Adsorption of PAHs on the Sediments from the Yellow River Delta as a Function of Particle Size and Salinity

In a seawater environment, the particle size of sediment and salinity play an important role in the adsorption behaviors of polycyclic aromatic hydrocarbons (PAHs) on sediment. In this study, batch adsorption experiments were carried out with the sediments from the Yellow River Delta (YRD) to explore the effect of particle size and salinity on the adsorption behaviors of phenanthrene (Phe), fluoranthene (Fla), and pyrene (Pyr). Adsorption isotherms of PAHs on different-sized sediments can be described by a Freundlich model with the correlation coefficients ranging from 0.96 to 0.99. The adsorption capacity of PAHs was in reverse proportion to the particle size of the sediments and in direct proportion to salinity. The sediments with smaller particle size possessed higher content of aromatic and fat components, which had strong adsorption capacity toward PAHs. Salinity influenced the adsorption behaviors of PAHs by changing the solubility of PAHs and the physicochemical properties of the sediments. The salting-out constants of Phe, Fla, and Pyr were in the range of 0.292 to 0.296, 0.230 to 0.289, and 0.293 to 0.307 l/mol, respectively. These research findings are of importance to an assessment of the fate and transport of PAHs in seawater-sediment systems.     

Size distribution of the quasi-circular vegetation patches in the Yellow River Delta,China

Recent empirical studies have suggested that the patch-size distribution of vegetation can be fitted by a power law, truncated power law, or lognormal model to provide explanatory mechanisms for vegetation pattern formation in arid and semiarid regions. However, contradictory results have been reported. Therefore, additional empirical studies are necessary to test the patch-size distribution of vegetation over several regions before it can be considered as an indicator for assessing the discontinuous transition of ecosystems and understanding the mechanisms of vegetation pattern formation. Analogous to arid and semiarid regions of the world, vegetation patterns are characterized by a two-phase mosaic composed of dense vegetation patches interspersed with areas of bare soil, referred to as quasi-circular vegetation patches (QVPs), in the Yellow River Delta (YRD), China. However, research on the patch-size distribution of the QVPs reflecting vegetation patterns and ecosystem functioning is lacking. To fill this gap, for the first time, we examined the patch-size distribution of the QVPs using the fused IKONOS high-spatial-resolution image and evaluated the statistical distributions that better fit the patch size data of the QVPs in the YRD. We found that a power law, truncated power law, or lognormal distribution was not supported in the study area, whereas gamma distribution reasonably fits the size data of QVPs, implying that micro-depressions, combined with the water-limited and salinization environments had considerable effects on vegetation pattern formation. Our results provide helpful insights and suggest that further studies are needed to classify different types of QVPs. Additionally, more efficient approaches need to be used to fit the statistical distributions for elucidating the spatial vegetation patterns in the YRD.     

黄河三角洲原生演替中土壤微生物群落结构分析

[目的] 黄河三角洲区域具有重要的湿地生态系统。碱蓬、野大豆和芦苇是该地区典型的盐生植物。本研究针对碱蓬、野大豆和芦苇混生植物的根际土壤微生物群落组成和功能基因进行了分析比较。[方法] 对碱蓬,野大豆-芦苇混生植物的根际微生物菌群和光滩土壤菌群进行了宏基因组测序,使用COG和KEGG数据库对微生物菌群的功能进行了注释和比较。[结果] 本研究结果表明,变形菌门是3个取样点的主要菌门,其在碱蓬、野大豆-芦苇根际土壤中的相对含量比光滩土壤分别多28.8%和10.6%。此外,拟杆菌门、放线菌门和芽单胞菌门是3个取样点中的优势物种。中华根瘤菌属是野大豆-芦苇混生植物根际土壤的最主要的属。对功能基因进行分析表明,光滩土壤中的功能基因的数量多于碱蓬根际土壤和野大豆-芦苇混生植物根际土壤的功能基因数。在这3个位点中,氨基酸代谢、碳水化合物代谢和能量代谢,以及无机离子转运和代谢的基因最多。[结论] 本研究为发掘有价值的微生物资源和海岸带盐碱土壤修复提供了一定的理论基础。     

