The Bear Brook Watershed in Maine: Multi-decadal whole-watershed experimental acidification     

Kaizad F. Patel  Ivan J. Fernandez  Sarah J. Nelson  Stephen A. Norton  Cheryl J. Spencer 《水文研究》2021,35(5):e14147

The Bear Brook Watershed in Maine (BBWM) is a long-term research site established to study the response of forest ecosystem function to environmental disturbances of chronic acidic deposition and ecosystem nitrogen enrichment. Starting in 1989, the West Bear (treated) watershed received bimonthly applications of ammonium sulfate [(NH₄)₂SO₄] fertilizer from above the canopy, whereas East Bear (reference) received ambient deposition. The treatments were stopped in 2016, marking the beginning of the recovery phase. Research at the site has focused on soils, streams, and vegetation. Here, we describe data collected over three decades at the BBWM—input and stream output nutrient fluxes, quantitative soil pits and soil chemistry, and soil temperature and moisture.  相似文献   

利用稳定同位素(15N)示踪技术研究浮游藻类氮素吸收速率特征     

韩菲尔  赵中华  李大鹏  张路 《海洋与湖沼》2019,50(4):811-821

浮游藻类对溶解态氮的吸收同化是湖泊氮生物循环和水体富营养化发生机制探讨的关键环节。本文通过~(15)N稳定同位素添加实验以铜绿微囊藻(Microcystis aeruginosa)、海链藻(Thalassiosira sp.)、卡德藻(Tetraselmis sp.)、剧毒卡尔藻(Karlodinium veneficum)以及盐水隐藻(Rhodomonas salina)为研究对象,从浮游藻类氮素吸收时间、营养盐基质以及藻种差异三个方面研究五种藻类对铵氮(NH_4~+-N)、硝氮(NO_3~--N)、尿素氮(Urea-N)三种形态氮的吸收特征。研究发现:(1)浮游藻类对三种形态氮的吸收均在1h时吸收速率最高,其氮素吸收过程为快速吸收。(2)浮游藻类优先吸收还原态氮,其中NH_4~+-N吸收速率最高,当培养周期为1d和4d时浮游藻类对NH_4~+-N吸收速率的均值分别为4.05和4.15μmol/(L·h);浮游藻类对Urea-N吸收相对偏好系数为25.18—713.42,表现出对小分子溶解态有机氮的特定偏好性。(3)不同藻种对氮素吸收具有不同特征,其中,剧毒卡尔藻对三种形态氮的吸收速率均为最高,而铜绿微囊藻的吸收速率均为最低;不同藻种不同培养时间氮素吸收速率差异与浮游藻类生长周期等特性有关。不同浮游藻类对不同形态氮素表现出吸收特异性,对水体氮负荷和浮游藻类水华优势种形成将产生重要影响。  相似文献   

