黄土高原丘陵沟壑区农业生态系统碳循环模拟研究

利用甘肃农业大学定西旱农综合试验站的2001—2008年长期定位试验数据对DNDC模型进行了验证,结果表明：模型可以用于安定区县域尺度农田土壤有机碳储量及其变化的模拟。模拟不同处理间碳的循环结果显示,秸秆还田或覆盖可提高作物秸秆与根系残留的外源碳携入量,也能提高土壤异氧呼吸对内源碳的消耗。利用DNDC模型以及区域气象、土壤和作物资料,对该区域表层（0～20 cm）农田土壤碳循环进行模拟研究的结果表明,2008年农田土壤（面积为1.2×109 m2）表层（0～20 cm）有机碳总储量为2.8×109 kg,平均土壤有机碳密度为2.33 kg.m-2。通过对该区域农田土壤模拟不同碳投入的情景,分析预测2008年至2037年土壤有机碳储量,得出增加有机肥能够显著增加土壤有机碳的积累,其次为免耕同时增加秸秆还田率50%,而单独实施这两种措施,土壤有机碳的积累速度较慢。     

密云水库上游地区农田土壤有机碳储量及变化模拟

农田土壤有机碳(SOC)库对粮食安全和全球气候变化具有重要影响,因此,开展农田土壤有机碳储量及其动态变化研究在政治经济和生态环境层面具有重要意义.采用农业生物地球化学模型--DNDC对密云水库上游地区农田土壤有机碳储量及其变化进行模拟研究,首先应用当地实测结果进行模型验证,然后根据当地气候条件、土壤性质和现行农业耕作管理特点等建立GIS区域数据库,并在数据库的支持下进行区域模拟和分析.结果表明:2006年密云水库上游地区214 920 hm~2农田土壤(0～25 cm)的总有机碳储量为7 646×10~6 kg,其中位于河北省境内的该地区63.1%的农田储存了全区68.1%的SOC;平均每公顷农田SOC储量为35 576.1 kg,低于全国平均水平;由于化肥和有机肥投入的增加,经过1 a耕种后,2006年该地区农田SOC储量增加142.5×10~6 kg,整个地区及各区县农田土壤碳收支均为正,是大气CO_2的一个汇.情景分析表明,气温升高对该地区农田SOC积累具有显著的负效应;而提高秸秆还田比例、适量施用化肥、增施有机肥、增加灌溉和采取免耕方式等措施均能有效增加土壤有机碳的积累.     

江西省表层土壤有机碳库储量估算与空间分布特征

土壤中碳较小幅度的变化能引起全球气候较大的变化,而表层土壤有机碳库易受人类活动的影响而发生变化,因此估算土壤有机碳库储量,对土壤碳库变化及土壤固碳潜力的研究具有重大意义.根据2006年江西省各县市典型土壤GPS定点采样样点的理化分析数据计算出有机碳密度并进行空间插值,利用江西省第二次土壤普查相关数据建立土壤空间数据库,结合各土壤类型分布面积,估算表层(0～20 cm)土壤有机碳密度和储量,并探讨其空间分布特征.研究表明:江西省表层土壤平均有机碳密度介于2.655～6.877 kg·m-2之间,有机碳库总储量为640 355.653×106 kg,其中,仅红壤和水稻土的土壤有机碳储量已占90.71%.表层土壤有机碳密度具有高度的空间变异性,赣西、赣东如萍乡、宜春、上饶地区土壤有机碳密度较高,赣南、赣北地区如九江、赣州等地区土壤有机碳密度较低,总体上呈东西走向高,南北走向低的趋势.江西省是一个农业大省,人类干扰下的土壤碳库研究却很少,其碳库动态变化还值得进一步的探讨.     

