典型内陆湖泊沉积物氮、磷和重金属分布特征及生态风险评价——以武汉市武湖为例     

何军  李福林  陶良  张傲  赵永波 《中国地质调查》2022,9(2):110-118

城市内陆型湖泊湿地对城市生态系统具有重要的作用。以武汉市武湖为例,采用数理统计、营养盐指数、地累积指数和潜在生态风险指数等方法,对武湖表层沉积物中的氮、磷、有机质和重金属的平面分布特征、影响因素、富集污染程度、生态风险进行评价。结果表明: 武湖西北部表层沉积物中总氮、总磷和有机质的含量明显高于东南部,武湖周边地表径流和农田是营养元素的主要来源,旱地较水田有利于沉积物中总磷的富集; 武湖沉积物中有机质为内源水生植物和外源陆生植物的混合来源,与总氮具显著正相关关系; 沉积物中重金属含量总体较低,局部呈现高镉,平面上总体北部高于南部; 沉积物中重金属富集程度和潜在风险较低,局部地区镉和铅为轻微富集,镉和汞具中等潜在风险; 沉积物的潜在生态风险为低至中等,潜在生态风险与沉积物中镉的分布高度一致。  相似文献   

Photosynthesis of Digitaria ciliaris during repeated soil drought and rewatering     

YaYong Luo  XueYong Zhao  JingHui Zhang  YuLin Li  XiaoAn Zuo  DianChao Sun 《寒旱区科学》2015,7(1):0081-0087

The ability of psammophyte photosynthesis to withstand and recover from severe droughts is crucial for vegetation stability in semi-arid sandy lands. The responses of gas exchange and chlorophyll fluorescence of an annual grass, Digitaria ciliaris, were measured through three soil drought and rewatering cycles. Results showed that the net photosynthesis rate(P n) decreased by 92%, 95%, and 63% at end of the three drought periods, respectively, water use efficiency(WUE) decreased by 67%, 54%, and 48%, while the constant intercellular CO2 concentration(C i) increased by 1.08, 0.88, and 0.45 times. During those three cycles, the trapping probability with no dark adaptation(F v′/F m′) decreased by 55%, 51%, and 9%, the electron transport per cross section(ET0′/CS0′) decreased by 63%, 42%, and 18%, and the dissipation per cross section(DI0′/CS0′) increased by 97%, 96%, and 21%. These results indicated that D. ciliaris was subjected to photoinhibition and some non-stomatal limitation of photosynthesis under drought. However, after four days of rewatering, its photosynthetic characteristics were restored to control values. This capability to recover from drought may contribute to making the plant's use of water as efficient as possible. Furthermore, the photosynthesis decreased more slowly in the subsequent drought cycles than in the first cycle, allowing D. ciliaris to enhance its future drought tolerance after drought hardening. Thus, it acclimatizes itself to repeated soil drought.  相似文献   

典型亚热带城市片林与草坪土壤全磷垂直分布特征     

郭利成  曾文静  李金全  李熙波 《福建地理》2011,(4):55-63

城市作为人类栖息的主要场所,其含有丰富P源的城市绿地土壤受到人为活动的强烈影响·为了探讨亚热带不同类型城市绿地土壤全P含量的分布特征,于2010年9--12月对福州市典型城市片林与草坪土壤全P垂直分布特征进行研究,结果表明：研究区绿地40cm以上土壤全P含量平均值为0．61g·kg^-1,其中城市片林和草坪土壤全P含量平均值分别为0．64g·kg^-1和0.58g·kg^-1;人为活动直接导致不同类型城市绿地土壤全P垂直分布规律不同：不同植被类型对城市土壤全P含量影响不同．土壤的人为扰动和植被类型及其生长年龄是影响亚热带城市绿地土壤全P垂直分布规律的主要因素．  相似文献   

青藏高原太阳辐射对高山草甸净生态系统二氧化碳的影响(英文)     

