Influence of peatland and land cover distribution on fire regimes in insular Southeast Asia

Anthropogenic biomass burning in insular Southeast Asia facilitates conversion and degradation of ecosystems and emits high amounts of carbon into the atmosphere. We analyzed the influence of peat soil and land cover distribution on the occurrence and characteristics of vegetation fires. Two years of satellite-based active fire detections over Peninsular Malaysia, Sumatra, Borneo and Java were examined together with land cover and peatland maps. Our results showed that fire occurrence nearly tripled (23,000 → 68,000) from a wet La Niña year (2008) to a drier El Niño year (2009). In both years, fires were concentrated in peatlands (in 2009 41% of fires vs. 10% of land area), and the majority of large-scale burning took place in peatlands. Variation in peatland land cover within the study area was noticed to create remarkable different fire regimes. Biomass burning in the intensely managed Sumatran peatlands was characterized by large-scale land clearance fires that took place annually to varying extent. The largely unmanaged degraded peatland ecosystems of Borneo, on the other hand, experienced very little fire activity in a wet year but were ravaged by large-scale wildfires when El Niño conditions arose. We conclude that fire regime characteristics in insular Southeast Asia are strongly connected to occurrence of peat soil and land management status. This leads to high variation of fire activity within this region both annually (depending on weather patters) and over longer time range (depending on land cover/management issues) and greatly complicates estimation of the effects of fires.     

Uranium distribution and cycling in Scots pine (Pinus sylvestris L.) growing on a revegetated U-mining heap

We determined the uranium distribution in soil and its allocation in compartments of 35-year-old Scots pine developed on a revegetated U-mining heap. The processes controlling the dynamics of U recycling were identified and further quantified in terms of annual fluxes. As pine developed, an acid humus layer emerged leading to weathering of the alkaline mining debris but this had little effect on U mobility in the soil profile. Increased U mobility mainly involved a translocation of U to metal-humus chelates in surface layers. The root compartment accounted for 99.3% of the U budget in tree, thus serving as an effective barrier which restricts U uptake. The current root uptake and transfer of U to upper parts of the tree amounted to about 3g ha(-1) y(-1), i.e. less than 0.03% of the current NH4-exchangeable U pool in the soil (0-30 cm). Allocation and translocation pattern made it clear that a dominant fraction of the translocated U moves passively with the ascent xylem sap, most likely as a soluble complex, and steadily accumulates in the needles. Consequently, 97% of the U annual uptake is returned to the soil through litterfall. At the studied site, the risk of U dissemination due to biomass turnover or trunk harvest was low when considered in relation to the current "exemption level" for U.     

Ecosystem carbon budgeting and soil carbon sequestration in reclaimed mine soil

Global warming risks from emissions of green house gases (GHGs) by anthropogenic activities, and possible mitigation strategies of terrestrial carbon (C) sequestration have increased the need for the identification of ecosystems with high C sink capacity. Depleted soil organic C (SOC) pools of reclaimed mine soil (RMS) ecosystems can be restored through conversion to an appropriate land use and adoption of recommended management practices (RMPs). The objectives of this paper are to (1) synthesize available information on carbon dioxide (CO2) emissions from coal mining and combustion activities, (2) understand mechanisms of SOC sequestration and its protection, (3) identify factors affecting C sequestration potential in RMSs, (4) review available methods for the estimation of ecosystem C budget (ECB), and (5) identify knowledge gaps to enhance C sink capacity of RMS ecosystems and prioritize research issues. The drastic perturbations of soil by mining activities can accentuate CO2 emission through mineralization, erosion, leaching, changes in soil moisture and temperature regimes, and reduction in biomass returned to the soil. The reclamation of drastically disturbed soils leads to improvement in soil quality and development of soil pedogenic processes accruing the benefit of SOC sequestration and additional income from trading SOC credits. The SOC sequestration potential in RMS depends on amount of biomass production and return to soil, and mechanisms of C protection. The rate of SOC sequestration ranges from 0.1 to 3.1 Mg ha(-1) yr(-1) and 0.7 to 4 Mg ha(-1) yr(-1) in grass and forest RMS ecosystem, respectively. Proper land restoration alone could off-set 16 Tg CO2 in the U.S. annually. However, the factors affecting C sequestration and protection in RMS leading to increase in microbial activity, nutrient availability, soil aggregation, C build up, and soil profile development must be better understood in order to formulate guidelines for development of an holistic approach to sustainable management of these ecosystems. The ECBs of RMS ecosystems are not well understood. An ecosystem method of evaluating ECB of RMS ecosystems is proposed.     