若尔盖高寒湿地表层土壤有机碳空间分布特征

若尔盖高寒湿地是世界上著名的高原湿地,分布着我国面积最大的泥炭地,土壤有机碳储量十分丰富,但其空间分布特征尚不清楚。运用野外调查采样、室内分析与地理信息系统的空间分析方法,对若尔盖高寒湿地表层土壤有机碳的空间分布特征以及碳密度和碳储量进行了研究。结果表明,若尔盖区域表层土壤有机碳含量高的地方分布于沼泽集中或密集的地方,例如年保也则沼泽区,阿当乔沼泽区,牙哥曲沼泽和龙日坝沼泽等。黑河流域表层土壤有机碳含量普遍高于白河流域,这也和黑河流域水系较多,沼泽率高于白河流域有关。从垂直分布上来看,很多地方有机碳含量在10～20cm深度要大于0~10cm深度的有机碳含量,20～30cm的有机碳含量最少。表层土壤有机碳密度与有机碳含量有密切关系,其空间分布格局相似,有机碳含量高的地方有机碳密度也高,且黑河流域的值明显高于白河流域,有机碳密度值变化范围在0～105kg·m-2之间,其中湿地土壤有机碳密度变化于21.5～105kg·m-2之间。     

基于InVEST模型的太行山沿线地区生态系统碳储量时空分异驱动力分析

提升区域的碳汇能力是中国生态文明建设的重点战略方向,是促进经济社会发展绿色转型的重要举措。太行山区是中国华北地区重要的生态屏障,其生态系统拥有良好的碳汇能力。研究太行山区生态系统碳储量时空分异特征及其影响驱动机制,对华北地区落实国家“双碳”工程建设,提升区域释氧固碳能力,乃至全面提升区域生态环境质量具有重要的意义。以太行山区为例,基于2005、2010、2015、2020年太行山区四期土地覆盖及碳密度数据,使用InVEST模型估算研究区碳储量,使用地理探测器探索驱动碳储量空间分异的主要因子,分析驱动机制。研究结果表明,(1)在2005—2020年期间,太行山区的土地利用类型发生明显变化。林地、建设用地土地利用面积增加,耕地、草地土地利用面积减少。耕地和草地主要转化为建设用地,同时也有一部分耕地转化为林地。(2)太行山区碳储总量在1.48×10⁹—1.50×10⁹t之间,整体逐渐增加。从土地类型来看,碳储量占比由大到小依次为：林地、耕地、草地、建设用地、水域、未利用地。林地增加是太行山区碳储量增加的主要原因;(3)太行山区碳储量空间分异主要受地...     

基于PLUS模型和InVEST模型的南京市生态系统碳储量时空变化与预测

土地利用变化对陆地生态系统碳储量变化有着重要影响,研究土地利用变化与碳储量的空间格局,有利于优化国土空间布局,协调生态保护与土地开发利用之间的关系。以南京市域为研究区,基于2000—2020年土地利用数据,采用InVEST模型对此20年间南京市土地利用变化及碳储量变化进行分析,同时采用PLUS模型预测不同发展情景下2040年南京市碳储量分布,结果表明：(1)土地利用变化直接影响研究区碳储量。2000—2020年,城市建设用地扩张65.62%,耕地、林地和草地随之减少,南京市碳储量减少2.62×10⁶ t;(2)根据预测,到2040年,在耕地保护情景下,碳储量下降最少,仅下降2.44×10⁵ t;在生态保护情景下,碳储量下降1.56×10⁶ t;在城镇发展情景下,碳储量下降最多,下降1.78×10⁶ t;在自然发展情景下,碳储量下降1.62×10⁶ t。这表明采取耕地保护和生态保护政策,可以有效控制碳储量减少;(3)碳储量空间分布特征与土地利用分布保持一致,对于碳储量较高的区域,...     

不同土地利用方式对土壤有机碳及其组分影响研究

测定了5种土地利用方式下（人工草地、围封样地、一年耕地、弃耕地、自由放牧样地）土壤有机碳、土壤微生物生物量碳、易氧化态碳和轻组有机碳组分含量特征,比较分析土地利用变化对典型草原土壤起源下土壤有机碳组分的变化。结果表明,1）人工草地土壤有机碳含量为（14．98±3．47）g·kg-1,围封样地的为（12．41±6．40）g·kg-1,一年耕地的为（12．20±5．59）g·kg-1,弃耕样地的为（10．39±5．08）g·kg-1,自由放牧样地的为（9．45±3．19）g·kg-1。人工草地土壤有机碳含量明显高于其他样地,围封样地和一年耕地的含量相似,自由放牧样地的含量最小。2）土壤微生物生物量碳、易氧化态碳和轻组有机碳的含量在不同土地利用方式下的变化趋势与土壤有机碳含量的变化趋势基本一致。土壤有机碳及其组分含量在土壤剖面上,随着土层深度的增加而逐渐降低。3）土壤微生物生物量碳、易氧化态碳和轻组有机碳的平均分配比率在不同类型样地范围分别为0．24％～0．66％、0．002％～0．019％和0．05％-0．25％,显示出各组分对土壤环境变化的敏感度不同,其中土壤微生物生物量碳更能反映土壤有机碳的早期变化,可以作为表征土壤有机碳变化和土壤肥力的敏感指标。     

