外秦淮河表层底泥中Pb,Cu和Zn与PAHs的复合污染

分析了外秦淮河丰水期表层底泥中Pb,Cu,Zn及PAHs的含量分布.结果表明:草场门河段底泥中Pb,Cu,Zn和PAHs的含量都达到了最大值,污染最为严重.Pb和Cu显著相关,具有相似的化学行为.三汊河口至集庆门河段的PAHs主要来自石油类和化石燃料的不完全燃烧(低温、中温)或天然成岩过程,而凤台桥至秦虹大桥河段PAHs主要来源于化石燃料的高温燃烧与裂解.外秦淮河表层底泥中Pb与二环和五环PAHs的相关性显著,易发生交互作用.     

墨水河表层沉积物中多环芳烃(PAHs)的分布特征、来源解析及生态风险评价

本文运用GC-MS测定了墨水河表层沉积物中16种优控多环芳烃(PAHs)浓度,采用多种数据分析技术解析了PAHs的来源.结果表明,苊烯、苊、蒽和苯并(a)蒽在部分样品中未检出,其余12种在所有样品中均有检出,16种PAHs总浓度为196.51—8549.33 ng·g~(-1),平均浓度为3320.03 ng·g~(-1).沉积物中PAHs的环数分布以高环为主,运用轻重比、分子比值和主成分分析-多元线性回归模型(PCA-MLR)等3种方法,共同确定PAHs的主要来源分别为混合源(煤炭、生物质和汽油燃烧源)、柴油燃烧源和石油源,这3种来源对总PAHs的贡献分别为59.8%、26.0%和14.2%.效应区间低/中值法(ERL/ERM)对PAHs生态风险分析表明,芴、菲、苯并(a)蒽、、苯并(b)荧蒽、苯并(k)荧蒽和苯并(a)芘在墨水河中下游偶尔会产生负面生态风险,二苯并(a,h)蒽存在经常产生负面生态效应的可能;平均效应区间中值商法(M-ERM-Q)分析表明,墨水河上游和入海口处PAHs的综合生态风险较低,而中下游站位则具有中低风险.     

汾河流域水系和表层沉积物中多环芳烃的空间变化规律及其生态风险研究

本研究在汾河流域上、中、下游及其部分支流布设29个采样点,对其水体和表层沉积物多环芳烃(PAHs)的空间分布规律及生态风险进行了分析和讨论。结果表明,汾河流域水相中丰水期PAHs总量浓度范围是0.530~16.002μg·L~(-1),平均浓度为(2.738±3.078)μg·L~(-1),枯水期PAHs总量浓度范围是0.588~12.916μg·L~(-1),均值为(2.762±3.132)μg·L~(-1)。就空间分布而言,汾河流域整体呈现上游污染较轻,中下游污染严重的特点。PAHs的组成规律显示,丰水期和枯水期PAHs含量均以低环(2~3环)为主,不同采样期低环PAHs所占比例分别为96.5%和90.4%。与其他15个研究地区水体PAHs含量比较,汾河流域水体中PAHs污染程度的国内外对比处于中等到较高程度的污染。丰水期和枯水期水体中PAHs来源于石油源和植物、木材、煤的燃烧,主要受到流域煤化工、燃煤电厂排放污染物的影响。地表水健康风险评价结果显示,汾河流域丰水期和枯水期分别有13.8%和20.7%的点位存在一定的健康风险。汾河流域沉积相中16种PAHs平均浓度为(3.774±1.987)μg·g-1,其污染主要集中在流域中下游地区。PAHs的组成规律显示,PAHs含量集中在低环(2~3环),约占总量的75%左右。与本研究提到的河流、湖泊及港口沉积物中PAHs含量比较,汾河流域沉积物中PAHs污染程度仍处于中等偏高的污染水平。丰水期沉积相中PAHs以燃烧源和石油源为主,部分来自典型石油类产品的输入。表层沉积物生态风险评价结果显示,对于提出的12种PAHs的生态风险的效应区间低值(ERL值)或效应区间中值(ERM值)以及苯并(b)荧蒽(Bb F)和苯并(k)荧蒽(Bk F)这2类没有最低安全值的PAHs化合物来说,汾河上、中、下游流域均有采样点的PAHs可能存在着对生物的潜在生态风险。通过本研究可全面地了解该流域多环芳烃的空间分布规律及其可能的来源,并且为汾河流域多环芳烃污染的控制和生态风险评价提供科学依据。     

