民用生物质燃烧挥发性有机化合物排放特征

民用生物质燃烧是我国人为源挥发性有机物（VOCs）排放的主要来源.采用罐采样-GC/MS和DNPH衍生-HPLC这2种方法联用采集和分析了5种主要民用生物质燃烧排放烟气中的VOCs组分,并利用碳平衡法确定其排放系数.研究表明,秸秆和木柴等民用生物质燃烧总的VOCs排放系数分别为（4.37±2.23）g·kg-1和（2.12±0.77）g·kg-1,秸秆燃烧排放高于木柴燃烧排放;民用生物质燃烧排放VOCs中,最为丰富的物种为芳香烃和醛类,含量均在25%以上;秸秆和木柴燃烧除卤代烃和腈类含量差异较大外,其余物种分布比较类似;秸秆和木柴燃烧VOCs排放总的臭氧生成潜势分别为（16.9±8.2）g·kg-1和（10.8±4.9）g·kg-1;臭氧生成潜势比较高的物种依次为：醛类、芳香烃和烯烃/炔烃,其中醛类贡献基本在50%以上.     

Root- and peat-based CO2 emissions from oil palm plantations

Measured carbon dioxide (CO₂) flux from peat soils using the closed chamber technique combines root-related (autotrophic + heterotrophic where rhizosphere organisms are involved) and peat-based (heterotrophic) respiration. The latter contributes to peat loss while the former is linked to recent CO₂ removal through photosynthesis. The objective of this study was to separate root- from peat-based respiration. The study was conducted on peatland under 6 and 15 year old oil palm (Elaeis guineensis Jacq.) plantations in Jambi Province, Indonesia in 2011 to 2012. CO₂ emissions were measured in the field from 25 cm diameter and 25 cm tall closed chambers using an infrared gas analyser. Root sampling and CO₂ emissions measurements were at distances of 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, and 4.5 m from the centre of the base of the palm tree. The emission rate for the six and 15 year old oil palm plantations at ≥3.0 m from the centre of the tree were 38.2?±?9.5 and 34.1?±?15.9 Mg CO₂ ha^?1 yr^?1, respectively. At distances <2.5 m, total respiration linearly decreased with distances from the trees. Heterotrophic respirations were 86 % of the 44.7?±?11.2 and 71 % of 47.8?±?21.3 Mg CO₂ ha^?1 yr^?1 of weighted surface flux, respectively for the 6 and 15 year old plantations. We propose that CO₂ flux measurements in oil palm plantations made at a distance of ≥3 m from the tree centre be used to represent the heterotrophic respiration that is relevant for the environmental impact assessment.     

Will funding to Reduce Emissions from Deforestation and (forest) Degradation (REDD+) stop conversion of peat swamps to oil palm in orangutan habitat in Tripa in Aceh,Indonesia?

Tripa is the last remaining peat-swamp forest that harbours a potentially viable Sumatran orangutan (Pongo abelii) sub-population in a formally but not effectively protected area. It appears to be a simple showcase where current efforts to financially support reducing emissions from deforestation and forest degradation (REDD+) converge with biodiversity and social co-benefits. In practice, however, situation is more complex. REDD+ efforts interact with global palm oil trade and regulatory approaches (the moratorium) to achieve national goals for emissions reduction under umbrella of nationally appropriate mitigation actions (NAMA). To contextualize this debate, we assessed (i) land-use history and formal basis of palm-oil companies’ rights; (ii) carbon (C) stocks, historical emission levels and potential emissions that can be avoided; (iii) economic benefits of land-use options and opportunity costs of avoiding emissions; (iv) biodiversity and environmental services; and (v) alternative options for “high C stock development” and employment generation. Natural forest cover declined (54 % in 1995, 18 % in 2009) while oil palm increased 4–39 %. Aboveground C stocks decreased from 148 Mg ha^?1 in 1990 to 61 Mg ha^?1 in 2009, leading to average annual emissions of 14.5 Mg (carbon dioxide) CO₂e ha^?1 year^?1. While 41 % of these emissions yield less than American Dollar (USD) 5 of current economic benefits per Mg CO₂e emitted and might be compensated by REDD+, nearly all new emissions derive from a breach of existing laws, regulations and voluntary palm-oil standards. Substantial investment in alternative employment is needed, rather than carbon payments per se, to support livelihoods in a low carbon emissions economy.     

