Impacts of Anthropogenic Land Use Changes on Nutrient Concentrations in Surface Waterbodies: A Review

Increased population leads to land use (LU) changes from natural to urban and agricultural LU. These disturbances not only decrease the natural treatment potential but they also worsen surface water quality (SWQ). The aim of this review is to assess studies about impacts of anthropogenic LU changes on levels of nutrient concentrations in surface waterbodies, highlighting the important parameters needed for an integrated simulation. The results reported in the literature are not always fully consistent. These contradictory results can sometimes be explained by field measurements under different climatic conditions, different features of landscapes, air deposition rates on ground surfaces, and groundwater flow interactions with surface water. Integrated modelling has been suggested to overcome these inconsistencies. Physical‐based and empirical models are the most popular approaches for LU‐SWQ studies. Generally, anthropogenic LU such as agricultural and urban areas usually enhances nutrient concentrations much more than natural lands such as forest and barren. Developing sustainable metropolitan areas instead of rural areas, establishing high‐standard wastewater treatment plants, and practicing efficient fertiliser application would ameliorate the poor nutrient conditions in SWQ. Riparian vegetation, grassed swales, and construction of artificial wetlands as buffer zones are the most promising natural water quality control measures.     

提高化肥利用率途径的土壤磁学研究

通过土壤磁学的角度来探讨我国农业生产急需解决的前沿课题之一——提高化肥利用率问题。125组土壤磁化率、营养元素氮、磷、钾和有机碳含量数据来自杭嘉湖平原的平湖地区,分布在560 km²面积内的36个深度剖面。分析这批数据随深度的变化规律,发现非耕作层的土壤磁化率与钾、氮、磷含量具有较好的相关性,而与有机碳含量相关性较差,说明决定土壤磁性的矿物具有保持营养元素的能力。耕作层的土壤磁化率与有机碳、磷含量具有较好的相关性,而与氮、钾含量相关性较差。耕作层的土壤磁化率以及氮、磷和有机碳含量高于非耕作层的土壤磁化率以及氮、磷和有机碳含量,钾含量则相反。从非耕作层至耕作层,土壤磁化率增幅为23.8%,远低于氮增幅55.3%、磷增幅36.6%和钾减幅95.8%,说明该区存在化肥施用不均衡现象,导致土壤磁化率与营养元素含量关系的失衡。提高磁肥或磁化肥的施用量,是提高肥效的持久性与利用率的途径之一。     

春玉米生长发育、产量和籽粒品质对减量施氮的响应

针对当前东北地区过量施氮的问题,研究减量施氮对春玉米生长发育、产量及籽粒品质的影响,对优化氮肥的科学管理技术,促进春玉米生产绿色高效发展具有重要意义。本研究以丹玉405为试验材料,通过大田播种的方式,以农民习惯性施氮量为对照,设置11.1%、55.5%和100%三个水平减量施氮试验,分析春玉米生长发育、产量和籽粒品质对减量施氮的响应机制。结果表明：玉米苗期,减氮导致生长发育指标（株高、茎粗、叶面积指数、生物量干、鲜重、叶片比重等）均减少,不利于地上部的生长和干物质向叶片分配,随着减氮量的增加,减少幅度增加。苗期以后,适量减氮促进玉米地上部的生长,株高、茎粗、叶面积指数、生物量和叶片占比等生物学性状有增加趋势。适量减氮导致果穗长、果穗粗、百粒重、理论产量、籽粒含水量和淀粉含量增加,籽粒脂肪含量减少,氨基酸和粗蛋白含量呈先增加后减少。随着减氮量的增加,果穗长、果穗粗、百粒重和理论产量增加幅度均减小,籽粒含水量和淀粉含量增加幅度增大,脂肪含量减少幅度减小。减氮11.1%时,果穗长、果穗粗和理论产量增加幅度最大,分别为1.9%、3.7%和11.5%。当施氮量为240 kg·hm^-2（减氮11.1%）时,玉米产量达到最大,为945.4 g·m^-2,籽粒脂肪含量最少,为2.4 g·100 g^-1;氨基酸含量最大,为83.9 μmol·g^-1;粗蛋白含量最高,为6.8%。研究结果可为当地的玉米生产提供更加完善的施肥管理,指导农户科学施肥。     

实施“油盐(钾)兼探”是加速我国找钾工作的重要途径

从理论和实践阐述了油气和钾矿的共存关系和特点,指出在油气勘查中,实施“油盐（钾）兼探”,加强钾矿的综合找矿,是加速我国找钾工作的重要途径。     

富钾海绿石的新发现:钾肥资源的评价研究的新方向

我国是一个人口众多的发展中国家,农业是国民经济的基础,农用钾肥主要都来自天然矿物资源,特别是我国东中部人口密集的主要农业基地的大部分省份,富钾的矿产资源十分贫乏。过去几十年来把蒸发盐建造的钾盐作为钾资源研究主要目标,到目前为止进展不大。根据最新矿产资...     

