Land-use dynamics and landscape pattern change in a coastal gulf region,southeast China

This study quantitatively analyzed spatiotemporal changes in land use and landscape pattern in a coastal gulf region of southeast China by comparing classified satellite images from 1988, 2002, and 2007, using a geographic information system (GIS), remote sensing (RS), and landscape pattern metrics. The results show an increase in cropland, built-up area, and aquaculture area and a decrease in orchards, woodland, and beach area during 1988–2007. Over the study period, 64.3% of newly-expanded cropland was from woodland; newly-expanded built-up area of 34.8, 27.2, and 20.4% was converted from cropland, woodland, and beach areas, respectively; and newly-expanded aquaculture increased by 45.1 and 29.4% from beach and water body areas, respectively. Trend analysis of landscape pattern metrics demonstrates fragmentation of the landscape, with landscape pattern structure becoming more complex over the last two decades in the Louyuan Gulf region. Urbanization and policy developed to transfer beach/seawater areas into built-up area/aquaculture are the two main driving forces contributing to dynamic changes in land use and landscape pattern in the last two decades in Louyuan.     

The effect of macrophytes on retention times in a constructed wetland for wastewater treatment

Retention times of treated water in a constructed wetland (CW) with horizontal subsurface flow were determined both in the vegetative and non-vegetative periods of 2005. Tracer experiments were performed using fluorescein, an organic compound detectable at extremely low concentrations. Nominal and tracer retention times were determined and compared. Winter tracer retention time (TRT 194 h) and nominal retention time (nHRT 190 h) were nearly exactly equal, while summer TRT (335 h) was approximately twofold higher than nHRT (158 h). Residence time distribution function (RTD) was used to compare retention times obtained for the vegetative and non-vegetative periods. The obtained results document a significant influence of dense common reed vegetation on retention characteristics of the studied system. Common reed can convert a significant volume of water from liquid to gas via evapotranspiration (ET) and thus prolong water retention times in the system. This is very important both technically and ecologically. Longer retention times mean a longer time for microbiological decay of wastewater. Water converted from liquid to gas causes cooling of the microclimate, which is very important, especially in intensively cultivated areas with a lack of water.     

影响胃肠间质瘤预后的相关因素

胃肠间质瘤（GIST）是来源于胃肠道间叶组织最常见的一种肿瘤[1],手术切除及术后辅助治疗是目前最主要的治疗方法.由于GIST生物学行为难以预测,术后复发可能性仍较大,找到能够较准确预测CIST预后的相关指标具有重要意义.现我们就胃肠道间质瘤预后相关因素做一综述,为评估术后复发提供更准确的参考.参50.     

Fermentative hydrogen production from beet sugar factory wastewater treatment in a continuous stirred tank reactor using anaerobic mixed consortia

A low pH, ethanol-type fermentation process was evaluated for wastewater treatment and bio-hydrogen production from acidic beet sugar factory wastewater in a continuous stirred tank reactor (CSTR) with an effective volume of 9.6 L by anaerobic mixed cultures in this present study. After inoculating with aerobic activated sludge and operating at organic loading rate (OLR) of 12 kgCOD?m^-3·d^-1, HRT of 8h, and temperature of 35°C for 28 days, the CSTR achieved stable ethanol-type fermentation. When OLR was further increased to 18 kgCOD?m^-3·d^-1 on the 53rd day, ethanol-type fermentation dominant microflora was enhanced. The liquid fermentation products, including volatile fatty acids (VFAs) and ethanol, stabilized at 1493 mg·L^-1 in the bioreactor. Effluent pH, oxidation-reduction potential (ORP), and alkalinity ranged at 4.1–4.5, -250–(-290) mV, and 230–260 mgCaCO₃?L^-1. The specific hydrogen production rate of anaerobic activated sludge was 0.1 L?gMLVSS^-1·d^-1 and the COD removal efficiency was 45%. The experimental results showed that the CSTR system had good operation stability and microbial activity, which led to high substrate conversion rate and hydrogen production ability.     

A modeling system for drinking water sources and its application to Jiangdong Reservoir in Xiamen city

Drinking water sources are highly valued by authorities for safeguarding the life of a city. Models are widely applied as important and effective tools in the management of water sources. However, it is difficult to apply models in water source management because water managers are often not equipped with the professional knowledge and operational skills necessary for making use of the models. This paper introduces a drinking water source simulation and prediction system that consists of a watershed model, a hydrological model and a water quality model. This system provides methods and technical guidance for the conventional management of water sources and emergency water event response. In this study, the sub-models of the system were developed based on the data of the Jiangdong Reservoir in Xiamen, and the model validation was based on local monitoring data. The hydrological model and water quality model were integrated by computer programming, and the watershed model was indirectly integrated into the system through a network platform. Furthermore, three applications for Jiangdong Reservoir water protection utilizing the system were introduced in this paper, including a conventional simulation, an emergency simulation, and an emergency measures evaluation.     

