海湖滨带沉水植物作用引起的植物残体向滨岸的输移特征,估算了沉水植物残体带出的N、P质量. 结果表明:①洱海湖滨带有残体输出的沉水植物总计10种,分别为菹草(Potamogeton crispus)、黑藻(Hydrilla verticillata)、轮藻(Eichhornia crassipes)、穿叶眼子菜(P. perfoliatus)、扭叶眼子菜(P. intortifolius)、穗花狐尾藻(Myriophyllum spicatum)、金鱼藻(Ceratophyllum demersum)、马来眼子菜(P. malaianus)、苦草(Vallisneria natans)及微齿眼子菜(P. maackianus);②沉水植物残体风浪输移量存在明显的时序变化,在4次采样中,2009年12月(冬季)风浪输移量最高;③微齿眼子菜和苦草的风浪输移量最大,植物残体风浪输移量主要受沉水植物的分布和生物量的影响;④单位岸线沉水植物残体风浪输移总量在空间上表现为西部(1.91t/km)>北部(1.73t/km)>南部(1.61t/km)>东部(0.86t/km);⑤洱海湖滨带沉水植物残体风浪输移总量约为2.27×103t/a(以鲜质量计),由此可输出的TN为5.64t,TP为0.85t.      

Spatial and Temporal Variations in Eastern U.S. Hydrology: Responses to Global Climate Variability

Coastal ecosystems are dependent on terrestrial freshwater export which is affected by both climate trends and natural climate variability. However, the relative role of these factors is not clear. Here, both climate trends and internal climate variabilities at different time scales are related to variations in terrestrial freshwater export into the eastern United States (U.S.) coastal region. For the recent 35‐year period, the intensified hydro‐meteorological processes (annual precipitation or evapotranspiration) may explain the observed streamflow variability in the northeast. However, in the southeast, streamflow is positively correlated with climate variability induced by the Pacific Ocean conditions (El Nino‐Southern Oscillation [ENSO] and Pacific Decadal Oscillation) rather than Atlantic Ocean conditions (Atlantic Multi‐decadal Oscillation and North Atlantic Oscillation). The centroid location for volume of terrestrial freshwater export integrated along the eastern U.S. has a positive temporal trend and is negatively correlated with ENSO conditions, suggesting the northward trend in freshwater export to U.S. eastern coast may be disturbed by the natural climate variability, especially ENSO conditions, i.e., the center of freshwater mass moves southward (northward) during El Nino (La Nina) years. The results indicate the spatial and temporal variations in freshwater export from the eastern U.S. are affected by both climate change and inter‐annual climate variability during the recent 35‐year period (1980‐2014).