黑龙江省县域黑土农田土壤氮残留估算

掌握农田土壤氮残留量的时空变化特征,可以为土壤养分资源的宏观管理提供依据。该文根据农田土壤生态系统氮素收支平衡原理,基于1980～2004年《黑龙江省统计年鉴》数据,估算了作物收获后黑龙江省县域黑土农田土壤氮残留状况。结果表明,1982～2002年,黑龙江省农田土壤氮输入增加了77.8%,平均值为118.1 kg·hm-2;氮输出增加了72.1%,平均值为74.8 kg·hm-2。土壤氮残留(RSN)增加了86.2%,平均值为43.3 kg·hm-2。黑龙江省西部的RSN值显著高于东部。农田土壤氮残留量随时间渐趋增加,在非生长季节,大部分RSN都转化成硝态氮（NO3-）,并通过径流和渗漏途径进入河流和地下水体,以及通过反硝化转化成氮气（N2O和N2）挥发进入大气,不仅造成氮资源浪费,还会危害生态环境。     

Comparison of approaches for estimating carbon sequestration at the regional scale

Abstract. Many former estimates of regional scale C sequestration potential have made use of linear regressions based on long-term experimental data, whilst some have used dynamic soil organic matter (SOM) models linked to spatial databases. Few studies have compared the two methods. We present a case study in which the potential of different land management practices to sequester carbon in soil in arable land is estimated by different methods. Two dynamic SOM models were chosen for this study, RothC (a soil process model) and CENTURY (a whole ecosystem model with a SOM module). RothC and CENTURY are the two most widely used and validated SOM models worldwide. A Geographic Information System (GIS) containing soil, land use and climate layers, was assembled for a case study in central Hungary. GIS interfaces were developed for the RothC and CENTURY models, thus linking them to the spatial datasets at the regional level. This allowed a comparison of estimates of the C sequestration potential of different land management practices obtained using the two models and using regression based approaches. Although estimates obtained by the different approaches were of the same order of magnitude, differences were observed. Some of the land management scenarios studied here showed sufficient C mitigation potential to meet Hungarian CO₂ reduction commitments. For example, afforestation of 12% current arable land could sequester 0.042–0.092 Tg yr^–1 in the soil alone, or 0.285–0.588 Tg C yr^–1 in both soil and biomass; 1990 level CO₂ emissions for the study area were 4.7 Tg C with a corresponding reduction commitment of 0.282 Tg C. It is not, however, suggested that this is the only, or the most favourable way, in which to meet the commitments.     

Plant-available water capacity of soils at a regional scale: Analysis of fixed and dynamic field capacities

Estimation of the plant-available water capacity (PAWC) of soils at a regional scale helps in adopting better land use planning, developing suitable irrigation schedules for crops, and optimizing the use of scarce water resources. In the current study, 72 soil profiles were sampled from the Barossa region of South Australia to estimate pedo-transfer functions deduced from easily estimated soil properties. These functions were then used to estimate the fixed (10 and 33 kPa) and dynamic pressure head (h_fc) water contents at field capacity (FC) for minimum drainage flux (0.01 and 0.001 cm d^-1), which serves as the upper boundary for plant-available water in soils. The estimated residual water content was corrected for subsoil constraints, especially the exchangeable sodium percentage (ESP). The results showed that the mean values of h_fc in sand-dominated light and medium textured soils (i.e., sand, loamy sand, sandy loam, and loam) varied in a narrow range (15.8–18.2 kPa), whereas those in the clay-dominated heavy textured soils (i.e., clay loam) showed a wide range (11.3–49.3 kPa). There were large differences in PAWC for dynamic FC (PAWC_fc) and fixed FC at 10 kPa (PAWC₁₀), 33 kPa (PAWC₃₃), and a mix of 10 and 33 kPa (PAWC_10,33) pressure heads depending on soil texture. Normally, the difference between PAWC at 10 kPa and h_fc (∆PAWC₁₀) was positive, whereas that between 33 kPa and h_fc (∆PAWC₃₃) was negative across all sites. Nevertheless, the estimation of PAWC assuming a fixed FC at 10 and 33 kPa pressures (i.e., PAWC_10,33) for sandy, clay, and silty soils reduced the difference between fixed and dynamic pressure PAWCs to < 10% across the region. The estimation of PAWC was improved by incorporating the impact of subsoil constraints, such as high ESP, which was more pronounced for clay and silty soils. These findings demonstrate the inherent inconsistencies between static pressure and flux-based dynamic FC estimations in soils. Soil heterogeneity, intra-texture variability, subsoil constraints, and swell-shrink clays can have great impacts on the water retention capacity in response to dynamic and fixed pressure FC values.     

