Interspecific competition in tree squirrels: do introduced grey squirrels (<Emphasis Type="Italic">Sciurus carolinensis</Emphasis>) deplete tree seeds hoarded by red squirrels (<Emphasis Type="Italic">S. vulgaris</Emphasis>)?

Red squirrels (Sciurus vulgaris) and introduced eastern grey squirrels (S. carolinensis) scatterhoard seeds of broadleaf trees. Scatterhoarded seeds are an essential resource in spring and their consumption increases red-squirrel fitness. We examined whether grey squirrels partly deplete the high-energy food resources cached by red squirrels, reducing their consumption, in two ways: (1) at the population level, comparing energy intake of feeding on cached seeds between a study site with red and grey squirrels and one with only red squirrels present; and (2) at the individual level, in the study site where species co-exist, relating hoard recovery of red squirrels to the amount of core-area overlap with grey squirrels. There were no significant site differences in the mean daily energy intake of red squirrels feeding on seeds recovered from caches. However, in the red-grey site, during spring, red squirrels that had a high percentage of their home-range core area overlapped by grey squirrels had a lower daily energy intake than low-overlap red squirrels. Body mass of red squirrels in spring was negatively correlated with the percentage of interspecific core-area overlap, but not with core-area overlap with other red squirrels. Our data suggest that interspecific competition for scatterhoarded seeds, with grey squirrels pilfering red squirrels' food caches, caused a reduced energy intake in red squirrels with a high degree of interspecific core-area overlap, and reduced body mass in spring. Therefore, cache pilfering is likely to reduce reproductive output in red squirrels, and thus play a role in the replacement of red by grey squirrels. Electronic Publication     

The Impact of the Hyperacid Ijen Crater Lake. Part II: A Total Diet Study

In Asembagus (East Java, Indonesia), surface water is contaminated with effluent from the hyperacid Ijen Crater Lake. In a previous study, we reported that food crops irrigated with this water had increased concentrations of various elements. Here, we present a total diet study for adults and 6-year-old children to determine if the mean daily intake of a broad range of elements is safe and adequate. For children, the intake of B, Mg, Mn and V is high with Hazard Quotients (HQ) of 1.1 (B), 1.4 (Mn) and 1.4 (V), respectively (no TDI is available for Mg). For Mn, the daily intake is high due to the consumption of locally produced rice. Drinking water is the main source of B, Mg and V. For adults, the intake of Mg, Mn and V is also high but HQ values are ≤0.7. For both children and adults, the intake of Ca, Zn and particularly Fe is below the RNI (Fe intake is 90% below the RNI for women). It is concluded the mean intake of elements is unbalanced and Fe deficiency is probably the most serious health problem. Toxic effects cannot be fully excluded since deficiency of essential elements such as Ca, Fe and Zn can increase the absorption and retention of various elements.     

水旱轮作土壤-小麦系统CO2排放及其影响因素

利用静态箱/气相色谱法对川中丘陵区水旱轮作区的小麦进行全生长季CO2排放观测.结果表明,(1)土壤-小麦系统的CO2排放通量存在着明显的日变化.凌晨400～600排放量最低,随着温度的升高,CO2的排放量逐渐增大,在午后100～300达到峰值.分析表明,气温和地表温度与土壤-小麦系统CO2排放通量之间存在显著的相关关系.(2)土壤-小麦系统CO2排放都有明显的季节变化.分析表明,小麦生物量和气温与土壤-小麦系统CO2排放季节变化之间存在显著的相关关系.(3)在小麦各个生育期中,CO2平均排放通量常规处理>无氮处理>空白>裸地.水旱轮作区小麦常规处理、无氮处理、空白点和裸地的CO2排放通量的平均值分别为574.51、362.23、239.91、129.47 mg/(m2·h).在小麦的各个生育期中,RH、RAR和RAS对土壤-小麦系统CO2排放的贡献率分别为20%、20%和60%.     

