Evaluation of microbial surfactants for recovery of hydrophobic pollutants from soil

Summary Several microbially produced biosurfactants were evaluated for their ability to remove hydrophobic compounds from soil. The biosurfactants produced byPseudomonas aeruginosa UG2 andAcinetobacter calcoaceticus RAG-1 displayed the best results, with recovery of [¹⁴C]hexachlorobiphenyl from soil slurries of 48.0 and 41.9%, respectively.P. aeruginosa UG2 produced higher levels of extracellular biosurfactants than four otherP. aeruginosa strains.P. aeruginosa UG2 culture filtrate containing biosurfactants enhanced the recovery of several other individual hydrocarbons and polychlorinated biphenyl compounds, as well as several hydrocarbons in a mixture, from soil. The results, suggest that biosurfactants produced byP. aeruginosa UG2 have the potential for remediation of hydrophobic pollutants in soil environments.     

不同人工林生态系统林地土壤质量评价

利用定位研究方法,综合比较了第2代连栽杉木纯林、杉木与阔叶树混交林以及阔叶纯林3种人工林生态系统对林地土壤质量的影响．结果表明,与连栽杉木纯林相比,在杉阔混交和阔叶树轮栽两种经营模式下,土壤养分含量增加,物理性状改善,土壤生物活性提高．利用土壤质量评价体系在对土壤功能评价的基础上,直观评价了3种经营模式的土壤质量状况．在研究区内,杉木与阔叶树混交以及阔叶树轮栽的水分有效性、养分有效性和根系适宜性以及最终的土壤质量指数均处于中等水平,而连栽杉木林的水分有效性、养分有效性和根系适宜性较差,土壤质量指数处于较低水平．总有机C、阳离子交换量和微生物生物量C与其它土壤理化性质和生物学性质之间明显相关,可将其作为研究区土壤质量的指示指标;土壤微生物生物量C、N、P与土壤总有机C、土壤全N、土壤全P含量之间也存在较好的相关性。     

Are boreal ecosystems susceptible to alien plant invasion? Evidence from protected areas

Although biological invasion by alien species is a major contributor to loss of indigenous biological diversity, few studies have examined the susceptibility of the boreal biome to invasion. Based on studies of other ecosystems, we hypothesized that alien plants will be restricted to disturbed areas near human activity and will not be found in natural areas of boreal ecosystems in Gros Morne National Park (Canada), a protected area experiencing a wide range of disturbance regimes. The distribution of alien plants in the region was evaluated using surveys, and study sites were established in naturally and anthropogenically disturbed habitats that had been invaded. Within study sites, randomization tests evaluated the importance of disturbance to alien plant invasion by examining changes in environmental conditions and species abundance within various disturbance regimes, while the importance of site characteristics limiting the distribution of alien plants were examined using Canonical Correspondence Analysis. Consistent with studies in a variety of biomes, areas of high disturbance and human activity had the greatest abundance of resources and the highest percentage of alien species. However, contrary to our hypothesis, natural areas of boreal ecosystems were found susceptible to alien plant invasion. Vegetation types vulnerable to invasion include forests, riparian areas, fens, and alpine meadows. Natural disturbance occurring in these vegetation types caused increases in bare ground and/or light availability facilitating alien plant invasion. Although high soil pH was associated with alien plants in these areas, disturbance was not found to cause changes in soil pH, suggesting susceptibility to invasion is pre-determined by bedrock geology or other factors influencing soil pH. Moose (Alces alces), a non-native herbivore, acts as the primary conduit for alien plant invasion in GMNP by dispersing propagules and creating or prolonging disturbance by trampling and browsing vegetation. The recurrent nature of disturbance within the boreal biome and its interaction with site conditions and herbivores enables alien plants to persist away from areas of high human activity. Managers of natural lands should monitor such interactions to decrease the invasion potential of alien plants.     