中国主要地区表层土壤多环芳烃含量及来源解析

以表层土壤多环芳烃(polycyclic aromatic hydrocarbons,PAHs)为研究对象,查阅2000—2016年间发表的101篇中国主要地区表层土壤多环芳烃的文献,系统分析了中国主要地区表层土壤中PAHs的含量、组分、分布特征及主要来源,为中国土壤多环芳烃污染防治提供科学依据。结果表明:中国主要地区表层土壤中16种优控多环芳烃总量(中位值)(∑PAHs)为515.70 ng·g~(-1),和其他国家相比处于中等水平。16种多环芳烃(PAHs)在表层土中以菲(Phe)、荧蒽(Fla)和萘(Nap)的含量(中位值)最高,苊烯(Acy)、苊(Ane)以及茚苯并(1,2,3,-cd)芘(Inp)含量(中位值)最低;∑PAHs含量(中位值)地域分布表现为西北地区华北地区东北地区华东地区华中地区华南地区西南地区。表层土壤PAHs组成以高环(4环及以上)为主,占60.06%,不同地区PAHs的组成不同;通过对16种检出PAHs进行聚类分析,得出中国主要地区PAHs主要有煤炭燃烧源、油类燃料燃烧源、焦油生产源、石油源和生物质燃烧源等5个来源。结合同分异构体比值法和污染物特征指数法,进一步对22个省区表层土壤PAHs进行聚类分析,得出新疆、天津、陕西表层土壤PAHs主要来源于液化石油燃料及原油的污染,燃料成分主要为汽油;福建、吉林、山西、贵州和江西表层土壤中PAHs主要来源于草、木材、煤炭及生物质燃烧;北京、湖北、黑龙江、安徽、西藏、江苏、广东、浙江、湖南、山东、宁夏、重庆及香港等表层土壤PAHs则主要来源于液体化石燃料、生物质及煤炭的燃烧,燃料成分为煤炭和汽油。     

北京地区表层土壤中多环芳烃的分布特征及污染源分析

根据北京地区不同环境功能区62个样品的分析结果,讨论了研究区表层土壤中多环芳烃的分布特征及污染源类型。结果表明：（1）研究区表层土壤中检测到的多环芳烃主要包括萘、苊、菲、惹烯、三芴、荧蒽、芘、、苯并蒽、苯并[b]荧蒽、苯并[k]荧蒽、苯并[e]芘、苯并[a]芘、苝、二苯并[a,h]蒽、茚并[1,2,3–cd]芘、苯并[g,h,i]苝及其同系物;（2）不同环境功能区表层土壤中多环芳烃的组成及质量分数均存在一定的差别,16种优先控制的多环芳烃质量分数为175.1~10 344 ng.g-1,其中城市中心区表层土壤中多环芳烃的质量分数最高,交通干线附近、工矿企业附近表层土壤中PAHs的质量分数较高,林地、果园和农田表层土壤中PAHs的质量分数较低;（3）表层土壤中PAHs既有来源于石油源,也有来源于化石燃料燃烧产物的,但不同功能区二者贡献存在差别,其中农业用地（林地、果园、农田）中PAHs主要来源于石油源（或部分来源于土壤母岩中的有机质）,城区、交通干线附近及工矿企业附近表层土壤中PAHs污染源以化石燃料燃烧产物输入为主。     

珠江水体表层沉积物中PAHs的含量与来源研究

沿珠江白鹅潭水域及大学城官州河流域设立6个采样点,利用沉积物捕获器收集沉积物。参照美国EPA8000系列方法及质量保证和质量控制,对各采样点表层沉积物中16种多环芳烃（polycyclic aromatic hydrocarbons,PAHs）进行分析,以阐明珠江广州河段表层沉积物中PAHs的含量和分布特征,并结合特征化合物指数对其来源作初步探讨。珠江广州河段表层沉积物中PAHs总量介于4 787.5～8 665 ng·g^-1,平均值为7 078 ng·g^-1,黄沙码头河涌出口沉积物中总量为最高（8 665 ng·g^-1）,芳村码头为最低（4 787.5 ng·g^-1）。16种多环芳烃中菲、荧蒽、芘含量较高,分别占PAHs总量的16.11%、14.47%和17.77%。特征化合物荧蒽/202比值均小于0.5,茚并[1,2,3-cd]芘/276比值均大于0.2,表明珠江广州段表层沉积物中PAHs主要来源于化石燃料的不完全燃烧。     

