Atmospheric input and origin of selected elements in Walker Branch Watershed,Oak Ridge,Tennessee

The elemental composition and relative contribution to input of precipitation and aerosols have been determined for the Walker Branch Watershed in Oak Ridge, Tennessee, U.S.A. Comparison of elemental ratios in rain to those in local soils indicates that Cu, Hg, and Pb are enriched with respect to soil by a factor of 30 to 170 and must have a non-soil source. Due to inherent problems encountered in determining elemental deposition velocities, elemental input by dry deposition was calculated using literature value upper and lower limits. If the higher deposition velocities are chosen, dry deposition could constitute from 62 to 96% of the total input for selected elements to the watershed. Enrichment factor and chemical mass balance calculations have been applied to aerosol data in an attempt to distinguish between atmospheric particulates derived from soil, automobiles, and three nearby coal-fired steam plants. Elemental deposition by wet and dry fallout has also been calculated using published deposition velocities. Mass balance calculations indicate that no more than 5% of the total aerosol load can be attributed to the three coal-fired steam plants. The steam plants can, however, account for up to 20% of individual elements collected in air above the watershed.     

降水变化和人类活动对纸坊沟小流域年径流的影响

为在小流域尺度上深入认识并定量区分人类活动和降水变化对黄土高原年径流变化的影响,统计了甘肃省平凉市纸坊沟小流域49a间(1955—2003年)的年降水量和径流量实测数据。结果发现,年降水量虽无明显变化,但年径流深却呈显著减少趋势。从20世纪50年代的59.1 mm降到21世纪初的12.2mm,相对降幅高达72.4%。根据年降水量—年径流深双累积曲线,划分出了5个降水—径流关系变化时段(1955—1964,1965—1976,1977—1985,1986—1995,1996—2003年),然后以1955—1964时段为基准期,定量估算了各时段内人类活动和降水变化对年径流变化的贡献。结果表明,除在干旱时段内降水对年径流减少有明显贡献外,其他时段的径流变化主要是由人类活动引起的,并且其绝对贡献量呈逐渐增大趋势。合理规划人类活动是解决黄土高原水问题的重要途径。     

降水和土地利用变化对罗玉沟流域水沙关系的影响

为探讨降水和土地利用变化对流域水沙关系的影响,以黄土高原丘陵沟壑区罗玉沟流域为研究区域,利用流域25年(1986—2010年)的年降水量、年径流量和年输沙量以及土地利用变化资料,分析罗玉沟流域水沙演变规律和水沙关系变化。结果表明:在1986—2010年罗玉沟流域年降水量和汛期降水量基本保持平稳,无明显的增减趋势,而流域年径流量和年输沙量整体呈波动递减的变化趋势,降水与径流相关分析得出,汛期产流产沙对流域年径流量和年输沙量影响最显著。对不同时期流域水沙变化分析,土地利用方式改变,主要是梯田、林草等水土保持措施,对于流域减水减沙作用有限,梯田和林草面积的增加并未明显改变流域水沙关系,淤地坝等工程措施对黄土高原丘陵沟壑区流域减水减沙具有重要作用。研究结果可为黄土丘陵沟壑区水土流失治理及水土保持措施布设提供理论依据。     

Long-Term Hydrological Impacts of Land Use/Land Cover Change From 1984 to 2010 in the Little River Watershed,Tennessee

Assessing long-term hydrological impacts of land use/land cover (LULC) change is of critical importance for land use planning and water resource management. The Little River Watershed, Tennessee, is an important watershed supporting drinking water and recreational activities within and around the Great Smoky Mountains National Park in the Unites States. However, the potential hydrological impacts of LULC change, especially urbanization in recent decades, are not quantified. This paper assessed the long-term impacts of LULC change on streamflow and non-point source pollution using the Soil and Water Assessment Tool (SWAT) and a detailed LULC record from 1984 to 2010. The SWAT was first calibrated and validated using observed streamflowin 2010 and then simulated using different LULC patterns in 1984-2010 to quantify the long-term hydrological impacts caused by the LULC change. Simulated results indicated a minor 3% increase in streamflow for the whole watershed from 1984 to 2010, but with a distinct spatial pattern. The increase in streamflow is closely related to urban development. Almost no streamflow increase occurred in the upper watershed within the national park, whereas > 10% increase occurred in the lower watershed, especially in areas close to cities. Model simulation also suggested 34.6% reduction in sediment and about 10% reduction in nutrient loads from 1984 to 2010, closely related to the decrease in agricultural land. However, without calibration and validation, the simulated reduction in the sediment and nutrient loads may be problematic because SWAT mainly simulates the static LULC patterns, whereas LULC transitions, such as construction phases, may generate more sediment and nutrient loads. In addition, the simulation also did not account for the sediment and nutrients generated from stream bank erosion.     