Effect of sampling density on regional soil organic carbon estimation for cultivated soils

An extensive knowledge of how sampling density affects soil organic C (SOC) estimation at regional scale is imperative to reduce uncertainty to a meaningful confidence level and aid in the development of sampling schemes that are both rational and economical. Using kriging prediction, this paper examined the effect of sampling density on regional SOC‐concentration estimations in cultivated topsoils at six scales in a 990 km² area of Yucheng County, a typical region in the N China Plain. Except the original data set (n = 394), five other sampling densities were recalculated using grids of 8 km × 8 km (n = 28), 8 km × 4 km (n = 44), 4 km × 4 km (n = 82), 4 km × 2 km (n = 142), and 2 km × 2 km (n = 257), respectively. Experimental SOC semivariances and kriging interpolations at six sampling density scales were calculated and modeled to estimate regional SOC variability. Accuracy of the effects of the five sampling densities on regional SOC estimations was assessed using the indices of mean error (ME) and root mean square error (RMSE) with 100 independent validation samples. By comparison with the kriged grid map derived from the 394 samples data set, the relative error (RE,%) was spatially calculated to highlight the spatial variability of prediction errors at five sampling‐density scales due to the intrinsic limitations of ME and RMSE in accuracy assessment. The results indicated that sampling density significantly affected the estimation of regional SOC concentration. Particularly when the sampling density was < 4 km × 4 km, the large spatial variation of SOC was concealed. Semivariance analysis indicated that different sampling density had significant effect on reasonable detection of the dominant factors which influenced SOC spatial variation. Greater sampling density could more exactly reveal regional SOC variation caused by human management. The prediction accuracy for regional SOC estimation increased with the increasing of sampling density. The critical areas with larger RE values should be intensified in the future sampling scheme, and the areas of lower RE values should be decreased relatively. A specific sampling scheme should be considered in accordance with the demand to the estimation accuracy of regional SOC stock at a certain confidence level. Our results will facilitate a better understanding of the effect of sampling density on regional SOC estimation for future sampling schemes by providing meaningful confidence levels.     

硫酸盐对锌和镉在可变电荷土壤上吸附的影响

SO4^2- and Zn^2 or Cd^2 were added to three variable charge soils in different sequences.In one sequence sulfate was added first ,and in the other,Zn^2 or Cd^2 first.The addition of sulfate to the system invariably caused an increase in adsorption of the heavy metal added,with the effect more remarkable whn the soil reacted with the sulfate prior to the metal.the shift in pH50 for both Zn and Cd adsorption was aslo comparatively larger in the first sequence of reactions .It was suggested that the increase in negative charge density and the resultant negative potential of the soil were the primary cause of the pronounced effect of sulfate on adsorption of Zn or Cd,and the formaiton of the ternary surface complex-S-SO4-M might also play a role in the effect.     

基于CSLE模型和抽样单元法的县域土壤侵蚀估算方法对比

为提高县域尺度地块(栅格)土壤侵蚀模数估算的准确性,以河北省怀来县为例,基于CSLE模型,分别采用全域覆盖计算和4%密度抽样单元推算方法对全县土壤侵蚀进行计算和对比分析。结果表明:全域覆盖计算比4%抽样单元推算水土流失面积大59.0 km~2,相对差异达12.94%。全域覆盖计算可实现空间全覆盖,更准确地反映县域水土流失空间分布特点,适用于中、小尺度土壤侵蚀定量计算,但需要较高精度和全面的数据源保证;抽样单元推算适用于流域、区域等大尺度土壤侵蚀估算,但结果受抽样方法、抽样密度、外推或插值方法等因素影响较大。应进一步加强遥感解译准确性、侵蚀因子精度等对CSLE全域覆盖计算结果影响的研究,完善模型参数数据库,率定因子值,实现参数本地化。     

The influence op soil treatments on elemental composition of corn and on zinc soil tests on two Missouri soils

Abstract

Corn (Zea mays L) was grown at three locations on soil treated with Zn at two levels of soil fertility. Corn leaves were sampled at 2 stages of growth and analyzed for several elements. Yields were measured and soils were analyzed for O.lN HCl and DTPA extractable Zn and by standard testing methods for other components.

