Soil availability,plant uptake and soil to plant transfer of 99Tc--a review

The fission yield of 99Tc from 239Pu and 235U is similar to that of 137Cs or 90Sr and it is therefore an important component of nuclear weapons fall-out, nuclear waste and releases from nuclear facilities. There is particular current interest in 99Tc transfer from soil to plants for: (a) environmental impact assessments for terrestrial nuclear waste repositories, and (b) assessments of the potential for phytoextraction of radionuclides from contaminated effluent and soil. Vascular plants have a high 99Tc uptake capacity, a strong tendency to transport it to shoot material and accumulate it in vegetative rather than reproductive structures. The mechanisms that control 99Tc entry to plants have not been identified and there has been little discussion of the potential for phytoextraction of 99Tc contaminated effluents or soil. Here we review soil availability, plant uptake mechanisms and soil to plant transfer of 99Tc in the light of recent advances in soil science, plant molecular biology and phytoextraction technologies. We conclude that 99Tc might not be highly available in the long term from up to 50% of soils worldwide, and that no single mechanism that might be easily targeted by recombinant DNA technologies controls 99Tc uptake by plants. Overall, we suggest that Tc might be less available in terrestrial ecosystems than is often assumed but that nevertheless the potential of phytoextraction as a decontamination strategy is probably greater for 99Tc than for any other nuclide of radioecological interest.     

Soil-fungi transfer coefficients: Importance of the location of mycelium in soil and of the differential availability of radionuclides in soil fractions

Soil-fungus transfer coefficients are usually defined as the ratio between the content of the fruiting bodies and that of the soil. Since, however, the methodology of how to determine the soil content is not firmly established, there exist a variety of definitions in the literature. We analyzed the 137Cs, 90Sr, 40K, and 226Ra content of mushroom and soil samples from two pine-wood ecosystems in Spain. The location of the mycelium in the soil profiles of these ecosystems was determined by means of the ergosterol concentration. The results showed the mycelium to generally be localized in the surface layer of soil (0-5 cm). We also carried out a speciation procedure for this layer of soil to determine the different degrees of association of the radionuclides in the soil. The results led us to propose some variations to the traditional definition used in quantifying radionuclide transfer. With these modifications, we were able to analyze Cs-K competition in several species of mycorrhizal and saprophytic fungi.     

Toxicokinetics/toxicodynamics of arsenic for farmed juvenile milkfish Chanos chanos and human consumption risk in BFD-endemic area of Taiwan

This paper presents a toxicokinetic/toxicodynamic analysis to appraise arsenic (As) bioaccumulation in farmed juvenile milkfish Chanos chanos at blackfoot disease (BFD)-endemic area in Taiwan, whereas probabilistic incremental lifetime cancer risk (ILCR) and hazard quotient (HQ) models are also employed to assess the range of exposures for the fishers and non-fishers who eat the contaminated fish. We conducted a 7-day exposure experiment to obtain toxicokinetic parameters, whereas a simple critical body burden toxicity model was verified with LC50(t) data obtained from a 7-day acute toxicity bioassay. Acute toxicity bioassay indicates that 96-h LC50 for juvenile milkfish exposed to As is 7.29 (95% CI: 3.10-10.47) mg l(-1). Our risk analysis for milkfish reared in BFD-endemic area indicates a low likelihood that survival is being affected by waterborne As. Human risk analysis demonstrates that 90%-tile probability exposure ILCRs for fishers in BFD-endemic area have orders of magnitude of 10(-3), indicating a high potential carcinogenic risk, whereas there is no significant cancer risk for non-fishers (ILCRs around 10(-5)). All predicted 90%-tiles of HQ are less than 1 for non-fishers, yet larger than 10 for fishers which indicate larger contributions from farmed milkfish consumptions. Sensitivity analysis indicates that to increase the accuracy of the results, efforts should focus on a better definition of probability distributions for milkfish daily consumption rate and As level in milkfish. Here we show that theoretical human health risks for consuming As-contaminated milkfish in the BFD-endemic area are alarming under a conservative condition based on a probabilistic risk assessment model.     