Extractability and Bioavailability of Mercury from a Mercury Sulfide Contaminated Soil in Oak Ridge, Tennessee, USA

Historically as part of its national security mission, the U.S. Department of Energy’s Y-12 National Security Facility in Oak Ridge, TN acquired a significant fraction of the world’s supply of elemental mercury. During the 1950s and 1960s, a large amount of elemental mercury escaped confinement and is still present in the watershed surrounding the Y-12 facility. A series of remediation efforts have been deployed in the watersheds around the Oak Ridge site. However, most recently, concentration of total mercury in fish and water of the lower East Fork Poplar Creek (EFPC) of Oak Ridge has increased although majority of the mercury contamination in the local soils is present in the form of mercury sulfide. We have studied the extractability, solubility, and bioavailability of mercury sulfide in Oak Ridge soils. Dynamics of the dissolution of mercury sulfide by various extractants, including acids and a chelating agent, have been investigated. After three seasons of planting, soil mercury sulfide is more easily dissolved by both 4 M and 12 M nitric acid than is pure mercury sulfide reagent as indicated by their dissolution kinetics. Mercury release by EDTA from HgS-contaminated soil increased with time of reaction and soil mercury level. This chelating chemical increases the solubility of mercury in HgS-contaminated Oak Ridge soil. The results also show that mercury sulfide in contaminated Oak Ridge soils was still to some extent bioavailable to plants. The increase of bioavailability of soil mercury sulfide after three seasons of planting may contribute to the recent increase of mercury levels in water of the Lower East Fork Popular Creek (LEFPC) of Oak Ridge.     

佳芦河流域1988—2013年土壤侵蚀时空变化特征

为了研究陕北风沙区近26年来的土壤侵蚀变化特征,利用中国坡面水蚀预报模型结合GIS和RS技术,定量估算了1988-1996,1997-2004,2005-2013年3个时段陕北佳芦河流域土壤平均侵蚀量,分析了不同植被覆盖条件下和不同土地利用类型下的土壤侵蚀时空变化特征.结果表明:(1)中国坡面水蚀预报模型适用于该地区;(2)土壤侵蚀等级和降雨侵蚀力,地貌和土地利用类型关系密切;(3)将26年划分为3个时段,第1时段1988-1996年、第2时段1997-2004年和第3时段2005-2013年.多年平均降雨侵蚀力分别为923.09,1 010.75,1 551.40 MJ·mm/(hm2·h),对应土壤侵蚀模数分别为4 513,5 855,3 556t/(km2·a).第1时段和第3时段总侵蚀量分别为5.10×106,4.02×106 t,相比减少了21.18％.还林还草工程后,流域内土地利用发生较大变化,耕地所占比重由53.38％减少到25.87％,草地所占比重由38.64％增加到69.64％,不同土地利用类型的水土保持效益从大到小分别是未利用土地,草地,林地和耕地.说明当还林还草工程后,佳芦河流域土壤侵蚀呈现总量减少,强度降低的趋势,表明还林还草工程取得了明显的水土保持效益.     

丹江口库区典型小流域生物结皮驱动土壤性质变化及分离响应

为探究生物结皮发育驱动下土壤水蚀特征及机理,选取苔藓发育为优势种的退耕样地,设计5个盖度等级(1%～20%,20%～40%,40%～60%,60%～80%,80%～100%),以裸地为对照,在不同水流剪切力(6.12～19.64 Pa)下进行冲刷试验。结果表明：结皮发育显著影响土壤养分含量,且高盖度结皮覆盖下养分表聚效应更加明显。生物结皮发育显著影响土壤分离能力,裸地土壤分离能力[1.465 6 kg/(m²·s)]为生物结皮[0.004 2～0.468 2 kg/(m²·s)]的3.58～348.95倍,裸地细沟可蚀性(0.293 5 s/m)为生物结皮(0.001 0～0.082 2 s/m)的3.57～293.50倍。相对土壤分离能力及细沟可蚀性均随结皮盖度增加呈指数函数衰减,结皮冲破时间随结皮盖度增加呈指数函数增长;非线性回归分析表明,土壤分离能力可用水流剪切力、生物结皮盖度和土壤黏结力进行模拟(NSE=0.749)。综上,生物结皮发育显著提升土壤抗侵蚀性能,研究结果可为半湿润区水土流失防治及生物结皮管理利用提供理论参考。     

