Critical Loads of Acid Deposition on Soil in China

Critical loads of acid deposition havebeen mapped for Chinese soils using a modifiedsemi-quantitative method, which is based on theminerals controlling weathering and soil development,and corrected by introducing an Arrhenius relationshipto describe the effect of temperature and a weightedaveraging approach to evaluate the effect of soiltexture, land use and precipitation. As a consequenceof these modifications, the method has been quantifiedand can be more widely used. Results from this studyshow that the lowest critical loads of acid depositionin China, i.e., those areas most sensitive to aciddeposition, occur in the Podzolic soils in theNortheast, followed by Latosol, Dark brown forest soiland Black soil areas. The Ferralsol areas in SouthChina are intermediate, tolerating about 0.8–1.6 g m^-2 yr^-1 sulfur deposition. The highestcritical loads of acid deposition are mainly locatedin the Alpine soil areas on the Plateau of Tibet andareas of Xerosol and Podocal soil in Northwest China.The reason for lower critical loads in the Northeastrelative to South China can be attributed to thedifference of temperature, soil moisture and soiltexture. Comparison of critical loads with the sulfurdeposition in 1995 identifies almost one fourth of theland area in southeast China to be subject to risk of acidification.     

Critical Nitrogen Deposition Loads in High-elevation Lakes of the Western US Inferred from Paleolimnological Records

Critical loads of nitrogen (N) from atmospheric deposition were determined for alpine lake ecosystems in the western US using fossil diatom assemblages in lake sediment cores. Changes in diatom species over the last century were indicative of N enrichment in two areas, the eastern Sierra Nevada, starting between 1960 and 1965, and the Greater Yellowstone Ecosystem, starting in 1980. In contrast, no changes in diatom community structure were apparent in lakes of Glacier National Park. To determine critical N loads that elicited these community changes, we modeled wet nitrogen deposition rates for the period in which diatom shifts first occurred in each area using deposition data spanning from 1980 to 2007. We determined a critical load of 1.4 kg N ha^?1 year^?1 wet N deposition to elicit key nutrient enrichment effects on diatom communities in both the eastern Sierra Nevada and the Greater Yellowstone Ecosystem.     

Critical Loads of Acid Deposition for Ecosystems in South China — Derived by a New Method

Critical loads of acid deposition for ecosystems in South China are derived by synthesizing the critical loads of acid deposition for soils, the critical loads of SO₂ dry deposition for ecosystems, as well their exceedance. The results show in the southeast of Sichuan province around Chongqing municipality, the central and north of Guizhou province around Guiyang municipality, and the most areas of Jiangsu province, both the critical loads for soils and critical loads of SO₂ dry deposition are exceeded. In Guangxi Zhuang Autonomous Region and some areas among Jiangxi, Zhejiang and Anhui provinces, the critical loads of SO₂ dry deposition is the only restricting factor. There is no area where the critical load for soil is the only restricting factor in South China, so only the critical load for soil is not enough to be the basis to make sulfur abatement scheme.     

Calculating Critical Loads of Sulfur Deposition for 100 Surface Waters in China Using the Magic Model

Although decades of acid deposition have apparently not resulted in surface water acidification in China, some surface waters may have the potential trend of being acidified, especially those in southern China. In this paper, a dynamic acidification model–MAGIC was applied to 100 surface waters in southern and northeastern China to evaluate the impact of acid deposition to surface waters and to determine their critical loads of S deposition, both regions having distinguishing soil, geological and acid deposition characteristics. Results indicate that most surface waters included in this paper are not sensitive to acid deposition, with critical loads of S for these waters comparatively high. On the other hand, surface waters in southern China, especially those in Fujian, Jiangxi and Guangdong provinces, are more susceptible to acidification than those in northeastern China, which coincides with their different patterns of soil, geological and acid deposition conditions. Among all the waters, a few small ponds, such as those on top of the Jinyun mountain and Emei mountain, are the most sensitive to acid deposition with critical loads of 1.84 and 3.70 keq·ha^?1·yr^?1, respectively. For the considerable ANC remaining in most 100 surface waters, it is not likely that acidification will occur in the near future for these waters.     