Climatic and human drivers of recent lake-level change in East Juyan Lake,China

Drying of an inland river’s terminal lake in arid regions is an important signal of environmental degradation in downstream regions. A long-term, high-resolution understanding of the lake’s retreat and expansion and the driving mechanisms will inform future adaptive water management strategies, ecosystem restoration, and government decision-making in the context of a growing water scarcity in the inland river basin. The shrubs that grow along the shore of a lake often provide evidence of lake retreat or expansion. The chronological results showed that the earliest germination dates of the lakeshore shrubs, tamarisk, were in 1901, 1943, 1966, 2009, and 1990 from the higher terrace to the lower terrace of East Juyan Lake, a terminal lake of China’s Heihe River. Coupled with river and lake hydrological data, six obvious lake’s fluctuations were identified: shrinkage from 1900 to 1940s and during the early 1990s, expansion and retreat in the late 1950s and early 1970s, continued expansion from 2002 to 2008, and stabilization at a water area of around 40 km² from 2009 to the present. The water elevation in the 1900s was below 905 m a.s.l., resulting in a water area <80 km², but decreased to 40 km² after 1960 and dried up completely by the 1990s. By analysing climatic and hydrological records since 1950, tree-ring climate proxy data, river runoff outside the observation period, and water resource consumption in the middle and lower reaches of the Heihe River, we found that the periodic expansion and retreat of East Juyan Lake was influenced by both climate change and human activities, but especially by human activities. The lake’s recent recovery and stability was achieved by government policy designed to provide environmental flows to the lake.     

Bushmeat consumption and its implications for wildlife conservation in the semi-arid region of Brazil

Hunting plays an important socioeconomic role in the semi-arid region of Brazil, by supplying meat and other products. Nevertheless, there is a lack of information on which species are most used by the local populations and what are the implications for conservation of exploited animals. This paper explores the bushmeat consumption in the Brazilian Caatinga region, where wild animals comprise an important protein source. A questionnaire was used to gather information from hunters, and the consumption of bushmeat by their families was monitored. Interviews revealed that 58 vertebrate species could potentially be consumed as bushmeat, but the samples provided by the monitored families comprised only 28 species. Birds were the animals most consumed, followed by mammals, although the biomass of both groups was similar. The consumption of bushmeat was not correlated with hunters’ socioeconomic data (income, age or schooling). Hunters recognized that the populations of some game species appeared to be declining, showing that bushmeat consumption, together with the cultural, economic and social aspects of the human populations involved in hunting, should be considered when discussing the conservation of animal resources in the Caatinga region.     

Educating for sustainable production and consumption and sustainable livelihoods: learning from multi-stakeholder networks

This paper examines how education for sustainable development (ESD) can be concretely advanced using the theoretical approaches of sustainable consumption and production (SCP) and sustainable livelihoods (SL). Five case examples illustrate a diverse set of strategic educational interventions focusing on: (1) education of specific organizational actors about these theoretical frameworks illustrated with case examples (such as SCP training by the United Nations University Institute of Advanced Studies [UNU-IAS] and CSR-Asia of government and business representatives), (2) regional education strategies focused on production and consumption in specific sectors (such as the food sector in Sk?ne, Sweden), (3) social learning directed at innovation for sustainable development (such as competitions of solar boats developed by universities in the region of Friesland, the Netherlands), (4) education of consumers and firms made possible by the adoption of certification systems affirming SCP and SL (such as Cradle-to-Cradle certification of a paper company in the Netherlands or the establishment of Fair Trade cities in Sweden), or (5) reorienting communities to address underutilized productive physical capital within communities (such as the sharing productive capital project in rural areas of Saskatchewan, Canada). The cases are drawn from the projects that the UNU-IAS, four of its regional centers of expertise (RCE) on ESD and other affiliates have conducted. In addition to documenting the educational processes emerging from specific regions, the paper highlights findings related to the success of these projects and opportunities for further research, including regional and inter-regional approaches.     

Addressing food supply chain and consumption inefficiencies: potential for climate change mitigation