荒漠草原典型群落土壤粒径和养分的分布特征及其关系研究

为了明确荒漠草原区土壤机械组成与养分的关系,以宁夏盐池荒漠草原4种典型群落为研究对象,通过对不同群落(柠条、沙蒿、蒙古冰草、短花针茅)表层(0~5cm)、亚表层(5~10cm)和深层(10~15cm)土壤粒径分布分形(PSD)、养分含量的动态变化分析,揭示荒漠草原区土壤结构与土壤养分的相关性。结果表明:(1)4种典型群落土壤PSD均呈正态分布,不同群落间的土壤PSD差异显著,粒径100~500μm颗粒含量对PSD影响最大,不同群落间的差异大于不同生境间或不同土层间。(2)4种典型群落除全磷(TP)外,其余土壤全肥均随土壤深度增加呈降低趋势,且冠下大于丛间,表现出荒漠草原区特殊的"肥岛"聚集效应,不同群落间分布特征均表现为:柠条短花针茅蒙古冰草沙蒿,速效养分含量相对较高,各群落均达到适宜水平。(3)土壤养分与土壤PSD显著相关,除速效磷(AP)外,其余土壤养分与土壤分形维数(D)均呈正相关关系,粒径100~250μm、250~500μm颗粒与土壤养分呈显著或极显著负相关关系,土壤中的黏粒、粉粒在有机无机胶结过程及土壤良好的结构维持中起主要作用。     

黄河三角洲草地退化的研究

黄河三角洲位于东经118°7′—119°10′,北纬36°56′—38°12′;东自山东省小清河口,西至徒骇河口,以利津县宁海为顶点向渤海湾呈扇形分布。自50年代以来,随着国营及地方农场的建立以及人口的不断增长,这一地区的草地资源得到了广泛的开发利用。但是,由于一些单位只顾盲目地开垦草地和过度放牧、割草,30多年来整个黄河三角洲盐碱化、退化草地达6.67×10~4ha多,约占当地草地总面积的40%。本文研究了该地区草地退化的现状并就退化程度与累计开发时间的关系初步进行了数     

土壤改良剂对黄河三角洲滨海盐碱土生化特性的影响

以黄河三角洲滨海盐碱土为研究对象,采用4因素4水平正交设计试验,将牛粪(A)、石膏(B)、秸秆(C)、保水剂(D)4种改良剂设置成不同比例,对黄河三角洲滨海盐碱土生化特性进行改良试验,以期筛选出适宜的改良方案。结果表明:牛粪(A)、石膏(B)、秸秆(C)3种改良剂对土壤呼吸强度、土壤磷酸酶、土壤脲酶、土壤脱氢酶和土壤微生物碳氮改良效果明显,保水剂(D)对土壤微生物碳氮改良效果明显,各处理间差异显著。各改良剂对盐碱土各生化指标的贡献值存在差异,综合考虑土壤呼吸强度、土壤酶、土壤微生物碳氮适宜配方为A_4B_3C_2D_2,土壤呼吸强度、土壤磷酸酶、土壤脲酶、土壤脱氢酶和土壤微生物碳氮分别比对照增高109.64%,89.54%,62.20%,81.75%,60.50%,118.00%,相关分析表明,除微生物氮和脲酶相关不显著外,上述各土壤生化指标间均显著相关,研究结果可为黄河三角洲盐碱土的改良利用提供一定的理论依据。     

黄河三角洲植物群落分布格局及其影响因素

利用双向指示种分析和去趋势典范对应分析的方法,对典型河口滨海湿地黄河三角洲植物群落类型和结构进行了分析,并探讨了植物群落分布格局及其影响因素。结果表明：134个样方可划分为7个群系,即刺槐群落（Form. Robinia pseucdoacacia）、荻群落（Form. Miscanthus saccharifleus）、翅碱蓬群落（Form. Suaeda heteroptera）、獐毛群落（Form. Aeluropus sinensis）、芦苇群落（Form. Phragmites communis）、柽柳群落（Form. Tamarix chinensis）和白茅群落（Form. Imperata cylindrica）。群落类型的划分主要反映了微地貌所决定的地下水埋深及土壤盐分含量的变化。在影响植物群落分布格局的因素中,环境因子解释的部分占45.2%,空间因子解释的部分占11.8%,空间因子和环境因子交互作用解释的部分占2.23%,空间因子和环境因子未能解释的部分占40.8%,这部分主要反映了群落自身互作及人类活动对群落的影响。     