Limitations on the renewability of renewable energy resources

The primary supposition about renewable forms of energy is that use of such resources will not result in depletion or exhaustion. While it is true that natural energy flows such assun and wind are not directly subject to degradation by use, there may still be indirect limitations on renewability. The exploitation of natural energy flows may require that systems of nonrenewable “support” resources be used to capture, store, and convert natural energy into useful forms. Poor resource management practices that degrade the support resources may therefore, in effect, endanger renewability. Biomass is an illustrative case of a renewable energy resource with nonrenewable support components. The soil and water management practices of American agriculture, a large-scale biomass production system, are resulting in serious degradation and depletion of these vital system elements. This degradation represents a threat to the future of biomass food and energy supplies.     

Soil erosion and the global carbon budget

Soil erosion is the most widespread form of soil degradation. Land area globally affected by erosion is 1094 million ha (Mha) by water erosion, of which 751 Mha is severely affected, and 549 Mha by wind erosion, of which 296 Mha is severely affected. Whereas the effects of erosion on productivity and non-point source pollution are widely recognized, those on the C dynamics and attendant emission of greenhouse gases (GHGs) are not. Despite its global significance, erosion-induced carbon (C) emission into the atmosphere remains misunderstood and an unquantified component of the global carbon budget. Soil erosion is a four-stage process involving detachment, breakdown, transport/redistribution and deposition of sediments. The soil organic carbon (SOC) pool is influenced during all four stages. Being a selective process, erosion preferentially removes the light organic fraction of a low density of <1.8 Mg/m(3). A combination of mineralization and C export by erosion causes a severe depletion of the SOC pool on eroded compared with uneroded or slightly eroded soils. In addition, the SOC redistributed over the landscape or deposited in depressional sites may be prone to mineralization because of breakdown of aggregates leading to exposure of hitherto encapsulated C to microbial processes among other reasons. Depending on the delivery ratio or the fraction of the sediment delivered to the river system, gross erosion by water may be 75 billion Mg, of which 15-20 billion Mg are transported by the rivers into the aquatic ecosystems and eventually into the ocean. The amount of total C displaced by erosion on the earth, assuming a delivery ratio of 10% and SOC content of 2-3%, may be 4.0-6.0 Pg/year. With 20% emission due to mineralization of the displaced C, erosion-induced emission may be 0.8-1.2 Pg C/year on the earth. Thus, soil erosion has a strong impact on the global C cycle and this component must be considered while assessing the global C budget. Adoption of conservation-effective measures may reduce the risks of C emission and sequester C in soil and biota.     

Aggregated Estimation of Basic Parameters of Biological Production and Carbon Budget of Russian Terrestrial Ecosystems: 3. Biogeochemical Carbon Fluxes

The biogeochemical cycle of organic carbon in Russian terrestrial ecosystems in 1990 is considered. Its components have been estimated as follows: net primary production, 4354 million metric tons of carbon (Mt C); annual amount of plant detritus, 3223 Mt C; heterotrophic soil respiration, 3214 Mt C; biomass utilization, 680 Mt C; damage to vegetation caused by fire and pests, 140 Mt C; and removal by surface and ground waters, 79 Mt C. Anthropogenically regulated fluxes of organic carbon (820 Mt C) are comparable to its amount involved in the natural cycle.     

城市边缘带土地利用特征与土壤资源压力

城市边缘带作为城乡交互作用界面,根据其形成机制可划分为不同类型,而土地利用/覆被空间结构的高度复杂性、土地利用形式在时间序列上的强烈可变性是所有边缘带类型的重要共有特征。在快速城市化背景下,城市边缘带土壤资源压力日趋严峻,一方面,土地利用的非农流转导致土壤资源特别是耕地资源面积快速萎缩,直接威胁农业生产和区域粮食安全;另一方面,“三废”物质向城市边缘带的扩散和集聚导致土壤环境容量明显下降,土壤质量严重退化,不仅影响农产品品质,而且对区域生态环境支撑能力产生严重影响。因此,开展城市边缘带土地利用变化及其土壤资源与环境的影响研究刻不容缓。     

Soil organic horizons as a major source for radiocesium biorecycling in forest ecosystems

