Influence of river discharge on plankton metabolic rates in the tropical monsoon driven Godavari estuary,India     

V.V.S.S. Sarma  S.N.M. GuptaP.V.R. Babu  T. AcharyaN. Harikrishnachari  K. VishnuvardhanN.S. Rao  N.P.C. ReddyV.V. Sarma  Y. SadhuramT.V.R. Murty  M.D. Kumar 《Estuarine, Coastal and Shelf Science》2009

To examine the influence of river discharge on plankton metabolic balance in a monsoon driven tropical estuary, daily variations in physico-chemical and nutrients characteristics were studied over a period of 15 months (September 2007 to November 2008) at a fixed location (Yanam) in the Godavari estuary, India. River discharge was at its peak during July to September with a sharp decrease in the middle of December and complete cessation thereafter. Significant amount of dissolved inorganic nitrogen (DIN, of 22–26 μmol l⁻¹) and dissolved inorganic phosphate (DIP, of 3–4 μmol l⁻¹) along with suspended materials (0.2–0.5 g l⁻¹) were found at the study region during the peak discharge period. A net heterotrophy with low gross primary production (GPP) occurred during the peak discharge period. The Chlorophyll a (Chl a) varied between 4 and 18 mg m⁻³ that reached maximum levels when river discharge and suspended loads decreased by >75% compared to that during peak period. High productivity was sustained for about one and half months during October to November when net community production (NCP) turned from net heterotrophy to autotrophy in the photic zone. Rapid decrease in nutrients (DIN and DIP by ∼15 and 1.4 μmol l⁻¹, respectively) was observed during the peak Chl a period of two weeks. Chl a in the post monsoon (October–November) was negatively related to river discharge. Another peak in Chl a in January to February was associated with higher nutrient concentrations and high DIN:DIP ratios suggest possible external supply of nitrogen into the system. The mean photic zone productivity to respiration ratio (P:R) was 2.38 ± 0.24 for the entire study period (September 2007–November 2008). Nevertheless, the ratio of GPP to the entire water column respiration was only 0.14 ± 0.02 revealing that primary production was not enough to support water column heterotrophic activity. The excess carbon demand by the heterotrophs could be met from the allochthonous inputs of mainly terrestrial origin. Assuming that the entire phytoplankton produced organic material was utilized, the additional terrestrial organic carbon supported the total bacterial activity (97–99%) during peak discharge period and 40–75% during dry period. Therefore, large amount of terrestrial organic carbon is getting decomposed in the Godavari estuarine system.  相似文献   

Contribution of benthic microalgae to the whole water algal biomass and primary production in Suo Nada,the Seto Inland Sea,Japan     

Md. Jahangir Sarker  Tamiji Yamamoto  Toshiya Hashimoto 《Journal of Oceanography》2009,65(3):311-323

Biomass and primary productivity of benthic microalgae (BMA) and planktonic algae in Suo Nada, the western part of the Seto Inland Sea, Japan were compared in terms of unit area with regard to their seasonal and spatial distribution in 2002. Judging from light compensation depth and water depth, the southwestern part of Suo Nada was considered to be a potential habitat for BMA. Whereas the contribution of sedimented planktonic algae was high in biomass at the sediment surface, BMA was obviously significant both in biomass and primary production in the shallow southwestern part. However, the contribution of BMA to the total biomass in the entire water column was 7% in winter and 2% in summer. The primary production of BMA varied between 4.0 and 74.0 mg C m⁻² d⁻¹ in the southwestern part, accounting for 2–12% of the whole water column primary production. The ecological roles of BMA in the Suo Nada ecosystem are discussed, such as reduction of benthic nutrient flux, oxidation of surface sediments and feed for higher animals.  相似文献   

Environmental controls on phytoplankton production in coastal ecosystems: A case study from Tokyo Bay     

Heather A. Bouman  Toru Nakane  Kenji Oka  Kisaburo Nakata  Kiyo Kurita  Shubha Sathyendranath  Trevor Platt 《Estuarine, Coastal and Shelf Science》2010

Phytoplankton biomass and primary production were examined in their environmental context, for a semi-enclosed bay (Tokyo Bay, Japan) using data from monthly samples collected over a three-year period. Heavy precipitation and high surface temperatures in the late spring and summer gave rise to a highly-stratified water-column and stimulated a series of phytoplankton blooms, whereas during the winter, a weakly-stratified and deeply-mixed water-column led to a rapid decline in phytoplankton biomass under light-limited growth conditions. By incorporating pigment, photophysiological and optical data into a primary production model we show that daily, water-column primary production ranges from ∼160 mg C m⁻² d⁻¹ to 7600 mg C m⁻² d⁻¹. High water turbidity and deep vertical mixing, both separately and in concert, limit the light available for algal growth over much of the year. Annual primary production varied from 370 to 580 g C m⁻² y⁻¹. The relative influences of nutrient limitation and light limitation are assessed. A model is developed that describes this in an explicit manner using photophysiological parameters.  相似文献   

Soil as a capacitor: Considering soil water content improves temporal models of productivity     