Zinc at 10 and 20 lb/A did not affect corn grain yields. The Zn treatments significantly increased leaf Zn concentrations. The influence of leaf sampling time differed between locations. The DTPA and O.lN HCl extractable soil Zn both reflected the Zn soil treatments. The DTPA appeared to extract a more soluble component of soil Zn which became more un‐extractable with time. In general, the extractable soil Zn was poorly correlated with Zn concentrations in the corn leaves. Under the conditions of the experiment the soil Zn levels as measured by the 2 extractants were a poor predictor of plant Zn when soil Zn levels were adequate.     

北京市东南郊灌区土壤和农产品酞酸酯污染风险评估

为明确北京市东南郊典型灌区土壤和作物酞酸酯PAEs含量和污染水平,2015年利用气象色谱-质谱仪检测了该灌区31个表层土壤样品和38个作物样品的6种优控PAEs含量.研究结果表明灌区表层土壤PAEs质量分数为1.8～12.2 mg/kg,均值5.1 mg/kg.与国内外相比,该研究中土壤PAEs含量处于较高水平.土壤中邻苯二甲酸正二丁酯(DnBP)和邻苯二甲酸二(2-乙基己基)酯(DEHP)含量均值分别占PAEs总量的60.4％和35.9％.土壤样品邻苯二甲酸二甲酯(DMP)和DnBP含量均超美国土壤PAEs控制标准,但总体上未超过美国土壤PAEs治理标准.冬小麦籽粒、夏玉米籽粒和果蔬可食用部位PAEs质量分数分别为2.34～3.66、1.76～3.15和2.26～3.76 mg/kg;与其他研究成果相比,该研究区农产品PAEs含量处于中等水平.不同污灌历史年限区域土壤和粮食作物籽粒PAEs含量均没有显著差异.冬小麦籽粒、夏玉米籽粒和果蔬中DEHP和DnBP含量分别占总量的50.3％和30.5％、45.1％和50.2％、47.16％～63.3％和31.96％～46.36％.农产品PAEs总量及各组分含量均低于欧洲的建议标准值.粮食作物籽粒中PAEs和DnBP含量与土壤中相应含量呈显著正相关,Pearson相关系数(r)分别为0.74～0.87和0.91～0.92.该研究中农作物对PAEs的迁移系数为0.24～1.65.儿童和成人PAEs致癌风险分别为1.34×10-5和3.87x10-5,非致癌指数分别为9.44x 10-1和3.83×10-1,均在可接受范围内;通过口-作物暴露对PAEs 2种风险贡献均最大,DEHP对人体2种风险贡献最大.     

石灰用量对污染红壤和黄泥土中有效态铜锌含量的影响

采用外源加入重金属铜锌硝酸盐的方法,制成铜、锌单一及复合污染的三级污染红壤和黄泥土（Cu 200mg/kg、Zn 400 mg/kg）,稳定一个月,施入低（0.50 g/kg）、中（1.50 g/kg）和高（2.50 g/kg）3种不同用量的石灰,稳定两个月后测定土壤有效态铜、锌含量和pH值,以阐明石灰用量对不同污染土壤中重金属有效态含量的影响。结果表明,随石灰用量的增加,复合污染红壤中有效态铜含量较对照依次降低31%、76%和87%;而石灰用量对黄泥土中有效态铜影响的差异不显著;两种土壤中有效态锌含量均随石灰用量的增加而显著减少;复合污染较单一污染相比,有效态铜及有效态锌的含量差异不显著。在复合污染下,低、中量石灰使黄泥土中有效态铜含量较红壤减少89%和63%,有效态锌减少27%和65%。但加入高量石灰,两种土壤差异不显著。石灰能够降低单一与复合污染铜、锌有效态的含量,但其效果因土壤类型而异,在红壤上选择施用高量石灰而在黄泥土上则适宜施用低中量石灰,以取得最佳的修复效果和效益。     