抚仙湖流域砾质土有机及常规肥料淋溶模拟研究

利用不同高度土柱进行模拟淋溶试验.比较研究了抚仙湖流域砾质土壤有机及常规肥料N、P流失规律及水体污染风险.试验结果表明:随着灌溉次数的增加,有机肥料淋洗液中 TDN (可溶性总N)浓度先升后降,而常规肥料则持续下降;除20 cm高度土柱常规肥料TDP(可溶性总 P )浓度快速下降外,其余各淋洗液中TDP浓度变化幅度很小.有机及常规肥料土壤N、P淋溶均以NO3--N和P04-P形态为主.不同高度土柱TDN、TDP的淋失总量平均值,常规肥料分别为有机肥料的1 57%、52%,可见常规肥料N素淋溶风险大于有机肥料,而P素淋溶风险则相反.     

汤峪河流域径流小区水土保持监测点2017—2019年监测结果分析

汤峪河流域径流小区水土保持监测点主要对气象因子(降水)、径流泥沙、田间管理、土壤含水量和植被覆盖度/郁闭度等进行监测,监测数据能反映宁南陇东丘陵沟壑区的典型特征.在监测点选择5个相同坡度不同治理措施的标准径流小区——人工草、灌乔混交、灌木、乔木和裸地小区,对治理前后小区径流深、径流系数、土壤流失量、雨前土壤含水量和雨后...     

花溪河流域景观格局变化与水土流失相关性研究

为了进一步分析景观格局与水土流失之间的关系,通过分析研究区2005~2015年景观格局和水土流失的变化情况,得出不同的景观格局类型具有不同的侵蚀模数,合理的景观格局有利于控制水土流失。结果表明:10年间建设用地斑块面积从7 094.47hm~2增加到16 613.28hm~2;10年间研究区的水土流失率先降低后增加,这与城市扩张具有紧密联系,特别是2010年贵州省贵安新区的建设,改变了花溪河流域的景观格局。园地斑块、森林斑块的生态功能、蓄水保土功能强,旱地易产生水土流失。     

科尔沁沙地不同土地利用结构硝酸盐氮淋失规律

采用小型回填式土柱动态淋溶实验方法,研究了科尔沁沙地不同土地利用结构耕层土壤硝酸盐氮淋失规律。结果表明,科尔沁沙地草地、林地和沙荒地结构淋溶液硝酸盐氮浓度平均值低于地下水Ⅰ类水质标准（2.0mg·L-1）,农田结构淋溶液硝酸盐氮浓度平均值大于地下水Ⅰ类水质标准。农田结构是造成地下水硝酸盐氮污染的重点区域。科尔沁沙地不同土地利用结构硝酸盐氮淋失强度依次为：农田（96.54kg·hm-2·a-1）〉沙荒地（32.84kg·hm-2·a-1）〉林地（28.66kg·hm-2·a-1）〉草地（15.48kg·hm-2·a-1）。农田是科尔沁沙地氮素营养管理的重点结构,硝酸盐氮淋失强度与土壤硝态氮含量呈极显著正相关。     

Bioremediation of a Crude Oil-Polluted Soil: Biodegradation,Leaching and Toxicity Assessments

The combined fate and effects of hydrocarbons (HC) on a soilecosystem affected by bioremediation were studied during 480days in a field experiment. The HC removal rates, the HC andmetabolites mobility and the potential toxicity were assessed.A clayey soil polluted by 18 000 mg HC kg^-1 dry soil, wastreated with either static-ventilated biopile or series of fivewindrows periodically tilled in order to determine the relativeinfluence of nutrients, bulking agents, aeration and soiltemperature. HC concentrations were determined by infraredspectrometry, gravimetry, gas chromatography andthermodesorption. Between 70 to 81% of the initial HC wereremoved through biological processes in fertilized soils,whereas natural attenuation without added nutrients was 56%.When adding fertilizers, residual HC were cyclic compoundspoorly biodegraded and strongly trapped on the organo-mineralmatter. Leaching of HC and water-soluble metabolites wasdemonstrated during the first stages of biodegradation. Lowlevels of the HC were detected in the leachates at day 480.Maximal toxicity was highest immediately after the introductionof oil then decreased as biodegradation proceeded. No toxiceffect was recorded on worms survival and on seeds germinationat day 480. However growth of plants was reduced in treatedsoils and a potential residual toxicity was observed on thebasis of photosynthesis inhibition and bacterial bioluminescence (Microtox) tests.     