黄河三角洲植被资源

概述了黄河三角洲贝沙植被、海滩涂植被、水生植被和低山丘陵植被4个自然植被类型,以及植物群丛的自然特征。     

黄河三角洲不同类型盐生植物土壤真菌群落结构特征

盐生植物种类及其所具有的不同耐盐调节方式影响着根际微生物群落的结构与组成。为明确不同类型盐生植物根际与非根际土壤中真菌群落结构与组成的差异及其与土壤环境间的相互关系,该研究采集了黄河三角洲地区芦苇、盐地碱蓬、獐毛3种不同类型盐生植物0～20 cm土层的根际和非根际土壤,通过高通量测序对其真菌群落多样性和结构进行了分析,以探究真菌群落特征与土壤理化因子间的关系。结果表明：(1)3种不同类型盐生植物根际土壤真菌群落丰富度显著大于各自非根际土,且獐毛根际土壤真菌群落丰富度显著大于芦苇和盐地碱蓬的根际土。(2)距离热图分析表明,芦苇和盐地碱蓬非根际土壤真菌群落间的相似性最大。(3)土壤真菌多样性和丰富度与土壤总碳、总氮、有效磷、pH呈正相关关系,与土壤盐分含量呈负相关关系。(4)3种不同类型盐生植物的根际与非根际土壤中,球囊菌门(Glomeromycota)均为绝对优势门,盾巨孢囊霉属(Scutellospora)为优势属。(5)RDA分析表明,土壤盐分含量是影响土壤真菌群落结构的重要因子,球囊菌门丰度与土壤总氮、总碳、有效磷、有机碳、pH呈正相关关系,与盐分呈负相关关系。(6)植物土壤真菌群...     

黄河三角洲盐碱地不同植被模式的土壤改良效应

黄河三角洲是我国滨海盐碱地的重要分布区,种植植被是盐碱地绿色改良的主要生态修复措施。为探讨滨海盐碱地不同植被模式的土壤改良效应,探索适宜植被模式,选取黄河三角洲盐碱地竹柳+NyPa草、旱柳+NyPa草、柽柳+紫花苜蓿、白蜡+柽柳+紫花苜蓿4种林草措施为研究对象,以纯竹柳为对照,测定土壤水分物理参数、盐碱含量、土壤养分及微生物数量等20个指标,并利用主成分分析、聚类分析和模糊数学隶属函数等统计方法评价了不同植被模式的土壤改良效应。结果表明: 林草复合模式可显著改善滨海盐碱地的土壤理化性能,增加土壤孔隙度和贮水量,降低土壤密度,提高土壤有机质、速效养分含量和土壤微生物数量。其中,白蜡+柽柳+紫花苜蓿的乔灌草混交模式在压碱抑盐、增加土壤养分和微生物数量的效果最好,而旱柳+NyPa草的乔草混交模式改良土壤水分物理性能的效果最好。不同植被模式对黄河三角洲滨海盐碱地的综合改良效应表现为白蜡+柽柳+紫花苜蓿>旱柳+NyPa草>竹柳+NyPa草>柽柳+紫花苜蓿。     

