Distribution of Cd,Ck, Pb and Zn in Soil and Vegetation Compartments in Stands of Five Boreal Tree Species in N.E. Sweden

Concentrations and total quantity of cadmium (Cd), cupper (Cu),lead (Pb) and zink (Zn) were determined in biomass and soil compartments in a replicated tree species experiment with 27-yr-old stands growing on former farmland in N.E. Sweden. Sequentialextractions of soil samples were performed in order to estimate the exchangeable and an organically bound fraction of each element. The tree species included were Picea abies (L.)H. Karst., Pinus sylvestris L., Pinus contorta Dougl., Larix sibirica Ledeb., and Betula pendula Roth.Tree species influenced the rate of removal of Cu, Pb and Zn incase of stemwood harvesting, and of Cd, Cu and Zn in the case ofwhole-tree harvesting. B. pendula and P. abies had higher quantities and average concentrations of Zn in the biomass. For all species, >50% of the Zn in the stems was found in the bark. P. abies and L. sibirica had higher quantities of Cu in the biomass than the other species.P. abies and P. contorta had high quantities of Cd inthe biomass in relation to the other species. Branches and stembark contained high concentrations of Cd and Pb in relation to foliage and stemwood. Dead branches had especially high concentrations of Pb. The high accumulation rate of Zn in thebiomass of B. pendula was related to a low exchangeable amount of Zn in the A horizon. In the superficial centimeters ofthe A horizon, a depletion similar to that found for Zn was detected for Cu, whereas for Cd and Pb, no correlations were found between quantities of elements in the trees and element pools in the soil.     

Impact of the 1998 Central American fires on PM2.5 mass and composition in the southeastern United States

The impact of the Central American fires on PM_2.5 mass concentration and composition in the Tennessee Valley region during portions of May, 1998, has been quantified. Elevated concentrations of smoke aerosol tracers—fine potassium, (and to a lesser extent, calcium and silicon) and, where available, organic and elemental carbon—were observed in the region during times in which satellite imagery (TOMS and GOES-8) showed regional transport of hazy, smoky airmasses from southern Mexico and adjacent areas of Central America. Back-trajectories from network sites in the Tennessee Valley network were consistent with this regional transport. The extent of transport of extra-regional fine particle mass during May, 1998, is discussed relative to the new US fine particle mass-based standards for fine particulate matter.     

A strategic quantitative approach for sustainable energy production from biomass

European legislation has created a growing interest in the field of renewable energy production in several countries, including Italy. The applications of biomass and/or biofuel for energy generation have been assumed to provide a high level of sustainability due to the perception that renewable resources are inherently sustainable. Thus, renewable fuels applied to heating and/or electricity generation are potentially carbon dioxide neutral. However, before accepting this assumption, it is essential to analyse the actual level of sustainability in the whole supply chain (SC). This requirement has been clearly identified by the recently updated European Directives on renewable biofuels for transportation. However, there is little evidence that this concern has been directed at energy production from biomass. Thus, approaches derived from Green SC Management (GSCM) methods could provide an effective tool for evaluating, from a strategic perspective, the sustainability level of a specific biomass SC. This paper examines how biomass SC activities can define the overall environmental sustainability level. The approach was based on environmental indicators and the resultant output could support more effective GSCM strategies (e.g. defining logistics carriers, evaluating new biomass suppliers, etc.) for managing biomass SCs. Moreover, the approach could be applied by competent authorities for a quick evaluation of the sustainability level of biomass energy production installations. The approach has been tested in a real case study based on an installation, located in Southern Italy, which uses liquid biomass for energy production.     

离子液体预处理纤维素及木质纤维素的研究进展

稳定性好、溶解能力强的离子液体,能够快速瓦解木质纤维素网络结构,提高纤维素酶的可及度和酶解效率,可大幅度降低预处理成本。本文综述了常见离子液体的组成、离子液体对木质纤维素的溶解分离等预处理方法及其原理。     

Biomass as the Renewable Energy Sources in Malaysia: An Overview

Past and current economic growths of Malaysia have been primarily energized by fossil fuels. Malaysia has very substantial potential for biomass energy utilization given its equatorial climate that is ideal for dense tropical forest growth and agricultural vegetation. There are five major sectors contributing wastes to biomass energy in Malaysia: forestry (wood products), rubber cultivation, cocoa cultivation, sugar cane cultivation and oil palm cultivation. Biomass in Malaysia contributes about 14% of the approximately 340 million barrel of oil equivalent (boe) of energy used every year. This paper provides an overview on the types of biomass being used, the research works on biomass conversion into energy and the present biomass energy projects in Malaysia.     