徐闻南山镇红树林沉积物及红树植物中重金属的累积特征与迁移规律     

罗松英  梁艺琼  陈碧珊  林梦婷  梁家新  邱锦坤 《热带地理》2019,39(3):347-356

为探究重金属在红树林沉积物及红树植物中的分布累积及迁移规律，选取了徐闻南山镇红树林为研究对象，通过测定红树林沉积物及红树植物不同部位（根、茎、叶）的重金属质量分数，运用富集因子、生物富集系数、转移系数及相关性分析等方法进行分析。结果表明：1）红树林沉积物重金属质量分数表现为铬（Cr）＞锌（Zn）＞镍（Ni）＞铜（Cu）＞铅（Pb）＞砷（As）＞汞（Hg）＞镉（Cd），为中等变异程度；除了镍（Ni）元素外，其余7种重金属未超过国家一级标准，除了铅（Pb）元素外，其余7种重金属均超过广东省土壤环境背景值，说明研究区沉积物中重金属具有一定的积累效应。2）沉积物中砷（As）、铜（Cu）、锌（Zn）、汞（Hg）、镍（Ni）、铬（Cr）富集因子值均＞1.5，说明受到轻微人为活动影响；各站位镍（Ni）富集因子值均＞5，结合研究区背景，反映了镍（Ni）受到自然和人为输入的共同影响。3）白骨壤体内重金属主要集中在根部，而红海榄体内重金属在根茎叶中分布相对均匀。白骨壤根茎叶部位的大多数重金属质量分数远高于红海榄，说明白骨壤对重金属的吸附能力比红海榄强。汞（Hg）集中分布在植物的叶片部位，且与其他重金属之间相关性不明显；推测汞（Hg）主要通过叶片吸收进入植物体内，与交通运输污染有关。4）不同红树植物对不同重金属富集能力各异，白骨壤对重金属的富集能力表现为：镉（Cd）＞砷（As）＞铜（Cu）＞锌（Zn）＞汞（Hg）＞铅（Pb）＞镍（Ni）＞铬（Cr），红海榄表现为：镉（Cd）＞铜（Cu）＞汞（Hg）＞锌（Zn）＞铅（Pb）＞砷（As）＞镍（Ni）＞铬（Cr）。白骨壤和红海榄对汞（Hg）的运移能力都较强；红海榄对镉（Cd）的富集能力和转运能力都较强，而白骨壤对镉（Cd）富集能力较强，转运能力却较弱，这说明红树植物对重金属元素的富集能力与转运能力不存在正比关系。  相似文献   

黑龙江省海伦市长发镇土地质量地球化学评价及开发建议     

刘国栋  杨泽  戴慧敏  张一鹤  肖红叶  陈江 《地质与资源》2020,29(6):533-542

基于海伦市长发镇1：1万土地质量地球化学调查获得的土壤重金属元素和养分元素数据，参照土壤环境质量标准（GB15618—2018）和土地质量地球化学评价规范（DZ/T0295—2016），采用单指标评价法对研究区土壤养分和土壤环境质量进行评价，并在此基础上，将两者叠加分析，对研究区进行土地质量地球化学综合判定.结果表明：研究区内土壤养分以丰富及较丰富为主，分别占长发镇总面积的37.49%和62.22%，区内缺乏B、Mo；研究区99.94%的土地为无风险（一等），0.06%的土地为风险可控（二等），风险可控土地主要受Cd及Hg元素的影响；土地质量地球化学综合评价结果显示，研究区以一等（优质）土地为主，占评价区总面积的99.66%；研究发现长发镇富Se土地资源面积19.25 km²，土壤中Se含量为0.4×10^-6～1.4×10^-6，平均值为0.44×10^-6；长发镇符合绿色食品产地的耕地面积138.44 km²，占调查区耕地面积的99.84%，其中绿色富Se、绿色食品产地分别为18.53 km²和119.91 km².  相似文献   

High-frequency monitoring of hydrological and biogeochemical fluxes in forested catchments of southern Chile     

Cristián Frêne  Juan J. Armesto  Freddy Véliz  Fernando D. Alfaro  Kathleen C. Weathers 《水文研究》2021,35(5):e14175

