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1.
福建某钢铁厂区域表层土壤PAHs污染特征与风险分析   总被引:5,自引:0,他引:5  
侯艳伟  张又弛 《环境化学》2012,31(10):1542-1548
采用气相色谱-质谱联用仪(GC-MS)分析福建某钢铁厂区域不同功能区表层土壤中16种优控PAHs含量,并对其组成、来源和环境风险进行了分析.结果表明,各样点土壤中16种优控PAHs的检出率达到100%,其总含量范围为68.7—18100.6μg.kg-1,平均值为5084.5μg.kg-1.7个功能区土壤中PAHs主要以高环(4—6环)为主.异构体比值法分析表明该钢铁厂区域各功能区土壤中PAHs主要来源于石油燃料的燃烧.土样中16种PAHs的TEQBaP为6.01—3110μg.kg-1,平均值为852μg.kg-1,7种致癌PAHs对16种PAHs总TEQBaP的贡献达到99.1%,其中BaP和DBA对总TEQBaP的贡献值较大,分别达到61.6%和14.5%.除郊区外,其它6个功能区土壤样品10种PAHs的总TEQBaP都超过荷兰土壤标准目标参考值,表明该钢铁厂区域多数功能区表层土壤均存在潜在的环境风险.  相似文献   

2.
为了探明山东省农业典型地区土壤中多环芳烃(PAHs)的污染现状,采用GC-MS联用技术定量分析了2008—2011年山东省农业典型地区(济宁、宁阳、寿光)土壤中16种PAHs的含量,并对其分布特征、来源以及生态风险进行了评价。结果表明,16种PAHs的平均质量分数为46.3~149.2μg·kg~(-1),且以萘(NAP)和菲(PHE)为主。寿光地区土壤中16种PAHs的平均质量分数最高,其次是宁阳和济宁。由于0~10 cm的表层土壤受人为干扰因素较大,导致16种PAHs含量在表层土壤中较高,且随土壤深度的增加而逐渐降低。不同使用类型土壤中PAHs含量高低为:水稻土旱作土自然土。特征分子比值法结果显示w(PHE)/w(ANT)15、w(FLT)/w(PYR)1、w(FLT)/[w(FLT)+w(PYR)]0.5以及w(IND)/[w(IND)+w(Bghi P)]0.5,表明该区域土壤中的PAHs主要来源于煤、薪柴和秸秆的不完全燃烧以及木灰和秸秆等有机肥的回田利用。根据荷兰Maliszewska-Kordybach分析方法得到,寿光地区0~10 cm土壤16种PAHs平均质量分数为227.9μg·kg~(-1),属于轻微污染,而宁阳和济宁地区土壤尚处于无污染水平。利用土壤苯并[a]芘的毒性当量浓度(TEQBap)评价PAHs的生态风险,结果表明具有致癌性的7种PAHs是TEQBap的主要贡献者,且荷兰土壤标准中的10种PAHs在济宁、宁阳和寿光3个典型农业区0~10 cm土层的TEQBap平均值分别为0.64μg·kg~(-1)、7.41μg·kg~(-1)和13.61μg·kg~(-1),均低于荷兰土壤管理条例规定的目标值,说明山东省农业典型地区土壤PAHs风险较低。  相似文献   

3.
土壤多环芳烃(PAHs)的污染日益受到关注,PAHs是垃圾渗滤液中的主要有害成分之一.以苏北某市城郊结合部露天垃圾堆放场为对象,采用高效液相色谱法分析周边农田土壤中16种PAHs的含量特征及分布规律.结果表明,垃圾场周边农田土壤PAHs含量总体表现为随距垃圾堆体的距离增大而降低的趋势.土壤中PAHs总量(平均值为1 208.5μg·kg-1)明显高于未污染土壤(509.25μg·kg-1),其中显著提高了土壤中难降解、难挥发的4环芳烃的含量,按照欧洲农业土壤PAHs含量与分布标准,达到中等或中等以上PAHs污染水平,说明垃圾堆填场周边农田土壤存在PAHs的污染风险.  相似文献   

4.
采用加速溶剂萃取-高效液相色谱法测定了武汉市6个远城区(蔡甸、东西湖、汉南、黄陂、江夏、新洲)农田土壤样品中16种多环芳烃(PAHs)的含量.结果表明,研究区土壤中16种PAHs总量范围为12.86—876.82μg·kg-1,平均含量为122.64μg·kg-1,土壤中PAHs以中高环PAHs为主.通过因子分析法和异构体比值法分析,研究区土壤中PAHs主要为化石燃烧来源(包括汽油燃烧和柴油燃烧)、生物质或煤炭燃烧来源.采用毒性当量评价方法对研究区土壤PAHs进行潜在致癌性分析,结果表明土壤中PAHs潜在致癌性较低.  相似文献   