水口电站对闽江河口咸潮入侵的影响

河流上大型电站的建设，在一定程度上会改变下游河道的径流特征，径流、潮流强度组合的变化，将影响咸潮的入侵，文章从水口电站前后闽江下游径流量变化入手，分析了水口电站对闽江河口咸潮入侵的影响。结果表明：（１）水口电站具有一定的季调节能力，有利于增大闽江河口咸潮入侵；（２）电站调峰不会加剧咸潮入侵的不利影响；（３）若电站关闸蓄水，则会加剧河口咸潮入侵。最后，提出了防止和减轻咸潮影响的对策措施。     

SALMONID SMOLT SURVIVAL RELATIVE TO TURBINE EFFICIENCY AND ENTRAINMENT DEPTH IN HYDROELECTRIC POWER GENERATION1

ABSTRACT: The hypotheses that fish survival probabilities may be lower (1) at less than peak operating turbine efficiency; (2) at deeper entrainment depth; and (3) with the deployment of extended‐length intake guidance screens, are not supported by results on yearling chinook salmon smolts (Oncorhynchus tshawytscha) at Lower Granite Dam, Snake River, Washington. Estimated 96 h survival probabilities for the six test conditions ranged from 0.937 to 0.972, with the highest survival at turbine operating towards the lower end of its efficiency. A blanket recommendation to operate all Kaplan type turbines within ± 1 percent of their peak efficiency appears too restrictive. Cavitation mode survival (0.946) was comparable to that at peak operating efficiency mode (0.937), as was the survival between upper (0.947) and mid depths (0.937). Survival differed only slightly among three turbine intake bays at the same depth (0.937 to 0.954), most likely due to differential flow distribution. Extended‐length intake fish guidance screens did not reduce survival. However, the sources of injury somewhat differed with depth; probable pressure and shear‐related injuries were common on fish entrained at mid‐depth, and mechanically‐induced injuries were common at upper depth. Operating conditions that reduce turbulence within the turbine environment may enhance fish survival; however, controlled experiments that integrate turbine flow physics and geometry and the path entrained fish traverse are needed to develop specific guidance to further enhance fish passage survival.     

草、藻型湖泊水体生态及理化特性的实验对比

2006年9月,根据营养水平和种植水草的差异设计了6个浅水湖泊模拟系统,实验用水草为菹草(Potamogeton crispusLinn.)和马来眼子菜(Potamogeton malaianus-Miq).在15个月实验期间,通过多次监测各系统的景观外貌和水质,对草、藻型湖泊生态及理化特性的差异进行研究,得出以下结论:(1)草、藻型系统分别对应清水和浊水2种状态,景观外貌差异很大.(2)水草可使湖泊系统维持在清水状态,在一定条件下,甚至可使富营养化湖泊维持在清水状态;但是水草腐烂分解等也可使水质迅速恶化,甚至引起湖泊草、藻状态的转变;关键在于,对于不断变化的环境条件,系统内水草能否健康生长.(3)由于营养和生产力水平低,贫营养系统的水质指标随时间变化较小,草、藻型系统间的差异不明显,DO变化范围分别为8.1～14.4 mg·L~(-1)、7.5～11.6 mg·L~(-1),pH 8.71～9.89、8.25～9.22,TP 0.006～0.012 mg·L~(-1)、0.006～0.053 mg·L~(-1),TN 0.11～0.71 mg·L~(-1)、0.10～0.83 mg·L~(-1),NH_4~+-N 0.01～0.17 mg·L~(-1)、0.01～0.26 mg·L~(-1),PO_4~(3-)-P 0.002～0.012 mg·L~(-1)、0.000～0.008mg·L~(-1).(4)由于水草和藻类的大量生长等,中营养与富营养系统湖水的DO、pH、水温和NH_4~+-N的日变化明显,日变化曲线呈“⌒”形,且具有季节性变化规律;由于水草向底泥中输氧气等原因,与藻型湖泊相比,草型湖泊水中TP、TN和NH_4~+-N的浓度较低,PO_4~(3-)-P浓度较高,草、藻型系统的TP均值分别为0.16、0.51 mg·L~(-1),TN 1.30、8.32 mg·L~(-1),NH_4~+-N 0.19、0.43mg·L~(-1),PO_4~(3-)-P 0.07、0.01 mg·L~(-1).     