典型城市河流表层沉积物中汞污染特征与生态风险

以北京市凉水河为研究对象,研究了典型城市河流表层沉积物中汞污染特征与生态风险.采用王水水浴消解法和BCR三步提取法分析沉积物中汞总量及其赋存形态特征,并利用潜在生态风险指数法和风险评估指数法评价汞的生态风险.结果表明,凉水河表层沉积物中总汞含量范围是0.018~3.48 mg·kg~(-1),平均值是0.974 mg·kg~(-1),多数样点高于北京市土壤背景值;表层沉积物中汞主要以残渣态(B4态)存在,平均含量为0.841 mg·kg~(-1),各形态汞所占比例顺序为:残渣态(B4态)可氧化态(B3态)可还原态(B2态)弱酸可溶解态(B1态),其中生物有效态汞占总汞的比例为23.21%.基于汞总量的潜在生态风险评价可知,凉水河各个河段表层沉积物中汞的潜在生态风险程度都处于很高水平(Ei平均值为565);但基于汞形态的生态风险评价可知,汞的生态风险都处于较低水平(B1所占比例平均值为4.80%).     

底物含氮量对厨余堆肥氮素转化及其损失的影响研究

采用静态好氧工艺研究了含氮量分别为32.4 g·kg-1、45.3 g·kg-1和58.2g·kg-1的厨余垃圾(N0、N1、N2)与木屑混合堆制时,堆肥过程中不同形态氮的转化及其氮损失规律.结果表明,堆肥中堆体全氮含量呈先升后降趋势,部分有机氮转化为铵氮导致堆体pH升高,在通风和高温的联合作用下,NH3挥发出堆体造成一定的氮损失.随着底物含氮量的增加,NH3挥发速率和氮损失率均呈上升趋势.堆肥结束时N0、N1、N2的堆体全氮含量分别下降了16.4%、26.3%和21.7%,NH3累计挥发量分别为7.0 g·kg-1、9.8 g·kg-1和29.4 g·kg-1,堆肥氮损失率分别为35.0%、49.9%和53.0%.NH3挥发主要集中在高温阶段的中后期,是厨余堆肥氮损失的主要原因.     

Greenhouse gas emission factors for land use and land-use change in Southeast Asian peatlands

Tropical peat swamp forests, which are predominantly located in Southeast Asia (SEA) and play a prominent role as a global carbon store, are being intensively degraded and converted to agricultural lands and tree plantations. For national inventories, updated estimates of peat emissions of greenhouse gases (GHG) from land use (LU) and land-use change in the tropics are required. In this context, we reviewed the scientific literature and calculated emission factors of peat net emissions of carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) in seven representative LU categories for SEA i.e. intact peat swamp forest, degraded forest (logged, drained and affected by fire), mixed croplands and shrublands, rice fields, oil palm, Acacia crassicarpa and sago palm plantations. Peat net CO₂ uptake from or emissions to the atmosphere were assessed using a mass balance approach. The balance included main peat C inputs through litterfall and root mortality and outputs via organic matter mineralization and dissolved organic carbon. Peat net CO₂ loss rate from degraded forest, croplands and shrublands, rice fields, oil palm, A. crassicarpa and sago palm plantations amounted to 19.4?±?9.4, 41.0?±?6.7, 25.6?±?11.5, 29.9?±?10.6, 71.8?±?12.7 and 5.2?±?5.1 Mg CO₂ ha^?1 y^?1, respectively. Total peat GHG losses amounted to 20.9?±?9.4, 43.8?±?6.8, 36.1?±?12.9, 30.4?±?10.6, 72?±?12.8 and 8.6?±?5.3 Mg CO₂-equivalent ha^?1 y^?1 in the same LU categories, respectively. A single land-clearing fire would result in additional emissions of 493.6?±?156.0 Mg CO₂-equivalent ha^?1.     