Land degradation and the decline of ranching in the Sierra Nevada foothills,California

Land use is a critical determinant of land degradation. In this article, I examine how changes in land use from 1957 to 1997 in El Dorado County, located in the Central Sierra Nevada of California, have resulted in the degradation of hardwood rangelands. To do so, I analyze the environmental discourse of land use and land degradation, and examine changes in land use, property rights, and laws and regulations governing land use from 1957 to 1997. I argue that understanding the political ecology of land use is essential to understanding why hardwood rangelands have been degraded while upland coniferous forest has been largely protected. This has implications for conservation of the Sierra Nevada Ecosystem, which is currently the focus of increased scholarly as well as political attention. Copyright © 1999 John Wiley & Sons, Ltd.     

Using Epiphytic Macrolichen Communities for Biomonitoring Ammonia in Forests of the Greater Sierra Nevada, California

Chronic, excessive nitrogen deposition is potentially an important ecological threat to forests of the greater Sierra Nevada in California. We developed a model for ammonia bioindication, a major nitrogen pollutant in the region, using epiphytic macrolichens. We used non-metric multidimensional scaling to extract gradients in lichen community composition from surveys at 115 forested sites. A strong ammonia deposition gradient was detected, as evidenced by a high linear correlation with an index of ammonia indicator species conventionally known as “nitrophytes” (r = 0.93). This gradient, however, was confounded by elevation (r = ?0.54). We evaluated three statistical techniques for controlling the influence of elevation on nitrophytes: simple linear regression, nonlinear regression, and nonparametric regression. We used the unstandardized residuals from nonlinear regression to estimate relative ammonia deposition at each plot, primarily because this model had the best fit (r ² = 0.33), desirable asymptotic properties, and it is easy to apply to new data. Other possible sources of noise in the nitrophyte-ammonia relationship, such as substrate pH and acidic deposition, are discussed. Lichen communities indicated relatively high deposition to forests of the southern Sierra Nevada, the Modoc Plateau, as well as in stands near urban areas. Evidence of elevated ammonia was also detected for popular recreation areas such as Sequoia and Yosemite National Parks. Lichen communities from forests in the Tahoe basin, northern Sierra Nevada, southern Cascades, and eastern Klamath Range appeared considerably less impacted. This model will be used for continual assessment of eutrophication risks to forest health in the region.     

Episodic acidification during snowmelt of high elevation lakes in the Sierra Nevada mountains of California

Atmospheric loads to dilute lakes in the Sierra Nevada mountains of California are very low, and fall almost entirely as snow. When acidic anions preferentially elute from melting snow, these low loads may nontheless be enough to acidify low ANC lakes. Two of the ten lakes included in the Sierra Episodes Study are discussed here: High Lake, the only lake in the study to become acidic during snowmelt; and Treasure Lake, typical of the remainder of the lakes. All lakes exhibited increases in NO₃ ^? concentrations during early snowmelt; these were accompanied by increases in base cations, primarily Ca²⁺. In the first few days of snowmelt, NO₃ ^? concentrations at High Lake increased more rapidly than concentrations of base cations, resulting in ANC values below zero. Export of both NO₃ ^? and SO₄ ^2? from the watersheds exceeded the inputs from the snowpack, suggesting that other sources (e.g., watershed minerals, stored inputs from the previous summer, transformations of other inputs) of these anions are important.     

A Literature Review of Uncertainties in Studies of Critical Loads for Acidic Deposition

Uncertainties in the assessment of critical loads for acidic deposition are caused by the choice of biological indicators (BI), critical chemical values (CCV), the current methods used to determine critical loads for an ecosystem, and deficient field data. This paper focuses on the present steady-state mass balance (SSMB) approach, dynamic models and the importance of changes in atmospheric base-cation deposition (BCD), particularly in China. It is argued that 1) for the SSMB approach much uncertainty may come from the choice of BI and the related CCV, and long-term and large-scale monitoring data on weathering rates and growth uptake are urgently needed, especially in China, 2) significant uncertainty may be caused by changes in BCD during SO₂ emission controls, particularly in China, 3) constructing a mechanistic Al submodel may be a promising direction for dynamic models, and 4) the nutrient cycle in the vegetation through biogeochemical processes should be incorporated into dynamic models but the input requirements should be moderate for broad application considerations. Generally higher BCD, different soil components and characteristics and different vegetation types in China compared to Europe and North America suggest that more field investigations on BI and their corresponding CCV be carried out before application of current approaches to specific areas, particularly in China.     

