Comparative Evaluation on Nitrogen Saturation of Forest Catchments in Japan and Northeastern United States

To analyze the differences in the status and processes of nitrogen saturation in Japan and northeastern United States, we examined the hydrobiogeochemistry of nitrogen of forested watersheds in these regions. Two distinct differences were found between watersheds in Japan compared with those in US. 1) In Japanese watersheds, marked decreases of NO₃ ^? concentration in surface waters during the summer growing season were not found and NO₃ ^? concentrations sometimes increased especially in the summer at nitrogen saturated sites. This contrast with watersheds in US where decreases in NO₃ ^? concentration during the summer are commonly observed except those watersheds in advanced stages of nitrogen saturation. These differences in NO₃ ^? concentration relationships can be attributed to climatic differences, with Japan having high precipitation and high discharge during the summer, while in many regions of North America lowest discharges are found in the summer. The climatic regime in Japan leads to high rates of mineralization and the rapid transport of NO₃ ^? to streams in summer. 2) Japanese watersheds, even those with high NO₃ ^? concentrations in surface waters, show little evidence of acidification. This is in contrast to sites in US where increased NO₃ ^? concentrations, especially during episodic events, result in surface water acidification.     

Dynamics of Dissolved Forms of Carbon and Inorganic Nitrogen in Small Watersheds of the Coastal Atlantic Forest in Southeast Brazil

Based on the fact that streamwater quality reflects landscape conditions, the objectives of this study were: to investigate nitrogen (N), carbon (C), and major ion concentrations in six streams crossing minimally disturbed Atlantic Forest areas, with similar geomorphological characteristics; to determine N and C fluxes in one of these pristine streams (Indaiá); and assess the impact of human activity on the biogeochemistry of two other streams in the same region, crossing urbanized areas. The distribution pattern of carbon and inorganic nitrogen dissolved forms, as well as the major ion and biogenic gas concentrations in the streamwater, was similar in pristine streams, indicating that the C and N dynamics were determined by influence of some factors, such as climate, atmospheric deposition, geology, soil type, and land covering, which were analogous in the forested watersheds. The urban streams were significantly different from the pristine streams, showing low dissolved oxygen concentrations, high respiration rates, and high concentrations of carbon dioxide, dissolved inorganic nitrogen, dissolved inorganic carbon, and major ion. These differences were attributed to anthropogenic impact on water quality, especially domestic sewage discharge. Additionally, in the Indaiá stream, it was possible to observe the importance of rainfall over temporal dynamics of dissolved carbon forms, and also, the obtained specific flux of dissolved inorganic nitrogen was relatively elevated (approximately 11 kg ha^?1 year^?1). These results reveal the influence of human activity over the biogeochemistry of coastal streams and also indicate the importance N export of Atlantic Forest to the ocean.     

Dose-response relationships for the addition of limestone to lakes and ponds in the Northeastern United States

A titration based model (DeAcid) has been used to predict treatment dose and times for reacidification for CaCO₃-treated lakes in the Living Lakes, Inc. (LLI) aquatic liming program. Water quality constitutents (pH, ANC and Ca) were used to measure the effectiveness of the dosing model and reacidification rates. Data from 22 lakes or ponds in 5 northeast states have been collected since June 1986. With few exceptions, pH and ANC values ranged from 4.5 to 6.5 and ?30 to +65 ueq L^?1, respectively, in untreated sites and 6.5 to 7.8 and 120 to 300 ueq L^?1, respectively, in sites approximately 30 days after treatment. Changes in Ca concentration levels have been used to evaluate the utility of the dose model for treatment of both inland and coastal waters. For coastal, seepage lakes application of a single-box mass transfer model to observed post-liming changes in ANC and Ca adequately simulates lake response.     

Organochlorine residues in brook trout from remote lakes in the Northeastern United States

Organochlorine residues were analyzed in brook trout (Salvelinus fontinalis) collected from six undisturbed lakes in Maine, New Hampshire and Vermont. The residues (whole body) were compared among age groups of fish and were correlated by regression analyses with water chemistry factors that might be affected by acid precipitation. There were significant differences in the organochlorine content of fish from different lakes but not among age groups of fish within each lake or among all lakes. There were no significant correlations between the water chemistry values measured and organochlorine content of the fish. Inasmuch as no organochlorine pesticides have been used within the lake watersheds, the compounds must have reached these lakes by atmospheric transport.     