Globally, more than 30 % of all food that is produced is ultimately lost and/or wasted through inefficiencies in the food supply chain. In the developed world this wastage is centred on the last stage in the supply chain; the end-consumer throwing away food that is purchased but not eaten. In contrast, in the developing world the bulk of lost food occurs in the early stages of the supply chain (production, harvesting and distribution). Excess food consumption is a similarly inefficient use of global agricultural production; with almost 1 billion people now classed as obese, 842 million people are suffering from chronic hunger. Given the magnitude of greenhouse gas emissions from the agricultural sector, strategies that reduce food loss and wastage, or address excess caloric consumption, have great potential as effective tools in global climate change mitigation. Here, we examine the challenges of robust quantification of food wastage and consumption inefficiencies, and their associated greenhouse gas emissions, along the supply chain. We find that the quality and quantity of data are highly variable within and between geographical regions, with the greatest range tending to be associated with developing nations. Estimation of production-phase GHG emissions for food wastage and excess consumption is found to be similarly challenging on a global scale, with use of IPCC default (Tier 1) emission factors for food production being required in many regions. Where robust food waste data and production-phase emission factors do exist—such as for the UK—we find that avoiding consumer-phase food waste can deliver significant up-stream reductions in GHG emissions from the agricultural sector. Eliminating consumer milk waste in the UK alone could mitigate up to 200 Gg CO₂e year^?1; scaled up globally, we estimate mitigation potential of over 25,000 Gg CO₂e year^?1.     

Monitoring of eutrophication and nutrient limitation in the Izmir Bay (Turkey) before and after Wastewater Treatment Plant

The distribution of inorganic nutrients and phytoplankton chlorophyll-a was investigated and N/P ratios were determined in Izmir Bay during 1996-2001. The average concentrations showed ranges of 0.01-0.19 and 0.01-10 microM for phosphate-phosphorus; 0.11-1.8 and 0.13-27 microM for (nitrate+nitrite)-nitrogen, 0.30-4.1 and 0.50-39 microM for silicate and 0.02-4.3 and 0.10-26 microg l(-1) for chlorophyll-a in the outer and middle-inner bays, respectively. The results are compared with the values obtained from the relatively unpolluted waters of the Aegean Sea. The N/P ratio is significantly lower than the assimilatory optimal (N/P=15:1) in conformity with Redfield's ratio N/P=16:1. Nitrogen is the limiting element in the Izmir Bay. Phosphate, which originates from detergents, is an important source for eutrophication in the bay, especially in the inner bay. In early 2000, a Wastewater Treatment Plant (WTP) began to treat domestic and industrial wastes. This plant treats the wastes about 60% capacity between 2000 and 2001. The sampling periods cover before and after treatment plant. Although the capacity of wastewater plant is sufficient for removal of nitrogen from the wastes, it is inadequate for removal of phosphate. This is also in accordance with the decreasing N/P ratios observed during 2000-2001 (after WTP) in the middle-inner bays.     

Energy consumption model and energy efficiency evaluation for CNC continuous generating grinding machine tools

Abstract

Machine tool, which is the basis energy consumed device in manufacturing system, its energy consumption model and energy efficiency evaluation are the prerequisites for energy saving in manufacturing. Considering the multi-energy-sources features,analysed the mathematical model of a CNC continuous generating grinding machine tool from the view of energy constitute. The energy sources of a CNC continuous generating grinding machine tool are classified into gear grinding system, grinding wheel dressing system and auxiliary system. Based on the power balance equations of energy flow, the energy flow system of a CNC continuous generating grinding machine tool is established. And then the energy consumption mathematical model of a CNC continuous generating grinding machine tool is set up by combining the power balance equations with the operating features of three kinds of energy sources. The case study shows that the proposed energy consumption model can provide fundamental support for energy consumption forecasting, energy efficiency analysis and energy-saving optimisation during the machine tool operation process.     

鄱阳湖主湖区与碟形湖水位变化及其对水质的影响

水位作为鄱阳湖重要的水文因子,对鄱阳湖水动力过程和水质变化具有重要影响。根据2014~2015年鄱阳湖主湖区和碟形湖水位、水质监测数据,分析了主湖区和碟形湖水位及主要水质指标的年内变化特征,阐述了主湖区和碟形湖水质对水位的响应特征。结果表明:(1)丰水期碟形湖与主湖区联通,碟形湖水位与主湖区水位呈直线型相关,枯水期碟形湖水位高于主湖区,主湖区年内月平均水位变异系数为0.13,而碟形湖年内月平均水位变异系数为0.08;(2)丰水期,主湖区和碟形湖的氮磷比分别为19.29和46.27,枯水期主湖区和碟形湖水体的氮磷比分别为17.88和40.39;(3)鄱阳湖主湖区水质主要指标与水位的相关性显著强于碟形湖,主湖区总氮、氨氮、总磷和溶解氧均与水位呈负相关性,而碟形湖中只有p H与水位有相关性;(4)枯水季节,碟形湖水体具有较高的总氮,而鄱阳湖主湖区则具有较高的总磷和氨氮。总之,枯水期进行合理的水位调控能够有效降低富营养化风险。     