川东高海拔山区红三叶、红三叶─鸭茅和红三叶─黑麦草人工群落生物量的比较研究

红三叶牧草作为一个优良牧草品种，在川东高海拔山区表现尤为突出。本文就红三叶、红三叶─鸭茅和红三叶─黑麦草三个人工群落进行了比较系统的生物量观测，比较了三个群落的总生物量、地上生物量、地下生物量特点，分析了各群落生物量在不同部位的分配情况，垂直空间上的配置，以及各器官在垂直空间上的配置和各个群落的茎、叶、花、立枯在垂直空间上所构成的分布带谱，通过以上分析发现，红三叶─黑麦草群落的总生物量最高，为４６．４７ｋｇ／ｈａ，其中地上部分为２４．５７ｋｇ／ｈａ，而红三叶─鸭茅群落的地下部分最为发达，地下生物量达２４．７４ｋｇ／ｈａ。根据群落生产结构，发现以红三叶为主的人工群落，其生产结构为不规则塔型分布，在离地面２０─４０ｃｍ处，生物量有一个高峰，并且红三叶─黑麦草群落的地上、地下生物量在垂直空间上分布较为均匀，其生产结构较为合理。通过各器官垂直空间分布分析，发现茎主要分布在４０ｃｍ以下，叶量最大是在４０ｃｍ左右，生殖器官最大量在５０ｃｍ附近，并且根据群落的茎：叶：花（穗）：立枯垂直分布带谱可以发现，各个器官在不同层次中所处的地位，而且根据此带谱可以掌握草地的刈割时间和刈割高度。     

Evaluating the Role of Plantations as Carbon Sinks: An Example of an Integrative Approach from the Humid Tropics

/ Despite their fast growth, tropical plantations are a small sink of atmospheric carbon because they occupy only a small area in relation to other land uses worldwide. Proper design and management of plantations can increase biomass accumulation rates, making them more effective C sinks. However, fast-growing plantations can extract large amounts of nutrients from the soil, and site fertility declines may limit sustained plantation forestry after a few rotations. We measured aboveground biomass accumulation, carbon sequestration, and soil chemistry in three young plantations of 12 indigenous tree species in pure and mixed designs in the humid lowlands of Costa Rica. Annual biomass increments for the three mixed plantations ranged from 10-13 Mg/ha. The mixtures of four species gave higher biomass per hectare than that obtained by the sum of one fourth hectare of each species in pure plots. At this early age of the plantations, estimated annual C sequestration values were comparable to other reports from young plantations of exotic species commonly grown in the tropics. Four years after planting, decreases in soil nutrients were apparent in pure plots of some of the fastest growing species, while beneficial effects on soils were noted under other species. The mixed plots showed intermediate values for the nutrients examined and, sometimes, improved soil conditions. A mixture of fast and slower growing species yields products at different times, with the slower growing species constituting a longer term sink for fixed carbon. Examination of the role of tropical plantations as C sinks necessitates integrative approaches that consider rates of C sequestration, potential deleterious effects on ecosystem nutrients, and economic, social, and environmental constraints.KEY WORDS: Native trees; Aboveground biomass; Stem increments; Rotation length; Soil nutrients; Economics     

ROOT BIOMASS IN RELATION TO CHANNEL MORPHOLOGY OF HEADWATER STREAMS1

ABSTRACT: Intact riparian zones are the product of an incredibly complex multitude of linkages between the geomorphic, hydrologic, and biotiè features of the ecosystem. Land‐use activities that sever or alter these linkages result in ecosystem degradation. We examined the relationship between riparian vegetation and channel morphology by sampling species composition and herbaceous root biomass in incised (down‐cut and widened) versus unincised (intact) sections of unconstrained reaches in three headwater streams in northeastern Oregon. Incision resulted in a compositional shift from wetland‐obligate plant species to those adapted to drier environments. Root biomass was approximately two times greater in unincised sections than incised sections and decreased with depth more rapidly in incised sections than in unincised sections. Total root biomass ranged from 2,153 g m^‐2 to 4,759 g m^‐2 in unincised sections and from 1,107 g m^‐2 to 2,215 g m^‐2 in incised sections. In unincised sections less than 50 percent of the total root biomass was found in the top 10 cm, with approximately 20 percent in successive 10‐cm depth increments. In contrast, incised sections had greater than 60 percent of the total root biomass in the top 10 cm, approximately 15 percent in the 10 to 20 cm depth, less than 15 percent in the 20 to 30 cm depth, and less than 10 percent in the 30 to 40 cm depth. This distribution of root biomass suggests a positive feedback between vegetation and channel incision: as incision progresses, there is a loss of hydrologic connectivity, which causes a shift to a drier vegetation assemblage and decreased root structure, resulting in a reduced erosive resistance capacity in the lower zone of the streambank, thereby allowing further incision and widening.     

Quantitative Relationships between Predatory and Nonpredatory Animals in Freshwater Ecosystems

The ratios between the sizes of predators and prey have been estimated. On average, the linear sizes and body weights of aquatic predatory animals are approximately three and nine times greater, respectively, than those of nonpredatory animals. The biomass of predators in waters with different productivity levels is, on average, about 20% of the biomass of nonpredatory animals. However, the ratio between the biomasses of predatory and nonpredatory animals in the same water body may vary seasonally and annually and differ in different parts of this water body. The average numbers of predatory fish in ichthyocenoses are no more than 3% of the numbers of nonpredatory fish. The living space (individual range) of predatory fish is about 40 times larger than that of their prey. The relatively low numbers of predators in water bodies may be accounted for by the lower number of predatory species and their higher mortality at early developmental stages, compared to nonpredatory species.