Developing an Ecosystem Perspective from Experimental Monitoring Programs: I. Demographic Responses of a Rare Geothermal Grass to Soil Temperature

The geysers panic grass [Dichanthelium lanuginosum Spellenberg var. thermale (Bol.) Spellenberg or DILA] is exclusively associated with surface geothermal manifestations in Sonoma County, California, USA (38°46′N, 122°38′W). Steam extraction by power plants could alter the subsurface distribution of heat and water to the site, potentially impacting subpopulations of this rare plant. The purpose of this study was to use demographic monitoring to determine: (1) temporal and spatial patterns of soil temperature in relation to the distribution of established DILA individuals at Little Geysers, (2) in situ response of experimental populations of DILA to spatial variations in soil temperature, and (3) habitat requirements of DILA as an indicator of its tolerance to variations in surficial geothermal features. Thermocouple transects and a datalogger provided data for characterizing the spatial and temporal patterns of soil temperature in four microhabitats (fumarole, DILA stand, Andropogon stand, and cleared). Experimental populations were established by precisely sowing and monitoring DILA seeds in these microhabitats. The results indicated that spatial and temporal variations in soil temperature had significant effects on the processes of germination, growth, survivorship, and reproduction, thus producing a readily observed metapopulation patch dynamic in relation to geothermal activity. Seasonal depressions of soil temperature near the fumaroles by cold air and prolonged rainfall events also promoted the emergence and survival of DILA seedlings in a microhabitat that was previously too hot to occupy. Over longer periods of time, DILA metapopulation dynamism reflected climatic and geothermal variation. Drought years inhibited germination for lack of water, but more importantly for the lack of requisite soil temperature depressions in the fumarole microhabitat. Wet years promoted subpopulation expansion into transition areas that were once too hot and dry. There have also been shifts in the underground distribution of steam into areas distant from known geothermal features. The demographic responses of DILA to spatial and temporal variations in soil temperature indicate that heat is an absolutely essential component of the steam resource. In its absence, germination, seeding survivorship, growth, and maturation are significantly inhibited even if soil conditions are favorable and potential competitors are controlled. Ultimately, persistence of the species depends on maintaining the ecosystem dynamic of colonization and extirpation in response to variations in surficial geothermal features over long spatial and temporal scales. This should shift management perspective from its narrow focus on individual plants to a wider focus on monitoring the essential habitat component of steam.     

采油废水人工湿地处理效果及植物作用分析

采用水平潜流人工湿地中试系统处理采油废水,考察湿地植物生长状况对污染物去除效果的影响,运用气相色谱-质谱(GC-MS)技术分析湿地植物对有机污染的吸附情况,并分析了湿地植物对氮、磷的吸收效果。研究结果表明:人工湿地出水达GB 8987—1996《污水综合排放标准》中的一级标准。湿地植物的生长状况与人工湿地的COD及NH 4+-N去除率呈现一定的耦合关系。芦苇及藨草均能吸附多种难降解有机污染物。植物吸收是人工湿地去除氮、磷的途径之一,但并非主要途径。     

番茄对污染土壤中邻苯二甲酸酯的吸收累积特征

利用盆栽实验研究了番茄对污染土壤中邻苯二甲酸酯(PAEs)的吸收积累特征。结果表明,番茄根系、茎、叶和果实均可以吸收累积PAEs化合物,其含量与土壤污染程度成正相关;相同处理的番茄茎、叶和果实中邻苯二甲酸正丁酯(DBP)含量均高于邻苯二甲酸异辛酯(DEHP),而番茄根系中DBP的含量低于DEHP; 4个不同处理方式土壤中DBP和DEHP的残留量顺序均为:灭菌土壤组灭菌土壤种植番茄苗组未灭菌土壤组未灭菌土壤种植番茄苗组。无论是灭菌处理还是未灭菌处理,有番茄苗组土壤中PAEs含量均低于无番茄苗组,未灭菌土壤种植番茄苗组土壤中PAEs残留量最低,PAEs削减率高达96.39%,有番茄苗组微生物数量大于无番茄苗组。这些说明土壤中PAEs的削减是番茄植物和微生物协同作用的结果。     

