共查询到19条相似文献，搜索用时 140 毫秒
1.
轮叶黑藻(Hydrilla verticillata)是我国浅水湖泊常见的沉水植物,经常用于湖泊生态修复工程.然而在生态修复中后期,轮叶黑藻又往往会过度繁殖,影响其他湖泊功能的发挥.镧改性膨润土(锁磷剂)可以有效地降低沉积物中生物可利用磷含量,近年来被用于控制湖泊沉积物磷释放,其对轮叶黑藻生长和形态的影响还有待阐明.本研究在2种不同上覆水营养盐浓度条件下,设置添加和不添加锁磷剂2种处理,探究沉积物添加锁磷剂对轮叶黑藻生长及形态特征的影响.结果表明:1)沉积物添加锁磷剂之后,铁锰结合态磷、有机磷、铝结合态磷等生物可利用磷浓度显著降低,而生物不可用磷,如钙结合态磷浓度显著升高; 2)沉积物添加锁磷剂显著降低了轮叶黑藻的生物量和生长率.添加锁磷剂的处理组植物的株高、地上部分生物量均明显低于无锁磷剂组;相反,添加锁磷剂显著增加了植物的根长和地下部分生物量,进而提高了植物的根冠比; 3)锁磷剂对轮叶黑藻生长的影响程度与水体营养盐浓度有关,在低营养盐浓度水体中锁磷剂对植物生长和形态特征的影响更为显著.本研究表明,锁磷剂的添加能降低沉积物中生物可利用磷浓度,抑制轮叶黑藻的生长,同时这种影响程度与在水体营养盐浓度有关. 相似文献
2.
水生植被恢复对城市景观水体磷浓度及沉积物磷形态的影响 总被引：2，自引：1，他引：1
以上海市两个水生植被恢复时间为5—10年的城市景观水体为研究对象,通过分析水体理化性质以及水和沉积物磷的含量和形态,研究水生植被恢复对富营养化水体修复的长期生态效应.结果表明,水生植被恢复能有效降低水体氮、磷浓度,对水体富营养化有明显的改善作用.在外源磷的污染源得到控制后,水体磷浓度会随着修复时间的增加而逐渐降低并相对稳定.沉积物磷形态以钙磷为主,随着水生植被恢复时间的增加,生物活性较强的可交换态磷、铝磷和铁磷的含量下降,而相对稳定的钙磷所占的比例增加.研究结果还表明,即使不进行底泥疏浚,长期的水生植被恢复也可以使城市河流沉积物中内源磷释放及水体磷浓度得到有效控制. 相似文献
3.
采用 SMT 法结合 X 射线荧光和 X 射线衍射分析了福建省发生富营养化的山仔深水库表层沉积物的磷赋存形态 及对水体的贡献．分析结果表明，山仔水库表层沉积物总磷含量在400-750 mg/kg 之间，铁/铝结合态磷和有机磷是沉积 物磷的主要赋存形态，分别占总磷含量的47%和37%左右．沉积物水-土界面存在明显的活性磷梯度，在一定条件下活 性磷可以从沉积物间隙水扩散到上覆水体，从而一定程度上影响山仔水库水体的营养水平． 相似文献
4.
模拟水体pH控制条件下太湖梅梁湾沉积物中磷的释放特征 总被引：9，自引：1，他引：8
采用缓冲溶液控制水体pH值,模拟研究了太湖梅梁湾沉积物扰动悬浮状态下水体磷的释放规律(48h),分析了实验前后沉积物中磷的赋存形态组成及变化特征.结果表明,pH条件对沉积物磷释放具有显著影响,强酸性(pH=2.0)及碱性(pH=9.5,11.8)条件下皆利于磷的释放,但强酸性水体磷含量随时间逐渐降低,而碱性水体磷呈持续释放状态;中性条件(pH=7.2)磷的释放释放作用不明显,磷释放达到稳定状态(14b)后,碱性条件下(pH=9.5,11.8)磷释放量为酸性(pH=2.0,4.6)及中性(pH=7.2)条件下的4倍以上,通过对比释放前、后沉积物中磷的形态组成可知,酸性条件主要为钙结合态磷的释放;碱性条件主要是铁结合态磷释放,部分可发生再沉淀,转化为钙结合态磷,研究表明,梅梁湾沉积物中铁结合态磷的解析是沉积物磷的主要释放源,是水体内源磷增加的重要贡献者. 相似文献
5.