采煤塌陷区复垦土壤微团聚体中有机碳组分对施肥的响应

为阐明复垦土壤微团聚体对有机碳的固存机制,采集不同施肥措施下连续复垦6年的耕层(0-20 cm)土样,采用物理分组方法,分析微团聚体中各有机碳组分[未受保护的细颗粒有机碳(fPOC)、受物理保护的微团聚体内颗粒有机碳(iPOC)、受化学或生物化学保护的矿质结合态有机碳(MOC)]储量的变化,以及SOC含量、微团聚体中各有机碳组分储量与玉米籽粒产量之间的关系.设对照(CK)、施化肥(NPK)、单施有机肥(M)、有机无机肥配施(MNPK)4个处理,另取未复垦生土(RS)和周边未破坏多年种植熟土(US)作为参照.结果显示,同CK相比,各施肥处理均显著提高了玉米籽粒产量,且以M处理的提高效果最佳. NPK处理显著降低了SOC含量,达6.02%;M和MNPK处理均显著提高了SOC含量、fPOC和iPOC储量,增幅分别为20.74%-33.44%、64.44%-115.56%和110.98%-173.17%,且以MNPK处理增幅最大;但MNPK处理显著降低了MOC储量,达13.35%.微团聚体中各有机碳组分储量与SOC含量均呈显著正相关,尤其是fPOC储量,说明复垦土壤有机碳主要固存在fPOC组分中. SOC含量与玉米籽粒产量呈极显著相关,表明该区域复垦土壤有机碳库仍未达到饱和.本研究表明连续6年复垦显著提高了土壤肥力,但同周边农田土壤相比,仍有待继续培肥;MNPK处理对提高该复垦区SOC含量的效果最佳,且增加的有机碳首先累积在fPOC组分中,因此需要长时间持续投入才能恢复土壤有机碳的稳定性.(图7表2参34)     

黄土台塬不同土地利用方式下土壤有机碳分解特性

为了探讨土地利用方式对土壤有机碳分解的影响,以黄土台塬的乔木林地、灌木林地、天然草地和耕地等不同植被类型土壤为研究对象,对土壤有机碳矿化分解特征进行分析。结果表明,不同土地利用方式下土壤有机碳含量、有机碳密度、土壤可矿化碳含量和有机碳矿化速率均表现为天然草地和灌木林地较高,耕地最低;而土壤有机碳矿化率和呼吸速率表现为耕地和乔灌混交林地较高,灌木林地和天然草地较低。在土壤孵化的1 575 h内,不同土地利用方式下土壤矿化过程均可划分为4个阶段:0.5~5 h(第1阶段)、5~111 h(第2阶段)、111~399 h(第3阶段)和399~1 575 h(第4阶段);前399 h是可矿化碳排放的主要时段,前111 h是土壤可矿化碳排放速率最大且排放速率下降速度最快的主要时段;总体上,土壤可矿化碳累积排放量随培养时间的延长呈增加趋势,可矿化碳累积排放速率则逐渐降低。土壤有机碳矿化速率随土层深度的增加而递减。土壤有机碳矿化分解速率与有机碳总量有关,土壤呼吸与有机碳总量、矿化碳总量相关性不显著(P>0.05)。     