Hurricane Katrina induced nutrient runoff from an agricultural area to coastal waters in Biscayne Bay,Florida

Water quality surveys conducted in Biscayne Bay, Florida, indicated enhanced nutrient input coupled with increased runoff as a result of precipitation associated with Hurricane Katrina. Nutrient concentrations before Katrina ranged from 0.06–24.2 μM (mean 3.3 μM) for nitrate and 0.01–0.18 μM (mean 0.1 μM) for soluble reactive phosphate. Five days after Katrina, nitrate concentrations ranged from 0.87–80.0 μM (mean 17.0 μM), with a bay-wide mean increase of 5.2-fold over pre-hurricane levels. Soluble reactive phosphate concentrations ranged from 0.07–0.62 μM (mean 0.2 μM), with a bay-wide mean increase of 2-fold over pre-hurricane levels. The maximum concentrations for both nitrate and soluble reactive phosphate were found at a water quality monitoring station near the mouth of Mowry Canal, which drains an agricultural area in the southern Biscayne Bay watershed near Homestead, Florida. At this station, nitrate and soluble reactive phosphate concentrations increased 7- and 10-fold, respectively. Storm-induced fertilizer runoff from this agricultural area caused a bay-wide increase in nutrient concentrations after Hurricane Katrina. Nutrient concentrations in the bay returned to pre-hurricane levels within three months after Hurricane Katrina, showing the resiliency of the Biscayne Bay ecosystem.     

东北黑土水稻主产区氮肥减施潜力研究

东北平原是中国重要的商品粮生产基地,水稻是该地区的主要粮食作物之一,虽然该地区黑土质量和肥力均较高,但农田施肥过量的现象仍较为普遍。因此,为了阐明黑土区水稻施肥空间格局、差异特征及减施潜力,本文选择东北平原黑土水稻种植区为研究对象,在黑龙江、吉林、辽宁三省水稻施肥和产量进行了大规模调研分析基础上,结合土壤本底供氮能力培养试验,开展相关研究。结果表明：区域内由南至北施氮强度和经济产量均逐渐下降,施氮强度下降幅度大于产量下降,氮肥偏生产力逐渐增加。通过与理论适宜施氮量对比发现,辽宁稻区理论减氮潜力达16.7%~24.7%,吉林中、西部稻区潜力达8.7%~17.8%,黑龙江稻区还有2.0%~11.4%理论减氮空间。三省典型水稻土土壤累积矿化量没有明显差异。因此,地上部生物量变化所引起的氮携出量的变化是引起东北黑土区黑龙江、吉林和辽宁水稻施氮量差异的主要影响因素。     

Crystallization Kinetics of Potassium Sulphate in Aqueous System Mg~(2+),K~+//Cl,SO_4~(2-)-H_2O

正As an excellent chemical fertilizer,Potassium Sulphate(K2SO4)could provide both potassium and sulfur elements for crops.However,it is well known that potassium resource is very poor in China.To understand the Crystallization Kinetics(CK)of K2SO4could be conducive to utilize the limited potassium resource,promote the yield and purity of K2SO4.In this study saturated solution of potassium sulphate was prepared according to the phase diagram of Mg2+、     

Multivariate statistical analysis to identify the major factors governing groundwater quality in the coastal area of Kimje,South Korea

The main purpose of this study is to identify the major factors affecting groundwater quality by means of multivariate statistical analysis of the physico‐chemical compositions. Cluster analysis results show that the groundwater in the study area is classified into four groups (A, B, C and D), and factor analysis indicates that groundwater composition, 81·9% of the total variance of 17 variables, is mainly affected by three factors: seawater intrusion, microbial activity and chemical fertilizers. These results might be related to the geographical characteristics of the study area. The main influence on groundwater in groups B, C and D, which are close to the Yellow Sea and contain reclaimed areas, is the seawater intrusion by the present seawater, the trapped seawater, and microbial activity. Group A, however, has been used for agriculture for a long time, and thus groundwater in this group has been largely affected by chemical fertilizers. As groundwater flows from group A to group D according to its path, the governing factor of the groundwater quality gradually changes from chemical fertilizers to microbial activity and seawater intrusion. Copyright © 2004 John Wiley & Sons, Ltd.     

几种农作物矿物增效复合专用肥的应用研究

由沸石、膨润土和麦饭石等几种物化性能优越的非金属矿物按一定比例配合并粉碎成一定的粒度，再根据不同农作物生长所需的养分特点，与氮、磷或氮、磷、钾肥和微素（ 肥） 混合制成矿物增效复合专用肥。这种肥料既具有普通复合专用肥的特点，还具有保水、保肥和改良土壤之功能