范玉枝  张宪洲  王景升  石培礼 《地理学报(英文版)》2011,21(4):666-676

On the Tibetan Plateau, the alpine meadow is the most widespread vegetation type. The alpine meadow has a low biological productivity and low vegetation coverage in the growing season. The daytime NEE between the atmosphere and the alpine meadow ecosystem was influenced by solar radiation. To analyze the characteristics of change in NEE and to calculate the parameters related to photosynthesis and respiration in different solar radiation environments, the NEE measurements were taken in Damxung from July to August in 2003, 2004, 2005 and 2006 using the eddy covariance technique. Solar radiation was grouped into three levels according to the net radiation, which was more than 155 W m-2 d-1 on clear days, 144±5 W m-2 d-1 on partly cloudy days and less than 134 W m-2 d-1 on cloudy days. The diurnal relationships between NEE and PAR varied with differences in solar radiation, which was a rectangular hyperbola form on clear days, two different concave curves on partly cloudy days and an irregular triangle form on cloudy days. The mean CO2 absorption rate showed a decreasing trend with increasing solar radiation. The daytime absorption maximum occurred around 10:00 on clear days with an average of slightly less –0.2 mg m-2 d-1, around 11:00 on partly cloudy days with an average of about –0.2 mg m-2 d-1, and around 12:00 on cloudy days with an average of about –0.25 mg m-2 d-1. As solar radiation increased, the Amax and the Q10 decreased. However, the R10 increased and the maximum of the α occurred on partly cloudy days. The optimum net solar radiation was about 134–155 W m-2 d-1, which induced a PAR of about 1800-2000 μmol m-2 s-1 and soil temperature at a depth of 5 cm of about 14℃. Therefore, on the Tibetan Plateau, the alpine meadow ecosystem will have a higher carbon absorption potential while solar radiation decreases in the future.  相似文献   

露天磷矿矿山测量中的数字电子图   总被引：1，自引：0，他引：1  

田大明 《北京测绘》2011,(3):83-85,93

结合露天磷矿测量实例,介绍数字电子图的测制,高边坡控制、工程量计算、采场运输道路设计,正是电子图在矿山测量的应用和推广,大大提高了矿山测量工作效率和磷矿开采效益。  相似文献   

广东省丰良地热田高氟地热流体成因及热储温度评价     

李义曼  罗霁  陈凯  黄天明  天娇  程远志 《地质论评》2023,69(4):1337-1348

广东丰顺丰良地区出露的地热水温度高达96℃,热储层为裂隙发育的下侏罗统的英安斑岩,F^-含量较高。但关于其地热流体的补给来源、循环演化过程及热储温度研究较少。笔者等基于早期开展的勘探工作和补充采集、测试的地热水和气体数据,探讨了该地热系统的流体成因及热储温度。结果表明,丰良地区地热水存在2类,A类地热水温度普遍低于40℃,Ca²⁺含量高,Na⁺和K⁺含量低,以HCO^-₃—Ca²⁺型为主;B类地热水Na⁺含量高,Ca²⁺含量低,为HCO^-₃—Na⁺型。A类地下水可能受浅层地下水混入影响,但缺少直接证据。B类地下水由周边山区的大气降水补给,沿裂隙或者断裂系统进入英安斑岩储层,循环深度和水—岩相互作用时间分别可达5200～6300 m和22 ka;储层温度条件下铝硅酸盐矿物的溶解以及阳离子交换作用促进了富N₂、S...  相似文献   

潜流交换温度示踪方法研究进展          下载免费PDF全文

任杰  程嘉强  杨杰  程琳 《水科学进展》2018,29(4):597-606

潜流带是河流生态系统中活跃的生态群落交错区,是地表水和地下水相互作用的重要界面。研究潜流带内存在的潜流交换机制对评估水资源的开发利用以及维持和修复河流生态系统健康有着重要意义。系统介绍了温度示踪方法的一维垂向稳态和瞬态热运移解析模型,梳理归纳了基于温度示踪的时序数据采集方法、信号分析方法和数值方法的相关研究进展,最后对比论述了温度示踪方法的优势和存在的主要问题,同时指出了地下水的多维流动、温度测量的不确定性以及非理想条件对解析模型的影响仍是未来温度示踪方法需要进一步研究的重点。  相似文献   