A design method of a plant alarm system for first alarm alternative signals using a modularized CE model

Management of a plant alarm system has been identified as one of the key safety issues because of disasters caused by alarm floods. When a chemical plant is at abnormal state, an alarm system must provide useful information to operators as the third layer of an independent protection layer (IPL). Therefore, a method of designing a plant alarm system is important for plant safety. Because the plant is maintained in the plant lifecycle, the alarm system for the plant should be properly managed through the plant lifecycle. To manage changes, the design rationales of the alarm system should be explained explicitly. This paper investigates a logical and systematic alarm system design method that explicitly explains the design rationales from know-why information for proper management of changes through the plant lifecycle. In the method, the module structure proposed by Hamaguchi et al. (2011) to assign a fault origin to be distinguished is extended. Using modules to investigate the sets of alarm sensors and the alarm limits setting for first alarm alternative signals to distinguish the fault origin, an alarm system design method is proposed. Also, the completeness of fault propagation for a branch of the cause–effect model as the plant model is explained. Using the modules and the set of fault origins to be distinguished by the alarm system, we try to explicitly explain the design rationales of the alarm system.     

内蒙古农牧交错带土地利用变化对CH4吸收的影响

于2008~2010年,根据邻近样地采样原则,选择位于内蒙古农牧交错带的天然草地和不同开垦时间的农田作为研究样地(G-草地; C5-开垦5a的农田;C10-开垦10a的农田;和C50-开垦50a的农田),利用静态箱法通过3a的野外试验,研究土地利用类型变化对CH4吸收的影响.结果表明:天然草地转变为农田后,不同开垦年限的农田土壤和草地土壤CH4吸收存在显著差异2008年(FCH4=273.7, P<0.001), 2009年(FCH4=264.8, P<0.001)和2010年(FCH4=362.4, P<0.001).草地转变为农田促进CH4吸收,2008, 2009 和2010年生长季的生长季(4~10月),草地CH4吸收量最低分别为141.4,210.0,236.0mg/m2.2008~2010年农田土壤CH4累积吸收量与草地土壤相比增加20%~280%.农田开垦年限影响CH4吸收,随着农田开垦年限的增加从开垦5~50a,CH4累积吸收量降低.相关分析表明,不同土壤CH4吸收与土壤水分含量和NH4+-N 含量呈负相关关系(R2=0.7380, P<0.01).草地转变为农田后,土壤水分含量和NH4+-N 含量驱动不同开垦年限的农田土壤和草地土壤CH4吸收差异.     

Source and Distribution of Heavy Metals in Food†

Diet is the major route of exposure to contaminants, therefore food monitoring programs are essential to estimate the degree of human risk. We present a study undertaken in Austria dealing with the total uptake of mercury, cadmium, arsenic and lead. The dates were calculated from diet as well as from commercial food. Higher contaminated foodstuffs are registered and a comparison was made between body burden of babies and adults on the basis of bodyweight. It was pointed out, that cooked or washed food ready to eat has a lower burden of lead and cadmium than non prepared food due to household processing, which may decontaminate food to some extent’ Arsenic content was not reduced, because it is bound chemically and not primarily deposited on the surface of food such as in the case of lead. It was mentioned that the type of compound plays an important role in the assessment of action of those elements on humans.

Their biological activity is not necessarily related to their concentration in food. As in the case of selenium and chromium one has to take into consideration that there is a narrow range between benefit and harm, toxicity, and minor supply.

Therefore we conclude, that due to interactions of elements, their different biological activity and due to the difference of compounds present in food, we have to relativate the terms toxicity and essentiality. Then we can get a more profound insight into the problems of trace elements in food.     

Chromium accumulation,transport and toxicity in plants∗

The predominant pathway for human exposure to chromium in non‐occupationally exposed individuals is via food with a daily intake of around 30–100 μgd^–1, with vegetables providing a major contribution. Unlike reports of chromium essentiality to man and animals, plants appear not to require chromium in spite of some early reports of a stimulatory growth effect.

