碳磷添加对黄土区农田土壤呼吸及温度敏感性的影响

黄土区耕地面积占全国耕地面积的15%以上,该区域降水资源贫乏,是我国土壤生产力和土壤有机碳储量最低的区域之一。营养的大量投入可以极大地提高土壤生产力,但对于营养添加下土壤CO_2排放有何变化以及是如何改变黄土区土壤环境,进而影响土壤呼吸及温度敏感性还尚不清楚。本文以长武实验田的黑垆土作为研究对象,分别对N12(施氮量120 kg?hm~(-2))土样设置不添加、添加磷源以及CK(长期连作不施肥)土样设置不添加、添加磷源、碳源、碳磷源(共计6个处理),比较分析在15℃和25℃培养下土壤呼吸速率的变化,以及培养周期内土壤温度敏感性Q_(10)(即温度每升高10℃,温室气体排放速率变化的倍数)的变化趋势。通过对呼吸前后土壤pH值、全碳全磷、有机碳、速效磷、硝态氮、铵态氮以及微生物生物量碳磷(MBC、MBP)的测定,分析其影响因素。碳磷添加在一定程度上提高了土壤的呼吸速率,其中碳源的添加明显增强了土壤呼吸速率以及土壤Q_(10)值。碳磷添加大幅度提高了土壤全碳、速效磷含量以及微生物活性,15℃条件培养后,土壤微生物生物量最高。碳磷添加后,土壤呼吸速率与土壤pH、全碳、铵态氮、MBC呈极显著相关关系。该研究为黄土区土壤生产力的提高以及降低温室气体的排放、恢复和改善生态环境提供理论依据。     

外秦淮河底泥污染及疏浚效果

外秦淮河是南京市一条重要的城市景观行洪河道,多年来受工业及生活污水影响,内源污染严重.为充分了解外秦淮河底泥污染特征,为疏浚提供决策依据,对河道上、中和下游典型断面底泥界面微环境以及营养物含量进行调查,采用有机指数法和污染指数法对底泥污染状况进行评估,同时根据污染物垂向分布特征模拟清淤对底泥内源释放削减的影响.结果表明,上中下游底泥界面以上DO均值分别为4.62、 3.25和3.41mg·L^-1,且分别在4.4、 3.5和5.5 mm处消耗殆尽,是典型的城市河道污染特征体现.调查河段表层底泥的ω(TN)、ω(TP)和ω(OM)均值分别为1 734mg·kg^-1、 1 337 mg·kg^-1和4.82%,底泥TN和OM的有机污染指数均值为0.48,处于尚清洁水平,TP的单项污染指数均值为3.18,处于重度污染水平.模拟30 cm清淤深度结果表明,底泥SRP和Fe²⁺的释放速率较清淤前分别削减42%～82%和88%～96%,而NH⁺₄-N的释放速率却较清淤前有...     

重庆市煤矸山周边农产品镉健康风险评价及土壤环境基准值推导

以重庆市煤矸山周边农用地土壤和农产品（玉米和水稻）为研究对象,测定土壤和农产品（玉米和水稻）中Cd含量,评估摄入农产品（玉米和水稻）对人体的潜在健康风险,并基于物种敏感性分布法（SSD）推导土壤环境基准值.结果表明,重庆煤矸山周边旱地土壤Cd含量超风险筛选值的点位占55.8%,水田土壤Cd含量超风险筛选值的点位占31.6%,土壤Cd以较高生态危害和高生态危害为主,分别占47.4%和36.8%.玉米Cd含量超标点位占4.4%,水稻Cd含量均未超标.健康风险评价表明因食用玉米和水稻摄入Cd的非致癌健康风险可忽略,食用玉米摄入Cd存在可耐受致癌健康风险,食用水稻摄入Cd存在不可耐受致癌健康风险,且玉米和水稻Cd含量敏感度最高.SSD推导出煤矸山周边旱地土壤在pH≤5.5、5.57.5时Cd的环境基准值分别为0.491、0.382、0.376和0.588 mg ·kg^-1,水田土壤Cd的环境基准值为0.807 mg ·kg^-1.水田土壤和旱地土壤pH≤7.5时,现行土壤标准（GB 15618-2018）相对偏严;旱地土壤pH>7.5时,现行土壤标准（GB 15618-2018）相对偏宽松.应加强煤矸山周边土壤Cd污染防治和农产品安全利用研究,并对土壤Cd环境基准值进行适当调整.     