夏季风过渡区的陆-气相互作用：述评与展望          下载免费PDF全文

张强  岳平  张良  王胜  张杰  赵建华  王润元  阳伏林 《气象学报》2019,77(4):758-773

夏季风过渡区是受夏季风影响最敏感的区域之一,其陆-气相互作用对夏季风气候动力学过程响应明显,该区域的陆-气相互作用及其对夏季风活动的响应是一个值得关注的重要科学问题。分析了中国夏季风过渡区的形成及其基本特征,讨论了夏季风过渡区陆-气相互作用过程研究的主要关注点,初步推测了该地区陆-气相互作用对夏季风变化的响应机制。指出该地区陆-气相互作用研究包含了多重互馈机制、陆面水-热-生过程耦合、近地层到自由大气的多界面交换、季风多尺度作用和特殊的陆面水分循环等一系列重要科学问题。同时,总结归纳了该领域的主要研究进展和关键科学问题,提出了未来应该重点研究的7个方面,并初步给出了研究试验的基本思路。为未来系统深入研究夏季风过渡区陆-气相互作用及其对夏季风活动响应问题提供了科学指导。   相似文献   

离子交换树脂法分离沉积物中锶和钕的影响因素研究   总被引：3，自引：3，他引：0  

尹鹏  何倩  何会军  赵志琦 《岩矿测试》2018,37(4):379-387

Sr和Nd同位素是地质学研究中经典的同位素定年和示踪体系。传统沉积物中Sr和Nd分离方法通常是利用AG50W-X8树脂分离Sr与稀土元素(REEs),再用Sr和Ln特效树脂分别对Sr和Nd纯化,但对于Fe元素含量较高的沉积物样品,该方法对REEs的洗脱率偏低,仅有50%。另外,AG50W-X8树脂高度、洗脱酸种类、Sr特效树脂淋洗酸体积以及Ln特效树脂过柱方式对Sr和Nd分离都有影响。为分析上述因素对Sr和Nd分离效果的影响,本文以水系沉积物标准物质GBW07309为例进行了研究,结果表明:(1)高含量的Fe会显著影响Sr和Nd的分离效果,而AG1-X8树脂可以有效去除Fe;(2)当AG50W-X8树脂高度为1 m L,硝酸作为洗脱酸时,Sr和REEs的分离效果较好;(3)Sr特效树脂淋洗酸中硝酸淋洗体积达到15 m L时可以有效分离Sr和Rb;(4)Ln特效树脂采用重力过柱方式时Sr和Nd分离效果较好,没有拖尾现象。本研究解决了Fe对分离Sr和Nd的干扰,K、Na、Ca、Mg、Fe、Rb、Sm去除率达到99%以上,完全满足Sr和Nd同位素分析的要求,为离子交换树脂法分离沉积物中Sr和Nd提供了较详细的前处理经验数据。  相似文献   

Comparative Studies on Phosphorus Uptake and Growth Kinetics of the Microalga Tetraselmis subcordiformis and the Macroalga Ulva pertusa     

NANChunrong DONGShuanglin 《中国海洋大学学报(英文版)》2004,3(1):56-59

Short-term uptake experiments and long-term semicontinuous culture experiments were performed under the condition of phosphorus (P) limitation to estimate and compare the P uptake and growth kinetics of the microalga Tetraselmis subcordiformis and the macroalga Ulva pertusa. Two new parameters, the maximum specific uptake rate (Vm^sp) and the maximal growth efficiency (β), are introduced to achieve uniformity for the comparison of nutrient uptake and growth efficiency between microalgae and macroalgae. T. subcordiformis possesses 3 times lower half saturation uptake constant, 4 times higher maximal growth rate and 20 times higher maximum specific uptake rate than U. pertusa, while U. pertusa possesses 4 times higher maximal growth efficiency than T. subcordiformis.  相似文献