Carbon storage and sequestration potential of selected tree species in India

A dynamic growth model (CO2FIX) was used for estimating the carbon sequestration potential of sal (Shorea Robusta Gaertn. f.), Eucalyptus (Eucalyptus Tereticornis Sm.), poplar (Populus Deltoides Marsh), and teak (Tectona Grandis Linn. f.) forests in India. The results indicate that long-term total carbon storage ranges from 101 to 156 Mg C?ha^?1, with the largest carbon stock in the living biomass of long rotation sal forests (82 Mg C?ha^?1). The net annual carbon sequestration rates were achieved for fast growing short rotation poplar (8 Mg C?ha^?1?yr^?1) and Eucalyptus (6 Mg C?ha^?1?yr^?1) plantations followed by moderate growing teak forests (2 Mg C?ha^?1?yr^?1) and slow growing long rotation sal forests (1 Mg C?ha^?1?yr^?1). Due to fast growth rate and adaptability to a range of environments, short rotation plantations, in addition to carbon storage rapidly produce biomass for energy and contribute to reduced greenhouse gas emissions. We also used the model to evaluate the effect of changing rotation length and thinning regime on carbon stocks of forest ecosystem (trees?+?soil) and wood products, respectively for sal and teak forests. The carbon stock in soil and products was less sensitive than carbon stock of trees to the change in rotation length. Extending rotation length from the recommended 120 to 150 years increased the average carbon stock of forest ecosystem (trees?+?soil) by 12%. The net primary productivity was highest (3.7 Mg ha^?1?yr^?1) when a 60-year rotation length was applied but decreased with increasing rotation length (e.g., 1.7 Mg ha^?1?yr^?1) at 150 years. Goal of maximum carbon storage and production of more valuable saw logs can be achieved from longer rotation lengths. ‘No thinning’ has the largest biomass, but from an economical perspective, there will be no wood available from thinning operations to replace fossil fuel for bioenergy and to the pulp industry and such patches have high risks of forest fires, insects etc. Extended rotation lengths and reduced thinning intensity could enhance the long-term capacity of forest ecosystems to sequester carbon. While accounting for effects of climate change, a combination of bioenergy and carbon sequestration will be best to mitigation of CO₂ emission in the long term.     

Impacts of land use,restoration, and climate change on tropical peat carbon stocks in the twenty-first century: implications for climate mitigation

The climate mitigation potential of tropical peatlands has gained increased attention as Southeast Asian peatlands are being deforested, drained and burned at very high rates, causing globally significant carbon dioxide (CO₂) emissions to the atmosphere. We used a process-based dynamic tropical peatland model to explore peat carbon (C) dynamics of several management scenarios within the context of simulated twenty-first century climate change. Simulations of all scenarios with land use, including restoration, indicated net C losses over the twenty-first century ranging from 10 to 100 % of pre-disturbance values. Fire can be the dominant C-loss pathway, particularly in the drier climate scenario we tested. Simulated 100 years of oil palm (Elaeis guineensis) cultivation with an initial prescribed burn resulted in 2400–3000 Mg CO₂?ha^?1 total emissions. Simulated restoration following one 25-year oil palm rotation reduced total emissions to 440–1200 Mg CO₂?ha^?1, depending on climate. These results suggest that even under a very optimistic scenario of hydrological and forest restoration and the wettest climate regime, only about one third of the peat C lost to the atmosphere from 25 years of oil palm cultivation can be recovered in the following 75 years if the site is restored. Emissions from a simulated land degradation scenario were most sensitive to climate, with total emissions ranging from 230 to 10,600 Mg CO₂?ha^?1 over 100 years for the wettest and driest dry season scenarios, respectively. The large difference was driven by increased fire probability. Therefore, peat fire suppression is an effective management tool to maintain tropical peatland C stocks in the near term and should be a high priority for climate mitigation efforts. In total, we estimate emissions from current cleared peatlands and peatlands converted to oil palm in Southeast Asia to be 8.7 Gt CO₂ over 100 years with a moderate twenty-first century climate. These emissions could be minimized by effective fire suppression and hydrological restoration.     