Transforming systems of consumption and production for achieving the sustainable development goals: moving beyond efficiency

The United Nations formulated the sustainable development goals (SDGs) in 2015 as a comprehensive global policy framework for addressing the most pressing social and environmental challenges currently facing humanity. In this paper, we analyse SDG 12, which aims to “ensure sustainable consumption and production patterns.” Despite long-standing political recognition of this objective, and ample scientific evidence both on its importance and on the efficacy of various ways of promoting it, the SDGs do not provide clear goals or effective guidance on how to accomplish this urgently needed transformation. Drawing from the growing body of research on sustainable consumption and production (SCP), the paper identifies two dominant vantage points—one focused on promoting more efficient production methods and products (mainly through technological improvement and informed consumer choice) and the other stressing the need to consider also overall volumes of consumption, distributional issues, and related social and institutional changes. We label these two approaches efficiency and systemic. Research shows that while the efficiency approach contains essential elements of a transition to sustainability, it is by itself highly unlikely to bring about sustainable outcomes. Concomitantly, research also finds that volumes of consumption and production are closely associated with environmental impacts, indicating a need to curtail these volumes in ways that safeguard social sustainability, which is unlikely to be possible without a restructuring of existing socioeconomic arrangements. Analysing how these two perspectives are reflected in the SDGs framework, we find that in its current conception, it mainly relies on the efficiency approach. On the basis of this assessment, we conclude that the SDGs represent a partial and inadequate conceptualisation of SCP which will hamper implementation. Based on this determination, this paper provides some suggestions on how governments and other actors involved in SDGs operationalisation could more effectively pursue SCP from a systemic standpoint and use the transformation of systems of consumption and production as a lever for achieving multiple sustainability objectives.     

Selenium and 17 other largely essential and toxic metals in muscle and organ meats of Red Deer (Cervus elaphus)--consequences to human health

Concentrations, composition and interrelationships of selenium and metallic elements (Ag, Ba, Cd, Co, Cr, Cs, Cu, Ga, Mn, Mo, Pb, Rb, Sb, Sr, Tl, V and Zn) have been examined in muscle and organ meats of Red Deer hunted in Poland. The analytical data obtained were also discussed in terms of Se supplementation and deficit to Deer as well as the benefits and risk to humans associated with the essential and toxic metals intake resulting from consumption of Deer meat and products. These elements were determined in 20 adult animals of both sexes that were obtained in the 2000/2001 hunting season from Warmia and Mazury in the north-eastern part of Poland. The whole kidneys contained Ba, Cd, Cr, Ga, Pb, Se, Sr and Tl at statistically greater concentrations than liver or muscle tissue from the same animal. Liver showed statistically greater concentrations of Ag, Co, Cu, Mn and Mo than kidneys or muscle tissue, and muscle tissue was richer in Zn, when compared to the kidneys or liver. Cs and Rb were similarly distributed between all three tissue types, while V was less abundant in liver than kidneys or muscle tissue. There were significant associations between some metallic elements retained in Red Deer demonstrated by Principal Component Analysis (PCA) of the data set. In organ and muscle meats (kidneys, liver and muscle tissue considered together) the first principal component (PC1) was strongly influenced by positively correlated variables describing Se, Ba and Cd and negatively correlated variables describing Ag, Co, Cs, Mn, Pb, Tl and V; PC2, respectively, by Cu, Mn and Mo (+) and Zn (-); PC3 by Ga (+) and PC4 by Sb (+). Selenium occurred in muscle tissue, liver and kidneys at median concentrations of 0.13, 0.19 and 4.0mg/g dry weight, respectively. These values can be defined as marginally deficient (< 0.6mg Se/kg liver dw) or satisfactory (≤ 3.0mg Se/kg kidneys dw) for the amount required to maintain the Deer's body condition and health, depending on the criterion for supplementation used. In terms of human nutritional needs, a relatively high selenium content of kidneys can be beneficial. The muscle meat, liver and kidneys of Red Deer can be considered as a very good source of essential Co, Cr, Cu, Mo, Mn, Se and Zn in the human diet. Lead is generally considered as toxic, and the concentrations found in Red Deer (via the food chain intake) were well below the European Union tolerance limit. Pb from the lead bullets can always create food hygienic problem, if not well recognized during sanitary inspection, and this was noted for one muscle meat sample in this study (5% surveyed). There is no tolerance limit of Cd in game animal meats. The median values of Cd noted in fresh muscle tissue, liver and whole kidneys were 0.07, 0.18, and 3.3mg/kg wet weight, respectively. Cd exists as a chemical element present at trace levels in plants and mushrooms in Deer's food chain in background (uncontaminated) areas. When these are consumed by the Deer, the amount of Cd sequestered with metallothioneins and retained in the organ and muscle meat in this study is low enough to be considered safe for human consumption.     

