城市河网区河流沉积物磷形态分布特征及释放贡献

以嘉兴城市河网区为研究区域,在调查区域水质和沉积物磷空间变化特征的基础上,分析沉积物中各形态磷的垂直与空间赋存状态,通过吸附释放参数计算EPC₀值,明确了沉积物-水界面磷迁移影响因素和沉积物中活跃磷素的释放风险和贡献.结果表明,研究区域水质氮磷污染较为严重,沉积物TP含量均值呈北部河网区>西部河网区>南部河网区,基于单因子指数法的生态风险评价为Ⅱ、Ⅲ和Ⅳ级的样本比例分别为10.91%、25.45%和63.64%.沉积物各形态磷整体呈现TP>IP>HCl-P>NaOH-P>OP,沉积物生物有效磷（BAP）整体呈现Olsen-P>AAP>WSP>RDP;在沉积物垂直剖面中,部分位点受到外界因素的强烈影响垂向波动较大,整体上是随深度的递增而减小,这与近年来研究区域接收的外源磷积累过程在加重有关.相关性分析表明,沉积物磷吸附容量（Q_max）与铁铝氧化物呈显著相关性 （p<0.05）;释放参数EPC₀与TP、IP与HCl-P呈显著相关性 （p<0.05）.结合BAP形态,研究区域河流沉积物NaOH-P、HCl-P、AAP、Olsen-P及WSP存在较高的释放潜力.南部河网区沉积物主要呈现磷“源”角色,西部和北部河网区部分区域沉积物充当磷“源”角色.南部河网区在长短时间尺度下的磷主要释放形态为NaOH-P、HCl-P和OP,北部河网区在长时间尺度下主要释放磷形态为NaOH-P、HCl-P,西部河网区在短时间尺度下主要释放形态以HCl-P为主,在长时间尺度下3种磷形态的释放风险仍然较高.     

基于空间尺度效应的西南地区植被NPP影响因子探测

植被净初级生产力(NPP)是评价陆地生态系统质量的重要参数,研究植被NPP时空演变特征及其驱动力对区域生态环境保护和可持续发展具有重大意义.基于MODIS NPP数据、气象数据、 DEM数据、人口密度数据、 GDP数据和土地利用类型数据,采用一元线性回归分析、 R/S分析和地理探测器模型,分析西南地区及其六大地貌单元植被NPP时空演变特征及未来变化趋势,探究植被NPP空间分异的影响因子.结果表明,2000～2020年西南地区植被NPP整体呈极显著上升趋势.地貌单元中,除青藏高原南部外,其余地貌单元植被NPP均表现为改善态势,其中四川盆地和云贵高原表现为极显著改善.西南地区的植被NPP变化斜率整体呈现“东高西低”的分布格局.西南地区及各地貌单元植被NPP呈上升趋势的区域面积均大于呈下降趋势的区域面积,但未来植被NPP变化趋势均以下降为主.地理探测器结果表明,除云贵高原植被NPP空间分异主要受气温影响外,海拔是西南地区及各地貌单元植被NPP空间分异的主导因子.交互探测结果表明,影响因子之间的交互作用均表现为双因子增强或非线性增强,其中,海拔∩温度对西南地区植被NPP空间分异的解释力最大.地...     

Key Features and Context‐Dependence of Fishery‐Induced Trophic Cascades

Abstract: Trophic cascades triggered by fishing have profound implications for marine ecosystems and the socioeconomic systems that depend on them. With the number of reported cases quickly growing, key features and commonalities have emerged. Fishery‐induced trophic cascades often display differential response times and nonlinear trajectories among trophic levels and can be accompanied by shifts in alternative states. Furthermore, their magnitude appears to be context dependent, varying as a function of species diversity, regional oceanography, local physical disturbance, habitat complexity, and the nature of the fishery itself. To conserve and manage exploited marine ecosystems, there is a pressing need for an improved understanding of the conditions that promote or inhibit the cascading consequences of fishing. Future research should investigate how the trophic effects of fishing interact with other human disturbances, identify strongly interacting species and ecosystem features that confer resilience to exploitation, determine ranges of predator depletion that elicit trophic cascades, pinpoint antecedents that signal ecosystem state shifts, and quantify variation in trophic rates across oceanographic conditions. This information will advance predictive models designed to forecast the trophic effects of fishing and will allow managers to better anticipate and avoid fishery‐induced trophic cascades.     