香溪河流域近60年来降雨量变化趋势及突变分析

为研究香溪河流域多年降雨特征,以流域1952—2011年10个雨量站日降雨资料为基础,得到流域面雨量序列。分别采用线性回归、滑动平均、Mann-Kendall趋势检验、M-K突变检验、Sen’s斜率估计和小波分析等方法,对流域60 a来降水量的年、季变化趋势和突变进行了检验。结果表明:香溪河流域年降水量以0.66 mm/a速率减少;春、秋季节降水量呈下降趋势,下降速率分别为0.33,0.81 mm/a,冬季降水量轻微下降趋势,夏季降水量呈上升趋势,速率为0.5 mm/a;年均和四季变化均未通过5%的显著性检验。研究时段内,年降水量发生了三次突变,分别在1954年,1989年,2006年。夏季降雨突变发生时间与年突变发生时间一致;春、秋、冬三季降雨在60 a内发生突变的时间分散、多变。     

几种低分子量有机酸淋溶对土壤铝、硅及盐基离子淋失的影响

采用50cm原状土柱进行模拟淋溶实验,比较研究了模拟酸雨和几种低分子量有机酸对红壤Al、Si及盐基离子淋失的影响。结果表明,模拟酸雨淋洗后土壤中有极少量的Al和一定量的Si及盐基离子淋出。与去离子水对照相比,pH3.5和pH4.5模拟酸雨处理Si的淋出总量分别增加了6.52%和3.26%;K 、Na 、Ca2 和Mg2 等盐基离子淋出量增加了2.41%~96.80%。100μmol/L的柠檬酸、苹果酸和草酸处理Al、Si的淋出量与模拟酸雨处理相差不大,而10mmol/L的柠檬酸、苹果酸和草酸处理则比模拟酸雨处理有显著的增加。有机酸淋洗后淋出液中各盐基离子含量均要高于模拟酸雨处理,盐基离子淋出总量是模拟酸雨处理的1.58~9.27倍。实验结果说明低分子量有机酸在酸化土壤方面比酸雨有更大的威胁。由于盐基离子的大量淋失,模拟酸雨和有机酸淋洗后淋出液pH均要高于原淋洗液pH。     

Effect of Ca-Rich Granulated Oil Shale Ash Amendment on Leaching Properties of Peat Soil: Experimental and Field Study

Eurasian Soil Science - The combustion of low-grade solid fuels such as oil shale generates huge amounts of solid wastes such as fly ash. Use of oil shale combustion ash in granulated form for...     

三岔河小流域水土保持基础效益评价研究

通过对“东北黑土区水土流失综合防治试点工程”中建立的不同措施的径流小区的监测,选择具有典型黑土的黑龙江省宾县三岔河小流域作为研究对象,分别对地埂植物带、荒山灌木埂、横垄、水平坑(坑内植树)、裸地、顺垄6个小区进行了为期2 a的观测。经实测分析计算得出:相对于裸地来说,水平台田、荒山灌木埂、横垄、地埂植物带和顺垄减少侵蚀量分别为99.14%,97.65%,90.66%,87.7%和58.72%,减沙保土效果最好的是水平台田,顺垄保土效果最差。     

Soil and Compost Type Affect Phosphorus Leaching from Inceptisol,Ultisol, and Andisol in a Column Experiment

A column leaching experiment using three soils (Inceptisol, Ultisol, and Andisol) and seven livestock manure composts that had different characteristics was conducted for 19 weeks to investigate the interactive effects of composts and soils on the phosphorus (P) leaching potential of compost-amended soils and to identify the principal variables that affect P leaching. Cumulative total P leaching (TP_cum) tended to increase with increasing total and available P concentration in the soils. Among various compost properties, total P concentration was positively correlated with TP_cum from the compost-amended soils, except for the Andisol, which has a high P-sorption capacity. There was no significant relationship between TP_cum and water-extractable P concentration of the composts, suggesting that total P rather than inorganic P concentration of composts may be successfully used in predicting P leaching potential from compost-amended soils except for soils that have a high P-sorption capacity, as in Andisol.     