不同硝/铵比值对小麦幼苗根系释放氢氧根的影响

为研发酸化土壤的生物修复技术,采用水培试验和自动电位滴定装置研究酸性条件下氮素形态对小麦幼苗根系释放氢氧根及培养液pH变化的影响。结果表明,小麦幼苗在初始pH值为4.0,n(NO3-)∶n(NH4+)比值(以下简称硝/铵比)分别为15∶1、3∶1和1∶1的营养液中培养6 d后营养液pH升高,且增幅随硝/铵比的增加而增大,小麦对硝态氮的吸收量和氢氧根释放量呈相同的变化趋势,说明小麦对硝态氮的吸收偏好导致根系释放氢氧根,进而使得培养液pH升高。小麦幼苗在硝/铵比为3∶1,初始pH值分别为4.0、4.5和5.0的营养液中培养6d后,培养液pH和氢氧根释放量的增幅随初始pH的升高而降低,说明低pH条件有利于小麦幼苗对硝态氮的吸收,可促进小麦根系释放更多的氢氧根。10 h的恒定pH试验结果表明,恒定pH条件下小麦根系释放的氢氧根数量大于非恒定pH条件,且硝态氮比例越大,差值越大。因此,可以根据小麦在酸性条件下对硝态氮的吸收偏好建立酸化土壤的生物修复方法,即调节硝态氮含量以加大小麦根系的氢氧根释放量,进而提高土壤pH。     

RBCA、CLEA及CalTOX模型在苯并[a]芘污染场地健康风险评估中的应用比较

为探讨不同模型对污染场地健康风险评估结果的影响,以苯并[a]芘为例,采用RBCA、CLEA和CalTOX模型对某工业污染场地表层土壤进行健康风险评估,分析了评估结果的差异和原因,同时对模型的主要暴露参数进行了敏感性分析,并推导出基于风险概率分布的土壤修复限值。结果表明,RBCA、CLEA和CalTOX模型计算的苯并[a]芘致癌总风险分别为2.40×10-4、6.32×10-4和7.04×10-6,且经口摄入和皮肤接触2个途径对人体健康造成的危害最大。降解作用是影响CalTOX模型风险评估结果不同于RBCA和CLEA模型的重要因素,3个模型间参数取值及方法学的差异也会导致风险评估结果不同。各模型暴露参数的敏感性排序也有差异。采用基于风险概率分布的方法推导土壤修复限值,RBCA、CLEA和CalTOX模型所得结果分别为0.18、0.08、0.13(不考虑降解作用CalTOX模型)和10.74(考虑降解作用CalTOX模型)mg·kg-1,为各模型直接推导值的1.5～2.6倍。基于风险概率分布的方法可有效降低风险评估过程中参数不确定性的影响,为工业污染场地土壤修复值的制定提供参考。     

纳米Fe3O4对小鼠肺细胞的氧化损伤

纳米Fe3O4作为一种功能材料,在生物医药、生物靶向材料、微波吸收材料和高梯度磁分离器等方面应用前景广阔,其潜在的生物毒性也备受关注。为研究纳米Fe3O4对生物体可能造成的氧化损伤,以昆明小鼠为受试体,设置5、10、20和40mg·kg-14个染毒组,腹腔注射染毒7d后,测定小鼠肺组织中活性氧(reactive oxygen species,ROS)、还原型谷胱甘肽(glutathione,GSH)和丙二醛(malondialdehyde,MDA)的含量。结果显示,随着纳米Fe3O4染毒剂量的升高,肺组织ROS和MDA含量逐渐上升,GSH含量逐渐降低,各指标均呈一定的剂量-效应关系。剂量≥10mg·kg-1,肺组织ROS含量与对照组相比有显著差异(p<0.05);剂量≥20mg·kg-1,肺组织MDA含量与对照组相比有显著差异(p<0.05);剂量≥40mg·kg-1,肺组织GSH含量与对照组相比有显著差异(p<0.05)。研究表明,较高剂量(≥20mg·kg-1)的纳米Fe3O4颗粒材料会引起小鼠肺细胞的氧化损伤。     

Species phylogenetic relatedness, priority effects, and ecosystem functioning

Species immigration history can structure ecological communities through priority effects, which are often mediated by competition. As competition tends to be stronger between species with more similar niches, we hypothesize that species phylogenetic relatedness, under niche conservatism, may be a reasonable surrogate of niche similarity between species, and thus influence the strength of priority effects. We tested this hypothesis using a laboratory microcosm experiment in which we established bacterial species pools with different levels of phylogenetic relatedness and manipulated the immigration history of species from each pool into microcosms. Our results showed that strong priority effects, and hence multiple community states, only emerged for the species pool with the greatest phylogenetic relatedness. Community assembly also resulted in a significant positive relationship between bacterial phylogenetic diversity and ecosystem functions. Interestingly, these results emerged despite a lack of phylogenetic conservatism for most of the bacterial functional traits considered. Our results highlight the utility of phylogenetic information for understanding the structure and functioning of ecological communities, even when phylogenetically conserved functional traits are not identified or measured.