Zinc Cu,Ni and Cd in the forest floor in the Northeastern United States

A regional study was conducted to assess current levels of trace metals in the forest floor, and to establish a baseline for future studies of metal accumulation. Quantitative forest floor samples collected from 78 sites in 9 states in the northeastern United States in 1978 and 1980 were analyzed for Zn, Cu, Ni, and Cd. Mean amounts present in the forest floor were 9.8 ± 1.9 (standard error of the mean), 1.7 ± 0.2, 0.86 ± 0.08, and 0.13 ± 0.01 kg ha^?1, for Zn, Cu, Ni, and Cd, respectively. Mean concentrations were 133 ± 25, 19.5 ± 1.6, 11 ± 0.8, and 1.7 ± 0.1 mg kg^?1, respectively. Differences in metal and organic matter concentrations and amounts among forest types were attributed to geographic location of specific forest types rather than to direct biotic influence. No element was strongly correlated with elevation for the entire sample area. Regional patterns of elemental amounts showed that trace metal levels are slightly higher in the southern part than in the northern part of the study region. Regional variation of Zn, Cu, Ni, and Cd in the forest floor was not indicative of atmospheric deposition except near point sources of pollution.     

氮磷富集对森林土壤碳截存的影响研究进展

大气氮磷沉降增加森林土壤养分的可利用性,改变底物的化学质量、土壤微生物组成和功能,进而影响土壤有机质的储量与稳定性。然而,现有研究主要集中在氮素富集对自然森林生态系统碳截存的影响,有关磷富集以及氮磷交互对人工林土壤有机碳(SOC)截存的影响及其微生物学机制尚不清楚。本文综述了氮磷富集对森林土壤碳转化和净交换通量、土壤有机质(SOM)的激发效应、SOM组成与稳定性以及介导碳转化功能微生物群落的影响,并指出各个研究环节的不足,包括:(1)森林土壤碳通量及其组分对氮磷富集的非线性响应方程及临界阈值尚未确定;(2)氮磷富集对森林SOM激发效应的影响程度与潜在机制知之甚少;(3)SOM的物理-化学协同稳定机制研究不够深入;(4)土壤活性微生物群落组成、SOM化学结构与SOC累积之间的耦联关系尚不清晰。据此,指出未来研究重点与研究思路:基于多水平氮磷添加控制试验和~(13)C标记培养实验,利用原位监测、土壤化学(~(13)C-NMR和Py-GC/MS)、宏基因组测序的分子生物学方法,重点研究氮磷添加及其交互作用对人工林土壤碳排放与流失通量、微生物激发效应、SOM组成与化学稳定性以及功能微生物群落组成的影响,确定土壤碳输出通量对氮磷添加的非线性响应方程与氮沉降临界负荷,阐明分解微生物群落组成与土壤碳转化及稳定性的耦联关系,揭示氮磷交互影响人工林土壤碳积累与损耗的微生物学机制。研究结果有助于控制森林尤其是人工林土壤碳损失,有效降低陆地"氮促碳汇"评估的不确定性,并可为森林生态系统应对全球变化提供科学依据。     

Inhibition of Extracellular Enzyme Activities in a Forest Soil by Additions of Inorganic Nitrogen

Abstract

Forest ecosystems are known to be nitrogen (N) limited, and productivity often increases with N additions. However, recent studies have suggested that additions of excessive N through atmospheric deposition may affect soil processes adversely. In this study, we conducted a laboratory‐based manipulation experiment to reveal the effects of N additions on extracellular enzyme activities in a temperate forest soil. Three different levels of N additions (water‐only control, low N addition, and high N addition) were applied to soil columns (2.5‐cm diameter×12 cm height) over 4 weeks. Overall, the additions of N decreased specific activities (enzyme activity per log bacterial cell number) of urease, glutaminase, phosphatase, and arylsulfatase significantly. However, dehydrogenase activity was increased with the high N addition. The results suggest that N deposition may impede nutrient cycling, particularly mineralization of organic nutrients. In addition, this enzyme inhibition may be one of the mechanisms for N retention observed in forest floors.     