黄河三角洲柽柳植株周围土壤盐分离子的分布

为探讨柽柳的盐分富集效应及其对不同盐分离子分布的影响,以黄河三角洲盐碱地柽柳为研究对象,分析了离植株不同距离不同土层中的盐分离子组成、含量、离子比及不同离子之间的相关性。研究结果表明:各土层阳离子中Na~+含量最高,其次是Ca~(2+)和Mg~(2+),K~(+)最低,Cl~(-)在阴离子中的含量最高,SO_4~(2-)次之,HCO_3~-最低,而未检测到CO_3~(2-)。在柽柳植株周围,尤其是表层土壤中,离植株越近盐分含量越高,显示出柽柳对盐分的富集效应,其中对不同阳离子的富集程度表现为K~+Na~+Mg~(2+)Ca~(2+),而对阴离子的富集程度表现为HCO_3~-Cl~-SO_4~(2-)。冠层下凋落物中盐分的释放和树干径流可能是导致盐分在柽柳植株周围水平方向上存在差异的主要原因。土壤总可溶性盐含量随着土层的加深而升高。阳离子和阴离子向下迁移程度分别表现为Na~+Mg~(2+)Ca~(2+)K+和Cl~-SO_4~(2-)≈HCO_3~-,因而随土层加深而升高的Na~+、Ca~(2+)、Mg~(2+)和Cl~-,显示出底聚特征,而K+、SO_4~(2-)和HCO_3~-含量则随着土层的加深而降低,具有表聚特征。降水淋溶、盐分离子迁移速率的差别和各土层中不同生物量根系对盐分吸收的差异可能是造成盐分在垂直方向上含量变化的主要因素。     

Dioxin-like Polychlorinated Biphenyls Contamination and Distribution in Soils from the Modern Yellow River Delta,China

The concentrations of 12 dioxin-like Polychlorinated Biphenyls (dl-PCBs) were determined from 37 soil samples collected from the modern Yellow River Delta (China) in March 2006. The PCB concentrations were determined by dual capillary GC-ECD. The total dl-PCBs concentrations were in the range of 108.7 to 2153 ng/kg with an average of 800.5 ng/kg. The toxic equivalency (TEQ) in this area varies from 2.3 × 10^{? 5} to 9.5 × 10^{? 5} ng-TEQ/kg, so the delta is slightly polluted by PCBs. PCB118, the main congener, accounted for 46.7% of the total dl-PCB. More than 60% dl-PCBs were penta-PCBs. The spatial distribution of the dl-PCBs is discussed in detail. The distribution of the PCBs suggests that water runoff is the main source of the total contaminant burden in the delta, and that atmospheric precipitation plays an important role.     

Distribution and Contamination Risk Assessment of Dissolved Trace Metals in Surface Waters in the Yellow River Delta

This study investigated the dissolved trace metal contamination levels of Zn, Sr, B, Al, Ba, Fe, Mn, Li, V, Be, Cd, Cr, Cu, Mo, Ni, Se, and Pb in 23 surface waters of the Yellow River Delta (YRD) in China. Coefficients of variation with 66–260% reflected large spatial variations of concentrations of metals. Compared to drinking water guidelines established by the World Health Organization and the U.S. Environmental Protection Agency, the primary trace metal pollution components (Al, B, V, and Zn) were above drinking water standard levels by 82.6%, 47.8%, 52.2%, and 52.2%, respectively. Preliminary risk assessments were determined via the Hazard Quotient (HQ) to evaluate the human health risk of these metals. HQ_ingestion of V indicated potential deleterious health effects for residents. Hierarchical cluster results revealed that clusters 1, 2, and 3 were primarily affected by pollution from industrial and domestic activities, natural and agriculture activities, and oil fields, respectively. Principal component analysis results indicated Fe, Mn, Al, and Ba were controlled by natural sources, whereas anthropogenic activities led to high pollution levels of Al, B, V, Zn, and Sr.     

黄河改道以来黄河三角洲演变过程及其驱动机制

基于1976—2009年的23期遥感影像,并结合1976—2008年利津站水沙数据以及黄河流域年均降水量数据,定量分析黄河入海水沙特征以及黄河三角洲演变过程及其驱动机制.结果表明:1976—2008年间,黄河入海年径流量和年输沙量呈现出年际变化大和丰枯水(沙)年交替的特征,但总体均呈下降趋势;清水沟流路河口三角洲岸线和面积变化总体呈淤积增长趋势,三角洲的发育过程大致分1976—1985年、1986—1995年和1996—2009年3个阶段,3个阶段的增长速率逐阶段递减;黄河三角洲岸线和面积与利津站累积输沙量之间均呈显著的指数函数关系;黄河流域降水量的年际波动与利津站入海输沙量年际波动基本同步,并具有相关性,说明黄河流域降水量的年际波动是引起入海径流量和输沙量波动的重要原因.     

