Natural and Anthropogenic Effects On Phytoplankton Primary Productivity in Mangroves

Abstract

Spatial and temporal variations and the factors influencing primary production have been studied in three different mangrove waters (Pichavaram, Ennore Creek and Adyar Estuary) of South India characterised by different anthropogenic impacts. the gross primary productivity in the unpolluted Pichavaram mangrove was 113 g Cm^?2yr^?1 exhibiting natural variability with the environmental forcing factors. Human activities have elevated primary productivity in the Ennore Creek mangrove (157g Cm^?2yr^?1) primarily through the direct discharge of fertilizer effluents. By contrast, a combination of domestic and industrial effluent discharges into the Adyar Estuary mangrove has considerably reduced phytoplankton primary productivity 83g Cm^?2yr^?1 the Redfield N: P ratio varies from 0.96 N: 1P at Ennore Creek, 1.75N: 1P at Adyar Estuary to 15.2 N: 1P at Pichavaram mangroves. This suggests that the Pichavaram mangroves represent a well equilibrated ecosystem with N: P ratio close to steady-state values in contrast to the anthropogenically altered mangrove ecosystems studied. Results show a significant temporal variability in nutrient concentration in the three mangrove areas. Distinct differences in nutrient concentrations between the dry and the wet seasons have been observed.     

人类活动对流域旱涝事件影响研究进展

人类活动对流域旱涝事件具有决定性影响,已经成为国内外热点研究问题之一。通过系统分析国内外人类活动对流域旱涝事件影响机理的研究,结果表明:人类活动导致大气温室气体和气溶胶含量上升,全球气候变化加剧,导致流域极端水文过程时空格局改变。另一方面,人类活动引起的土地退化将影响流域水资源时空分布和水循环过程,削弱流域防洪抗旱能力;水利工程的修建将增大流域储水状况,有效应对流域旱涝事件,但同时存在加剧流域旱涝事件的风险。此外,论文还概述了人类活动对流域旱涝事件影响的量化方法。     

重庆大气汞人为排放及其预测

利用排放因子法和灰色预测法对重庆大气汞人为排放进行了研究. 重庆大气汞人为排放量从1997年的6.18 t增加到2008年的13.47 t. 重庆自1997年成为直辖市以来,大气汞排放量累计达99.76 t,年均增长率为9.82%,其中燃煤和水泥生产汞排放量分别达58.34和22.37 t. 以1997─2008年重庆大气汞人为排放数据为依据,运用灰色系统理论建立GM(1,1)大气汞人为排放预测模型,预测了2009─2015年重庆大气汞排放趋势. 如果不采取控制措施,预计2015年重庆大气汞人为排放量约30.92 t,年均增长率将高达16.20%.      

太湖北部流域水化学特征及其控制因素

为了解太湖北部流域主要河网区水质受该流域地质状况、岩石和土壤的化学风化作用以及人类活动的影响等方面,对太湖北部流域河网区主要河道水体中的主要离子进行了采样研究。结果表明：太湖北部流域水体中的TDS平均值为355．74mg·L-1,变化范围为276．08--681．54mg·L-1,其中ca2＋和HCO3-是占绝对优势的离子,分别占阳离子和阴离子总量的46．2％和48．9％;其次是Na＋和SO42-,分别占阳离子和阴离子总量的35．9％和27．5％。进而判断出该流域水化学类型是以碳酸盐岩石和蒸发岩来源为主的HCO3-Ca2＋-Na＋型。再从离子的自然起源和人类活动角度分别对水化学类型的控制因素进行分析,一方面利用吉布斯分布模式投点作图得出结论：其离子自然起源的优势机制是岩石的风化作用,而蒸发一结晶和大气降水的输入作用十分微弱,这与该流域的水文、地理、地质背景相一致;另一方面通过SPSS软件的相关关系分析得出结论：NO3-、SO42-、心、ca2＋和Mg2＋的相关性较强,与cl‘也呈正相关,说明水体中这些主要离子都具有共同的来源,其中NO3-的较高含量（平均值为14．74mg·L-1）反映了该流域受人类影响较大。尤其是NO3-与sO42-的相关性达到0．83,再次说明氮污染对该流域水体的酸化和水质变化有较大影响。     