CO2 emissions from tropical drained peat in Sumatra,Indonesia

With the increasing use of tropical peatland for agricultural development, documentation of the rate of carbon dioxide (CO₂) emissions is becoming important for national greenhouse gas inventories. The objective of this study was to evaluate soil-surface CO₂ fluxes from drained peat under different land-use systems in Riau and Jambi Provinces, Sumatra, Indonesia. Increase of CO₂ concentration was tracked in measurement chambers using an Infrared Gas Analyzer (IRGA, LI-COR 820 model). The results showed that CO₂ flux under oil palm (Elaeis guineensis) plantations ranged from 34?±?16 and 45?±?25 Mg CO₂ ha^–1 year^–1 in two locations in Jambi province to 66?±?25 Mg CO₂ ha^–1 year^–1 for a site in Riau. For adjacent plots within 3.2 km in the Kampar Peninsula, Riau, CO₂ fluxes from an oil palm plantation, an Acacia plantation, a secondary forest and a rubber plantation were 66?±?25, 59?±?19, 61?±?25, 52?±?17 Mg ha^–1 year^–1, respectively, while on bare land sites it was between 56?±?30 and 67?±?24 Mg CO₂ ha^–1 year^–1, indicating no significant differences among the different land-use systems in the same landscape. Unexplained site variation seems to dominate over land use in influencing CO₂ flux. CO₂ fluxes varied with time of day (p?<?0.001) with the noon flux as the highest, suggesting an overestimate of the mean flux values with the absence of night-time measurements. In general, CO₂ flux increased with the depth of water table, suggesting the importance of keeping the peat as wet as possible.     

CH4 emission model from the waste of Sus Domesticus and Gallus Domesticus in Nigerian local farms: environmental implications and prospects

The potential of CH₄ (methane) greenhouse gas (GHG) emissions based on a model of prevailing behavioural pattern of livestock waste management in Nigerian local farms was investigated in this paper. Livestock waste, from Sus domesticus, pig, and Gallus domesticus, poultry, were employed as substrates in the study which uses water from a fish rearing farm as the matrix medium to simulate wastewater pool/river environment. A substrate to fish-water ratio of 1:3 by mass was used in developed laboratory-size digesting reactor system with U-tube water displacement, to facilitate volumetric readings of gas production, for each mix of the livestock waste. Volumetric readings from these, at ambient temperature conditions in the retention time of 32 days, follow the Normal probability density function, in accordance with Kolmogorov-Smirnov goodness-of-fit criteria. These readings showed that CH₄-containing gas as high as 67.3?×?10^?3 dm³ was produced on the 14th day from the pig and 86.8?×?10^?3 dm³ on the 13th day from the poultry substrates. The overall CH₄-containing gas productions of 255.4?×?10^?3 dm³/kg and 323.58?×?10^?3 dm³/kg were observed for the pig and the poultry substrates, respectively. A 70% scale-up analysis, modelled from these results, for the nation yield potential emission of about 4 kg CH₄ (that could be as potent as 84 kg CO₂-equivalent) annually. The environmental implications on global warming and possible prospects of recoverable domestic benefits from the waste through the adoption of sustainable policy of livestock waste managements for mitigating the CH₄ emissions in Nigerian local farms are presented.     

‘Carbon stocks in a Scots pine afforestation under different thinning intensities management’

Thinning, as a forest management strategy, may contribute towards mitigating climate change, depending on its net effect on forest carbon (C) stocks. Although thinning provides off-site C storage (in the form of wood products) it is still not clear whether it results in an increase, a reduction or no change in on-site C storage. In this study we analyze the effect of thinning on C stocks in a long-term experiment. Different thinning intensities (moderate, heavy and unthinned) have been applied over the last 30 years in a Scots pine (Pinus sylvestris L.) stand, with a thinning rotation period of 10 years. The main C compartments were analyzed: above and belowground tree biomass, deadwood, forest floor and upper 30-cm of the mineral soil and tree biomass removed in thinning treatments. The results revealed that unthinned stands had the highest C stocks with 315 Mg C ha^?1, moderate thinning presented 304 Mg C ha^?1 and heavy thinning 296 Mg C ha^?1, with significant differences between unthinned and heavily thinned stands. These differences were mainly due to C stock in live biomass, which decreased with thinning intensity. However, soil C stocks, forest floor and mineral soil, were not influenced by thinning, all of the stands displaying very similar values 102–107 Mg C ha^?1 for total soil; 15–19 Mg C ha^?1 for forest floor; 87–88 Mg C ha^?1 for mineral soil). These results highlight the sustainability of thinning treatments in terms of C stocks in this pinewood afforestation, and provide valuable information for forest management aimed at mitigating climate change.     