The variability of rainfall-dependent streamflow at catchment scale modulates many ecosystem processes in wet temperate forests. Runoff in small mountain catchments is characterized by a quick response to rainfall pulses which affects biogeochemical fluxes to all downstream systems. In wet-temperate climates, water erosion is the most important natural factor driving downstream soil and nutrient losses from upland ecosystems. Most hydrochemical studies have focused on water flux measurements at hourly scales, along with weekly or monthly samples for water chemistry. Here, we assessed how water and element flows from broad-leaved, evergreen forested catchments in southwestern South America, are influenced by different successional stages, quantifying runoff, sediment transport and nutrient fluxes during hourly rainfall events of different intensities. Hydrograph comparisons among different successional stages indicated that forested catchments differed in their responses to high intensity rainfall, with greater runoff in areas covered by secondary forests (SF), compared to old-growth forest cover (OG) and dense scrub vegetation (CH). Further, throughfall water was greatly nutrient enriched for all forest types. Suspended sediment loads varied between successional stages. SF catchments exported 455 kg of sediments per ha, followed by OG with 91 kg/ha and CH with 14 kg/ha, corresponding to 11 rainfall events measured from December 2013 to April 2014. Total nitrogen (TN) and phosphorus (TP) concentrations in stream water also varied with rainfall intensity. In seven rainfall events sampled during the study period, CH catchments exported less nutrients (46 kg/ha TN and 7 kg/ha TP) than SF catchments (718 kg/ha TN and 107 kg/ha TP), while OG catchments exported intermediate sediment loads (201 kg/ha TN and 23 kg/ha TP). Further, we found significant effects of successional stage attributes (vegetation structure and soil physical properties) and catchment morphometry on runoff and sediment concentrations, and greater nutrients retention in OG and CH catchments. We conclude that in these southern hemisphere, broad-leaved evergreen temperate forests, hydrological processes are driven by multiple interacting phenomena, including climate, vegetation, soils, topography, and disturbance history.  相似文献   

南海南部次表层叶绿素a质量浓度最大值及其影响因子*     

廖秀丽  戴明  巩秀玉  刘华雪  黄洪辉 《热带海洋学报》2018,37(1):45-56

文章分析了2013年南海南部4个季节航次的叶绿素a (Chl a)调查数据, 结果显示: 150m以浅水柱Chl a质量浓度均值分别为早春0.14mg•m^-3、初夏0.12mg•m^-3、初秋0.18mg•m^-3、初冬0.16mg•m^-3。早春和初夏偏低的原因与早春风速小, 初夏水温高, 不利于水体的垂直混合, 限制了深层海水中丰富的营养盐向上层水体补充有关。4个季节中海水次表层Chl a质量浓度最大值层(SCML)均出现在50m和75m, 这两个水层的Chl a质量浓度差异小, 季节变化不大, 平均值变化范围分别为0.24~0.26mg•m^-3和0.22~0.26mg•m^-3。受混合层深度和温跃层上界深度的共同影响, 50m水层Chl a质量浓度主要受制于深层富营养盐海水的向上补充, 75m水层Chl a质量浓度受水温的影响明显。  相似文献   

台湾海峡冬、夏季氮通量的数值模拟研究     

杨金湘  王佳 《海洋学报》2018,40(4):30-40

本文建立了一个气候态驱动的台湾海峡物理-生态耦合模型（ROMS-NPZD）。与遥感观测数据的比较表明，模型能够较好地模拟出冬、夏季台湾海峡主要的温度和叶绿素分布特征。模型揭示了夏季台湾海峡营养盐输运的东、西通道，与南海次表层水的入侵通道一致；冬季，海峡中的营养盐来源于闽浙沿岸水和通过澎湖水道入侵的南海次表层水。模拟结果表明:夏季，通过海峡流入东海的氮主要为有机氮；冬季，闽浙沿岸流为海峡和南海北部陆架提供了丰富的营养盐，不仅如此，南海次表层水进入海峡的营养盐通量与夏季相当。  相似文献   