Here we review some of the main processes and key parameters affecting the mobility of radiocesium in soils of semi-natural areas. We further illustrate them in a collection of soil surface horizons which largely differ in their organic matter contents. In soils, specific retention of radiocesium occurs in a very small number of sorbing sites, which are the frayed edge sites (FES) born out of weathered micaceous minerals. The FES abundance directly governs the mobility of trace Cs in the rhizosphere and thus its transfer from soil to plant. Here, we show that the accumulation of organic matter in topsoils can exert a dilution of FES-bearing minerals in the thick humus of some forest soils. Consequently, such accumulation significantly contributes to increasing 137Cs soil-to-plant transfer. Potassium depletion and extensive exploration of the organic horizons by plant roots can further enhance the contamination hazard. As humus thickness depends on both ecological conditions and forest management. our observations support the following ideas: (1) forest ecosystems can be classified according to their sensitivity to radiocesium bio-recycling, (2) specific forest management could be searched to decrease such bio-recycling.     

The Effect of Soil Cultivation on the Humus State of Gray Forest Soil in the Middle Urals

The results of studies on the humus state of soils in agrosystems of the Middle Urals (1984–1997) are described. It is shown that the change of agricultural technologies (crop rotation, doses of organic fertilizers, etc.) transforms environmental conditions and the direction of humus formation processes. Parameters such as the concentrations of humus and water-soluble carbon and soil potential for humus accumulation reliably characterize the humus state of arable soil and allow the mobility and migration rate of humic substances to be monitored.     

The use of ultra filtration in trace metal speciation studies in sea water

During this work, size fractionation technique "ultra filtration" is used in speciation studies of trace elements in the coastal sea water. Filtration is the most commonly used method to fractionate trace metal species, but often only "dissolved" and "particulate" fraction. The purpose of the present study is to determine colloidal and suspended particulate concentrations of Fe, Zn, Cu, Ni, and Mn in sea water. Suspended particulate matter were separated in three different size groups namely (>2.7 microm, <2.7->0.45 microm and <0.45->0.22 microm) by suction filtration using cellulose acetate and nitrate filter membranes. Thereafter to concentrate the solution with colloidal particle <0.22 microm-1.1 nm (0.5 k Nominal Molecular Weight cut-off Limit {NMWL}), the solution obtained from filtration through <0.22 microm, is sequentially passed through the ultra-filtration membranes having pore diameters of 14 nm (300 k NMWL), 3.1 nm (50 k NMWL), 2.2 nm (30 k NMWL), 1.6 nm (10 k NMWL) and 1.1 nm (0.5 k NMWL) by using Stirred Ultra-filtration Cells, operating in concentration mode. The concentration of Fe, Zn, Cu, Ni, and Mn were measured in suspended and dissolved fraction by ion chromatography, ICP-AES and Atomic Absorption Spectrometer. The salinity of the solution in various dissolved fractions of sequential filtration varies between 30.89-34.22 parts per thousand. The maximum concentrations of colloidal Zn, Cu, Ni and Mn in dissolved fraction were in <2.2->1.6 nm fraction. In case of Fe, colloidal fractions <2.2->1.6 nm and <1.6-<1.1 nm shows higher concentration. The concentration of Zn, Cu, Ni and Mn increase with decrease in size in suspended particulate matter, while the reverse is observed in case of Fe. This size separation data that specifies the partitioning of metals between dissolved and suspended solid phases is necessary for developing physically based models of metal transport in aquatic system.     

Phytocenotic organization of algal groups as a possible indicator of the trophic status of bog ecosystems

In the soils of bog ecosystems studied in Plesetskii raion of Arkhangelsk oblast, 169 species and infraspecific taxa of algae have been recorded. Their flora includes typical divisions of soil algae and is dominated by Chlorophyta, which is typical for the soil–climatic conditions of the taiga zone in general and bog ecosystems in particular. The phytocenotic organization of algal groups can serve as an indicator of bog trophicity, since a certain trophicity level is characterized by an individual combination of dominant species, life forms, morphotypes, and ecological groups of soil algae.     