韦伯-费希纳模型在湖泊(水库)预警评价中的应用

[目的]对福建省的莆田东圳水库、福清东张水库、三明东牙溪水库水环境质量及预警等级进行评价,为湖泊(水库)水环境预警评价提供一种过程简单,结果科学合理的评价方法。[方法]根据韦伯—费希纳模型(Weber-Fechner’s model)的基本原理,以表征水库水环境的溶解氧(DO),化学需氧量(CODMn),总磷(TP),NH_3-N,总氮(TN)等参数作为评价指标,利用水环境综合指数ki来评价水库水环境质量及预警等级。[结果]莆田东圳水库2010年第1,2季度以及2012年第3季度处于中重警。福清东张水库2013年第3季度为轻警,2012年第1季度处于中重警。三明东牙溪水库2010年第4季度、2011第3季度、2012年第3季度、2013第3,4季度为轻警。其余季度上述水库水质预警等级为中警。[结论]韦伯—费希纳模型能够定量描述湖泊(水库)水环境质量的感觉强度变化关系,客观反映湖泊(水库)水环境质量变化的影响;该模型具有计算过程简单,评价精度高,应用性强等优点,为湖泊(水库)水质预警等级综合评价提供了新方法,拓展了评价模型的应用范围。     

Exploring Ground Vegetation Change for Different Deposition Scenarios and Methods for Estimating Critical Loads for Biodiversity Using the ForSAFE-VEG Model in Switzerland and Sweden

The ForSAFE-VEG model was used to investigate the impacts of climate change and air pollution scenarios on soil chemistry and ground vegetations composition. In particular, the model involves a ground vegetation model incorporating plant changes to ambient site conditions in terms of climate and chemistry, but the model also incorporate competition between the different plant groups. The model was validated against observed values and reproduced observations of tree growth, soil chemistry, and ground vegetation compositions to satisfaction. The results show that the ground vegetation reacts strongly to changes in air pollution, in particular nitrogen as well as to climate change with major shifts in plant composition. A procedure for estimating critical loads for nitrogen, using ground vegetation biodiversity as criterion, was tested and the method seems operable. It suggests that if we want to protect the present biodiversity of the ground vegetation, this will face significant difficulties because of permanent climate change that induced changes in the ecosystem. We conclude that the reference state for ground vegetation biodiversity is rather to be sought for in the future, hopefully using models, than in the past or present.     

The role of nitrogen oxides in oxidant production as predicted by the Regional Acid Deposition Model (RADM)

Regional oxidant distributions produced under various atmospheric conditions and emission scenarios are investigated using the Regional Acid Deposition Model (RADM). RADM is a complex, evolving three-dimensional Eulerian model that describes the chemistry, transport and deposition of tropospheric trace species including SO₂, sulfate, NO _x and volatile organic compounds as well as O₃, other major oxidants and acids. The model calculates the short-term temporal evolution of atmospheric trace gas concentrations and their deposition on the regional scale. This study is focused on oxidant production in the eastern United States and southeastern Canada. The influence of atmospheric conditions is explored by comparing three characteristic winter, summer and spring/fall cases. Base-case 1985 emissions of SO _x , NO _x , volatile organic compounds (VOCs), NH₃ and CO are specified using the comprehensive pollutant emissions inventory developed as part of the National Acid Precipitation Assessment Program (NAPAP). The perturbed case, which represents projected anthropogenic emission changes for 2010, indicates changes in daily total 80 km grid average NO _x emissions ranging from increases of 75% to decreases of 45% and VOC emission changes ranging from increases of 65% to decreases of 20%. The largest NO _x emission changes occur in the northeast, and the largest VOC changes occur in the Gulf Coast area. Ground level grid average midday O₃ concentrations for the 1985 emission cases are highest (on the order of 70 to 100 ppb) in the New York City and Houston metropolitan areas for the summer and spring cases; the summer case also indicates relatively high grid average O₃ concentrations of greater than 80 ppb in the southeast. Winter case values are much lower than summer O₃ values throughout the region, with highs of 40 to 50 ppb occurring in the southeast and the Great Lakes area. Changes in NO _x and other emissions under the complex 2010 emissions scenario for the summer case result in maximum O₃ concentration reductions of 10% in the Houston area and increases in O₃ of a few percent in some rural areas of the southeast. This study underscores the need for more comprehensive assessment of the complex relationships among regional emission changes, oxidant production and atmospheric conditions.     