崇明东滩盐沼湿地土壤碳氮储量分布特征

滨海盐沼湿地是碳氮的重要储库,其碳氮储量时空分布特征受生物及环境因素的影响。研究了2013年不同季节长江口崇明东滩滨海湿地土壤(0~50 cm深度)有机碳和全氮储量的时空分布与垂直分布特征。结果表明,土壤有机碳储量与全氮储量季节分布均表现为冬季秋季夏季春季,土壤有机碳储量和全氮储量呈现随时间推移而积累的特性;其空间分布特征表现为高潮滩芦苇(Phragmites australis)带中潮滩互花米草(Spartina alterniflora)带低潮滩海三棱草(Scirpus mariqueter)带光滩,且北样线土壤有机碳和全氮储量高于南、中样线。不同区域土壤有机碳和全氮储量垂直分布特征较一致,总体表现为光滩和海三棱草有机碳储量在10~15 cm土层最大,互花米草与芦苇有机碳储量较大值出现在0~10和20~30 cm土层。土壤全氮储量垂直分布特征与有机碳相似,且与有机碳储量呈极显著线性正相关(P0.01)。不同盐沼湿地植被类型是影响土壤有机碳和全氮储量分布的重要因素,而光滩区域土壤有机碳与全氮储量分布则主要受潮汐与沉积作用的影响。     

The use of composite sampling in contaminated sites—a case study

Simulated composite sampling was carried out using data from a contaminated site. The values obtained by composite sampling were compared with the results obtained using discrete (individual) samples. It is appropriate to use a modified investigation level (MIL) when using composite samples. The MIL is lower than the standard investigation level, (IL). Various MILs were considered in this study. Too low an MIL will indicate that some composite samples require further investigation, when none of the discrete samples comprising the composite would have exceeded the IL. Too high an MIL will result in some discrete samples that exceed the IL being missed. A suggested MIL is IL/ where n is the number of discrete samples in the composite sample. This MIL was found to give few false negatives but many fewer false positives than the IL/n rule. Although this MIL was effective on the test data it could be site specific. Some local areas of high concentration may be missed with composite samples if a lower investigation level is used. These however do not make a large contribution to the health risk because they will have a contaminant level only slightly higher than the IL, and the neighboring samples must have a low concentration of the contaminant. The increased risk due this cause may be more than offset by the higher sampling density made possible through the economies of composite sampling When composite sampling is used as the first phase of an adaptive cluster-sampling scheme, it must be augmented by additional samples to delineate the contaminated area to be cleaned up. Composite sampling can also be effectively used in a clean up unit technique, where a clean up unit is represented by one or more composite samples. Suggestions are given for when composite sampling can be used effectively.     

Blood lead level in the children of western Uttar Pradesh,India

The objective of this study was to determine the blood lead levels (blls) of children under an age of 5 years living in western Uttar Pradesh, India. A total of 100 blood samples, 100 drinking water samples, and 21 vegetable samples were assessed for lead contamination. Blood levels in the range of 30–116?µg?L^?1 were observed at Kazipur village. The levels of lead in water samples were reported to be in the range of 0.006–0.095?ppm and identified at up to 9.5 times the stated permissible limit. A significant positive correlation (+0.679) was obtained between blls and water lead levels. All vegetable samples were also contaminated with lead up to 12 times higher than the permissible limit of 2.5?mg?kg^?1 of Prevention of Food Adulteration Act (PFA) 1954. The cottage lead battery industry, industrial effluents, and lead paints were identified as possible factors for lead incidence in the study area. Lead may be associated with increased antisocial activities of the children living in western Uttar Pradesh. Children with elevated blls had poorer nutritional status than those with normal levels, and parents did not know that lead causes health problems. A national population-based study is recommended to determine the prevalence of elevated blls.     

Risk assessment of children's blood lead level in some rural habitations of western Uttar Pradesh,India

The objective of this study was to determine the blood lead level (BLL) of children aged under 5 living in western Uttar Pradesh, India. A total of 100 blood samples, 100 drinking water samples, and 21 vegetable samples were assessed for lead (Pb) contamination. BLL was observed in the range of 3–11.58?µg?dL^?1 with a maximal level of 11.58?±?0.05?µg?dL^?1 in Kazipur village. Lead in water samples was detected in the range of 0.006–0.095?ppm and identified at upto 9.5-fold higher than the stated permissible limit. A significant positive correlation (+0.679) was obtained between BLL and water Pb levels. All vegetable samples were also contaminated with Pb upto 12-fold higher than the permissible limit of 2.5?µg?g^?1 of Prevention of Food Adulteration Act (PFA) 1954. Untreated industrial effluents were identified as the responsible factors for Pb occurrence in the study area. The presence of lead may be associated with the increased antisocial activities of children living in western Uttar Pradesh. Children with elevated BLL had poorer nutritional status than those with background Pb levels. There is an urgent need for a national campaign to monitor the BLL of children in India.     