Effect of arsenic contamination on microbial biomass and its activities in arsenic contaminated soils of Gangetic West Bengal, India

A study was conducted to see the effect of arsenic contamination on soil quality indicators, viz., microbial biomass, soil respiration, fluorescein diacetate and dehydrogenase (DHG) activity in arsenic contaminated soils of West Bengal. All the parameters were significantly and negatively correlated with all the form of arsenic (bioavailable and total) but the microbial metabolic quotient was significantly and positively correlated with all forms of arsenic, indicating arsenic induced stress to the soil microbial community. This may be due to part of the microbial biomass, which is located in the inner parts of the micro-aggregates of soil, which is affected by arsenic accumulates present in soil particles. Linear regression analysis revealed that the bioavailable arsenic exerted greater inhibitory effect on the soil microbial population than the total arsenic content of soils. Water-soluble arsenic showed more inhibitory effect than NaHCO(3) extractable form, in their association with biological properties of the contaminated soils. Water-soluble form of arsenic was much more toxic than insoluble forms. This signified that with increase in bioavailability, the arsenic exerted more inhibitory effect on these parameters. It is thus suggested that the microbial biomass, fluorescein diacetate and dehydrogenase activity alone and expressed on a soil organic matter basis along with the soil respiration parameters can be helpful in assessing the effects of arsenic on the size and activity of microbial biomass in soils.     

洞庭湖退田还湖区不同土地利用方式对土壤养分库的影响

以钱粮湖垸为例,研究了洞庭湖退田还湖区的林地（Ⅰ）、园地（Ⅱ）、旱地（Ⅲ）、水田（Ⅳ）和荒地（Ⅴ）等不同土地利用方式下的土壤养分含量、养分库综合指数以及养分相关性。研究表明：土壤养分分布的表聚效应明显,0～50 cm土层土壤有机质含量为3.40～32.32 g/kg,全氮、水解氮含量为2.23～9.71 g/kg、12.95～112.00 mg/kg,全磷、速效磷含量为29.50～69.35 g/kg、4.15～75.68 mg/kg,全钾、速效钾含量为603～3069 g/kg、37.70～217.50 mg/kg;林地土壤全氮含量最高,有机质含量最低,水田有机质、全钾及速效磷含量均最高,旱地水解氮含量最高,而荒地土壤全氮、全磷、全钾、水解氮及水解磷均最低;土壤养分库综合指数变化范围为24.33～295.93,排序为IⅣ（231.96）＞IⅢ（193.46）＞IⅡ（70.90）＞IⅠ（59.57）＞IⅤ（35.59）;土壤养分要素的相关性分析结果表明,有机质与全磷、全磷与速效磷、全氮与全钾、水解氮与速效磷均呈显著正相关关系,相关系数分别为 0.5760、0.5961、0.6864 和 0.5701。     

Harmonising conflicts between science,regulation, perception and environmental impact: The case of soil conditioners from bioenergy

As the global population is expected to reach 9 billion by 2050, humanity needs to balance an ever increasing demand for food, energy and natural resources, with sustainable management of ecosystems and the vital services that they provide. The intensification of agriculture, including the use of fertilisers from finite sources, has resulted in extensive soil degradation, which has increased food production costs and CO₂ emissions, threatening food security. The Bioenergy sector has significant potential to contribute to the formation of a circular economy. This paper presents the scientific, regulatory and socioeconomic barriers to the use of the nutrient waste streams from biomass thermal conversion (ash) and anaerobic digestion (digestate) as sustainable soil amendments for use in place of traditional fertilisers. It is argued that whilst the ability of combined ash and digestate to remedy many threats to ecosystems and provide a market to incentivise the renewable bio-energy schemes is promising, a step-change is required to alter perceptions of ‘waste’, from an expensive problem, to a product with environmental and economic value. This can only be achieved by well-informed interactions between scientists, regulators and end users, to improve the spread and speed of innovation with this sector.     

Distribution Of Cadmium And Nickel Among Various Forms In Natural And Contaminated Soils Amended With Edta

Because of its strong chelating capacity, application of ethylenediaminetetraacetic acid (EDTA) to soils may change the amount and distribution of heavy metals among their various chemical forms. Therefore, a greenhouse experiment was conducted using two cultivars of Brassica species (Brassica juncea and Brassica carinata) as hyper accumulator test crops on natural and artificially Cd and Ni contaminated soils. Both natural and metal amended soils were treated with disodium salt of EDTA at 0 and 1 g kg^–1 soil. After harvest of crops, soil samples were fractionated into water soluble plus exchangeable (WE), carbonate (CARB), organic matter (OM), Mn oxide (MnOX), amorphous Fe oxide (AFeOX), crystalline Fe oxide (CFeOX) and residual (RES) fractions. In metal amended soils, Cd and Ni were found predominantly in the AFeOX fraction in the absence of EDTA application and in the WE fraction in EDTA treated soil. Application of EDTA resulted in the redistribution of Cd among different forms and increased significantly Cd in the WE fraction with a concomitant significant decrease in the OM fraction. In natural soils, more than 40% of the total Cd was present in the RES fraction while in contaminated soil it was only 5%. Nickel in the WE fraction increased significantly while it considerably decreased in the CARB, OM, MnOX, AFeOX and CFeOX fractions with EDTA addition. This indicated that applied EDTA is capable to move Cd and Ni from the less soluble or more stable forms (CARB, OM, MnOX, AFeOX and CFeOX) to the most soluble form (WE). N natural soils, Ni in the RES fraction was found upto 49%, whereas only 10% of the total Ni was observed in contaminated soil, irrespective of EDTA treatment. In general, the amount of Cd recovered after harvest of both the Brassica cultivars did not differ significantly in any fraction except the WE fraction. The amount of Ni recovered in the AFeOX fraction was significantly higher after harvest of B. juncea as compared to B. carinata.Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