杭埠-丰乐河表层沉积物中多环芳烃的污染特征、来源分析及生态风险评价

对杭埠-丰乐河12个采样点的表层沉积物中16种优控多环芳烃(PAHs)的含量进行了测定.结果表明:16种PAHs均被普遍检出,总含量(∑PAHs)范围为71.3±15—3372±402 ng·g~(-1)干重(dw),平均值为938 ng·g~(-1)(dw),与国内主要河流相比其浓度处于中等水平.底泥中多环芳烃组成以4环和5环为主,共占∑PAHs的81%,其中,二苯并[a.h]蒽(DBA)浓度最高,平均浓度为254 ng·g~(-1).底泥总有机碳(TOC)与∑PAHs之间有良好线性关系.利用特征比值法和主成分分析探讨了PAHs的可能来源,结果显示,杭埠-丰乐河底泥中PAHs主要来自于流域周边居民生物质、煤燃烧及汽车燃油污染.利用沉积物质量基准法和苯并[a]芘毒性当量(TEQBa P)法分别评价了杭埠-丰乐河沉积物PAHs的生态风险和致癌风险,发现部分采样点某些多环芳烃含量超过了效应区间低值(ERL),具有潜在的生态风险;沉积物中TEQBa P均值高达343 ng·g~(-1),具有相当高的致癌风险.     

辽河沉积物中多环芳烃的污染水平与特征

测定了辽河干流15个沉积物样品中16种EPA优先控制多环芳烃的含量.结果表明,辽河沉积物中总PAHs含量介于27.8-1479 ng·g-1,平均值为285.5ng·g-1,其中蒽、菲、芴含量较高.特征化合物荧蒽/202与茚并[1,2,3,2cd]芘/276的比值表明辽河沉积物中的PAHs主要来源于燃烧产物.     

上海市河流表层沉积物中的氯酚、溴酚及多环芳烃

应用气相色谱/质谱（GC/MS）分析了上海市黄浦江、苏州河及蕰藻浜表层底泥样品中19种氯酚（CPs）、2种溴酚（BPs）和美国环保局（EPA）优先控制的16种多环芳烃（PAHs）的含量.结果表明,黄浦江底泥中19种CPs的总平均浓度最高（18.3 ng.g-1干重（dw））,苏州河次之（14.8 ng.g-1dw）,蕰藻浜最低（4.44 ng.g-1dw）,而两种BPs的含量相当.4-氯酚（4-CP）和五氯酚（PCP）是占主导的污染物,表明底泥中CPs可能受人类生活生产活动的影响较大;而BPs的来源有待进一步深入的研究.CPs的毒性当量贡献值随着氯原子取代数的增加而增加.底泥中16种PAHs的总浓度范围是132—6800 ng.g-1dw（平均值为3050 ng.g-1dw）.PAHs组成特征及源解析表明,底泥中PAHs主要来自燃烧源.生态风险分析显示,上海市水体底泥中的PAHs均未超过生态风险评价中值（ERM）,表明不存在严重和频发的PAHs生态毒理风险.     

珠江口八大口门PAHs时空分布特征

2019年2月、4月、8月和10月分别采集了珠江口八大口门入海口海水样品,采用气相色谱方法对10种多环芳烃(PAHs)(萘、苊、苊烯、芴、菲、蒽、荧蒽、芘、苯并蒽、?)进行定量源解析,PAHs的检出率较高,表明PAHs在八大口门海域水体中普遍存在.在空间分布上,鸡啼门、虎门海域水体PAHs含量相对较高,蕉门、磨刀门、虎跳门和崖门居中,洪奇门和横门相对较少.各口门PAHs含量呈现明显的表底分层现象,八大口门表层水PAHs的浓度范围为ND—27260.00 ng·L^-1,最大值出现在虎跳门4月份水样;底层水PAHs的浓度范围为ND—31175.00 ng·L^-1,最大值出现在鸡啼门10月份水样.在时间分布上,各口门表、底层海水PAHs含量平均值均呈现出8月份最小的特征,是由于8月雨量大,雨水冲刷及径流作用增大,对入海口区域污染物进行一定程度的稀释.从来源上看,八大口门海水中PAHs的来源主要为交通、煤焦油炼制、化石燃料的燃烧及加工炼制、木材燃烧、煤炭燃烧、油类不完全燃烧及油类泄漏混合污染等.研究珠江口八大口门入海口水体多环芳烃污染情况,对珠江三角...     

