不同退耕年限下菜子湖湿地土壤磷素组分特征变化

选取菜子湖区不同退耕年限(2、5、8、10a和20a)湿地为研究对象,以仍耕作油菜地和原始湿地为参照,分析了土壤全磷(TP)、有效磷(AP)、有机磷(OP)和无机磷(IP)各形态含量,探讨退耕还湖后湿地土壤磷素组分特征变化规律。结果表明:研究区土壤无机磷各形态含量大小顺序为:铁磷(Fe-P:73.55—391.76 mg/kg)钙磷(Ca-P:21.64—108.04 mg/kg)闭蓄态磷(O-P:17.15—29.57 mg/kg)铝磷(Al-P:5.84—25.97 mg/kg),其中Fe-P占了土壤无机磷总量的54.20%—74.13%;退耕还湖2—8a期间,湿地土壤Al-P、Fe-P和O-P含量有逐渐降低趋势,而退耕8—20a后逐渐上升,以Fe-P为主的这3形态磷左右着退耕后土壤无机磷的变化;Ca-P随退耕年限增加整体呈上升趋势,对土壤无机磷的贡献逐渐增加;无机磷占土壤全磷的比例为35.90%—67.27%,主导着退耕后湿地土壤全磷变化;有机磷占土壤全磷的17.82%—50.51%,在退耕2a后下降,随后开始逐渐上升,对退耕后湿地土壤磷库恢复的贡献逐渐增加;其中Fe-P、O-P和Al-P控制着退耕后土壤磷素有效性变化。退耕后水文条件、植被生长和土壤黏粒含量变化不仅影响退耕后湿地土壤磷素组分特征,也影响着退耕后湿地土壤磷素有效性。     

哈尼梯田湿地土壤不同形态磷的时空分布特征

磷是湿地和农业生态系统中的重要元素之一,其中土壤磷形态的迁移转化广受关注。以哈尼梯田湿地为例,分别在哈尼梯田湿地的水稻生长期、收获期和休闲期,采集湿地不同海拔（梯田区上部、中部和下部）和不同深度的土壤（0-20 cm,20-40 cm,40-60 cm,60-80 cm）进行磷形态分析,研究了哈尼梯田湿地土壤中不同形态磷的时空分布规律和影响因素。结果表明：（1）哈尼梯田湿地土壤中总磷（TP）含量均值为318.74 mg/kg,在水稻收获期含量最高,无机磷（IP）含量均值在水稻休闲期最高（85.95 mg/kg）,湿地土壤磷总体呈缺乏状态。（2）受外源磷输入影响,铁铝结合态磷（NaOH-P）占无机磷比重最大,且季节差异性显著（P<0.05）;而钙结合态磷（HCl-P）在各季节无显著差异（P>0.05）,这与湿地生态环境和地质背景有关。（3）哈尼梯田湿地对磷的迁移有截留作用,表现为各形态磷含量总体呈现在上部梯田湿地较高,并随海拔的降低而降低;不同形态磷含量在20-40 cm土层富集。（4）除HCl-P外,其余形态磷与土壤粒径在不同土层表现为负相关;不同土层TP和有机磷（OP）与pH值呈正相关;土壤总有机碳（TOC）与不同形态磷在收获期呈显著负相关（P<0.05）。研究表明了哈尼梯田湿地立体空间结构和人为活动能影响湿地生态系统中磷的分布与迁移循环,该结论可为梯田湿地的可持续发展提供参考。     