黄河三角洲土壤动物多样性初步调查研究

1995～1996年对黄河三角洲9个代表性样区,进行了土壤动物定性、定量调查,并对古代、近代、现代黄河三角洲3个代表性样区开展了土壤动物周年调查,研究了土壤动物的种类组成、分布和季节变化,以及土壤动物多样性。调查研究结果：黄河三角洲共鉴定出土壤动物38种,土壤动物种类组成和数量分布因三个三角洲成土年龄不同而存在差异,土壤动物多样性以夏季为丰富。黄河三角洲土壤动物多样性与均匀度表现为正相关关系,与单纯度呈负相关趋势。     

Variation in Phosphorus Sorption with Soil Particle Size

Phosphorus (P) is considered a primary cause for surface water eutrophication that leads to anoxia. Understanding the relationships between soil particle size and P sorption helps devise effective best management practices (BMPs) to control P transport by erosion, leaching, and overland flow from agricultural land. Consequently, this study examined the effect of surface soil particle size on the sorption of P in five soil series (four Ultisols and one Entisol) from the Mid-Atlantic region. The sorption of P in each soil was assessed by equilibrating (after shaking for 24?h) 5?g soil containing varied amounts of KH₂PO₄ in 20?mL of 0.01?M KCl solution. Phosphorus in solution was determined by the molybdate blue method of Murphy and Riley. The P adsorption characteristics of these soils were described using the Langmuir isotherm. Results indicated that variability in P sorption was related to particle size and soil type. Soil organic matter content contributed a great deal to P sorption in the Entisol. However, soil clay had influence on the P sorption characteristics of each soil. The maximum P retentive capacities of soils (as determined by Sm from Langmuir equation) and P sorbed at 500?mg P kg^?1 addition showed a linear relationship (r2 = 0.94). Therefore, based on the results obtained, the single point method of Bache and Williams may be appropriate to describe the maximum P sorption capacity of non-sandy soils, as observed in this study.     

黄河三角洲丹顶鹤秋冬季生境选择机制

影响水禽生境选择要素可分为水、食物、隐蔽物和干扰4类,对其划分等级标准,确定采样点的生境类型。在研究区内分秋冬两季调查丹顶鹤(迁徙期和越冬期)生境选择机制的差异;在不同时期按区域的特点和丹顶鹤的生活习性分别选择样点;经过实地野外调查后再利用方差分析和频数对丹顶鹤生境选择机制进行研究。结果表明,迁徙期影响丹顶鹤生境选择的主要因子是干扰,最适生境为远离人类干扰、有浅水域分布的、植被覆盖率较低的地区;越冬期影响丹顶鹤生境选择的主要因子是食物,最喜欢选择人类干扰相对较小的、有水域分布的、动物性食物占主导地位的植被覆盖率较低的地区栖息。     

1995—1999年黄河三角洲东部自然保护区湿地景观格局变化

基于1995和1999年的LandsatTM遥感影像,结合地理信息系统技术,分析黄河改道清8汊(1996年)前后的1995—1999年黄河三角洲东部自然保护区(位于黄河现行流路入海口处)湿地景观格局的变化特征,以及影响湿地景观格局变化的驱动因素.结果表明:1995—1999年,保护区湿地仍以天然湿地为主,人工湿地比重极小,期间非湿地面积大幅增加,而天然湿地和人工湿地面积则呈下降趋势,其中,裸露淤泥质滩涂和沼泽湿地面积明显萎缩;尽管保护区湿地景观类型、形状、结构的变化程度不均一,且各景观类型在空间分布上的团聚程度变化不均衡,但总的看来,保护区景观整体结构趋于复杂化,破碎化程度有所加深,内部各景观类型从大块连续的镶嵌分布向小块离散分布转变;影响保护区湿地景观格局变化的主要因素有3个:黄河改道、黄河断流和人类活动.