人类活动净氮输入时空变化特征及其影响因素——以香溪河流域为例

为了阐明人类活动对三峡库区第一大支流香溪河流域氮输入的影响程度,基于人类活动净氮输入（NANI）模型估算了2001~2015年间香溪河流域乡镇水平的人类活动净氮输入,分析了氮输入的主要来源及其动态变化.结果表明：时间尺度上,香溪河流域人类活动净氮输入（NANI）因氮素施用的变化而呈现先上升后下降最后上升的趋势,但2015年相对2001年的NANI下降了143kg N/（km²·a）;空间尺度上,香溪河流域NANI整体呈现北低南高的分布格局,其中NANI输入强度差异较大的区域主要有昭君镇、峡口镇和黄粮镇.从人类活动净氮输入的组成上来看,氮肥施用仍然是最主要的来源（40.06%）,其次为大气氮沉降（29.98%）和食品/饲料净氮输入（27.75%）,作物固氮仅占净氮输入总量的2.21%.香溪河流域的NANI与人口密度和耕地面积比例极显著相关（P<0.001）;而NANI与河流氮输出的相关性不显著,香溪河流域河流氮输出占NANI的比例仅为24.28%.因此,可以通过减少氮素施用降低流域尺度氮素净输入量,但该流域NANI与河流氮输出无直接的响应关系.     

Marine Ecological Research in New Zealand: Developing Predictive Models through the Study of No-Take Marine Reserves

Abstract:  New Zealand established its first no-take marine reserve more than 25 years ago. Twenty no-take marine reserves have now been created, although few of these are considered comparable. We considered whether existing conceptual models of population and community structure based only on data from exploited systems lack the baseline information of natural states necessary to make accurate predictions for new reserves. Three of the oldest and best-studied reserves are situated on the northeastern coast of New Zealand. These reserves are considered broadly comparable replicates, and research has shown the recovery of previously exploited predator populations and the reestablishment of trophic controls over community structure and productivity. None of the major changes was predicted when the reserves were created. All the observations from and experimental tests of hypotheses in these three ecologically comparable reserves have provided predictive models for future reserves. Recent surveys in newly created reserves, however, suggest that these models are bioregion and habitat specific. In these new reserves the recovery of previously exploited predators was predicted but did not always occur. Where trends were correctly predicted, the speed and amplitude of the changes were not accurately predicted. Research in New Zealand suggests that it is not yet possible to predict explicit outcomes for newly created reserves and less possible to predict detailed results for systems of reserves. Results from a representative system of reserves, including all major habitats within all bioregions and broadly comparable reserves, are needed. Such a system will enable the range and variety of natural ecosystem dynamics to be investigated and provide the controls necessary to measure the effects of exploitation.     

考虑保护层响应的炼化过程系统风险动态转移模型

为适时、有效地控制炼化过程系统风险,以模糊Petri网(FPN)为基础,针对炼化系统动态退化性和系统中保护层对风险转移的干预性,建立考虑保护层响应的炼化过程系统风险动态转移模型。描述基于FPN的保护层作用动态机制,分析炼化系统在保护层干预下,从非正常干扰触发开始至炼化系统退化过程的风险变化趋势。最后通过正己烷缓冲罐案例分析验证模型。结果表明:正己烷缓冲罐在开始运行的30 000 h内,系统风险等级呈阶段性变化,在工作的前16 800 h,风险为Ⅰ级;第16 800~27 600 h,风险为Ⅱ级;第27 600~30 000 h,风险为Ⅲ级。     