农田杂草还田对土壤磷素形态的影响

提高农田土壤磷素的可利用性,减少磷肥施用,对促进农业的可持续发展及缓解全球磷素危机具有重要意义。通过盆栽试验模拟夏季田间植物还田,比较红薯(Ipomoea batatas)、绿豆(Vigna radiata)以及杂草(千金子(Leptochloa chinensis)+水苋菜(Ammannia baccifera)混合) 3种夏季经营模式在还田期间土壤磷形态的变化,探索农田杂草还田提高土壤磷素可利用性的潜力。结果表明:绿豆还田主要通过增加碱性磷酸酶和土壤微生物活性促进有机磷矿化;红薯还田在腐解前期增加土壤速效磷,而后期磷素易流失或被固定成有效性较低的磷形态;杂草还田可以显著提升土壤速效磷,使有效性较低的闭蓄态磷(OP)、磷灰石(Ca₁₀-P)及磷酸铁盐(Fe-P)持续性地向有效性较高的磷酸二钙(Ca₂-P)、磷酸八钙(Ca₈-P)及磷酸铝盐(Al-P)转化,并整体保持在有效性较高的水平。杂草还田使以Ca₈-P形式保留在土壤中的磷素显著增加,提升土壤磷素可利用性的同时减小磷素流失的风险;杂草还田也显著...     

鹭鸟栖息对杭州湾湿地土壤磷累积及形态分布的影响

土壤中磷含量对维持生态系统平衡起着重要作用。为研究杭州湾湿地迁徙候鸟栖息以及鸟粪的输入对栖息地土壤生态环境的影响,开展了鹭鸟筑巢树林下（影响区）和无鹭鸟筑巢树林下（对照区）土壤磷累积、土壤及鸟粪磷形态分布研究。结果表明：鹭鸟影响区土壤有机碳（Soil Organic Carbon,SOC）、全氮（Total Nitrogen,TN）、全磷（Total Phosphorus,TP）、有效磷（Available Phosphorus,AP）含量显著高于对照区（P<0.05）;对照区土壤TP含量为718.33 mg/kg,影响区土壤TP平均含量最高可达2040 mg/kg,其中钙结合态磷（Ca-bound P,Ca-P）含量最高,约占55.22%-62.96%,其次是残渣态磷（Residual Phosphorus,RP）、有机磷（Organic Phosphorus,OP）、铁铝结合态磷（Fe/Al-bound P,（Al+Fe）-P））、交换态磷（Exchangeable P,Exch-P）。鸟粪中有机碳（Organic Carbon,OC）、TN、TP含量分别是表层土壤的11.18-40.90倍,94.22-148.11倍,15.41-43.22倍,差异极显著（P<0.01）。TP含量与Exch-P、（Fe+Al）-P、Ca-P、AP极显著正相关,与RP显著正相关,与pH显著负相关。结果表明鸟粪输入使杭州湾湿地土壤TP含量显著提高,Exch-P、（Fe+Al）-P、Ca-P、AP含量均有提高,且占TP百分比增大,鸟粪输入造成了该地土壤磷素累积的同时增加了土壤磷素的流失风险。     

土壤中铁锰的形态分布及其有效性研究

以乌鲁木齐雅马里克山的土壤为研究对象,采用Tessier连续提取法对土壤铁、锰各种化学形态进行浸提.研究了土壤中有效铁、锰和土壤的理化性质与土壤铁、锰形态之间的关系,及对铁、锰在土壤中存在形态的影响;并通过盆栽试验对铁、锰的植物有效性进行了分析.结果表明,土壤铁主要以残渣态为主,占全铁的92.3%,其它形态含量均小于全量的8%.土壤锰主要是以铁锰氧化态和残渣态为主,分别占全锰的49%和41.6%,其它形态含量均小于全量的10%.用二级出水灌溉处理可增加铁、锰的有效性,原污水灌溉不利于铁、锰的供应,土壤缺铁、锰的现象可通过施加一定量的铁盐和锰盐而得以改善.相关分析还表明,土壤的理化性质与铁锰形态之间有一定的相关性.供试土壤的pH值、CaCO3含量、有机质及阳离子交换态等对土壤铁、锰的有效性影响较大.逐步回归分析表明,铁的氧化物结合态对植物最为有效,锰的有机结合态对植物有效性贡献最大.     