农田固碳措施对温室气体减排影响的研究进展

农田是CO2,CH4和N2O三种温室气体的重要排放源,在全球范围内农业生产活动贡献了约14%的人为温室气体排放量,以及58%的人为非CO2排放,不合理的农田管理措施强化了农田温室气体排放源特征,弱化了农田固碳作用。土壤碳库作为地球生态系统中最活跃的碳库之一,同时也是温室气体的重要源/汇。研究表明通过采取合理的农田管理措施,既可起到增加土壤碳库、减少温室气体排放的目的,又能提高土壤质量。农田土壤碳库除受温度、降水和植被类型的影响外,还在很大程度上受施肥量、肥料类型、秸秆还田量、耕作措施和灌溉等农田管理措施的影响。本文通过总结保护性耕作/免耕,秸秆还田,氮肥管理,水分管理,农学及土地利用变化等农田管理措施,探寻增强农田土壤固碳作用,减少农田温室气体排放的合理途径。农田碳库的稳定/增加,对于保证全球粮食安全与缓解气候变化趋势具有双重的积极意义。在我国许多有关土壤固碳与温室气体排放的研究尚不系统或仅限于短期研究,这也为正确评价各种固碳措施对温室气体排放的影响增加了不确定性。     

Evaluation of carbon stock variation in Northern Italian soils over the last 70 years

Carbon (C) sequestration in soils is gaining increasing acceptance as a means of reducing net carbon dioxide (CO₂) emissions to the atmosphere. Numerous studies on the global carbon budget suggest that terrestrial ecosystems in the mid-latitudes of the Northern Hemisphere act as a large carbon sink of atmospheric CO₂. However, most of the soils of North America, Australia, New Zealand, South Africa and Eastern Europe lost a great part of their organic carbon pool on conversion from natural to agricultural ecosystems during the explosion of pioneer agriculture, and in Western Europe the adoption of modern agriculture after the Second World War led to a drastic reduction in soil organic carbon content. The depletion of organic matter is often indicated as one of the main effects on soil, and the storage of organic carbon in the soil is a means of improve the quality of soils and mitigating the effects of greenhouse gas emission. The soil organic carbon in an area of Northern Italy over the last 70 years has been assessed In this study. The variation of top soil organic carbon (SOC) ranged from −60.3 to +6.7%; the average reduction of SOC, caused by agriculture intensification, was 39.3%. This process was not uniform, but related to trends in land use and agriculture change. For the area studied (1,394 km²) there was an estimated release of 5 Tg CO₂-C to the atmosphere from the upper 30 cm of soil in the period 1935–1990.     

Changes in physicochemical forms of lead and cadmium added to freshwater

Transformation of physicochemical forms of cadmium and lead added at 1 μ/L to Lake Michigan water have been studied by anodic stripping voltammetry. Unfiltered, 0.45 μ membrane filtered, ultrafiltered, and UV irradiated ultrafiltered samples were used to differentiate metal binding by particulate, colloidal, and dissolved organic matter. The reaction of added metal with colloids and particles is rapid. Their reaction with soluble organic matter is slow, requiring 1 to 2 days for complexation of one-half the added metal.     

Distribution of the Forms of Heavy Metals in Natural Landscapes of Belarus

Studies on the distribution of the forms of heavy metals (HMs) in the humus soil horizon were performed in the Berezinskii Reserve and Braslavskie Ozera National Park. The ratios of active to inert HM forms (with trace values of the mobile form) in these areas proved to be similar and independent of the total HM content. The calculated coefficients of technogeneity (Kt and Xt) and mobility (Km and Xm) are proposed, which reflect the natural ratio between the forms of HMs in the Northern and Central lithogeochemical provinces of Belarus.