Atlantic salmon resources in the Northeastern United States and the potential effects of acidification from atmospheric deposition

The Atlantic salmon (Salmo salar) was formerly abundant in northeast coastal rivers in the United States from the Canadian border to the Connecticut River, and possibly as far south as the Delaware River. It was eliminated from most of its former range by a combination of overfishing, construction of dams impassable to migrating fish, and municipal and industrial pollution. Reproducing populations are now limited to a few rivers in Maine, but attempts are under way to reintroduce the species to some rivers where populations formerly existed. Most of the native Atlantic salmon rivers are low in acid neutralizing capacity and receive acidic precipitation. The third order streams are not now acidic; however, in some first and second order streams in Maine, pH episodically declines to 4.7 and Al increases to 350 μg g^?1. These conditions could be toxic to sensitive early life history stages of Atlantic salmon. Comparison of chemical conditions in two Maine rivers in 1980–1982 with those in 1969–1970 indicated that the streams have not become more acidic during this interval. Data on the sport catch of Atlantic salmon indicated that populations have generally remained stable or recently increased in the Maine rivers having naturally reproducing populations. The recent increase probably resulted from introductions of hatchery smolts to supplement natural reproduction, and the occurrence of strong year classes in 1978 and 1980. The population in one stream has declined significantly in recent years, but the cause of the decline is probably not related to acidic precipitation. Atlantic salmon resources in the U.S. have apparently not been adversely affected by atmospheric deposition at the present time.     

湿地土壤氮素研究概述

湿地是自然界最富生物多样性的生态景观和人类最重要的生存环境之一,具有巨大的环境调节功能和效益。湿地发挥着N素的源、汇和转换器的功能,而湿地土壤中N素含量及其迁移转化过程也显著影响着湿地生态系统的结构和功能,所以湿地土壤N素过程研究成为当前研究热点之一。本文对湿地土壤N素贮量,湿地对N素的截留能力以及湿地N素的迁移转化过程等方面进行了综述。     

森林土壤氧化亚氮排放对氮输入的响应研究进展

大气中氧化亚氮（N2O）浓度的上升加剧了全球变暖。森林土壤在调节大气N2O浓度中发挥着至关重要的作用。近年来,氮（N）输入对森林土壤N2O通量的影响备受关注。然而,森林土壤N2O排放对N输入响应的机制,尤其是植物和微生物对N2O通量的调控作用尚缺乏系统研究。因此,本文综述了N输入如何通过森林植被（根系N吸收、凋落物分解和形成丛枝菌根）和土壤微生物（微生物量和群落组成）调控N2O产生途径从而影响森林土壤N2O排放。结果表明,植物的竞争性氮吸收能降低氮输入对N2O排放的促进作用,其作用大小可能主要取决于土壤“氮饱和”状态。植物凋落物主要通过分解过程中的养分归还和次生代谢产物释放来影响氮输入背景下的森林土壤N2O排放,前者具有促进作用,而后者具有抑制作用。丛枝菌根主要通过吸收有效氮和水分、促进团聚体形成以及改变N2O相关功能基因群落调控森林土壤N2O通量。N输入导致的土壤酸化或养分限制,通常会降低微生物量和/或改变微生物群落组成,从而控制N2O排放。N输入对N2O不同产生途径也会造成影响,受土壤湿度、N2O底物浓度以及N2O相关功能基因丰度（AOB、 AOA、nirK、 nirS和nosZ）的调控。未来在模型预测中,需要将植物氮吸收、凋落物分解、菌根以及N2O产生途径充分纳入模型,以提高模型预测准确性,为全球变化背景下制订森林管理政策和温室气体减排措施提供支持。     

Inorganic and organic sulfur profiles in nine Sphagnum peat bogs in the United States and Czechoslovakia