区域尺度侵蚀产沙估算方法研究

 区域土壤侵蚀模型是大区域土壤侵蚀普查和水土保持宏观决策的支持工具,土壤侵蚀模型的研发是土壤侵蚀学科的前沿领域。基于DEM将区域划分为规则网格,设计产流、产沙过程的单元模型,包括植被截留、入渗、填洼、流速、携沙能力、径流剥蚀量、泥沙沉积等算法。将月降水当作1次降雨事件,并划分若干时段进行迭代计算,利用GIS空间分析功能完成水沙汇集运算,并在ArcGIS支持下进行计算机程序设计,有效地完成了区域侵蚀产沙量的计算。将模型应用于延河流域得到:1995年7月份平均径流深为35.6mm,径流系数为0.237,流域出口径流量为2.72亿m3,流域出口输沙量为0.38亿t,流域平均侵蚀模数为4575t/(km2.月);输出图形空间格局和结构符合实际情况,初步模拟结果令人较满意。     

绿洲盐化潮土施镁对玉米幼苗生长、活性氧自由基代谢和锌营养的影响

【目的】甘肃河西走廊绿洲盐化潮土地玉米缺锌现象非常普遍,土壤镁含量高通常被认为是造成土壤和作物缺锌的重要因素之一,本文探讨了绿洲盐化潮土锌、镁之间的关系。【方法】采用盆栽模拟试验方法,以硫酸镁为原料,设加入Mg2+0、74、147、221、515 mg/kg,形成交换性Mg含量分别为287.3、349.2、411.6、487.9、755.2 mg/kg的混合土壤,来模拟绿洲盐化潮土含镁量低、较低、中等、较高、极高5种类型。在玉米生长期间浇灌去离子水,用重量法控制水分的供应。玉米生长45 d收获,测定株高后,采集心叶下第二个叶片鲜样用于测定叶绿素含量,超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性和丙二醛(MDA)含量。植株分地上部和根系,烘干粉碎后用于测定锌的含量。【结果】1)较高和极高的土壤交换性镁抑制玉米幼苗的生长。镁加入量为22l mg/kg,土壤交换性镁含量达到487.9 mg/kg时,玉米植株矮小,生长已受到胁迫,加入量为515 mg/kg,土壤交换性镁含量达到755.2 mg/kg时,玉米株高显著降低了14.5%,植株叶缘焦枯,个别植株叶片出现白色条纹,表现出明显的镁中毒症状和典型缺锌症状。2)随施镁量的增加或土壤含镁量水平的提高,玉米地上部和地下部的干重分别降低了11.9%~38.3%和4.6%~23.0%,茎叶干重的降低幅度明显高于根系。3)随施镁量的增加或土壤含镁量水平的提高,玉米叶片叶绿素含量降低了9.4%~45.9%,用量达到515 mg/kg时几乎降低了一半,导致地上部叶片出现枯黄。叶片SOD、POD、CAT活性都是先升高再迅速降低,峰值分别出现在147 mg/kg、74 mg/kg和147 mg/kg,用量达到515 mg/kg时分别降低了49.75%、48.06%和32.21%;MDA含量始终呈增加趋势,增幅在20.39%~183.58%。4)施镁显著降低了玉米幼苗的锌含量和吸收量,但对茎叶和根系的抑制程度不同。与不施镁处理相比,茎叶锌含量降低了4.05%~57.09%,吸收量降低了15.41%~73.55%;根系锌含量降低了7.55%~18.99%,吸收量降低了11.62%~37.40%,不管是锌含量还是吸收量,根系的降低幅度都明显低于茎叶。这也导致锌从根系向地上部的转运显著降低,施镁147 mg/kg时锌的转运率还有46.60%,施镁515 mg/kg时只有34.55%,仅达到不施镁水平的62%。5)随着施镁量的增加或土壤含镁量水平的提高,土壤有效锌含量也显著降低,降幅在11.4%~46.6%,特别是施镁515 mg/kg,土壤交换性镁含量达到755.2 mg/kg时,土壤有效锌含量已降至0.47 mg/kg,超过了土壤缺锌临界值(DTPA-Zn0.5 mg/kg)。【结论】绿洲盐化潮土上的玉米缺锌问题与土壤含镁量水平密切相关,随着施镁量的增加,玉米幼苗的生长受到抑制,株高、干重、叶片中的叶绿素含量和SOD、POD、CAT活性都显著降低,MDA含量显著增加。施镁抑制了玉米幼苗对锌的吸收,对茎叶的抑制程度明显高于根系,导致锌从根系向地上部的转运率显著降低。施镁降低了土壤有效锌含量,用量达到515 mg/kg时,土壤有效锌含量已低于缺锌临界值。     