磷的过度输入是湖泊富营养化的关键原因,由于内源(沉积物)磷的释放,即使外源磷输入得到控制,富营养化湖泊的水质仍难以改善.近年来,利用镧改性膨润土(lanthanum modified bentonite,LMB)原位钝化沉积物中的磷,抑制湖泊内源磷释放备受关注.为了更好地理解和应用镧改性膨润土钝化磷技术,本文首先介绍镧改性膨润土的组成和其钝化磷的原理,其次梳理LMB磷钝化技术在富营养化湖泊中的应用效果,再分析影响LMB钝化磷效率的因素,最后阐述LMB在应用过程中可能产生的生态风险;并根据以上分析,提出LMB磷钝化技术应用中需要注意的方面,对该技术的后续研究方向进行展望. 相似文献
6.
以自主研发的煅烧改性净水厂污泥（C-WTPS）作为污染底泥活性覆盖材料，室内静态模拟实验研究C-WTPS覆盖强度对控制底泥磷释放效果的影响，分析C-WTPS和底泥中不同形态磷含量变化，探讨C-WTPS薄层覆盖对上覆水体中pH、DO和ORP的影响.结果表明，实验历时40天，在底泥TP释放强度为6.25~10.87 mg/（m2·d）时，覆盖强度为0.25、0.50、1.00、1.50和2.00 kg/m2的C-WTPS对TP平均削减率分别为59.68%、75.71%、88.75%、92.42%和96.28%，可见覆盖强度为1.00 kg/m2以上的C-WTPS能控制底泥中90%以上TP释放.C-WTPS吸附的磷主要以无机磷（IP）中的铁铝结合态磷（NAIP）形式存在，有机磷（OP）和钙磷（AP）形式较少.C-WTPS促进了底泥中易释放形态磷迁移到C-WTPS中，并转化较为稳定的形态磷，可见C-WTP覆盖不仅控制了底泥磷释放，而且也削减了底泥磷释放风险.C-WTPS覆盖后，上覆水体中pH开始呈现下降趋势，最终维持在pH=7范围波动；C-WTPS覆盖强度越大，上覆水体pH下降也明显；C-WTPS覆盖改善上覆水体中DO和ORP环境的效果不明显. 相似文献
7.
湖泊富营养化是世界面临的重大环境问题,磷在沉积物-水界面的循环在富营养化过程中起关键作用,因此,研究沉水植物对沉积物-水界面磷循环的作用及其机理具重要的理论和实践意义.本实验通过在水泥池中(4.0 m×7.0 m×1.5 m)种植苦草(Vallisneria natans),并采用定期更换原位上覆水的方式模拟自然状态下的水体交换,研究了沉水植物苦草从定植到生长末期沉积物中不同形态磷含量的变化,以期揭示期间苦草对沉积物中磷赋存形态的影响.结果表明,本实验条件下苦草经历了两个生长阶段,在约1个月的快速生长期内能显著降低沉积物中的总磷(TP)含量,TP含量降低了78.79 mg/kg,其中有机磷(Org-P)含量降低49.99 mg/kg,对TP降低的贡献度为62.67%,而钙结合态磷(Ca-P)比对照组减少2.20%,因此,苦草可能主要通过促进Org-P的矿化向水柱和间隙水中释放磷的方式降低沉积物中TP含量,其次苦草可促进Ca-P的分解;此外,苦草为满足植株生长,所吸收的沉积物铁结合态磷(Fe-P)和铝结合态磷(Al-P)分别为2.99和4.10 mg/kg,但苦草对沉积物中闭蓄态磷(Oc-P)含量没有显著影响.在缓慢生长阶段,苦草促进有机物的沉降以及Fe-P和Oc-P的形成,Fe-P和Oc-P含量分别增加14.82和101.53 mg/kg.苦草对Al-P的形成也略有促进作用,其含量升高7.39%.研究结果表明,苦草在不同生长阶段对沉积物中磷形态的转化以及各形态磷的迁移方向具有不同的影响.在快速生长期苦草转化吸收高活性磷,将其固定到植株体内;缓慢生长阶段则促进水体中的磷转化成沉积物中难分解态的磷,对磷的沉降表现出积极促进作用. 相似文献
8.