农田土壤中磷素有效性及影响因素

土壤中磷的有效性直接决定着农田生产力. 基于分布于我国不同气候区长期定位施肥试验,总结了不同农田土壤的磷素含量、有效性及转化的影响因素.结果表明： 目前我国不同类型的土壤中全磷含量在0.31～1.72 g·kg^-1,速效磷含量在0.1～228.8 mg·kg^-1.土壤母质、理化性质和施肥方式是影响农田土壤磷素有效性的主要因素,未来应注重有机肥和化肥的混合施用以提高农田土壤磷素有效性,并关注可能导致的环境影响.     

农田开垦对三江平原湿地土壤种子库影响及湿地恢复潜力

种子库是湿地植被恢复的重要途径之一,不同时期的耕作土壤中残留的种子对开垦湿地恢复具有重要的作用.本文采用温室萌发法在两种水分条件下对三江平原天然湿地、不同开垦年限湿地种子库结构和规模进行了研究,以了解不同开垦年限湿地种子库特征及其在湿地植被恢复中的潜力.本次实验共萌发物种50种,随着开垦年限增加,萌发物种逐渐减少,天然湿地、开垦1年、3年、10年、20年的湿地分别为34种、31种、21种、21种和8种,萌发物种数与种子库规模均表现出极显著差异(F1=8.32,F2=5.946,P＜0.001).种子库密度以天然湿地和开垦1年湿地最大,分别为7624粒/m2,9836粒/m2.随着开垦年限增加,种子库规模逐渐减小,开垦3年、10年种子库密度为4336粒/m2,4872粒/m2.开垦20 a后,显著减少为432粒/m2.湿润条件下萌发物种数及种子密度显著高于淹水处理,种子库具有明显的分层现象,0-5 cm土层种子库规模显著高于5-10 cm.小叶章(Calamagrostis angustifolia)作为该地区优势物种,由最初的1192粒/m2,经过20 a开垦后在种子库中消失.研究表明,在一定的开垦年限范围内,开垦湿地土壤中仍然保留大量的湿地物种种子,在湿地恢复中具有重要的作用.     

林下养鸡年限对杨树人工林土壤磷素形态和生物有效性的影响

林下养殖是一种经济有效的林地空间利用方式,但长期高负载的林下养殖对林地土壤性状究竟产生何种影响,目前尚无定论.以不同林下养鸡年限(0年、1年、3年和5年)的美洲黑杨(Populus deltoides)人工林为对象,采用Hedley磷素分级法,分析其林地土壤的磷素组成和形态变化,探讨林下养鸡年限对土壤磷库特征及其生物有...     

鸟粪对同里湿地公园土壤重金属及其形态的影响

为了解鸟粪对同里湿地公园土壤重金属全量及形态转化的影响,测定了公园内有鸟粪土壤、无鸟粪土壤、鸟粪沉积物的理化性质,Co、Cr、Cu、Ni、Zn全量及其形态分布,并进行统计分析。结果显示:同里湿地公园土壤及沉积物p H值平均含量达4.5,N、C、H、S和TP平均含量分别达到3.69、38.07、10.97、0.52、1.43g/kg,有鸟粪土壤中N、C、H和S含量显著高于无鸟粪土壤。Cu、Zn、Co平均含量呈现出鸟粪沉积物有鸟粪土壤无鸟粪土壤;Cr的平均含量表现为鸟粪沉积物无鸟粪土壤有鸟粪土壤;Ni呈现出有鸟粪土壤鸟粪沉积物无鸟粪土壤。总体上,鸟粪的进入增加了土壤Cu、Zn、Co、Ni含量。因此应及时清理土壤上覆鸟粪,降低对当地重金属污染风险。相对于无鸟粪土壤中不同重金属形态的分布,有鸟粪土壤中Co、Cr、Cu、Zn的活性态占全量的百分比均略有下降,非活性态呈上升趋势。鸟粪的加入,虽然会在一定程度上降低活性态重金属占总量的比例,但因总量和活性态含量均上升,向植物系统的迁移量会呈现增加趋势,因此对鸟粪施肥再利用应慎重。     

Planktonic phosphorus pool sizes and cycling efficiency in coastal and interior British Columbia lakes