Estimation of optimum requirements for indoor air quality and energy consumption in some residences in Kuwait.

Contrasting effects of the dilution of indoor generated pollutants and the energy efficiency of heating and ventilating air conditioning systems (HVAC) for indoor air quality (IAQ) and thermal comfort were studied for 10 Kuwaiti residences. The levels of volatile organic compounds (VOCs) and the calculated cooling load of the HVAC systems were used as indicators for the IAQ and for the energy consumption, respectively. Air exchange rates and VOCs levels (both indoor and outdoor) were measured. It was found that the outdoor VOC concentrations were always less than the indoor values. Therefore reduction of indoor VOC levels can be accomplished either by increasing the ratio of the makeup air to the recirculation air of the HVAC system or by increasing the infiltration airflow rate through openings. A single compartment IAQ model, modified by the authors, was used to test for the variation in the above two dilution modes and to test the performance sensitivity. Hence, the optimum parameters in terms of IAQ and energy consumption were determined. The results indicated that it was necessary to increase the ratio of the makeup air to the recirculation air from its typical design value of 0.5 to a range of 0.7-1.3 in order to reduce indoor VOC to acceptable levels.     

Influence of fish size and sex on mercury/PCB concentration: importance for fish consumption advisories

Fish advisories for polychlorinated biphenyls (total-PCBs) and mercury are often given on a length-specific basis and fish sex is usually not considered. The relationship between concentration and length is well established for mercury, however its suitability for total-PCBs and the influence of sex over the large scale covered by most monitoring programs is not well known. Here we use what is perhaps the largest consistent sport fish contaminant dataset to evaluate the relationship between total-PCB/mercury and length and sex. We evaluated seven of the most commonly consumed fishes from the Canadian Great Lakes and two Ontario (Canada) inland lakes. For mercury, the relationship between concentration and length was significant (p<0.05) in most fish species and locations. For total-PCB, this relationship was also generally significant in Chinook salmon and lake trout, which are the species with the most advisories for this compound. In contrast, significant relationships were found less often for whitefish, northern pike, smallmouth bass, walleye, and especially yellow perch. However, mercury usually drives fish consumption advisories for these species. Overall, our results support the protocol of issuing contaminant advice on a length-specific basis in fish monitoring programs with reasonable confidence when at least a moderate number of samples over the natural size range of a species are included in the analysis. Sex differences were common for walleye (males>females, p<0.05) but not other species, suggesting that an equal number of male and female walleye should be used in deriving fish advisories for walleye.     

土地流转与农民收入变化研究

土地流转作为我国农村土地制度改革的重点受到了广泛的关注,但土地流转能否显著增加农民收入,达到改善农村内部收入差距的目的,现有研究并未得到一致结论。本文在文献回顾和总结的基础上,依据中国家庭追踪调查(CFPS)数据,运用倾向值匹配(PSM)方法和基于回归的夏普里值分解(Shapley Value)方法,从收入水平和收入差距两个维度实证分析土地流转对农民收入的影响。研究结果表明:(1)参与土地流转能够显著提高农户家庭收入水平。土地流转使转入户家庭人均总收入和农业收入显著提高18.18%和72.46%,并且大规模转入的农户人均总收入的增加程度显著高于小规模转入农户,说明土地流转存在规模效应。土地流转对转出户的收入水平没有显著影响,可能的原因一方面由于土地流转市场发育不完善,没有显化租金;另一方面劳动力转移先于土地流转,使土地流转对农户家庭劳动力的释放作用不显著。(2)土地流转对农村内部收入差距的贡献度为4.19%,排名第五,表明土地流转不是造成农村内部收入差距拉大的主要原因。人力资本和村庄特征对农村内部收入差距影响较大。根据研究结论提出三点政策建议:第一,通过完善农地流转市场,稳定土地租金水平,使转出户获得合理的租金收入;第二,促进农地适度规模经营,提高转入户农业经营收入,缩小农户与非农经营户之间的收入差距;第三,提高农户就业竞争力,促进劳动力转移,增加转出户非农务工收入。     