Depth profiles of total S, organic S, soluble SO ₄ ^2? -S, FeS, and FeS₂ were characterized for Sphagnum-derived peat cores collected from 9 sites. Marcell S-2 Bog (MN), Tamarack Swamp (PA), Cranesville Swamp (MD/WV), and Big Run Bog (WV) receive water from precipitation and upland runoff; atmospheric S deposition is 13, 47, 54, and 114 mmol m^?2, yr^?1, respectively. McDonald's Branch Swamp (NJ) is predominantly groundwater fed. Tub Run Bog (WV) and Allegheny Mining Bog (MD) receive augmented SO ₄ ^2? inputs through acid coal mine drainage. Jezerní slat' and Bo?í Dar Bog in Czechoslovakia receive atmospheric S inputs of 33 and 243 mmol m^?2 yr^?1, respectively. In the peat from all sites except Allegheny Mining Bog, where the substantially augmented SO ₄ ^2? input was reflected in an unusually high dissolved SO ₄ ^2? pool in the surface peat, organic S (probably mostly carbon bonded S) was the dominant S fraction; FeS₂ was generally the dominant inorganic S fraction. Subsurface peaks in total S, organic S and FeS₂-S in peat from the runoff water fed sites were interpreted as indicative of depth-dependent patterns in S reduction/oxidation and in S immobilization/mineralization. Unless SO ₄ ^2? inputs to a site are tremendously augmented (e.g., Allegheny Mining Bog), the rapid turnover of the dissolved SO ₄ ^2? pool combined with the relative stability of the other inorganic and organic S pools, apparently functions as an effective buffer against site differences in S inputs, leading to a general similarity in vertical S profiles in the peat deposits.     

An Overview of Nitrogen Critical Loads for Policy Makers, Stakeholders, and Industries in the United States

Critical load values are calculated to determine ecosystem responses to deposition in a given area; these values may act as a tool to identify sensitive ecosystems in further need of protection. This overview provides an introduction to nitrogen critical loads for policy makers and parties involved in managing nitrogen deposition including electric utility generators, transportation managers and automobile manufacturers, and large-scale agricultural operators in the United States. It examines the use of the critical loads concept in European nations for establishing policy guidelines, current research on nitrogen critical loads in the U.S., and the development of nitrogen critical loads modeling and mapping.     

Increasing turtle strandings in the southeast United States: A complicating factor

Increased strandings of dead loggerhead sea turtles Caretta caretta on southeast US shores may be the result of increased fishing efficiency and improved recruitment of young turtles to the population. Possibly, the practice of discarding overboard large amounts of unwanted fish and biological material may provide a major energy resource for loggerhead sea turtles and crabs, which are also loggerhead food items. Our observations show that many dead loggerheads stranded on Cumberland Island had eaten man-caught food in addition to the expected diet of crabs and other bottom-dwelling animals. Consideration of alternative methods of handling the incidental fish catch while trawling for shrimp may be useful in reducing the problem of killing of sea turtles in shrimp trawls.     

我国森林土壤健康评价研究进展

保持和提高森林土壤健康是实现森林健康的基础。本文综述了森林土壤健康的概念、评价指标、评价方法及其优缺点。森林土壤健康评价是相对的而不是绝对的,主要以土壤的功能为基础,不同类型土壤的评价应采用不同的标准。因此,须进一步加强评价指标的标准化、综合化和应用化,选择适宜的方法来评价森林土壤健康,从而探索有利于某地区森林土壤健康的管理措施,以实现森林土壤的可持续发展。     

青海省小流域综合治理回顾与展望

青海省小流域综合治理已从起步阶段的重点治理发展到目前的全面规模治理,突出了流域清洁、城镇防洪、防污治污以及提升品位的建设特点,经过综合治理的小流域实现了"三增、三减、三改善"的建设目标,形成了科学合理、效益明显、特色各异的水土保持综合防治体系,有力推进了三江源、青海湖流域、湟水流域、柴达木盆地和祁连山等"五大生态圈"建设,水土流失得到有效控制,植被涵养水源的能力显著提高,凸现了水土保持在整个生态建设中的关键作用。今后应紧紧围绕"构建生态系统,恢复生态屏障"这个大原则,加快水土流失综合防治步伐,努力促进青海省向生态文明的美好目标迈进。     

Nitrogen oxides,regional transport,and ozone air quality: Results of a regional-scale model for the midwestern United States

An overview of the role of NO _x in the formation of rural O₃, regional transport and its potential impact on urban air quality is presented. An analysis of a specific O₃ excursion in southeast Michigan (8-2-90) is performed based on a combined urban and regional-scale model. The regional component of the model represents transport and photochemistry from sources as far away as Texas. Results suggest that rural O₃ and regional transport sensitive to NO _x emissions and relatively insensitive to changes in volatile organic carbon (VOC) emissions. This differs from the situation in urban areas, where O₃ is sensitive to both NO _x and VOC. Regional transport and upwind NO _x emissions have a significant impact on peak O₃ in Detroit. Implications for urban and regional-scale abatement strategies are discussed.     