1. Limnologists have long acknowledged the importance of phosphorus (P) in determining the organism biomass and productivity of lake ecosystems. Despite a relatively large number of studies that have examined P cycling in lake ecosystems, there remain several substantial methodological issues that have impeded our understanding of P cycling in limnetic plankton communities. Two critical issues confronting ecologists are (1) a lack of precise measurements of the dissolved inorganic phosphorus (PO) and (2) accurate or complete measurements of dissolved P regeneration rates by plankton communities. 2. Here, we examine patterns of epilimnetic planktonic P pool sizes and turnover rates in eight lakes in British Columbia, Canada over a 2‐year period. We determine the concentrations and turnover times of P in various planktonic compartments (dissolved and various planktonic size fractions), using recently developed methods for estimating phosphate concentration and planktonic regeneration rates. 3. The pico‐ and nanoplankton size fraction (0.2–20 μm) played a central role in planktonic P cycling in lakes examined by this study. On average across lakes, pico‐ and nanoplankton contained >60% of the planktonic P, accounted for >90% PO uptake, and contributed 50% of the plankton community dissolved P regeneration rate. 4. PO concentrations determined by steady state bioassays (ssPO) were extremely low (87–611 pmol L⁻¹) and were 2–3 orders of magnitude less than simultaneously measured colorimetric soluble reactive phosphorus estimates. Lake ssPO concentrations increased linearly with total phosphorus (TP), and the slope of this relationship was approximately 1, indicating that PO remained a consistent proportion of the TP pool across a range of TP concentrations. 5. Turnover rates of the total planktonic P pool and the <20 μm pool became more rapid with increasing lake TP, indicating that, according to this metric, planktonic P cycling efficiency increased with TP concentrations. We also detected a significant relationship between particulate phosphorus (PP) <20 μm turnover time and seston N : P ratios, with PP <20 μm turnover times becoming slower with increasing seston N : P. These findings suggest that long‐standing conceptual models of nutrient cycling that predict slower cycling rates and decreasing cycling efficiency with increasing TP concentrations require further empirical examination. We postulate that patterns in lake P turnover and cycling efficiency are a result of complex interactions between plankton biomass and composition, and the ratios of multiple nutrients (C, N, P), rather than solely a function of the TP pool.     

Dynamics of nitrogen and phosphorus retention during wetland ecosystem succession

We compared the mechanisms of nitrogen (N) and phosphorus (P) removal in four young (<15 years old) constructed estuarine marshes with paired mature natural marshes to determine how nutrient retention changes during wetland ecosystem succession. In constructed wetlands, N retention begins as soon as emergent vegetation becomes established and soil organic matter starts to accumulate, which is usually within the first 1–3 years. Accumulation of organic carbon in the soil sets the stage for denitrification which, after 5–10 years, removes approximately the same amount of N as accumulating organic matter, 5–10 g/m²/yr each, under conditions of low N loadings. Under high N loadings, the amount of N stored in accumulating organic matter doubles while N removal from denitrification may increase by an order of magnitude or more. Both organic N accumulation and denitrification provide for long-term reliable N removal regardless of N loading rates. Phosphorus removal, on the other hand, is greatest during the first 1–3 years of succession when sediment deposition and sorption/precipitation of P are greatest. During this time, constructed marshes may retain from 3 g P/m²/yr under low P loadings to as much as 30 g P/m²/yr under high loadings. However, as sedimentation decreases and sorption sites become saturated, P retention decreases to levels supported by organic P accumulation (1–2 g P/m²/yr) and sorption/precipitation with incoming aqueous and particulate Fe, Al and Ca. Phosphorus cycling in wetlands differs from forest and other terrestrial ecosystems in that conservation of P is greatest during the early years of succession, not during the middle or late stages. Conservation of P by wetlands is largely regulated by geochemical processes (sorption, precipitation) which operate independently of succession. In contrast, the conservation of N is controlled by biological processes (organic matter accumulation, denitrification) that change as succession proceeds.     