Achieving Open Access to Conservation Science

Conservation science is a crisis discipline in which the results of scientific enquiry must be made available quickly to those implementing management. We assessed the extent to which scientific research published since the year 2000 in 20 conservation science journals is publicly available. Of the 19,207 papers published, 1,667 (8.68%) are freely downloadable from an official repository. Moreover, only 938 papers (4.88%) meet the standard definition of open access in which material can be freely reused providing attribution to the authors is given. This compares poorly with a comparable set of 20 evolutionary biology journals, where 31.93% of papers are freely downloadable and 7.49% are open access. Seventeen of the 20 conservation journals offer an open access option, but fewer than 5% of the papers are available through open access. The cost of accessing the full body of conservation science runs into tens of thousands of dollars per year for institutional subscribers, and many conservation practitioners cannot access pay‐per‐view science through their workplace. However, important initiatives such as Research4Life are making science available to organizations in developing countries. We urge authors of conservation science to pay for open access on a per‐article basis or to choose publication in open access journals, taking care to ensure the license allows reuse for any purpose providing attribution is given. Currently, it would cost $51 million to make all conservation science published since 2000 freely available by paying the open access fees currently levied to authors. Publishers of conservation journals might consider more cost effective models for open access and conservation‐oriented organizations running journals could consider a broader range of options for open access to nonmembers such as sponsorship of open access via membership fees. Obtención de Acceso Abierto a la Ciencia de la Conservación     

Some polyphagous Homoptera gain protection from their natural enemies by feeding on the toxic plantsSpartium junceum andErythrina corallodendrum (Leguminosae)

Summary Interactions were studied among alkaloid-containing legumes (Erythrina corallodendrum andSpartium junceum) and non-toxic plants (Citrus sinensis, Cucurbita moschata andEuphorbia tirucalli), several polyphagous homopterans,Aphis craccivora (Aphididae),Icerya purchasi, I. aegyptiaca (Margarodidae),Lepidosaphes ulmi (Diaspididae) andPlanococcus citri (Pseudococcidae), and some major natural enemies of these homopterans. Significant reductions in survival due to negative effects of alkaloid containing as compared with non-alkaloidal plants were recorded for the predatorsRodolia cardinalis andChilocorus bipustulatus, but not forCryptolaemus montrouzieri (Coleoptera: Coccinellidae),Chrysoperla carnea (Neuroptera: Chrysopidae) andSympherobius sanctus (Neuroptera: Sympherobiidae). The development time of the larvae or pupae ofR. cardinalis, C. carnea andS. sanctus was longer on the toxic plants than on the non-toxic ones. The percentage of parasitism ofA. craccivora collected from the non-alkaloidal plantsVicia palaestina andMelilotus albus was much higher than that onS. junceum. The parasitoid complexes ofA. craccivora differed between both plant groups. The nutritive value of honeydew ofI. purchasi andA. craccivora, as expressed by the life span ofEncyrtus infelix (Hymenoptera: Encyrtidae) adults, was also investigated. Life spans were significantly longer when the wasps fed on honeydew produced on non-alkaloidal plants (C. sinensis andPittosporum tobira) than on alkaloid containing plants whenI. purchasi — but notA. craccivora — was the producer. It is suggested that the chemical defense ofE. corallodendrum andS. junceum is exploited by polyphagous phytophages to reduce predation. In nature, population growth and density of four of the investigated homopterans are conspicuously high when they developed on the alkaloid containing plant species, and very low on non-alkaloid plants. The efficiency of their natural enemies may be reduced by sequestration of alkaloids (or other toxic plant compounds) or their transfer into excreted honeydew. Therefore it is assumed that a generalist phytophagous homopteran may be protected from its natural enemies, although at different rates of efficiency, if it can safely sequester the host allelochemical when it develops on toxic species within its host range.     