生物炭对有机无机污染物的修复作用与机理研究进展

生物炭作为高温热解下富碳、多孔的特殊结构和功能有机资源,在结构修复、吸附改良、水分持留、肥料缓释及土壤固碳减排等方面具有非常重要的作用。作为一种新型有机无机物的修复材料,生物炭由于其炭源材料、热解温度及速率各异而体现出系列吸附特征。综述了不同碳源材料置于各种缺氧热解制备条件下生成的各类生物炭对有机无机物料的吸附作用及其吸附解析机理,在此基础上,对生物炭吸附能力的科学表达形式及其应用前景进行了展望。     

Conservation of Lepidoptera in the United States

The need to conserve United States populations of Lepidoptera has been recognised for a century, but intensive programmes to do so have only recently come into being. The evolution of the butterfly and moth conservation movement in the United States is followed from the earliest instances to the present state of progress. The origin and growth of the Xerces Society as the chief body for terrestrial arthropod conservation in America are described. Currently, ecological research and political action aimed at specific lepidopteran protection issues are under way. Several of these are examined and the most acute needs for further study and action indicated. Habitat alteration emerges dramatically as the chief problem in the decline of butterfly and moth populations. The relative importance of pesticides and overcollecting is discussed and reinforces the conclusion that the habitat is paramount. Introductions of organisms for purposes of conservation likewise receive consideration, showing this strategy to be problematical and subject to careful review prior to its use. The various levels of government as well as private bodies and individuals have distinct roles in insect conservation. Greater public awareness of beneficial insects must precede optimal effectiveness of conservation schemes. The appointment of an official federal insect conservator is announced along with his initial proposal for endangered species listings for certain North American butterflies. The prognosis for a national programme is suggested. Lepidoptera conservation in the United States has become a fully fledged movement with numerous successes and with many difficult problems to face. The situation is viewed with immediate alarm but cautious long-term optimism as well.     

Soil Ammonium Diffusion Constraints Contribute to Large Differences in Nitrogen Supply to Rice in the Southern United States

This study was to determine if diffusion of soil ammonium may explain why many sandy soils have greater nitrogen (N)–supplying capacity to rice than clay soils. A laboratory procedure using transient-state methods measured the linear movement of soil ammonium (NH₄) in tubes packed with five field soils under aerobic conditions. Ammonium diffusion was measured by sectioning tubes after 48 h of equilibration and then measuring NH₄ by steam distillation. Effective diffusion coefficients, D_e, and NH₄ diffusion distance, d, per day ranged from D_e = 4.6 × 10^?5 cm² d^?1 and 1.5 cm d^?1 for Katy sandy loam to D_e = 2.9 × 10^?7 cm² d^?1 and 0.11 cm d^?1 for League clay. Ammonium diffusion distance d was strongly related to soil clay content and hence was predicted by d = Y × {[100/(% clay)] ? 1}, where Y is set to 0.1. Predicted d and measured d were highly related (R² = 0.99).     

森林生态系统土壤呼吸研究进展

森林土壤碳是全球碳库的重要组成部分,在全球碳循环方面发挥着重要作用。土壤呼吸是当前碳循环研究领域中的一个热点问题,而且目前土壤呼吸已经成为陆地生态系统中向大气释放CO2最大的源。把土壤呼吸量与植物群落生长之间的关系进行分析比较,是理解森林生态系统碳素平衡的核心。在综合介绍国内外有关土壤呼吸的各种测定方法的基础上,对国内外有关森林土壤呼吸的已有研究成果进行了述评,指出了森林土壤呼吸研究工作今后的努力方向。