软质岩边坡挂网植草绿化防护技术研究

挂网植草解决了红砂岩、紫砂岩等软质岩石坡面因没有土层而不能绿化的难题。在经平整的软质岩石边坡上,铺粘10～15cm厚的泥浆层,满植规格为40×40cm狗牙根(Cynodon dactylon)、假俭草(Eremochloa ophiuroides)、结缕草(Zoysia japonica)等具有匍匐枝茎、耐瘠薄土壤、有良好的水土保持力等特性的草皮,草层上盖2.5×30m高强度的专用塑料网,用钢钉和竹签加以固定,造价为28～30元/m~2,是混凝土喷射、窗式护面墙等其它防护方法成本的1/3～1/5。在京珠、潭邵等高速上推广了近400 000 m~2,能在最短的时间内恢复植被,形成优美的景观,又能发挥较好的生态防护作用。该技术材料来源广、工艺操作易、实用性强,可广泛应用于公路、铁路、水库、堤坡等软质岩石地段的景观绿化与生态防护。     

中国陆地植被生态系统生产有机物质价值遥感估算

可持续发展的战略要求推进生态资产研究,对生态系统生产有机物质功能价值的估算则是生态资产评估的重要组成部分。利用改进的CASA模型对中国陆地生态系统1995年NPP进行了估算,它与实测数据和国内其他研究成果的比较验证证明了该方法的可靠性;进而对1995年全国陆地生态系统生产有机物质的价值进行了估算,结果表明,1995年中国陆地生态系统净第一性生产力生产有机物质的总价值为1.902049×1012元.a-1,其空间分布是从东部向西北递减、由中部向东北和南部递增;从类型上看,常绿阔叶林的单位面积值最高,裸地和极稀疏植被的单位面积值最低。     

Damage to Cauliflower Coral by Monofilament Fishing Lines in Hawaii

Abstract:  Many fishing methods and gear types used in coral reefs cause physical damage to the reef substratum. Only recently have monofilament fishing lines been recognized as a cause of coral damage and death. We assessed the extent of damage caused by monofilament fishing lines to the cauliflower coral (  Pocillopora meandrina ) colonies in fished and adjacent unfished zones at seven sites in the main Hawaiian islands. We examined coral colonies for the presence or absence of fishing line and for the degree of damage (dead, no live coral surface; damaged, some dead coral surface; or intact, no dead coral surface) in nine 25-m² grids. The mean proportion of colonies entangled with fishing lines in fished zones ranged from 0.18 to 0.44. The mean proportion of dead or damaged colonies was higher in fished than adjacent unfished zones, and there was a positive linear relationship between the proportion of colonies entangled with fishing lines and the proportion of dead or damaged colonies. These results indicate that monofilament fishing lines have a negative impact on the health and survival of P. meandrina colonies. Because tourism and related recreational fishing activities are expanding rapidly in many tropical states and nations, we recommend that the degrading effects of fishing lines on corals be considered in the design and management of tourism development.     

浙江天台山茶树光合日变化及光响应

自然条件下使用LCA－4型便携式光合测定系统研究了栽培天天台山主峰华顶山的茶树连体叶片的光合日变化及光响应。结果表明：在初夏晴天,上年越冬叶片（下称二年生叶）的光合速率,表观量子效率,羧化效率和饱和光强比展叶红16d的一年生叶高,CO2补偿点和光补偿点比一年生叶低,两者的净光合速率日进程曲线均为“双峰”型,午间胞间CO2浓度上升表明,此时净光合速率下降主要受非气孔限制因素的影响。一年生叶蒸腾速率高于二年生叶,它们日进程曲线为单峰河,午间最高,而气孔阻力进间最低。不同时段作光响应和CO2响应试验表明,上午茶树的表观量子效率,饱和光强和羧化效率较高,光补偿点和CO2补偿点较低。图3表4参26