基于STIRPAT模型的环境压力空间差异分析——以能源消费为例

定量分析区域人文驱动力对环境的影响,对认识我国区域环境压力及其影响因素具有一定的科学意义.利用STIRPAT模型,以人口数量、富裕度为自变量,以能源消费总量为因变量,应用岭回归函数拟合得到环境压力模型.以研究结果为依据.利用Mapinfo7.0 软件分别绘制人口数量和富裕度对环境压力影响的空间差异图.结果显示,不同省份间人口数量和富裕度对环境压力影响存在显著差异.尽管各省份人口数量对环境压力都产生线性正效应影响,但影响强度有明显差异,最大者是最小者的8.079倍.富裕度对环境压力影响,有正效应或者负效应;有线性作用或者弹性作用.30个考察对象中,北京、上海、四川、新疆4个省市的富裕度二次项系数为负,这说明,在数据观测范围内以上4个省市的结果支持富裕度与环境压力间存在倒"U"型环境库兹涅茨曲线的观点;但这4个省市的环境压力并没有出现下降,这是由于各种人文驱动力影响的净效应决定了环境压力变化趋势.人口数量的增长对环境压力的上升存在较强正效应.因此,控制人口数量的速度对改善环境压力将起到关键作用.     

东天山乌鲁木齐河源1号冰川雪冰中痕量元素揭示的大气污染信息

为认识东天山乌鲁木齐河源1号冰川地区大气中痕量元素的组成特征和污染信息,利用高分辨电感耦合等离子体质谱仪对2008年10月采自乌鲁木齐河源1号冰川雪坑中24个样品中可溶性痕量元素Al、Ba、Co、Cr、Cu、Li、Ni、Sb、Sr、U、V、Fe、Cd、Zn和Pb的浓度进行了测试和研究.结果表明,痕量元素的浓度最大值和最...     

重点源大气砷铅污染排放模型及特征

在我国的非常规性污染物质中,大气重金属砷、铅已越来越多地被关注和重视。文章综述了国内外人为源对大气中重金属排放的贡献,结果显示中国是全球人为活动向大气排放重金属最多的国家之一,燃煤和有色金属冶炼行业在相当长的时间内都将是最主要且最为重要的人为排放源。通过系统调研燃煤及有色金属冶炼业资源及产业布局状况,构建目前我国大气重金属相关清单模型,进行了我国重点源大气砷、铅排放清单分析,结果表明：（1）2000-2008年我国燃煤大气砷、铅排放量共为93733t,年均增长率为7．93％,2004-2008年有色金属冶炼业大气砷、铅排放量共为18836t,年均增长率为15．2％;（2）2000-2008年各经济部门中电力部门燃煤大气砷、铅放量始终最高,占燃煤大气排放总量的44．6％-57．1％,且呈逐年升高的趋势;（3）2000-2008年各省区中山西、河北、河南和湖南省是大气砷、铅的排放大户。其中,燃煤大气砷、铅排放量主要集中在人口密集、工业集中、经济发展速度较快的北部和中东部省区,包括山西、山东、河北、河南和江苏五省,占全国燃煤排放总量的39．1％,有色金属冶炼大气砷、铅排放量主要集中在我国有色金属工业较为发达的河南及湖南省,占全国有色金属冶炼业排放总量的47．3％。可以看出,我国需要高度重视大气重金属砷、铅的污染防治,加强排放控制基础能力建设,加快建立适合中国的大气砷、铅污染防治技术政策体系。     