The role of local and landscape level measures of greenness in modelling boreal plant species richness

Measurements of primary productivity and its heterogeneity based on satellite images can provide useful estimates of species richness and distribution patterns. However, species richness at a given site may depend not only on local habitat quality and productivity but also on the characteristics of the surrounding landscape. In this study we investigated whether the predictions of species richness of plant families in northern boreal landscape in Finland can be improved by incorporating greenness information from the surrounding landscape, as derived from remotely sensed data (mean, maximum, standard deviation and range values of NDVI derived from Landsat ETM), into local greenness models. Using plant species richness data of 28 plant families from 440 grid cells of 25 ha in size, generalized additive models (GAMs) were fitted into three different sets of explanatory variables: (1) local greenness only, (2) landscape greenness only, and (3) combined local and landscape greenness. The derived richness–greenness relationships were mainly unimodal or positively increasing but varied between different plant families, and depended also on whether greenness was measured as mean or maximum greenness. Incorporation of landscape level greenness variables improved significantly both the explanatory power and cross-validation statistics of the models including only local greenness variables. Landscape greenness information derived from remote sensing data integrated with local information has thus the potentiality to improve predictive assessments of species richness over extensive and inaccessible areas, especially in high-latitude landscapes. Overall, the significant relationship between plants and surrounding landscape quality detected here suggests that landscape factors should be considered in preserving species richness of boreal environments, as well as in conservation planning for biodiversity in other environments.     

Evaluation of delta-aminolevulinic acid levels in the urine of Angooran Lead & Zinc Company staff

Currently, attention has shifted to chronic or subclinical disorders attributed to lead (Pb) exposure. The aim of this study was to determine delta-aminolevulinic acid (δ-ALA) levels in urine of Angooran Lead &; Zinc Company workers. This cross-sectional study was conducted on 170 workers, in which 24 h urinary samples were collected and δ-ALA levels were measured spectrophotometrically. Questionnaire forms were completed indicating age, location, and duration of work. The mean δ-ALA level in urine was 5.44 mg L^?1. δ-ALA levels were correlated with age, location, and duration of work in the company. The mean δ-ALA level in the urine of workers was in the upper limit of normal ranges. δ-ALA level in urine may not be the best discriminating factor of Pb exposure from the baseline to the high levels, but is recommended as a regular and routine test for all Pb-exposed workers in addition to the measurement of Pb in blood for subjects with higher δ-ALA levels.     

海平面上升对珠江口水位影响的分析

珠江三角洲水位变化存在着大量不确定性、不精确性,这些特性既具有模糊特征,也具有灰色特征。在分析珠江三角洲灯笼山站年平均水位的变化特征和闸坡站海平面变化趋势的基础上,利用灰关联法分析代表站灯笼山站年平均水位与流量、海平面、潮差等8个因素的关系,年平均水位与影响因素之间的灰关联度均大于0.7,说明各因子对年平均水位均产生显著影响,其中海平面变化与年平均水位的灰关联度为0.736,说明海平面变化是年平均水位的重要影响因素。选取灰关联度较大的（马＋三）流量、闸坡站海平面、灯笼山站的年最高水位、年最低水位、年平均低潮、年平均潮差这6个指标进行主成分分析。结果表明：第一主成分为径流潮汐作用,第二主成分的代表因素为海平面上升,第三主成分的代表因素为年最高水位;其中海平面上升为代表的第二主成分对年平均水位的贡献率为20.1%。因此,海平面上升对灯笼山站年平均水位的影响虽然弱于径流潮汐作用,但其影响也是显著的。     