Phosphorus cycling and partitioning in an oligotrophic Everglades wetland ecosystem: a radioisotope tracing study

1. Our goal was to quantify short‐term phosphorus (P) partitioning and identify the ecosystem components important to P cycling in wetland ecosystems. To do this, we added P radiotracer to oligotrophic, P‐limited Everglades marshes. ³²PO₄ was added to the water column in six 1‐m² enclosed mesocosms located in long‐hydroperiod marshes of Shark River Slough, Everglades National Park. Ecosystem components were then repeatedly sampled over 18 days. 2. Water column particulates (>0.45 μm) incorporated radiotracer within the first minute after dosing and stored 95–99% of total water column ³²P activity throughout the study. Soluble (<0.45 μm) ³²P in the water column, in contrast, was always <5% of the ³²P in surface water. Periphyton, both floating and attached to emergent macrophytes, had the highest specific activity of ³²P (Bq g^?131P) among the different ecosystem components. Fish and aquatic macroinvertebrates also had high affinity for P, whereas emergent macrophytes, soil and flocculent detrital organic matter (floc) had the lowest specific activities of radiotracer. 3. Within the calcareous, floating periphyton mats, 81% of the initial ³²P uptake was associated with Ca, but most of this ³²P entered and remained within the organic pool (Ca‐associated = 14% of total) after 1 day. In the floc layer, ³²P rapidly entered the microbial pool and the labile fraction was negligible for most of the study. 4. Budgeting of the radiotracer indicated that ³²P moved from particulates in the water column to periphyton and floc and then to the floc and soil over the course of the 18 day incubations. Floc (35% of total) and soil (27%) dominated ³²P storage after 18 days, with floating periphyton (12%) and surface water (10%) holding smaller proportions of total ecosystem ³²P. 5. To summarise, oligotrophic Everglades marshes exhibited rapid uptake and retention of labile ³²P. Components dominated by microbes appear to control short‐term P cycling in this oligotrophic ecosystem.     

湿地碳循环过程与计算机模拟研究

湿地是地球4大陆地生态系统之一,全球湿地碳储量(450Pg C)约占陆地生态圈总碳量的20％。湿地系统因兼有“碳源”与“碳汇”的双重角色,其碳循环对大气全球碳收支以及与之有关的全球气候变化可能有重要影响。本文概述了湿地生态系统变化与碳排放的关系、湿地碳循环基本过程及其主要影响因子和湿地碳循环计算机模拟研究进展,提出了拟进一步研究的重要问题。     

白骨壤模拟湿地系统中磷的分配循环及其净化效应

在温室中建立红树林植物白骨壤模拟湿地系统 ,分别用正常、5倍和 10倍 3种不同浓度的人工配置的污水每周定时定量对模拟系统进行污灌 1a。研究营养污染物 P在系统中的分配、循环及其被净化的效果。结果表明 :随污水处理浓度的升高 ,被更换的潮汐水中的含 P量和土壤含 P量都有明显提高 ;植物体各部分含 P量的高低顺序排列为 :叶 >茎 >根 ;在植物 -土壤系统中4个组分 CA0 、CA1 、CA5和 CA1 0 植物中 P元素的周转期依次为 4 .70 a、4 .6 1a、3.80 a和 5 .4 4 a;模拟植物 -土壤系统对污水中 P的净化效果显著 ,CA1 、CA5和 CA1 0 组的净化率分别为 81.2 3%、94 .4 0 %和 95 .6 3%。     