福建山仔水库不同季节表层沉积物内源磷负荷分析 总被引：4，自引：0，他引：4
对山仔水库沉积物各形态磷的季节性特征以及夏、冬季磷释放速率进行研究.结果表明,该水库表层沉积物含有较丰富的磷,4个季节各采样点表层沉积物总磷含量范围为(521.23±7.60)~(1255.54±11.03)μg/g,夏季各采样断面中总磷含量及各形态磷含量均高于其他季节.表层沉积物磷以无机磷为主,且主要赋存形态为铁/铝结合态磷.活性较大的铁/铝结合态磷和有机磷占总磷量的77%~90%.柱状样模拟实验结果表明:夏季溶解性磷释放平均速率范围在1.66~2.49 mg/(m2·d),冬季溶解性磷释放平均速率范围为0.69~1.29 mg/(m2·d),夏季各采样点表层沉积物磷释放速率约为冬季的2倍.由于水温分层,夏季沉积物释放的溶解性磷主要滞留在上覆层,但夏季暴雨天气可能导致水温分层破坏,沉积物释放的溶解性磷对水体将产生重要影响;冬季由于水温分层破坏导致上、下水层混合,沉积物释放的溶解性磷被带到上层,对上覆水体水质的影响不容忽视. 相似文献
9.
滇池水-沉积物界面磷形态分布及潜在释放特征 总被引：14，自引：3，他引：11
通过现场调查和室内模拟实验,对滇池35个上覆水-沉积物磷的分布特征以及沉积物中磷释放动力学特征进行研究,结果表明:滇池表层沉积物中不同形态磷含量表现为:有机磷(OP)(1482.49±1156.82 mg/kg)钙结合态磷(Ca-P)(865.54±558.40 mg/kg)金属氧化物结合态磷(Al-P)(463.77±662.18 mg/kg)残渣态磷(Res-P)(218.52±83.11 mg/kg)可还原态磷(Fe-P)(128.13±101.56 mg/kg)弱吸附态磷(NH4Cl-P)(2.26±3.05 mg/kg);滇池上覆水草海总磷浓度处于劣Ⅳ类水平,外海不同湖区总磷浓度介于Ⅳ~Ⅴ类之间;滇池水体中的磷以颗粒态磷含量最高;滇池表层沉积物中磷的释放是由快反应和慢反应两部分组成.释放过程主要发生在前8 h内;不同区域沉积物磷的最大释放速率、最大释放量、磷的释放潜力平均值均表现为:草海外海北部外海南部湖心区;滇池表层沉积物中磷的释放主要由NH4Cl-P、Fe-P、Al-P和OP进行,其中,NH4Cl-P和Fe-P所占比重较大;磷的释放与上覆水中溶解性总磷、溶解态无机磷和溶解态有机磷呈显著正相关,预示着上覆水中磷的迁移转化更多地受到水-沉积物界面浓度梯度的控制,进一步说明不能以总磷含量来评价湖泊磷素释放的状况,需与磷形态及分布特征相结合进行分析. 相似文献
10.
长江中下游湖泊沉积物中磷的形态及藻类可利用量 总被引：13，自引：1，他引：13
调研了长江中下游地区25个浅水湖泊的35个样点表层沉积物中磷的地球化学形态特征,以及太湖沉积物中藻类可利用磷(AAP)的空间分布,垂向分布特征及其蓄积量,探讨了浅水湖泊表层沉积物中磷的赋存量,地球化学形态及其与水草,湖水磷浓度,叶绿素(Chl-a)浓度之间的关系.结果表明,长江中下游地区浅水湖泊的表层沉积物中可交换态磷(Ex-P)含量与水体总磷(TP),溶解性总磷(DTP)及溶解性反应活性磷(SRP)浓度关系密切,有水草湖区的沉积物中生物易利用磷(Bio-P)含量显著低于无水草湖区及藻型湖区.太湖梅梁湾沉积物泥芯中,表层3 cm沉积物中Ex-P含量显著增高,而夏季还原条件下容易转变为溶解态磷的铁磷(Fe-P)含量峰值则出现在4～10cm深度.太湖表层沉积物的Bio-P含量与夏季叶绿素浓度密切相关,说明表层沉积物的Bio-P及AAP可以作为沉积物内源释放风险的指示参数.太湖表层1 cm底泥中所含有的AAP量估计多达268.6吨,风浪扰动能将大量的AAP带入水体,对太湖蓝藻水华暴发起着不可忽视的作用. 相似文献
11.