基于长江三角洲地表水典型土壤铜、锌环境容量探究

我国水污染日益严重,Ⅰ类地表水地区较少,目前可供饮用的Ⅲ类水成为研究土壤地表水体系污染状况的热点。选取具有代表性的长江三角洲地区4种母质（河相、湖相、海相沉积物和沟沟堆积物）发育而成的土壤,通过加入不同量的外源铜、锌金属培育污染土样,使其分别达到国家土壤环境质量三级标准的0.25、0.5、1.0、1.5、2.0、2.5倍。在此基础上研究雨水和模拟酸雨条件下,对模拟污染的土样进行解吸,并对解吸曲线进行拟合,在基于地表水Ⅲ类水质标准的铜、锌环境容量的基础上,计算了4种土壤在不同情况下的土壤环境容量,并通过探讨国家土壤标准的吻合性,提出针对不同母质的土壤,对其重金属的土壤污染临界值进行适当的调整,以达到Ⅲ类水标准,保障人类的安全与健康。结果表明,在模拟雨水情况下,基于地表水Ⅲ类标准的4种土壤的环境容量分别为：SEBC-06：铜10002mg·kg^-1,锌848.1mg·kg^-1;SEBC-19：铜1162mg·kg^-1,锌612.9mg·kg^-1;SEBC-20：铜9796mg·kg^-1,锌1047mg·kg^-1;SEBC-25：铜720mg·kg^-1,锌180.2mg·kg^-1。     

Adapting the Profile Model to Calculate the Critical Loads for East Asian Soils by Including Volcanic Glass Weathering and Alternative Aluminum Solubility System

Adaptation of the steady-state soil chemistry model PROFILE was studied, on the following two parts, to calculate the critical loads for East Asian soils: (1) Dissolution rate coefficients of volcanic glass were derived from published experimental data, and calculated field weathering rate was compared with the rate estimated based on Sr isotope analysis. When BET surface area of sand fraction was regarded as mineral surface area, the calculated rates fairly agreed with the estimate, suggesting that sand fraction surface area is a reasonable estimate of weatherable mineral surface area of volcanic soils. (2) In repeated leaching experiments, Al solubility of a number of Japanese soils was explained by a model which assumed complexation of Al to soil organic matters. Such an Al solubility model is more appropriate for predicting soil chemistry than apparent gibbsite dissolution equilibrium.     

Steady-State Prediction of Sodium Adsorption Ratio (SAR) in Drainage Water Based on Irrigation Water Quality in a Lysimetric Study

Different types of equations have been proposed to predict the drainage water sodium adsorption ration (SAR; SAR_dw). These equations are verified here against the data of a lysimetric study. Cylindrical lysimeters with diameter of 40 and height of 180 cm were filled with a sandy loam soil and irrigated weekly with natural water. A set of 30 drainage water analyses was used for which measurements of irrigation and drainage water quality and quantities were done. Then a set of 116 water analyses throughout Iran was used to adjust some of available equations for local conditions. Simple correlations between irrigation water SAR and that of drainage water yielded to poor regression coefficient (R² = 0.108), whereas steady-state assumption could fairly predict SAR_dw (R² = 0.802), which is comparable with more complex methods recently proposed. The WatSuit model predicted values of the mean SAR_dw based on average leaching fraction (LF) that were very close to the measured mean of drainage water SAR.     

Perfluorooctane Sulfonate (PFOS) and Perfluorooctanoic Acid (PFOA) in Water Environment of Singapore

Recently, there has been increasing concern about perfluorinated compounds, especially perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) due to their biotic and abiotic persistence and chronic toxicity. To characterize the spatial distribution and seasonal variation of PFOS and PFOA in the aquatic and oceanic environment of Singapore, more than 100 water samples from reservoirs, rivers/canals, coastal waters, and treated effluents of wastewater treatment plants (WWTPs) were collected and analyzed in this study. Solid-phase extraction followed by high-performance liquid chromatography (HPLC) coupled with tandem MS (HPLC/MS/MS) was applied to quantitatively identify PFOS and PFOA. PFOS concentrations in surface waters, wastewaters and coastal waters were in the range of 2.2?C87.3 ng/L, 5.8?C532 ng/L, and 1.9?C8.9 ng/L, respectively, while those of PFOA were 5.7?C91.5 ng/L, 7.9?C1,060 ng/L, 2.4?C17.8 ng/L, respectively. Compared with surface waters and wastewaters, coastal waters had lower concentrations of PFOS and PFOA. Highest concentration of PFOA (532 ng/L) and PFOA (1,060 ng/L) were observed in treated effluents of two WWTPs. Our results suggest that coastal waters in the western area of Singapore are more heavily contaminated than those in the middle and eastern areas. The release of effluents from WWTPs is an important pathway by which perfluorinated compounds enter the oceanic environment. Between dry season and wet season, significant seasonal differences (p?=?0.025) were observed in surface waters for PFOS only, while no discernable seasonal differences were found for both PFOS and PFOA in coastal waters and wastewaters.     