Rapid,recurring, structured survey versus bioblitz for generating biodiversity data and analysis with a multispecies abundance model

A bioblitz inexpensively and quickly generates biodiversity data, but bioblitzes are often conducted with haphazard, unreplicated sampling. Results tend to be taxonomically, geographically, or temporally biased, lack metadata, and consist of lists of observed taxa that do not enable further analyses or correction for imperfect detection. A rapid, recurring, structured survey (RRSS) uses a structured sampling design and temporal and spatial replication to survey randomly selected sites on a conservation property. We participated in a loosely structured bioblitz and a subsequent RRSS at Big Canoe Creek Nature Preserve in Springville (St. Clair County), Alabama (USA) to compare observed richness derived from the 2 survey approaches. The RRSS data structure enabled us to fit models that accounted for imperfect detection to estimate abundances, occupancy probabilities, and habitat associations. The loosely structured bioblitz data could not be used in such models. We present a new integrated multispecies abundance model that we applied to avian RRSS data. Our model extension enables estimation for the community, employs data augmentation to estimate the number of undetected species, and incorporates covariates. The RRSS generated a more comprehensive and less biased list of observed taxonomic richness than the loosely structured bioblitz (e.g., 73 vs. 45 bird species and 104 vs. 63 insect families from the RRSS vs. loosely structured bioblitz, respectively). Models fit to the RRSS data identified seasonal patterns in avian community composition and allowed for estimation of habitat–occupancy relationships for insect taxa. The RRSS protocol has potential for broad transferability as a standardized, quick, and inexpensive way to inventory biodiversity and estimate ecological parameters while providing an outreach opportunity.     

Compliance with and ecosystem function of biodiversity offsets in North American and European freshwaters

Land-use change via human development is a major driver of biodiversity loss. To reduce these impacts, billions of dollars are spent on biodiversity offsets. However, studies evaluating offset project effectiveness that examine components such as the overall compliance and function of projects remain rare. We reviewed 577 offsetting projects in freshwater ecosystems that included the metrics project size, type of aquatic system (e.g., wetland and creek), offsetting measure (e.g., enhancement, restoration, and creation), and an assessment of the projects’ compliance and functional success. Project information was obtained from scientific and government databases and gray literature. Despite considerable investment in offsetting projects, crucial problems persisted. Although compliance and function were related to each other, a high level of compliance did not guarantee a high degree of function. However, large projects relative to area had better function than small projects. Function improved when projects targeted productivity or specific ecosystem features and when multiple complementary management targets were in place. Restorative measures were more likely to achieve targets than creating entirely new ecosystems. Altogether the relationships we found highlight specific ecological processes that may help improve offsetting outcomes.     

Sequestration of cucurbitacin analogs by New and Old World chrysomelid leaf beetles in the tribe Luperini

Summary Two South American polyphagous leaf beetles,Diabrotica speciosa andCerotoma arcuata, selectively accumulated the bitter tasting compound 23,24-dihydrocucurbitacin D in their body after ingesting root tissues of cucurbit plants. Similarly, three Asian Cucurbitaceae-feeding specialists in the genusAulacophora were found to sequester the same compound. Cucurbitacin analogs were shown to deter feeding by a bird predator, indicating an allomonal role for these compounds in cucurbitacin-associated chrysomelid leaf beetles both of New and Old Worlds. The strong affinity to cucurbitacins, selective sequestration of the analogs and consequent protection from predators suggested an ecological adaptation mechanism developed in common among these two geographically isolated subtribes in the Luperini.     

Effects of Controlled Fire and Livestock Grazing on Bird Communities in East African Savannas

Abstract: In East Africa fire and grazing by wild and domestic ungulates maintain savannas, and pastoralists historically set fires and herded livestock through the use of temporary corrals called bomas. In recent decades traditional pastoral practices have declined, and this may be affecting biodiversity. We investigated the effects of prescribed fires and bomas on savanna bird communities in East Africa during the first and second dry seasons of the year (respectively before and after the rains that mark the onset of breeding for most birds). We compared abundance, richness, and community composition on 9‐ha burned plots, recently abandoned bomas, and control plots in the undisturbed matrix habitat over a 3‐year period. Generally, recently burned areas and abandoned bomas attracted greater densities of birds and had different community assemblages than the surrounding matrix. The effects of disturbances were influenced by interactions between primary productivity, represented by the normalized difference vegetation index, and time. Bird densities were highest and a greater proportion of species was observed on burned plots in the months following the fires. Drought conditions equalized bird densities across treatments within 1 year, and individuals from a greater proportion of species were more commonly observed on abandoned bomas. Yearly fluctuations in abundance were less pronounced on bomas than on burns, which indicate that although fire may benefit birds in the short term, bomas may have a more‐lasting positive effect and provide resources during droughts. Several Palearctic migrants were attracted to burned plots regardless of rainfall, which indicates continued fire suppression may threaten their already‐declining populations. Most notably, the paucity of birds observed on the controls suggests that the current structure of the matrix developed as a result of fire suppression. Traditional pastoralism appears critical to the maintenance of avian diversity in these savannas.     