分析湖泊中磷浓度的变化特征,揭示其变化的驱动机制,是有效实施湖泊水体磷浓度控制的前提.本文整理分析了太湖70年来(1949 2020年)水体磷浓度监测历史资料,对比了太湖不同湖区、不同时间尺度水体磷浓度的差异性及波动性,发现影响太湖磷浓度变化的原因既有人为的因素,也有自然的因素.无论是污染较轻的1950年,还是污染负荷相对较重的近30年,太湖水体磷浓度一直存在较大时空差异性.暴雨引发入湖河流携带磷污染的扩散、风浪扰动引起的内源释放及蓝藻水华期间藻类生物量的大幅时空变化,都加剧了太湖水体磷浓度的不稳定性.近20年的太湖水污染治理对磷浓度的时空分布影响明显,1998年的太湖水污染治理"零点行动",2007年以来的水利调度等系列水污染治理工程,以及2017年以来的藻情变化等,都对太湖水体磷浓度的时空格局产生了影响.然而,高强度治理投入下太湖水体磷浓度依然偏高,其原因与流域建设用地比例增加、人口增加、耕地种植结构变化等外源负荷因素发生变化有关,也与湖体沉水植被退化、出入流结构发生变化、气候变化引发的蓝藻水华扩张等内源强度及水体表观磷浓度决定因素的生态环境变化有关.近70年来太湖水体磷浓度的变化过程对类似大型浅水湖泊的磷控制策略具有启示意义:大型浅水湖泊存在磷浓度较大波动的自然属性,在水环境保护目标考核中应充分考虑其不确定性,制定切实可行的控制目标;在控制策略上应将外源负荷控制放在首位,在流域污水处理厂深度除磷及流域土地利用调整等方面采取措施,实现入湖磷负荷的大幅削减,同时实施湖体生态修复与食物链调控措施,才能逐步实现湖泊水体磷浓度的控制目标. 相似文献
12.
菹草、伊乐藻对沉积物磷形态及其上覆水水质的影响 总被引：3，自引：1，他引：2
采集武昌南湖湖水、沉积物进行沉水植物的盆栽试验,试验设置沉积物未施磷处理和施100mg/kg磷处理,分别对应沉积物低内源磷和高内源磷状态,同时种植菹草、伊乐藻,以研究沉积物中磷形态及上覆水水质的变化特点.研究从2007年9月15日开始,历时160d.结果表明,高内源磷沉积物处理后,上覆水中水溶性总磷含量在沉水植物的作用下明显降低;种植沉水植物可使水体总磷、总氮、叶绿素a含量显著降低,且伊乐藻对总磷的净化效果优于菹草;沉水植物对高内源磷沉积物的上覆水中叶绿素a的控制比对低内源磷条件下的效果更好;无论沉积物是否输入磷,在盆栽条件下,上覆水中叶绿素a随时间的变化均能较好地用一级动力学模型来描述;上覆水TDP、TP与沉积物中Ca_(10)-P之间有极显著正相关;种植菹草或伊乐藻的沉积物中Ca_(10)-P与上覆水中TDP和TP的相关系数分别为0.990(P≤0.01)和0.977(P≤0.05). 相似文献
13.
氮、磷浓度是制约湖泊营养状态和生产力水平的重要环境因子,而氮磷化学计量比是湖泊生态系统的主要指标,因此,判识氮磷比变化趋势及其驱动力对湖泊生态恢复具有重要意义.研究基于19882018年连续观测数据,分析了滇池氮磷浓度和氮磷摩尔比(简称氮磷比)的时空分布演变特征;采用多元线性回归模型分别对滇池草海和外海氮磷比驱动效应进行定量解析,筛选出影响湖体氮磷比变化的潜在驱动因子.结果表明:①19882018年滇池氮磷比呈现显著的线性上升趋势,其中草海和外海氮磷比分别上升1.3和0.7 a^-1.②草海和外海分别在2008年和2004年发生了氮磷比上升突变,突变前上升归因于总氮浓度快速增加,突变后则是由于总磷浓度下降较快.③滇池的氮磷浓度变化主要是受流域氮磷输入负荷、跨流域调水、流域氮磷削减、风速和水位的综合影响,但受控因子在不同区域可能存在差异.④气温是滇池氮磷比变化的主要驱动因子,流域人为氮磷输入差异是滇池氮磷比变化的次要驱动因子. 相似文献
14.