日粮共轭亚油酸对黄羽肉鸡腹脂沉积的影响

选择1日龄黄羽肉鸡60只,随机分成2组。在实验组中添加3%共轭亚油酸（conjugated linoleic acid,CLA）,对照组日粮中添加3%的食用菜籽油。49日龄屠宰,采集腹部脂肪组织。用RT-PCR方法,以β-actin为内标,相对定量测定腹脂中鸡生长激素受体（cGHR）、胰岛素样生长因子-1（cIGF-1）、胰岛素样生长因子Ⅰ型受体（cIGF-ⅠR）、过氧化物增殖剂活化受体γ（cP-PARγ）、脂联素（cAdiponectin）及其Ⅰ型受体（cAdipoⅠR）的mRNA丰度。结果显示,CLA处理使肉鸡的腹脂沉积下降了20.93%（P〈0.05）,分别使腹脂cGHR mRNA和cPPARγmRNA降低了24.74%（P〈0.05）和66.52%（P〈0.01）;而对cIGF-1、cIGF-ⅠR、cAdiponectin和cAdipoⅠR基因表达无显著影响（P〉0.05）;cGHR和cPPARγmRNA的表达与腹脂率正相关（P〈0.05）。数据说明,CLA降低肉鸡脂肪沉积的作用可能通过降低GHR和PPARγmRNA水平实现,而与IGF-1和（或）GH-IGF-1途径、Adiponectin的作用无关。     

小流域范围土壤锰、铝形态分布及其相关性研究

分别在湖南的郴州和长沙选定两小流域(SZY和LKS),从小流域规模分析了酸雨频降区两小流域土壤的主要理化特性和土壤锰铝形态及其分布,并讨论了锰铝各形态和土壤有机质,土壤pH值之间的相关性。结果表明:在小流域SZY土壤中,各种形态的锰铝含量均高于小流域LKS土壤中对应形态的锰铝含量;在同一剖面,各种形态的锰铝含量有表土高于底土的趋势。在两小流域土壤中,除无定形锰(Mnox)外各种形态的锰铝均与土壤有机质呈正相关。铝的溶出与土壤有机质和土壤pH值有关。酸沉降能影响毒性元素铝形态的转化和淋溶。活性铝、锰形态可能富集在土壤表层或植物根际等富含有机质的区域,酸沉降或其它环境条件可能促进铝、锰形态在土壤表层或植物根际的转化和溶出,从而导致毒害。     

Acid Deposition and Acidification of Soil and Water in the Tie Shan Ping Area, Chongqing, China

Chongqing is among the heaviest polluted cities in China. Combustion of coal with relatively high sulfur content causes high sulfur emission and deposition in the area. Effects on soils and waters of the acid deposition in the Chongqing area have been studied in the field at a forested site outside the city. Deposition chemistry and fluxes, soil and soil water chemistry as well as surface water chemistry are presented for the period 1996–1998. There are some stress symptoms at the forest in the area and severe forest damage has been reported at Nanshan, closer to Chongqing center. Monitoring of the acidification situation in the area must be followed closely as impacts may be expected if the deposition is not reduced in the future. The deposition of sulfur, H⁺ as well as calcium at the site is high. Wet deposition of sulfur is estimated to 4.7 – 5.7 g S m^?2 yr^?1 during the three years sampled; dry deposition is probably of similar size. Annual volume-weighted pH in bulk deposition was 4.0 – 4.2 and the calcium wet deposition flux was 2.6 – 3.6 g Ca²⁺ m^?2. There are considerable seasonal variations in the concentrations, related to the seasonal variations in precipitation amount (dry winter, wet summer). The soils at the site are acid with median base saturation of 12% and 8% in the topsoil and subsoil, respectively. In soil water, aluminum concentrations are typically in the range 3–8 mg L^?1. However, due to the high base cation deposition, the Al/(Ca²⁺+Mg²⁺) molar ratio is below unity in most samples, indicating little damage of forest due to aluminum in soil water.