北极快速变化的生态环境响应   总被引：1，自引：0，他引：1  

陈建芳  金海燕  白有成  庄燕培  李宏亮  李杨杰  任健 《海洋学报》2018,40(10):22-31

北冰洋由于其特殊的地理位置，成为全球变化响应最为敏感的地区。本文聚焦北极海冰变化幅度最大的西北冰洋，从营养盐、叶绿素、浮游植物群落和沉积碳埋藏等变化来讨论海洋生态环境对北极快速变化的响应。尽管太平洋北向流和北极周边河流输入加强可以增加西北冰洋上层营养盐储库，但由于夏季硅藻旺发向沉积物迁出大量生源元素，使得上层营养盐相对亏损，部分海域存在显著的氮限制和硅限制。随海冰减退，尽管夏末海盆区浮游植物呈现小型化趋势，但西北冰洋总体上浮游植物现存量和初级生产力呈现增高的趋势；伴随叶绿素极大层下移、北扩，以硅藻为代表的生物泵过程得以更高效的运转。在沉积物埋藏的有机碳中，除原先北冰洋生态系统占据重要比份的冰藻外，硅藻等藻类的有机碳埋藏也逐渐增加。西北冰洋海洋初级生产力的增加不仅促进了生物泵的运转和碳的埋藏，而且给海洋生态系统提供了更多的食物来源。北极海域目前已成为全球碳源汇格局变化最大、海洋生态系统改变最显著的地区之一。  相似文献   

Sediment and nutrient storage in a beaver engineered wetland          下载免费PDF全文

Alan Puttock  Hugh A. Graham  Donna Carless  Richard E. Brazier 《地球表面变化过程与地形》2018,43(11):2358-2370

Beavers, primarily through the building of dams, can deliver significant geomorphic modifications and result in changes to nutrient and sediment fluxes. Research is required to understand the implications and possible benefits of widespread beaver reintroduction across Europe. This study surveyed sediment depth, extent and carbon/nitrogen content in a sequence of beaver pond and dam structures in South West England, where a pair of Eurasian beavers (Castor fiber) were introduced to a controlled 1.8 ha site in 2011. Results showed that the 13 beaver ponds subsequently created hold a total of 101.53 ± 16.24 t of sediment, equating to a normalised average of 71.40 ± 39.65 kg m². The ponds also hold 15.90 ± 2.50 t of carbon and 0.91 ± 0.15 t of nitrogen within the accumulated pond sediment. The size of beaver pond appeared to be the main control over sediment storage, with larger ponds holding a greater mass of sediment per unit area. Furthermore, position within the site appeared to play a role with the upper‐middle ponds, nearest to the intensively‐farmed headwaters of the catchment, holding a greater amount of sediment. Carbon and nitrogen concentrations in ponds showed no clear trends, but were significantly higher than in stream bed sediment upstream of the site. We estimate that >70% of sediment in the ponds is sourced from the intensively managed grassland catchment upstream, with the remainder from in situ redistribution by beaver activity. While further research is required into the long‐term storage and nutrient cycling within beaver ponds, results indicate that beaver ponds may help to mitigate the negative off‐site impacts of accelerated soil erosion and diffuse pollution from agriculturally dominated landscapes such as the intensively managed grassland in this study. © 2018 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.  相似文献   

A method for uncertainty constraint of catchment discharge and phosphorus load estimates          下载免费PDF全文

Michael J. Hollaway  Keith J. Beven  Clare Mc W. H. Benskin  Adrian L. Collins  Robert Evans  Peter D. Falloon  Kirsty J. Forber  Kevin M. Hiscock  Ron Kahana  Christopher J. A. Macleod  Mary C. Ockenden  Martha L. Villamizar  Catherine Wearing  Paul J. A. Withers  Jian G. Zhou  Nicholas J. Barber  Philip M. Haygarth 《水文研究》2018,32(17):2779-2787

River discharge and nutrient measurements are subject to aleatory and epistemic uncertainties. In this study, we present a novel method for estimating these uncertainties in colocated discharge and phosphorus (P) measurements. The “voting point”‐based method constrains the derived stage‐discharge rating curve both on the fit to available gaugings and to the catchment water balance. This helps reduce the uncertainty beyond the range of available gaugings and during out of bank situations. In the example presented here, for the top 5% of flows, uncertainties are shown to be 139% using a traditional power law fit, compared with 40% when using our updated “voting point” method. Furthermore, the method is extended to in situ and lab analysed nutrient concentration data pairings, with lower uncertainties (81%) shown for high concentrations (top 5%) than when a traditional regression is applied (102%). Overall, for both discharge and nutrient data, the method presented goes some way to accounting for epistemic uncertainties associated with nonstationary physical characteristics of the monitoring site.  相似文献