5.
江苏省部分地区农田表土多环芳烃含量比较及来源分析   总被引:8,自引:0,他引:8  
采集江苏省兴化市、吴江市、宜兴市、南京市六合区的农田表层(0-15 cm)土壤样品共30个,用高效液相色谱测定土壤中16种多环芳烃(PAHs)含量.结果表明,土壤中∑PAHs含量介于45.6~2 286.8 μg·kg-1之间.兴化市、吴江市土壤中PAHs平均含量分别为1 370.3、801.1 μg·kg-1,污染严重;宜兴市、南京市六合区土壤中PAHs平均含量分别为210.8、126.7 μg·kg-1,为轻微污染或无污染.根据不同环数PAHs相对丰度和菲(Phe)/蒽(Ant)、荧蒽(Fla)/芘(Pyr)比值以及对4地的实际调查,发现调查区土壤样品中PAHs来源复杂,主要有机动车尾气排放,煤、草和木材的燃烧以及石油泄漏等.  相似文献   

6.
天津市土壤多环芳烃污染特征、源解析和生态风险评价   总被引:6,自引:0,他引:6  
采用气相色谱-质谱联机方法(GC-MS)分析了天津市不同功能区10个采样点表层土壤样品中16种多环芳烃(PAHs)的浓度,并对其污染特征、来源和生态风险进行了分析.结果表明:天津市土壤中16种多环芳烃的总浓度(∑PAHs)范围为142—1.49×103ng·g-1,平均浓度765 ng·g-1,Bap浓度范围7.06—118 ng·g-1,平均值37.6 ng·g-1.∑PAHs浓度均值呈工业区近郊区城区远郊区趋势.采用PAHs成分谱、污染物的特征比值和主成分分析的污染来源解析结果表明:工业区PAHs主要来源于焦化、煤和天然气的燃烧,以及机动车的污染排放;城区和郊区土壤中PAHs除来自于煤和焦炭的燃烧外,机动车污染是一个非常重要的污染源.根据荷兰土壤质量标准,所有采样点均有PAHs单体超标,其中西青、津南、北辰、汉沽、塘沽和大港采样点超过荷兰土壤标准规定的10种多环芳烃的苯并(a)芘(Bap)毒性当量浓度(TEQ Bap10)限值33 ng·g-1,说明天津近郊区和工业区土壤已受到PAHs的污染,存在潜在的生态风险.  相似文献   

7.
采用气相色谱-质谱联机方法(GC-MS)分析了东北某钢铁厂及周边居住区、风景区共11个采样点表层土壤样品16种多环芳烃(PAHs),结果表明,钢铁工业区16种PAHs(∑PAHs)浓度范围为3.39×103—1.54×105ng·g-1,平均浓度3.21×104ng·g-1;居住区∑PAHs浓度范围为587—6.70×103ng·g-1,平均浓度3.82×103ng·g-1;风景区千山∑PAHs浓度385 ng·g-1.∑PAHs和Bap浓度均呈工业区>居住区>风景区趋势.与国内外其他研究结果相比,该钢铁工业区及其周边居住区土壤PAHs污染相对较为严重,11个采样点中有9个采样点土壤∑PAHs为严重污染,4个采样点苯并(a)芘(Bap)浓度超过加拿大土壤质量基准.利用特征比值法(Diagnostic Rate)和主成分分析法(Principal component analysis,PCA)对钢铁工业区及其周边地区土壤进行了源解析,结果表明,钢铁工业区土壤中PAHs主要来源于焦炉、燃煤、柴油燃烧等污染源,周边地区土壤除受工业污染源排放影响外,机动车汽油、柴油污染排放也有重要影响.  相似文献   