A palaeo-hydrogeological model for arsenic contamination in southern and south-east Asia

An argument is presented in which areas of natural arsenic contamination of modern groundwaters throughout Asia have a common origin. Arsenic originally accumulated in oceanic ferro-manganoan sediments of the eastern Palaeo-Tethys. This was further concentrated through oceanic crustal extinction in what later became the south-east Chinese accreted mineralised terrain. Proto-Himalayan uplift of this area created the palaeo-drainage systems of the Ganges – Brahmaputra, Irrawaddy, Mekong, and Red Rivers, with consequent headwater erosion of arsenic-rich sediments. Their downstream deposition as immature and easily redistributed Neogene sandstones, silts, and iron-rich clays has created secondary and tertiary reservoirs of adsorbed and authigenic arsenic, from which the current arsenic-rich groundwaters have evolved. Considering river basins within the above palaeo-hydrogeological framework provides a basis for assessing the risk of arsenic in groundwater basins of south and south-eastern Asia.     

Threats to intact tropical peatlands and opportunities for their conservation

Large, intact areas of tropical peatland are highly threatened at a global scale by the expansion of commercial agriculture and other forms of economic development. Conserving peatlands on a landscape scale, with their hydrology intact, is of international conservation importance to preserve their distinctive biodiversity and ecosystem services and maintain their resilience to future environmental change. We explored threats to and opportunities for conserving remaining intact tropical peatlands; thus, we excluded peatlands of Indonesia and Malaysia, where extensive deforestation, drainage, and conversion to plantations means conservation in this region can protect only small fragments of the original ecosystem. We focused on a case study, the Pastaza‐Marañón Foreland Basin (PMFB) in Peru, which is among the largest known intact tropical peatland landscapes in the world and is representative of peatland vulnerability. Maintenance of the hydrological conditions critical for carbon storage and ecosystem function of peatlands is, in the PMFB, primarily threatened by expansion of commercial agriculture linked to new transport infrastructure that is facilitating access to remote areas. There remain opportunities in the PMFB and elsewhere to develop alternative, more sustainable land‐use practices. Although some of the peatlands in the PMFB fall within existing legally protected areas, this protection does not include the most carbon‐dense (domed pole forest) areas. New carbon‐based conservation instruments (e.g., REDD+, Green Climate Fund), developing markets for sustainable peatland products, transferring land title to local communities, and expanding protected areas offer pathways to increased protection for intact tropical peatlands in Amazonia and elsewhere, such as those in New Guinea and Central Africa which remain, for the moment, broadly beyond the frontier of commercial development.     

What Every Conservation Biologist Should Know about Economic Theory

Abstract: The last century has seen the ascendance of a core economic model, which we will refer to as Walrasian economics. This model is driven by the psychological assumptions that humans act only in a self‐referential and narrowly rational way and that production can be described as a self‐contained circular flow between firms and households. These assumptions have critical implications for the way economics is used to inform conservation biology. Yet the Walrasian model is inconsistent with a large body of empirical evidence about actual human behavior, and it violates a number of basic physical laws. Research in behavioral science and neuroscience shows that humans are uniquely social animals and not self‐centered rational economic beings. Economic production is subject to physical laws including the laws of thermodynamics and mass balance. In addition, some contemporary economic theory, spurred by exciting new research in human behavior and a wealth of data about the negative global impact of the human economy on natural systems, is moving toward a world view that places consumption and production squarely in its behavioral and biophysical context. We argue that abandoning the straightjacket of the Walrasian core is essential to further progress in understanding the complex, coupled interactions between the human economy and the natural world. We call for a new framework for economic theory and policy that is consistent with observed human behavior, recognizes the complex and frequently irreversible interaction between human and natural systems, and directly confronts the cumulative negative effects of the human economy on the Earth's life support systems. Biophysical economics and ecological economics are two emerging economic frameworks in this movement.