柴达木盆地荒漠土壤蓝藻群落的初步研究

本文分析了柴达木盆地东部和中部具有代表性地区的丘陵、戈壁和沙丘的蓝藻种类组成、生物量及主要的土壤化学成分;采用了模糊聚类、系统聚类及多元线性回归等方法分析藻类的群落及其与环境因子的关系。共鉴定出21种蓝藻,其中6种为国内首次报道。研究表明:土壤含磷量、总盐量及与粘性和湿度有关的土壤结构是决定柴达木盆地蓝藻群落组成的重要因素。     

Distinguishing sources of base cations in irrigated and natural soils: evidence from strontium isotopes

Strontium isotope ratios (⁸⁷Sr/⁸⁶Sr) of soil solids, soil cation extracts, irrigation water and plant material are used to determine strontium and therefore cation sources and fluxes in irrigated and natural soil–plant systems. Strontium isotopes of soil solids from four soil profiles (two irrigated vineyard soils and two 'natural' profiles from nearby reserves) show large differences between soil horizons with depth. These differences are not reflected in ⁸⁷Sr/⁸⁶Sr ratios of soil labile cations, which show both little variation down-profile and much lower ratios than soil solids. In the undisturbed, natural soil profiles, labile cation ⁸⁷Sr/⁸⁶Sr ratios are close to the ratio of modern seawater, indicating that solutes of marine origin from precipitation are the primary input of strontium (and calcium) to the labile cation pool. In the irrigated soil profiles, ⁸⁷Sr/⁸⁶Sr ratios of labile cations are consistently shifted towards that of the irrigation water. Mass-balance calculations using ⁸⁷Sr/⁸⁶Sr ratios of the different inputs to the labile cation pool indicate more than 90% of labile strontium is derived from precipitation solutes in unirrigated soils, and up to 44% from irrigation water solutes as an additional source in irrigated soils. The ⁸⁷Sr/⁸⁶Sr ratios of grapes grown in irrigated soils match precisely with those of the labile soil cations, demonstrating that cation nutrients are drawn wholly from the labile cation pool and have the same mix of precipitation, irrigation, and soil solid sources. The ⁸⁷Sr/⁸⁶Sr ratios of grapes grown in the irrigated soils may therefore vary over time depending on (1) the changing mix of irrigation water and local precipitation and (2) potential change to irrigation water. These findings suggest limitations to the use of strontium isotopes in the tracing of grapes and wines to their soil of origin.     

SWAT模型在气候变化对水资源影响研究中的应用——以河南省中部农业区为例

为了研究气候变化对水资源的影响,应用具有物理基础的SWAT(Soil and Water Assessment Tool)模型,针对河南中部农业区(淮河上游沙河周口水文站上游区域)的特点,构建了该区域气候变化影响水资源(径流)评估模型。通过加载1∶4000000电子河系数据,消除了SWAT在平原区从1∶250000 DEM自动提取河系的误差;在对模型参数敏感性分析的基础上,将1999—2002年作为校准期,2003—2006年作为验证期,对模型的参数进行了校准和验证,模型校准期Nash-Sutcliffe效率系数Ens=0.96,r2=0.95,验证期Ens=0.81,r2=0.87,表明模型应用于该区域的月径流模拟精度较高。将1966—2007年的气象资料应用于模型进行模拟,分析结果表明,地表径流、基流年内变化趋势与降水量变化趋势一致,蒸散发是该地区水量的主要输出项,地表径流是基流的2倍左右,地表径流相对于降水有滞后性,基流滞后于降水3个月时间。     

山西耕作土壤样品磁性空间分异及其环境意义

本文分析了山西高原土壤耕作层(0-20cm)25个样品的磁性,用GIS空间分析方法,得出土壤磁化率平面分布等值线图和空间三维模型。磁化率空间分布机理如下:首先,强烈的人为影响使土壤中磁性矿物人为来源占有重要地位。第二,土壤磁性矿物以亚铁磁性的磁铁矿和磁赤铁矿为主导。第三,土壤磁化率极值差及其与母质之间的差异均受广泛而较均一的黄土母质的影响。第四,晋西北和晋中等区域出现土壤磁化率高值区域。第五,人为作用强烈影响掩盖了气温、降水等气候因子对土壤磁化率的作用。     

Individual vs. population plastic responses to elevated CO2, nutrient availability, and heterogeneity: a microcosm experiment with co-occurring species