《Journal of Arid Environments》2013

Above-ground net primary production (ANPP) in arid and semiarid ecosystems is mainly explained by precipitation (ppt). However, when this relationship is evaluated taking into consideration data from different years in the same site (i.e. temporal models of productivity) the relation is weak, and sometimes it does not exist. In spite of this, the inclusion of previous year's ppt and/or ANPP frequently improves temporal models. In this study we analyze if considering NDVI and mean annual soil water content or transpiration (instead of different combinations of current-year ppt and previous year's ppt or ANPP) improves temporal models of productivity in the Southern Monte (Argentina). Current-year ppt only explained 39.7% of variation in ANPP, while mean soil water content explained 85.3%. The remaining models, which include current-year ppt together with previous-year's ppt or previous-year's ANPP, improve the first model; but the explanatory power of the model based only on mean soil water content is never reached. Our results also show that water losses exceed annual ppt in dry years, whereas the opposite occurs during years with above-average ppt. This carryover effect of soil water indicates that soil acts as a capacitor, accumulating water during wettest years and releasing it during following years.  相似文献   

花岗岩中原生与次生白云母的鉴别特征及其地质意义——以赣南富城强过铝质花岗岩体为例   总被引：3，自引：0，他引：3  

章邦桐  吴俊奇  凌洪飞  陈培荣 《岩石矿物学杂志》2010,29(3):225-234

通过显微镜下观察和电子探针成分分析,发现赣南富城强过铝质花岗岩中存在3种类型白云母,即原生白云母、交代型白云母和次生白云母,其平均晶体化学式分别为:K1.62Na0.06Fe0.32Mg0.39Ti0.02Al4.89Si6.54O10(OH)4(原生白云母)、K1.55Na0.07Fe0.43Mg0.24Ti0.03Al4.96Si6.50O10(OH)4(交代型白云母)、K1.51Na0.07Fe0.27Mg0.21Ti0.00Al4.98Si6.65O10(OH)4(次生白云母)。根据富城花岗岩主要造岩矿物的结晶顺序(斜长石→钾长石→黑云母→白云母→石英),结合白云母、黑云母稳定曲线及合成花岗岩初融曲线对比分析,富城强过铝质花岗岩中交代型白云母是在花岗岩结晶过程中交代较早晶出的黑云母形成的,其形成温度高于花岗岩熔体的固相线温度(～650℃),故应归属于原生白云母。本文提出根据岩石学宏观特征、岩石化学特征及岩相学微观特征区分花岗岩中原生白云母与次生白云母的综合鉴别方法。  相似文献   

新疆红石金矿床原生晕特征与隐伏矿预测   总被引：1，自引：0，他引：1  

曹洁  邱斌  晁会霞  马立成  杨兴科  孙继东 《地球学报》2010,31(1):83-89

通过对新疆鄯善县红石金矿床野外调研、总结矿床地质特征, 对该矿床钻孔中原生晕分布特征和规律进行了专题研究, 采用多种计算方法相互印证, 确立红石金矿床原生晕轴向分带序列为Bi-Mo-Hg-Zn-Pb-Ag-As-Cu-Sb-Au, 同中国典型金矿床轴向分带序列对比, 发现其具有逆向分带的特征, 从而建立分带评价及矿体叠加模式, 为深部隐伏矿预测提供依据。  相似文献   

2007—2011年春季呼和浩特市空气质量特征分析     

王晓丽  李扬  王佳  都尼雅 《内蒙古气象》2012,(3):26-28

文章对2007—2011年春季(3—5月)呼和浩特市逐日环境空气主要污染物SO2、NO2和PM10的日平均值进行了分析,得出可吸入颗粒物PM10是呼和浩特市近5a春季环境空气出现Ⅲ级(轻微污染)以上污染天气的唯一的首要污染物;在此基础上,对发生在2011年春季(3—5月)内蒙古中西部沙尘天气下,呼和浩特市同期首要空气污染物的变化做了分析,以期对今后呼和浩特市空气质量预报能提供一些参考。  相似文献   

基层台站实时气象观测资料质量控制初探   总被引：4，自引：0，他引：4  

何文旺  谢东  雷红萍 《气象研究与应用》2012,33(3):61-63

介绍基层台站实时气象观测资料质量控制流程,台站级实时资料质量控制方法,从探测环境保护、仪器设备维护、实时资料采集监视、处置等方面阐述基层台站如何做好气象资料质量控制。  相似文献   

The Weavers of the “Western Isles”     

《The Journal of geography》2012,111(4):160-167

This study provides an in-depth investigation of Turkish primary school students’ perceptions of geography. Gender differences in students’ perceptions of geography were investigated, including definitions of geography and its field of study. The findings showed that landforms, our geographical regions/Turkey, mapwork, and countries dominated among students’ definitions. Geography topics cited were mainly within the physical geography category and mostly those of landforms and cartography. A chi-square test revealed a statistically significant difference between girls and boys in the Turkey category and the history-related issues category.  相似文献   

青海省草地资源净初级生产力遥感监测   总被引：8，自引：1，他引：7  

卫亚星  王莉雯  石迎春  李路子 《地理科学》2012,(5):621-627

在研究特定区域的草地光能利用率和环境影响因素典型特点的基础上,建立基于光能利用率的草地NPP遥感估算模型,模拟并分析2006年青海省草地FPAR、光能利用率、NPP的空间分布和季相变化特征。研究结果表明,2006年青海省草地净初级生产力平均值为173.28 gC/(m2.a)。青海省东南部、南部和青海湖周围三个地区,是青海省草地NPP较高的区域。不同草地类型的NPP存在差异,高覆盖度草地的单位面积平均NPP为193.82 gC/(m2.a),中覆盖度草地NPP为157.14 gC/(m2.a),低覆盖度草地NPP为121.08 gC/(m2.a)。  相似文献