三峡库区支流库湾消落带土壤磷形态赋存特征及其释放风险

三峡库区消落带经历反复的淹水-落干循环影响,消落带土壤磷迁移转化过程加快,可能加剧支流库湾水体富营养化.采集了三峡库区腹心支流库湾典型消落带土壤,测定磷赋存形态与磷素饱和度(DPS)等,分析磷释放风险.结果表明,(1)消落带土壤ω[总磷(TP)]、ω[无机磷(IP)]和ω[有机磷(OP)]均值分别为771.80、485.33和166.30 mg·kg^-1,IP和OP均以非活性形态磷为主.(2)消落带土壤形态磷的赋存格局受落干-淹水方式影响,Ex-P和NaHCO₃-Po含量显著高于对照土壤,Fe-P、HCl-Po和Fulvic-Po含量沿高程下降而显著降低(P<0.05),反复的干湿交替促进了消落带土壤活性磷的生成和中等活性磷的释放和积累.(3)消落带土壤生物ω[有效磷(Bio-P)]为49.19～148.78 mg·kg^-1,占TP的质量分数为7.71%～24.78%,磷素饱和度(DPS)为5.85%～22.00%.目前,支流库湾消落带土壤整体磷释放风险较低,170 m高程土壤需要重点关注.Fe-P、HCl-Po和...     

Floristic contamination of suburban forests near the city of Ivanovo

In the course of floristic studies in suburban forests near the city of Ivanovo, 206 species of vascular plants have been recorded, including 39 invasive species (18.9%). Information on specific features of distribution and activity of introduced species growing feral and accidental weeds in different forest types is presented. The most aggressive species are distinguished. Factors responsible for the invasion of alien species to forest cenoses and main tendencies in their dynamics are discussed.     

Effect of water pH and total dissolved solids on the species diversity of pelagic zooplankton in lakes: A statistical analysis

Statistical analysis of the combined influence of lake surface area (S), water pH, and total dissolved solids (TDS) on the formation of zooplankton communities in lakes has been made on the basis of available data on the number of species (N _sp ) of pelagic zooplankton in 256 lakes of the temperate zone of Europe, Asia, and North America. Graphic analysis and analysis of variance have shown that extremely high or extremely low values of pH and TDS inhibit lake zooplankton. If the value of one of these factors is extremely high, any increase in the other factor is favorable for the inhibited zooplankton, and this second factor determines the value of N _sp .     

Altitudinal zonality and diversity of butterflies in the southern Far East and Transbaikalia

Species richness, taxonomic diversity, and qualitative composition of the butterfly fauna (Lepidoptera, Diurna) are discussed in the light of data on the altitudinal zonality of local faunas in the southern Far East and Transbaikalia. It is shown that qualitative elevation-dependent changes in the fauna occur only in the western and northern parts of the region.     

Effects of the Surrounding Matrix on Tree Recruitment in Amazonian Forest Fragments

Abstract:  Little is known about how the surrounding modified matrix affects tree recruitment in fragmented forests. We contrasted effects of two different matrix types, Vismia - and Cecropia -dominated regrowth, on recruitment of pioneer tree species in forest fragments in central Amazonia. Our analyses were based on 22, 1-ha plots in seven experimental forest fragments ranging in size from 1 to 100 ha. By 13 to 17 years after fragmentation, the population density of pioneer trees was significantly higher in plots surrounded by Vismia regrowth than in plots surrounded by Cecropia regrowth, and the species composition and dominance of pioneers differed markedly between the two matrix types. Cecropia sciadophylla was the most abundant pioneer in fragments surrounded by Cecropia regrowth (constituting nearly 50% of all pioneer trees), whereas densities of species in Vismia -surrounded fragments were distributed more evenly. Thus the surrounding matrix had a strong influence on patterns of tree recruitment in Amazonian forest fragments.     

Protection of Mammal Diversity in Central America

Abstract:  Central America is exceptionally rich in biodiversity, but varies widely in the attention its countries devote to conservation. Protected areas, widely considered the cornerstone of conservation, were not always created with the intent of conserving that biodiversity. We assessed how well the protected-area system of Central America includes the region's mammal diversity. This first required a refinement of existing range maps to reduce their extensive errors of commission (i.e., predicted presences in places where species do not occur). For this refinement, we used the ecological limits of each species to identify and remove unsuitable areas from the range. We then compared these maps with the locations of protected areas to measure the habitat protected for each of the region's 250 endemic mammals. The species most vulnerable to extinction—those with small ranges—were largely outside protected areas. Nevertheless, the most strictly protected areas tended toward areas with many small-ranged species. To improve the protection coverage of mammal diversity in the region, we identified a set of priority sites that would best complement the existing protected areas. Protecting these new sites would require a relatively small increase in the total area protected, but could greatly enhance mammal conservation.