生活垃圾焚烧厂周边土壤汞污染特征及评价

生活垃圾焚烧汞污染排放问题一直受到广泛的关注,特别是汞在其周边环境土壤中沉积,可能影响环境和人体健康.以华北某生活垃圾焚烧厂为研究对象,对其周边土壤中汞的含量及分布特征进行了分析,并对土壤中汞的污染状况及对周边人群的健康风险进行了评价.土壤中汞的浓度范围为0.015~0.25 mg·kg-1,平均值为(0.088±0.064)mg·kg-1.土壤中汞的浓度明显受到了风向影响,在焚烧厂西北方向(下风向)上汞的浓度高于东南方向(上风向)上汞的浓度.通过克里格插值绘制的汞等浓度值线图进一步给出了汞在周边土壤中的空间分布特征,图中显示在焚烧厂的周边存在3个浓度相对较高的区域,分别位于焚烧厂的西北偏北、东北偏北、西南偏西方向.单项污染指数及地累积指数评价结果表明焚烧厂部分周边土壤样品受到了一定影响,但健康风险评价表明土壤汞未对当地人群造成健康危害.     

Insectivorous birds consume an estimated 400–500 million tons of prey annually

In this paper, we present an estimate of the predation impact of the global population of insectivorous birds based on 103 (for the most part) published studies of prey consumption (kg ha^?1 season^?1) of insectivorous birds in seven biome types. By extrapolation—taking into account the global land cover of the various biomes—an estimate of the annual prey consumption of the world’s insectivorous birds was obtained. We estimate the prey biomass consumed by the world’s insectivorous birds to be somewhere between 400 and 500 million metric tons year^?1, but most likely at the lower end of this range (corresponding to an energy consumption of ≈?2.7?×?10¹⁸ J year^?1 or ≈?0.15% of the global terrestrial net primary production). Birds in forests account for >?70% of the global annual prey consumption of insectivorous birds (≥?300 million tons year^?1), whereas birds in other biomes (savannas and grasslands, croplands, deserts, and Arctic tundra) are less significant contributors (≥?100 million tons year^?1). Especially during the breeding season, when adult birds feed their nestlings protein-rich prey, large numbers of herbivorous insects (i.e., primarily in the orders Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera, and Orthoptera) supplemented by spiders are captured. The estimates presented in this paper emphasize the ecological and economic importance of insectivorous birds in suppressing potentially harmful insect pests on a global scale—especially in forested areas.     

Assessing the net atmospheric impacts of wood production and utilization

The main objective of the study was to calculate net atmospheric impacts for wood production and utilization in Finnish boreal forest conditions. Net atmospheric impacts were calculated by comparing net CO₂ exchanges of the wood production and utilization to the reference management regime. Net CO₂ exchanges were simulated with a life cycle assessment (LCA) tool for a Scots pine (Pinus sylvestris L.) stand (MT, Myrtillys-type) in central Finland (Joensuu region, 62°39 N, 29°37 E) over two consecutive rotation periods (100?+?100 years/200 years). Net atmospheric impacts were calculated both for sawn timber and pulpwood, and expressed in kgCO₂m^?3. According to the results, the production of pulp and sawn timber produced emissions of 0.20 and 0.59 kgCO₂m^?3 over the 200-year period, respectively, when the unmanagement regime was used as the reference management regime. When 50 % of the processing waste of timber was accounted as an instant emission to the atmosphere, the atmospheric impact increased to 0.55 kgCO₂m^?3 in pulpwood and to 1.27 kgCO₂m^?3 in sawn timber over the 200 year period. When turnover rates of sawn timber in the technosystem were decreased by 30 % and the share of energy use was decreased to 30 %, the atmospheric impact decreased by 17 % and 4 % for pulpwood and sawn timber, respectively, compared to the default wood degradation and energy use of 50 %. The utilized LCA approach provided an effective tool for approaching net atmospheric impacts originating from the ecosystem carbon (C) flows and variable wood utilization. Taking the ecosystem production and utilization of wood (i.e. degradation of technosystem C stock) into account, in terms of net CO₂ exchange, the mitigation possibilities of wood compared to other products can be accounted for more precisely in the future and C sequestration credited more specifically for a certain wood product.     