Rinsing of Saline Water from Road Salt in a Sandy Soil by Infiltrating Rainfall: Experiments,Simulations, and Implications

Saline melt water from road salt applications that has percolated into a fine sandy soil in winter is rinsed out of the soil by infiltrating rainwater in the following warmer seasons. This sequence of saturated and unsaturated flow processes associated with saline water transport in a fine sandy soil was studied by simulation and exploratory laboratory experiments. Experiments in soil columns of 300-μm sand revealed that two rinses of pure water, each of one pore volume, were sufficient to reduce the salt concentration by 99% of its original value in the soil column. Simulated time variations of salt concentration in the effluent from the column agreed with experimental results. Based on simulated and experimental results, a sandy soil must become saturated to experience pore water flow in order to efficiently rinse saline snowmelt water. Depending on the saturated hydraulic conductivity and the soil depth, days, weeks, or months of freshwater infiltration in summer are needed to rinse saline melt water from an unsaturated sandy soil after road salt applications in winter. This explains findings of significant salt concentrations in surface and shallow groundwater during summer months, long after road salt application and infiltration has ceased.     

Nutrient Uptake and Leaching from Soil Amended with Cattle Manure and Nitrapyrin

We investigated whether nitrification inhibitor nitrapyrin can reduce nutrient leaching and increase nutrient uptake by corn (Zea mays L.) in cattle manure amended soil. Amendments included non-amended check (CK), urea (Urea), REG (manure from cattle fed barley grain), and DDGS (manure from cattle fed 60% dried distillers grains with solubles), co-applied with or without nitrapyrin and leached or unleached with water. Nitrapyrin reduced (P < 0.01) leaching of nitrate by 56, 32, and 24% from DDGS, REG, and Urea treatments, respectively, and also reduced (P < 0.05) leaching of phosphate (58%), potassium (39%), calcium (39%), and magnesium (39%) from DDGS treatment. While nitrapyrin reduces the rate of ammonium conversion to nitrate, higher magnesium and phosphate levels in DDGS-amended soil favor struvite formation and reduce their leaching. Corn biomass and nutrient uptake were higher (P < 0.01) in DDGS and Urea than CK and REG treatments, but remained unaffected by nitrapyrin. The benefits of nitrapyrin should be further investigated under field conditions.

Abbreviations: DCD, dicyandiamide; DDGS, dried distillers grains with solubles; NI, nitrification inhibitor; TP, total P; TN, total N.     

长期定位试验土壤钾素肥力变化及其对不同测钾方法的响应

土壤K素肥力因长期施肥管理可能会发生变化.本文以土壤K素肥力相对较高的河南封丘 16 年长期定位试验土壤为研究对象,分析比较了不同施肥处理对土壤K素肥力的影响,以及常规速效K、缓效K、全K和两种四苯硼钠法等土壤测K方法对土壤K素变化的响应能力.16 年K肥施用量和作物吸K量的差值表明,不施K土壤K素发生耗竭,任何肥料都不施的CK处理K耗竭较少,为 K 28.5 kg/(hm2·a),而不施K的NP处理中K的耗竭速率较高,为 CK 处理的 5.2 倍, 所有施K土壤中由于作物吸K量小于K肥施用量,表现为土壤K素盈余,其中不施P或N的NK和PK处理K素盈余最高,分别达 K 207 和 190.5 kg/(hm2·a),平衡施用化肥或有机肥土壤K的盈余较少,为K 31.5 ～ 63.0 kg/(hm2·a).不同土壤测K方法反映的 16 年前后土壤K素变化与以上理论值均有差异,醋酸铵法、沸硝酸法、两种四苯硼钠法和碱熔法反映的 7 个不同施肥处理K素变化的回收率(测定值与理论值的比率)平均值分别为 39% 、51%、66%、71% 和176%,7 个施肥处理回收率的变异系数5种方法分别为103%、74%、36%、30% 和141%.回收率偏离估计值较大并且不稳定,说明土壤常规测K方法(速效K、缓效K和全K)不能够准确地反映土壤K素肥力的变化,而四苯硼钠法较常规方法可以较准确地反映土壤K素变化.