We conducted an experiment to evaluate the plastic phenotypic responses of individuals, growing under intra-specific competition, and populations of three co-occurring grassland species (Lolium perenne, Plantago lanceolata, and Holcus lanatus) to joint variations in atmospheric CO₂ partial pressure (P _CO2; 37.5 vs. 70 Pa), nutrient availability (NA; 40 vs. 120 mg N added as organic material), and the spatial pattern of nutrient supply (SH; homogeneous vs. heterogeneous nutrient supply). At both the population and individual levels, the aboveground biomass of the three species significantly increased when the nutrients were heterogeneously supplied. Significant two- (SH × NA) and three-term (P _CO2 × NA × SH) interactions determined the response of traits measured on populations (aboveground biomass and below: aboveground biomass ratio, BAR) and individuals (aboveground biomass and specific leaf area). The combination of a high SH and NA elicited the highest plasticity of aboveground biomass in populations and individuals of the three species evaluated, and of BAR in Holcus. Soil heterogeneity and elevated P _CO2 elicited the highest plasticity in the SLA of Plantago and Lolium individuals. Our results show that populations, and not only individuals, respond to soil heterogeneity in a plastic way, and that plastic responses to elevated P _CO2 are complex since they vary across traits and species, and are influenced by the availability of nutrients and by their spatial distribution. They also emphasize the importance of soil heterogeneity as a modulator of plant responses to global change drivers. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Responsible Editor: Angela Hodge     

某冶炼厂周围8种植物对重金属的吸收与富集作用

采用野外采样系统分析法,研究了沈阳冶炼厂的8种植物对重金属(Pb、Zn、Cu和Cd)的吸收与富集作用以及可能的耐性机制.结果表明,植物对重金属的吸收和富集,因植物种类、部位及重金属种类而不同.茼麻(Abutilon theophrasti)对Pb的吸收和富集能力较强,小白酒花(Conyza canadensis)、三裂叶豚草(Ambrosia trifida)、酸模叶蓼(Polygonum lapathifolium)、茼麻、龙葵(Solanum nigrum)、绿珠藜(Chenopodium acuminatum)和菊芋(Helianthus tuberosus)对Zn的吸收和富集效果较好,绿珠藜和茼麻对Cu的吸收和富集能力较强,龙葵、绿珠藜、茼麻、酸模叶蓼和小白酒花对Cd的吸收和富集能力较强.这些植物向地上部转移某些重金属的能力很强,转移系数大于1,可用于植物提取方式的污染土壤修复.其他转移系数小于1的植物,适合于重金属污染土壤的植物稳定.     

黄土高原不同土壤结构体有机碳库的分布

根据不同植被类型和土壤类型,分别从黄土高原不同地域分层（0～20 cm、20～40 cm和40～60 cm）采集22个土壤剖面样品,研究土壤有机碳库在不同结构体中的分布特征.结果表明,所有结构体,从表层向下有机碳含量和贮量皆呈递减趋势;而各土层,从＞5 mm、2～5 mm、1～2 mm到0.25～1 mm结构体有机碳含量呈递增趋势,而从0.25～1 mm到＜0.25 mm呈下降趋势,以0.25～1 mm结构体中有机碳含量最高.由于不同大小结构体所占比例不同,因此不同结构体中的有机碳贮量与含量并不完全一致：从＞5 mm、2～5 mm到1～2 mm结构体中有机碳贮量呈递减趋势,而从1～2 mm、0.25～1 mm到＜0.25 mm呈递增趋势,以1～2 mm结构体有机碳贮量最低.有机碳含量除土垫旱耕人为土在＜0.25 mm结构体中最大外,干湿砂质新成土、黄土正常新成土和简育干润均腐土在0.25～1 mm结构体中最高;但有机碳贮量在干湿砂质新成土和黄土正常新成土中以＜0.25 mm结构体所占比例最大,在简育干润均腐土和土垫旱耕人为土中以＞5 mm结构体所占比例最大.在不同植被下有机碳含量、贮量不同,表现为自然林地＞裸地＞人工林地＞农地.