闽江河口湿地土壤全磷高光谱遥感估算

磷是湿地生态系统必需和限制性元素,利用高光谱遥感数据对其进行估算对实现湿地土壤磷素快速和准确定量具有重要意义。选取闽江河口湿地作为研究区,于2013年5月,采集16个土壤剖面80个样本作为估算与验证模型样本;基于光谱指数建立土壤全磷(TP)含量估算模型,其中光谱指数包括原始光谱反射率(R)、比值土壤指数(RSI)、归一化土壤指数(NDSI)和有机质诊断指数(OII)。此外进一步分析反射光谱与不同形态磷,TP与有机质之间关系,以期初步揭示河口湿地土壤TP估算的机理。研究结果表明,闽江河口湿地土壤TP含量与R相关系数较高的区域分布在360-560 nm,并在406 nm处达到最大值-0.816;光谱指数RSI(R_(430),R_(830))、RSI(R_(460),R_(810))、RSI(R_(560),R_(580))、NDSI(R_(430),R_(830))、NDSI(R_(460),R_(830))、NDSI(R_(560),R_(580))和OII(R_(446))与土壤TP含量均有较高的相关系数,能较好的用于TP含量的估算;各估算模型决定系数(r~2)和均方根误差(RMSE)分别在0.657-0.805和0.052-0.067之间;验证模型r~2和RMSE分别在0.606-0.893和0.037-0.044之间。分潮滩建立TP含量估算模型是可行的,并且能提高部分光谱指数的估算精度。土壤TP含量的估算精度与磷素的组成有关,其中与铁吸附态磷关系较为密切,钙吸附态和铝吸附态磷关系较弱。土壤TP与有机质和氧化还原环境的存在密切关系可能是湿地土壤TP含量估算的重要机理。     

Effects of climate on soil phosphorus cycle and availability in natural terrestrial ecosystems

Climate is predicted to change over the 21st century. However, little is known about how climate change can affect soil phosphorus (P) cycle and availability in global terrestrial ecosystems, where P is a key limiting nutrient. With a global database of Hedley P fractions and key‐associated physiochemical properties of 760 (seminatural) natural soils compiled from 96 published studies, this study evaluated how climate pattern affected soil P cycle and availability in global terrestrial ecosystems. Overall, soil available P, indexed by Hedley labile inorganic P fraction, significantly decreased with increasing mean annual temperature (MAT) and precipitation (MAP). Hypothesis‐oriented path model analysis suggests that MAT negatively affected soil available P mainly by decreasing soil organic P and primary mineral P and increasing soil sand content. MAP negatively affected soil available P both directly and indirectly through decreasing soil primary mineral P; however, these negative effects were offset by the positive effects of MAP on soil organic P and fine soil particles, resulting in a relatively minor total MAP effect on soil available P. As aridity degree was mainly determined by MAP, aridity also had a relatively minor total effect on soil available P. These global patterns generally hold true irrespective of soil depth (≤10 cm or >10 cm) or site aridity index (≤1.0 or >1.0), and were also true for the low‐sand (≤50%) soils. In contrast, available P of the high‐sand (>50%) soils was positively affected by MAT and aridity and negatively affected by MAP. Our results suggest that temperature and precipitation have contrasting effects on soil P availability and can interact with soil particle size to control soil P availability.     

施磷对川西北高寒草地土壤磷形态及有效性的影响

以川西北高寒草地为研究对象,采用随机区组设计,设置0、10、20、30、40、50、60 g/m²的过磷酸钙(P₂O₅,16%)施肥试验,分析土壤不同形态磷含量和有效磷(Olsen-P)含量变化特征,探究施磷对川西北高寒草地土壤磷形态及有效磷的影响。结果表明：(1)随施磷量增加,土壤总磷(TP)含量先增加后趋于平稳而Olsen-P含量减少。高水平(50、60 g/m²)施磷下氢氧化钠有机磷(NaOH-Po)及残留磷(Residual-P)是高寒草地主要的磷素累积形态,其含量显著高于不施磷处理;(2)树脂交换态磷(Resin-Pi)、碳酸氢钠无机磷(NaHCO₃-Pi)、碳酸氢钠有机磷(NaHCO₃-Po)和氢氧化钠无机磷(NaOH-Pi)含量随施磷量增加整体呈先增加后降低趋势,表层土壤30 g/m²磷肥用量下其值均为最高,分别为21.54、22.94、65.86、64.48 mg/kg。酸溶性无机磷(HCl-Pi)随施磷量增加整体呈下...