Spatiotemporal variations of internal P-loading and the related mechanisms in the large shallow Lake Chaohu 总被引：2，自引：1，他引：2
Spatiotemporal variations of P species and adsorption behavior in water column, interstitial water, and sediments were investigated in the large shallow eutrophic Lake Chaohu. Ortho-phosphate (Ortho-P) and total phosphorus (TP) concentrations were significantly higher in the western part than in the eastern part of the lake, due to different nutrient inputs from the surrounding rivers. Moreover, paniculate phosphorus (PP) concentration was in a similar spatial pattern to Ortho-P and TP concentrations, and also showed significantly positive correlation with the biomass of Microcystis, indicating more uptake and store of phosphorus by Microcystis than by other algae. Increase of pH and intensive utilization of P by phytoplankton were the main factors promoting P (especially Fe-P) release from the sediment to interstitial water during the cyanobacterial blooms in Lake Chaohu. Spatial dynamics in TP concentration, P species and adsorption behavior of the sediment, coupled with the statistical analyses, suggested that the spatial heterogeneity of P contents in the sediment was influenced by various factors, e.g. human activities, soil geochemistry and mineral composition. In spite of similar TP contents in the sediments, increase in proportion of Fe-P concentration in the sediment may result in a high risk of P release. 相似文献
15.
《国际泥沙研究》2020,35(2):146-156
Many of the dams built in estuaries in the last century have difficulty with water quality management.Numerous factors have affected the estuary lake water,most importantly external loadings,tidal currents,and increases in the phosphorus(P) release from sediment,so that most water quality characteristics in the estuary are highly interactive and dynamic.In the current study,water quality measurements were made in the laboratory and field,and a series of phosphorus release experiments was done to understand the behavior of P in an estuary lake.The concentrations of chemical oxygen demand(COD),chlorophyll-a(Chl-a),and total P(TP) showed an increasing trend when the pollutant loading of the influent stream water was high.The measurements showed increasing trends,which indicates the constituents are produced in the internal environment of the lake.When a large amount of freshwater flowed in from the upper watershed,density stratification was observed,which forms strongly because of the salinity of seawater.During the period of stratification,a hypoxic layer formed,which can accelerate P release.Comparing the open and dosed conditions of the release experiments,the P release rate was much higher under the closed condition than under the open condition.The maximum P release rates from the sediment collected from the five main sites of the lake were more than 2.5 times the P loading from the inflowing streams in April.Spatially,the release rate was higher mid-reservoir than down-reservoir where a halocline was evident The pollutant load discharged from the tributary watershed was deposited on the bottom mid-reservoir,whereas it was washed out downreservoir because of the density stratification and strong tide in that area.To sustainably manage water quality and decrease lake eutrophication in brackish environments formed by freshwater from streams mixing with seawater entering through sluice dikes,different measures than those applied in strictly freshwater environments are required.Considering the spatial characteristics of an estuary lake,these measures include 1) blocking settleable particles discharged from the rivers upstream,2) controlling hypoxia to avoid P release from the sediment and inhibiting algae growth mid-reservoir,and 3)decreasing stratification caused by the halocline down-reservoir. 相似文献
16.
Peter Herzsprung Martin Schultze Bertram Boehrer Anja Duffek Andrea Van der Veen Kurt Friese 《Limnologica》2010,40(2):182-190
Between 1999 and 2002, a former open-cast mine was filled with river water forming the recent Lake Goitsche. During filling initially acid water was neutralised. Phosphorus (P) imported from Mulde River was nearly completely removed from the water column by co-precipitation with iron (Fe) and aluminium (Al) and deposited in the sediment.During extremely high waters of the Mulde River in 2002, a dike breach facilitated a second high import of P into Lake Goitsche with suspended and dissolved matter. The analysis of total phosphorus (TP), however, showed that P again had been eliminated from the water body a few months after the flood event. Sediment investigations before filling with river water, during filling, and after the flood event were used to analyse the process of P immobilisation in a lake with acid mine drainage history.The ratios of Fe to soluble reactive P (SRP) of sediment pore water were up to three orders of magnitudes higher than in natural lakes and can serve as an indicator for potential internal P loading from sediments. The SRP concentrations at the oxic/anoxic boundary were near or below the limit of quantification (< 0.2 μmol/L). Fe and manganese (Mn) redox cycling were responsible for hindering P dissolution from sediment to lake water.Finally it can be stated, that the risk of eutrophication for such a lake seems to be low. 相似文献
17.