Mercury accumulation and dynamics in montane forests along an elevation gradient in Southwest China

Understanding atmospheric mercury (Hg) accumulation in remote montane forests is critical to assess the Hg ecological risk to wildlife and human health. To quantify impacts of vegetation, climatic and topographic factors on Hg accumulation in montane forests, we assessed the Hg distribution and stoichiometric relations among Hg, carbon (C), and nitrogen (N) in four forest types along the elevation of Mt. Gongga. Our results show that Hg concentration in plant tissues follows the descending order of litter > leaf, bark > root > branch > bole wood, indicating the importance of atmospheric Hg uptake by foliage for Hg accumulation in plants. The foliar Hg/C (from 237.0 ± 171.4 to 56.8 ± 27.7 µg/kg) and Hg/N (from 7.5 ± 3.9 to 2.5 ± 1.2 mg/kg) both decrease along the elevation. These elevation gradients are caused by the heterogeneity of vegetation uptake of atmospheric Hg and the variation of atmospheric Hg° concentrations at different altitudes. Organic soil Hg accumulation is controlled by forest types, topographic and climatic factors, with the highest concentration in the mixed forest (244.9 ± 55.7 µg/kg) and the lowest value in the alpine forest (151.9 ± 44.5 µg/kg). Further analysis suggests that soil Hg is positively correlated to C (r² = 0.66) and N (r² = 0.57), and Hg/C and Hg/N both increase with the soil depth. These stoichiometric relations highlight the combined effects from environmental and climatic factors which mediating legacy Hg accumulation and selective Hg absorption during processes of organic soil mineralization.     

民用燃煤含碳颗粒物的排放因子测量

通过烟尘罩稀释通道系统采样,实验室模拟民用燃煤的燃烧方式,获取了不同成熟度的散煤、蜂窝煤的PM2.5、EC和OC的排放因子.民用燃煤的排放与煤炭成熟度有很大相关,不同煤种排放因子差距很大.在6种实验煤炭中,烟煤散烧的排放因子较大,其中S3煤种的排放因子最大,其PM2.5、EC和OC的实测值分别为11.06、3.51和5.39 g·kg-1;无烟煤散烧排放因子较少,S1煤种的排放因子最小,其PM2.5、EC和OC分别为0.78、0.02和0.49 g·kg-1;蜂窝煤的颗粒物以及OC排放因子与相似成熟度的散煤燃烧相当,但是EC排放相对散煤较低.EC、OC源清单工作需要对民用燃煤源进行更详细的分类,结合相应的排放因子,才能更加准确的估计这一重要排放源的贡献率.     

长白山地区大气气态总汞含量的季节性特征研究

利用高时间分辨率自动大气测汞仪(Tekran(R) 2537A),于2005-08～2006-07对长白山地区大气气态总汞进行了连续1a的野外观测.结果表明,长白山地区气态总汞的年平均含量为(3.22±1.78)ng·m-3,按季节表现为:冬季＞春季＞秋季＞夏季.长白山地区气态总汞含量高于北半球大气汞含量的背景值(1.5～2.0 ng·m-3),表明该地区已受到一定程度的大气汞污染.在对长白山地区气态总汞来源的解析中,该区频率最高的指示风向西南(SW)、西北(NW)和非主导风向东北(NE)方位上,城镇人为采暖、燃煤以及对生物燃料的使用成为该地区的气态总汞的主要来源,而土壤释放或其他来源的大气汞经中长距离的迁移也是造成该区域大气汞含量升高的原因.     