浅谈日常安全工作的两个“五”

从安全管理的思维方式入手,具体地落实到如何使安全教育、督导等工作在实际生产过程中发挥其应有的效果,以保证安全生产和生产安全。     

青岛市不同下垫面微生物气溶胶分布特征

分别在青岛市市区街道、海滨区域、饮用水水源地、城市垃圾填埋场和人工湿地污水处理厂设置监测点,分析比较不同下垫面空气细菌和真菌浓度、日变化和粒径分布. 结果表明:5个下垫面空气细菌浓度依次为城市垃圾填埋场>市区街道>饮用水水源地>海滨区域>人工湿地污水处理厂,真菌浓度依次为城市垃圾填埋场>人工湿地污水处理厂>饮用水水源地>市区街道>海滨区域,其中城市垃圾填埋场空气细菌和真菌浓度最高,分别为(613.1±68.9)、(1300.4±74.3)CFU/m3,其他下垫面空气的细菌和真菌浓度分别在(155.5±14.2)～(596.6±396.4)和(401.9±78.7)～(994.7±63.4)CFU/m3之间. 海滨区域空气细菌浓度下午明显高于上午和中午,其他下垫面表现为上午>下午>中午,但无显著性差异;市区街道、饮用水水源地、人工湿地污水处理厂的空气真菌浓度日变化表现为上午>中午>下午,城市垃圾填埋场则始终升高,除人工湿地污水处理厂和城市垃圾填埋场不同时段间空气真菌浓度有显著性差异外,其余下垫面无显著性差异. 细菌气溶胶粒径分布为F1级(粒径>7.0μm)最高,呈偏态分布;真菌气溶胶粒径呈对数正态分布,除城市垃圾填埋场峰值出现在F3级(3.3~4.7μm)外,其余下垫面均出现在F4级(2.1~3.3μm). 不同下垫面细菌气溶胶中值直径在2.8~4.6μm,存在差异;而不同下垫面空气真菌气溶胶中值直径均在2.0μm左右,无显著性差异.      

校园学生群体食物汞暴露现状及风险评价——以天津大学为例

通过测定校园学生主要食物中(包括主食、鱼类、肉类、蔬菜等)总汞和甲基汞浓度,同时采集志愿者头发作为生物指示物,结合外暴露和内暴露数据系统评估学生群体的汞暴露风险.校园食堂食物总汞浓度范围为0.57~207.50ng/g(以湿重计),甲基汞浓度范围为0.06~49.20ng/g(以湿重计),与已有研究相比处于较低水平.不同食物中汞浓度水平存在显著差异,如水产品中总汞和甲基汞浓度均比其他食物要高.所调查人发中总汞浓度为0.03~0.77 μg/g,甲基汞浓度为0.02~0.67 μg/g,男性发汞浓度要显著高于女性.人体汞浓度与个人饮食习惯存在一定联系,水产品食用频次较高的人群中发汞浓度也相对较高.男性学生总汞摄入量约为9200ng/d,女性约为7500ng/d.总汞摄入主要通过主食摄入,而甲基汞则主要通过水产品摄入.根据现行人群汞摄入风险评价标准,本研究中校园人群汞暴露风险较低,但水产品食用频次增加仍可能造成大量的汞摄入.     

我国某肺癌高发区人群多环芳烃和微量元素的日暴露量研究

在我国某肺癌高发区采集大气颗粒物样品,测定了其中16种多环芳烃(PAHs)的浓度,并收集人群的日饮食样品,以苯并(a)芘(Bap)为代表,计算人群通过空气和饮食的Bap日暴露量.用ICP-MS测定饮食中14种微量元素的日摄入量.结果表明,该地区室内空气PAHs污染显著高于室外,且毒性强的5、6环PAHs所占比例高于对照点.高发区Bap日暴露总量均值为3.758μg/d,比对照点(0.257μg/d)高近14倍.高发区有毒重金属Cd和Tl日摄入量显著高于对照点; 高发区元素Se日摄入量显著低于对照点,且该地区人群从环境中摄入Se严重不足;Fe、Cu和Zn的日饮食摄入量明显低于营养元素日摄入量推荐值(RDA).