Experimental study on phosphorus release from sediments of shallow lake in wave flume 总被引：2，自引：2，他引：2
Influence of wave on sediment resuspension and nutrients release from sediments, collected from Lake Taihu and Lake Chaohu, was studied in flume experiments. Under strong-wave conditions, concentrations of suspended solids (SS), total phosphorus (TP) and dissolved total phosphorus (DTP) in overlying water were increased significantly following the sediments re-suspension. During the experiments on sediments of Lake Taihu and Lake Chaohu, TP concentrations increased 6 times and 3 times, and DTP concentration increased 100% and 70% more than it in presuspension, respectively. Concentration of soluble reactive phosphorus (SRP) of experiment on sediment of Lake Taihu increased 25%. During the massive sediment suspension, the dissolved phosphorus in pore water and much of the phosphorus adsorbed by the sediment particles were released into overlying water. The phenomena in this wave flume experiment are quite similar to the situation observed in situ of Lake Taihu. The critical wave stresses of sediment re-suspension are nearly equal. The change of concentrations of SS, TP, and SRP was the same as that in situ situation. This study showed that concentrations of TP and SRP in lake water could be increased significantly by wave disturbance. Phosphorus release was significantly enhanced by wave disturbance at the beginning of massive sediment re-suspension, but decreased later. 相似文献
18.
The mechanisms which controls the fixation and/or release of P in sediment of an extremely acidic lake（pH = 2.0 to 3.0） and its response to the influence of eutrophic urban waste water were investigated.The results,in the chemical composition,in the mineralogy of the sediment and in the material as obtained from sediment traps,show that the lake sediments are mainly volcanic material reflecting volcanic features of the basin.The sedimentation rate calculated for the lake(2.5×10-2 mg m-2 day-1) was higher than that observed in other similar glacial lakes in both Andean Patagonia and also elsewhere in the world.The Total Phosphorus concentration in sediments was higher than figures reported by other authors for mining acid lakes,and the main fraction of P was found associated with organic matter.There was no control by Fe or Al on P,because both are in solution at pH < 3.0.It was concluded that changes in the natural input of nutrients（derivatives of Copahue volcano fluid,the discharge of sewage,or basin run-off） are responsible for a high concentration of SRP and N-NH4+ in the lake.Laboratory experiments showed that sediments have no ability to retain phosphorus and a continuous release of P from the sediments into the water column was observed.The assays where the pH was artificially increased showed that the P still remains in solution until at least pH 7.0.It was concluded that changes in the natural input of nutrients due to:1) the volcanic fluids,2) the increase in sewage charges,or 3) surface runoff upstream,maintain a high trophic state with high concentrations of dissolved P and N-NH4+,although the threshold of neutral pH in the lake is exceeded.This study will enable a better understanding about of the mechanism of release/fixation of phosphorus in acidic sediments in order to assist in making decisions regarding the conservation and management of this natural environment. 相似文献
19.
Peter M. Homyak James O. Sickman John M. Melack 《Aquatic Sciences - Research Across Boundaries》2014,76(4):511-525
In high-elevation lakes of the Sierra Nevada (California), increases in phosphorus (P) supply have been inferred from changes in phytoplankton growth during summer. To quantify rates of sediment P release to high-elevation Sierran lakes, we performed incubations of sediment cores under ambient and reducing conditions at Emerald Lake and analyzed long-term records of lake chemistry for Emerald and Pear lakes. We also measured concentrations of individual P forms in sediments from 50 Sierra Nevada lakes using a sequential fractionation procedure to examine landscape controls on P forms in sediments. On average, the sediments contained 1,445 µg P g?1, of which 5 % was freely exchangeable, 13 % associated with reducible metal hydroxides, 68 % associated with Al hydroxides, and the remaining 14 % stabilized in recalcitrant pools. Multiple linear regression analysis indicated that sediment P fractions were not well correlated with soluble P concentrations. In general, sediments behaved as net sinks for P even under reducing conditions. Our findings suggest that internal P loading does not explain the increase in P availability observed in high-elevation Sierran lakes. Rather, increased atmospheric P inputs and increased P supply via dissolved organic C leaching from soils may be driving the observed changes in P biogeochemistry. 相似文献