Most reports on chromium in plants have been concerned with their growth on soils amended with sewage sludge, pF‐ash, tannery waste, or on ultra basic soils, which contain extreme concentrations of the element. Experimental studies with plants grown in hydroponic solution have often been undertaken at unrealistically high concentrations to examine the uptake of chromium in various forms, either as CrIII or CrVI at different pHs. In most cases, reports on chromium in plants deal with element concentrations and plant/soil relationships rather than detailed biochemical and physiological processes.

In general, chromium is largely retained in the roots of plants, although the oxidation state of chromium, pH, presence of humates and fulvates and plant species, affect plant uptake and transport. Leaves usually contain higher concentrations than grains. The uptake of CrIII is largely a passive process, whereas CrVI uptake is a metabolically mediated process via the sulphate pathway and is thus readily transported around the plant. The presence of a compound similar to trioxalate CrIII has been recorded while little chromium has been reported to be associated with cell organelles or soluble proteins.     

Cadmium uptake by a phytoplankton species in the presence of different inhibitors&

The uptake of cadmium by the Haptophyceae Hymenomonas elongata was studied as regards the energetic processes and Ca‐transport. For this purpose, experiments were carried out in the presence of an uncoupler of the phosphorylation : CCCP and of an inhibitor of calcium channels and also of Ca²⁺‐ATPase : verapamil. To reduce the number of assays, a factorial experimental design was used, in which all variables:— concentration of Cd in the medium—incubation time and—the presence of the inhibitor, are at two levels. In the absence of inhibitor, Cd uptake was found to vary as a function of metal concentration in the medium and of incubation time. CCCP significantly increased Cd uptake by H. elongata at sufficient incubation time. Therefore Cd uptake seemed linked to an energy‐dependent process, involving an ATPase. Verapamil immediately increased Cd uptake, implying an interaction between Cd and Ca.     

Influence of short-term irrigation of textile mill wastewater on the growth of chickpea cultivars

The effect of textile mill wastewater on germination, delay index, physiological growth parameters, and plant pigments of two cultivars of chickpea was studied. The aim of this study was to evaluate the suitability of textile mill wastewater (treated and untreated) at different concentrations (0, 6.25, 12.5, 25, 50, 75, and 100%) for irrigational purposes. The textile effluent did not show any inhibitory effect on seed germination at a lower concentration (6.25%). The other reported plant parameters (delay index, root length, shoot length, dry weight, chlorophyll, and carotenoid) also followed a similar trend. Seeds germinated in 100% effluents but did not survive for longer periods. It has also been concluded that the effect of the textile effluent is cultivar-specific, and due care should be taken before using the textile mill wastewater for irrigation purposes.     

氮输入对沼泽湿地植物生长和氮吸收的影响

氮是湿地植物生长必不可少的营养元素之一,但当外源氮输入超出植物生长需要时,氮素将抑制植物生长。不同植物对氮输入的响应不同,同一植物不同器官对氮输入的响应也不一致。为了探讨氮输入对湿地植物生长和氮吸收的影响机制,本文选取滇西北典型湖泊湿地纳帕海湖滨挺水植物茭草（Zizania caduciflora）和水葱（Scirpus validus）为对象,通过控制实验,研究了3个不同氮输入水平[0 g·m-2·a-1（对照,CK）、20 g·m-2·a-1（N20）、40 g·m-2·a-1（N40）]对茭草和水葱生物量积累、根冠比、氮吸收的影响。结果表明：培养期内,茭草地上生物量始终表现为N40〉N20〉CK,即氮输入促进茭草地上生物量积累;而水葱地上生物量随培养时间不同而发生变化,培养早期N20处理促进水葱地上生物量积累,N40处理抑制水葱地上生物量积累。茭草地下生物量表现为N40〉CK〉N20,即氮输入不足抑制茭草地下生物量积累,足够氮输入促进茭草地下生物量积累;水葱地下生物量表现为CK〉N20〉N40,即氮输入抑制水葱地下生物量积累。植物地上部分和地下部分生长对氮输入的响应也不一致,导致植物根冠比发生变化,茭草根冠比表现为N20