伊洛河流域河水来源及水化学组成控制因素

伊洛河是黄河中游南岸重要支流,由伊河和洛河在洛阳偃师汇合而成.流域上游矿产资源开采活动较多,下游城镇密集,工农业活动分布广泛.为探究不同类型人为活动对伊洛河流域河水水化学组成的影响,分别在丰水期(8月)和平水期(12月)采集伊洛河流域干流和支流河水样品,借助水体氢氧同位素组成和阴阳离子组成的时空分布特征,阐明水体来源以及水化学组成控制因素,说明人为活动的影响途径和方式.结果表明:①洛河干流河水丰水期和平水期δD和δ~(18)O均值分别为-56‰和-7.9‰以及-55‰和-8.1‰,伊河干流河水丰水期和平水期δD和δ~(18)O均值分别为-49‰和-6.9‰以及-53‰和-7.8‰,丰水期和平水期河水主要接受当地大气降水补给;②洛河及伊河干流河水水化学类型均为HCO_3-SO_4-Ca-Mg型,丰水期干流河水Ca~(2+)和HCO~-_3当量浓度占比低于平水期,而丰水期SO_4~(2-)当量浓度占比则高于平水期,显示丰水期较多硫酸盐输入;③碳酸和硫酸参与流域内碳酸盐岩和硅酸盐岩风化过程,洛河流域碳酸盐岩风化较明显,伊河流域硅酸盐岩风化较明显;④伊洛河流域人为输入影响表现在上游河水水化学组成受到金属矿产采选活动影响,下游河水水化学组成受工业废水和城镇生活污水的影响;⑤伊洛河流域上游和下游两种不同类型人为活动是河水硫酸盐硫同位素组成空间上变化的重要原因,上游河水硫酸盐硫同位素组成偏负,证实来自硫化物矿物氧化过程产生的硫酸盐贡献较大,进而间接证实硫酸参与岩石化学风化过程.下游河水硫酸盐硫同位素值偏正,与工业废水和城镇生活污水有关.     

Diversity of Ontogenetic Pathways in Plant Populations

Population heterogeneity in cespitose, fibrous-rooted, brevirhizomatous, stoloniferous, and tap-rooted herbaceous and woody plants is described. This heterogeneity is caused by the multivariant character of plant ontogeny (i.e., its dimensional, morphological, rhythmological, and temporal multiversality), which is regarded as the main adaptation mechanism operating in plant populations because it provides for the diversity of ontogenetic pathways under different ecological conditions.     

Metal Fractionation Studies in Surfacial and Core Sediments in the Achankovil River Basin in India

The Fractionation of Fe, Zn, Cu, Pb, Mn and Cd in the sediments of the Achankovil River, Western Ghats, India using a sequential extraction method was carried out to understand the metal availability in the basin for biotic and abiotic activities. Spatial distribution of heavy metals has been studied. Sediment grain size has significant control over the heavy metal distribution. The fluctuations in their concentration partly depend upon the lithology of the river basin and partly the anthropogenic activities. The sediments are dominated by sand and are moderately to strongly positively skewed and are very leptokurtotic in nature. The quartzite and feldspars are abundant minerals along with significant amount of mica with low clay content. The core sediments show increasing trend of heavy metal concentration with depth due to the recent addition of anthropogenic sources and post-diagenic activities. Significant amount of Cd (18%) was found in carbonate fraction, which may pose environmental problems due to its toxic nature. Small concentrations of metals, except Cd and Cu, are in exchangeable fraction, which indicate low bio-availability. Enrichment Factor (EF) for individual metals shows the contribution from terrregious and in part from anthropogenic sources. Selective Sequential Extraction (SSE) study shows the variation in specific metal distribution pattern, their distribution in different phases and their bio-availability. Maximum amount of the metals were bound to the non-residual fractions (mainly Fe-oxides). Overall, bio-availability of these micronutrients from sediments seems to be very less. Non-residual phase is the most important phase for majority of heavy metals studied. Among the non-residual fraction, maximum amount of the heavy metals bound to Fe-oxides. The study high lights the need for in-depth study of heavy metals distribution and fractionation in the smaller river basins to get precise information on the behavior and transport of heavy metals in the fluvial environment and their contribution to the world ocean.