葫芦岛市土壤、蔬菜重金属污染空间变化规律

采用Ｋrige插值法分析葫芦岛市土壤重金属的空间变化规律,测定葫芦岛市土壤、蔬菜、粮食中Hg、Pb、Cd、Zn、Cu的含量,应用指数方程和幂指数方程描述重金属与污染源的关系,分析土壤重金属的来源,并通过对当地种植和市售蔬菜、粮食重金属的比较,研究冶炼-氯碱工业对土壤与农作物生态系统的影响.结果发现葫芦岛市土壤受到重金属污染严重,Hg、Pb、Cd、Zn、Cu的平均含量分别是1.422、 443.1、 60.94、 4 084、 247.8 mg·kg^-1,最大值分别达到6.092、 3 195、 341.7、 35 157、 1 557 mg·kg^-1,Cd、Zn污染属于重污染,Hg、Pb、Cu属于中度污染.土壤中Hg、Pb、Cd、Zn、Cu的污染主要呈现以葫芦岛锌厂为中心,向外围辐散降低的规律,其中Hg还受到氯碱工业的影响.葫芦岛市土壤重金属主要来源于大气沉降,指数方程和幂指数方程均能很好地描述Pb、Cd、Zn、Cu在土壤中随距离的变化趋势.地产农作物的重金属含量远高于市售农作物,则进一步说明了重金属对葫芦岛市土壤生态系统带来了严重影响.     

黄土塬区小流域深层土壤有机碳变化的影响因素

以黄土高原沟壑区王东沟小流域为对象,研究了地形(塬面、塬坡和沟道)、土地利用(自然草地、人工草地、人工林地、农地和果园)对0～200cm土层内土壤有机碳(soil organic carbon,SOC)垂直分布特征的影响,以揭示黄土高原小流域深层SOC储量及其影响因素.结果表明,SOC含量除表层(0～20cm)沟道(10.0g·kg-1)大于塬面(7.8g·kg-1)和塬坡(8.2g·kg-1)外,塬面底层SOC均显著高于塬坡和沟道;塬坡和沟道SOC含量随深度增加而降低,而塬面上呈现SOC随深度增加降低-升高-降低的变化趋势.塬面上,SOC含量呈现人工草地(5.4g·kg-1)农田(5.2g·kg-1)和果园(5.1g·kg-1)的趋势,影响深度为表层40cm;塬坡上,呈现自然草地(4.3g·kg-1)人工林地(3.8g·kg-1)人工草地(3.3g·kg-1)和果园(3.3g·kg-1)的趋势,影响深度达到100cm;而沟道内,林草地利用方式对整个垂直剖面分布的差异无显著影响.20～100cm土层SOC储量占0～100cm储量的67.6%;100～200cm土层SOC储量占0～200cm储量的37.3%,相当于0～100cm的63.8%.研究结果表明地形、土地利用显著(p0.05)影响SOC垂直分布特征;黄土高原沟壑区深层SOC储量巨大,不容忽视.     

Phenanthrene sorption to environmental black carbon in sediments from the Song-Liao watershed (China)

Black carbon (BC) in ten contaminated sediments from the Song-Liao watershed, NE China, was isolated upon treatments using a combustion method at 375°C, and the isolates’ sorption isotherms for phenanthrene (Phen) were determined. All sorption isotherms were nonlinear and fitted well by the Freundlich model. A negative relation was found between Freundlich sorption nonlinearity parameter (n values) and BC/total organic carbon (TOC) content of the original sediments (r ² = 0.687, p<0.01), indicating the dominance of BC in Phen sorption nonlinearity. The BC isolates from this industrialized region had n values of 0.342 to 0.505 and logK _FOC values of 6.02 to 6.42 (μg·kg⁻¹·OC⁻¹)/(μg·L⁻¹) ⁿ for Phen. At a given C _e, the BC had higher K _oc value than the original sediments, revealing a higher sorption capacity for BC. BC was responsible for 50.0% to 87.3% of the total sorption at C _e= 0.05 S _w, clearly indicating the dominance of BC particles in overall sorption of Phen by sediments.