Geologic composition influences distribution of microbiotic crusts in the Mojave and Colorado Deserts at the regional scale

Abiotic and biotic factors influencing distribution of microbiotic crusts within hot deserts, such as the Mojave and Colorado Deserts, are poorly known. Our objective was to examine microbiotic crust distribution with reference to soil and parent material characteristics as well as plant functional groups in wilderness areas of Joshua Tree National Park (JTNP). A total of 75 sites were visually assessed for crust abundance and plant community composition; soil physical and chemical factors also were measured. Microbiotic crusts of JTNP, in particular lichen and moss crusts, were not as well-developed or as widely distributed as in other arid regions of North America. Algal crusts were most prevalent, lichen crusts were sparse, and crusts containing mosses were rare, with average percent land surface absolute (and relative) cover for these three cover categories being 11.4% (17.4%), 1.7% (2.7%), and 0.02% (0.02%), respectively. Previously reported individual drivers of crust development, such as pH, electrical conductivity (EC), and soil texture, did not appear to strongly influence crust development in this study of the Mojave and Colorado Deserts. Proximity to granitic bedrock and grusy granitic soils associated with it were the key determinants of microbiotic crust distribution in the wilderness areas of JTNP. In particular, crusts were best developed in grusy granitic soils. Overall, our study emphasized the importance of geology in driving crust distribution and its potential value as a predictor of where crusts may occur in the hot deserts of North America.     

基于多源环境变量和随机森林的橡胶园土壤全氮含量预测

土壤全氮与土壤肥力和土壤氮循环紧密相关。掌握土壤全氮详细的空间分布信息对提高土壤肥力管理效率和更好地了解土壤氮循环至关重要。该文以儋州国营橡胶园为研究区域,采集2511个土壤样品,利用随机森林(random forest,RF)、逐步线性回归(stepwise linear regression,SLR)、广义加性混合模型(generalized additive mixed model,GAMM)以及分类回归树(classification and regression tree,CART)结合多源环境变量(成土母质、平均降雨量、平均气温和归一化植被指数)对研究区橡胶园土壤全氮含量进行空间预测,并通过754个独立验证点比较了4种模型的预测精度。结果表明RF对土壤全氮的预测值和实测值的相关系数(0.82)明显高于SLR(0.68)、GAMM(0.70)和CART(0.69),而RF的预测平均绝对误差(0.08836 g/kg)和均方根误差(0.13090 g/kg)均低于SLR、GAMM和CART。此外,RF模型预测结果能反映更为详细的局部土壤全氮含量空间变化信息,与实际情况更为接近。可见,RF模型可作为橡胶园土壤全氮含量空间分布预测的高效方法,为其他土壤属性的空间分布预测提供了一种新的方法。     

4种改良剂对铅锌尾矿污染土壤中光叶紫花苕生长及重金属吸收特性的影响

通过盆栽试验研究了铅锌尾矿污染土壤中施用有机肥、石灰、蛭石和白云石等4种改良剂对光叶紫花苕生长发育、叶绿素及重金属Cu、Cd、Pb、Zn积累特性的影响,并分析了施用改良剂后土壤pH和有效态重金属含量的变化。结果表明,与对照相比,不同改良剂及其不同施用水平均能不同程度地提高土壤pH,显著降低土壤各重金属有效态含量,并显著抑制了Cd、Pb向光叶紫花苕地上部转移,降低了重金属在光叶紫花苕植株地上部的积累,改善了光叶紫花苕的生长和发育,光叶紫花苕株高、地上部鲜重和地下部鲜重、叶绿素含量均有不同程度增加,其中株高和地上部鲜重增加达到显著水平。4种改良剂的不同处理水平对光叶紫花苕地下部重金属含量影响均达显著水平。