栽培水分对采摘后油菜硝酸盐与亚硝酸盐含量的影响

采用盆栽方法栽培油菜(Brassicaca mpestrisL.),研究了灌水水平对采摘后油菜植株体硝酸盐与亚硝酸盐含量随时间变化的影响。共设高(灌水控制上限为田间持水量)、中(灌水控制上限为田间持水量的75%)和低(灌水控制上限为田间持水量的50%)3个灌水水平。油菜采摘后恒温贮存,定期测定油菜植株体内硝酸盐、亚硝酸盐含量。研究结果表明:不同灌水水平和贮存时间以及两者的交互作用都能显著地影响油菜植株体硝酸盐和亚硝酸盐含量;在采摘后的8d时间里,低灌水水平处理(0.50θf处理)的油菜植株体硝酸盐含量一直高于其它两处理;采摘后当天测定高灌水水平处理(1.00θf处理)的油菜植株体硝酸盐含量最低,以后则以中等灌水水平处理(0.75θf处理)的油菜植株体硝酸盐含量为最低。采摘后当天测定油菜植株体亚硝酸盐含量,亦以高灌水水平处理(1.00θf处理)为最低。采摘后油菜植株体硝酸盐和亚硝酸盐含量都经历一个先降低、后升高、再降低的变化过程。因此,从对人体健康及卫生的角度出发,以较高灌水水平栽培油菜,采摘后在一两天内食用,有利于将其硝酸盐和亚硝酸含量控制在较低水平。     

铀尾矿库区稻田土中放射性核素的空间分布和放射性水平评价

以我国南方某铀尾矿库下游稻田土壤为研究对象,通过现场取样与室内检测,对土壤中放射性核素238U、226Ra、232Th、40K的比活度进行空间分析。同时采用γ辐射吸收剂量率和年有效剂量法进行土壤环境放射性水平评价,得出土壤中所检测的4种典型核素放射性比活度差异较大。在土壤表层和剖面,226Ra和40K的均值、最大比活度和标准差均较高,232Th和238U较低。而226Ra含量超出当地背景值较多。剖面上4种放射性核素比活度均有随深度降低的趋势,高值出现在土壤浅层,这可能与土壤的有机质含量等有关。综合垂向和平面上的分布特征可知核素232Th、40K的迁移能力比238U、226Ra弱。放射性水平评价结果显示:研究区土壤年有效剂量率平均值小于联合国原子辐射效应科学委员会和全国年有效剂量率的推荐背景值,但是γ辐射吸收剂量率均值高出全国和世界平均水平的3倍。准确定量评价了尾矿库对居民造成的辐射影响,同时为放射性核素在周边稻田植物根系中的迁移机理研究提供基础资料。     

Cross‐sectional epidemiological study on the lead burden of children and workers in Greece

Exposure of the general population to lead in the environment is mainly caused by motor traffic exhaust and by industrial pollution. The aim of the study in Greece was to assess lead exposure in children living in point source impacted areas (Lavrion and Aspropyrgos‐Eleusis) using the biological monitoring parameter “blood lead concentration”;.

In addition, workers of a lead smelter, a battery plant and an oil refinery were investigated in these areas at the same time.

Five hundred and thirty‐four children and 105 workers took part in this investigation.

The highest blood lead levels (mean: 24.16 μg/100ml; range: 10.40–60.49 μg/100 ml) were found in children living in a 500m‐area around the lead smelter at Lavrion. Blood lead decreases corresponded to the increasing distance from the emitter. Nevertheless the values of children living in a 1500 m distance to the smelter are significantly higher than those of children living next to other kinds of industrial lead sources.

The mean values of the children living in the two industrial towns were manifold higher than those of the control group.

The blood lead levels of the investigated workers did not exceed the German BAT‐value (Biologischer Arbeitsstoff‐Toleranzwert) of 70 μg/100ml.     

Ecoregions and ecosystem management in China

Ecological regionalization is a base for rational management and sustainable utilization of ecosystems and natural resources. It can provide a scientific basis for constructing healthy ecological environments and making policies of environmental management. In this paper, based on synthetic analysis of the characteristics of the ecology and environments of China, the principles of ecological regionalization are discussed, and indices and nomenclature of ecological regionalization are proposed. The ecoregions on a national scale are divided. The results show that there are 3 domains, 13 ecoregions and 57 ecodistricts. The present scheme can be used as a framework for ecosystem assessment and management. Based on the ecoregions, measurements of management for forest, grassland, agriculture and wetland ecosystems are recommended. The experience and information can be used within and beyond the national scale for land-use planning, biodiversity conservation and ecosystem restoration.