不同时段洞庭湖区土地利用/覆被变化及退田还湖的影响

土地利用/覆被变化的研究与分析,可以科学阐述区域人-地关系地域系统的结构变化规律、驱动力等,有助于规范人类行为、协调人地关系,从而为更好的进行自然资源综合管理和生态系统管理提供科学依据.本文以1995、2000和2005年的土地利用/覆被变化分析为基础,以退田还湖工程为切入点,系统分析洞庭湖区三个时期的土地利用格局、变化及其驱动力,初步阐述了退田还湖工程这一重要的生态恢复工程对湖区土地利用变化的影响.研究发现,退田还湖工程促进了耕地向湿地的转化,使移民迁入区和迁出区的土地利用结构都会发生重大变化.最后,指出对于洞庭湖区退田还湖工程的实施与管理,各级政府一定要起到宏观调控的指导作用,包括要从战略上予以规范、规划,积极引导人们的土地利用活动向着科学、和谐的方向发展,必要时还需要辅以行政、经济或法律措施,促进各种土地资源间的合理流转,以实现土地利用综合效益的最大化,为区域的适应性和可持续性管理提供了参考依据.     

A model testing study for the transfer of radioactivity to fruit

This paper compares predictions of the foodchain model SPADE with experimental data for the transfer of (134)Cs and (85)Sr to strawberry plants following acute foliar and soil contamination. The transfer pathways considered in this exercise included direct deposition to fruit, leaf-to-fruit, soil-to-leaf and soil-to-fruit transfers. Following foliar contamination, the difference between predicted and measured radionuclide activity values varied between a factor of 0.5-10 for fruit and 4.5-7 for leaf. Following soil contamination, the difference between predicted and measured values varied between a factor of 3-74 for fruit and 32-44 for leaf. In all cases the difference between measured and predicted values was smaller for (85)Sr than (134)Cs. Measured and predicted activities were higher for leaf than fruit. Both measured and predicted (134)Cs concentrations in fruit and leaf are higher when deposition occurs at ripening than at anthesis. These results confirm the need for more data on fruit, even for Cs and Sr, to support models in predicting the transfer of radionuclides to fruit crops. Ongoing research projects funded by the UK Food Standards Agency aim to provide some data on radionuclide transfer to herbaceous, shrub and tree fruits, which will help improve radiological assessment models in order to provide better protection for consumers.     

Soil-to-plant transfer of radiocaesium for selected tropical plant species in Bangladesh

Soil-to-plant transfer factors (TF) of radiocaesium (137Cs) were determined under field condition for grassy vegetation grown in Bangladesh at contaminated land in the Atomic Energy Research Establishment (AERE) campus. TF values for rice, grass and grassy/root vegetations grown in the same type of soil were also measured under pot condition. TF values of 137Cs for grassy vegetation (2.4 x 10(-2) -4.2 x 10(-2) with an average of 3.1 x 10(-2) +/-0.005) obtained under field condition were slightly lower than the values for grass and grassy/root vegetations (2.9 x 10(-2) -6.6 x 10(-2) with an average of 4.8 x 10(-2) +/-0.01 for grass and grassy vegetations and 2.3 x 10(-2) -5.6 x 10(-2) with an average of 4.0 x 10(-2) +/-0.009 for root vegetations, respectively) obtained under pot condition. However, TF values (9.0 x 10(-3) -2.6 x 10(-2) with an average of 1.9 x 10(-2) +/-0.004) obtained for rice were about a factor of 4 lower than the values obtained for grass and grassy/root vegetations. When the properties of the AERE soils as input parameters were used in the soil-plant transfer model of Absalom, the estimated TF values (4.5 x 10(-2) -6.7 x 10(-2) with an average of 5.3 x 10(-2) +/-0.006) were consistent with the measured values obtained for grass and grassy vegetations under pot condition, however, the model overestimates the TF values for rice.     

Temporal and Spatial Variations of Phytoplankton Community Structure in Lake Erhai,a Chinese Plateau Lake,with Reference to Environmental Factors

Russian Journal of Ecology - Temporal and spatial variations of phytoplankton community in Lake Erhai were investigated from May 2010 to April 2011. A total of 124 species belonging to 8 phyla and...