8.
为了解与评价同一地区2个燃煤电厂(A和B)周边农田土壤多环芳烃的污染状况,按照点源扇形布点原则,在电厂周边常年主导上下风向1500 m范围内布点,在远离电厂10 km以上的常年主导风向的上风向设置对照点,参照《土壤环境监测技术规范》(HJ/T 166-2004)共采集33个农田土壤样品.取经过处理的样品5.00 g,用乙腈超声提取、浓缩后,HPLC法测定15种PAHs的含量.描述其空间分布特征,采用特征污染物分析、环数分析法及聚类分析等方法分析污染来源,运用荷兰分级标准评价法进行生态安全评价.结果显示运行57年的A电厂周边农田土壤中BaP为30.3μg·kg~(-1)(0.668—81.5μg·kg~(-1)),15种PAHs总量为482μg·kg~(-1)(107—1000μg·kg~(-1)),TEQ(BaP)为43.5μg·kg~(-1)(2.27—124μg·kg~(-1)),明显高于运行8年B电厂的7.32μg·kg~(-1)(2.56—15.0μg·kg~(-1))、227μg·kg~(-1)(158—415μg·kg~(-1))和10.3μg·kg~(-1)(3.90—20.1μg·kg~(-1))以及对照区的9.62μg·kg~(-1)(0.347—23.9μg·kg~(-1))、193μg·kg~(-1)(76.1—329μg·kg~(-1))和12.7μg·kg~(-1)(0.499—31.9μg·kg~(-1)).A电厂周边的常年主导上风向农田土壤样本的BaP和TEQ(BaP)_(15)含量基本维持在对照区水平,下风向的超出对照区水平,最大值均位于1500 m处,超出荷兰土壤质量标准.B电厂周边的常年主导上、下风向农田土壤样本的BaP和TEQ(BaP)_(15)含量与对照区相当,且均不超标.A电厂周边农田土壤中具有致癌风险的7种PAHs占总∑PAHs的41.3%,远高于B电厂的20.7%和对照区的25.8%.A电厂周边农田土壤中33.3%的PAHs点位处于中度污染水平,TEQ(BaP)_(15)高于国内相似污染源,存在亟需关注的生态风险.B电厂周边农田土壤中PAHs整体处于轻微污染水平,TEQ(BaP)_(15)低于生物质电厂.  相似文献   

9.
污灌区农田土壤可能受到多环芳烃(PAHs)的严重污染.本文以山西省黎城污灌区为研究对象,对其中农田土壤中16种优控PAHs的含量水平、组成特征以及风险进行分析和评价.结果表明,该污灌区农田土壤中PAHs总含量范围为16.03—1320.95 ng·g~(-1),平均值为226.74 ng·g~(-1).土壤中PAHs以4—6环的PAHs为主,占总量的61%.风险评价结果显示该区域有40%的样品受到污染,其中重度、中度和轻微污染所占比例分别为2.9%、2.9%和34.3%.健康风险评价结果显示,该区域已具有潜在的致癌风险.从污染评价结果以及与山西省内其它区域农田土壤多环芳烃含量比较来看,研究区土壤已经受到PAHs不同程度的污染.在未来环境管理和控制过程中应采取有效措施,以保护人体健康和生态环境安全.  相似文献   

10.
广州周边菜地中多环芳烃的污染现状   总被引:28,自引:0,他引:28  
以GC/MSD内标法分析了广州五个地区菜地中 1 6种多环芳烃 (PAHs)的分布 ,结果表明 ,菜地土壤中∑PAHs最大为 30 77μg·kg- 1 ,最小为 42 μg·kg- 1 ,绝大部分土壤样品中的∑PAHs含量在 2 0 0 μg·kg- 1 以上 ,属中度污染 .  相似文献   

11.
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  相似文献   

12.
Protected areas (PAs) are often implemented without consideration of already existing PAs, which is likely to cause an overrepresentation of certain biophysical conditions. We assessed the representativeness of the current PA network with regard to the world's biophysical conditions to highlight which conditions are underprotected and where these conditions are located. We overlaid terrestrial and marine PAs with information on biophysical conditions (e.g., temperature, precipitation, and elevation) and then quantified the percentage of area covered by the PA network. For 1 variable at a time in the terrestrial realm, high temperature, low precipitation, and medium and very high elevation were underrepresented. For the marine realm, low and medium sea surface temperature (SST), medium and high sea surface salinity (SSS), and the deep sea were underrepresented. Overall, protection was evenly distributed for elevation across the terrestrial realm and SST across the marine realm. For 2 variables at a time, cold and very dry terrestrial environments had mostly low protection, which was also the case for low SST and low and medium SSS across most depths for marine environments. Low protection occurred mostly in the Sahara and the Arabian Peninsula for the terrestrial realm and along the Tropic of Capricorn and toward the poles for the marine realm. Although biodiversity measures are of prime importance for the design of PA networks, highlighting biophysical gaps in current PAs adds a frequently overlooked perspective. These gaps may weaken the potential of PAs to conserve biodiversity. Thus, our results may provide useful insights for researchers, practitioners, and policy makers to establish a more comprehensive global PA network.  相似文献   

13.
Summary The adaptation of defensive secretions to their target organisms was examined for the abdominal gland secretions ofBledius furcatus, B. spectabilis andB. arenarius. Therefore the target organisms of the secretion of theseBledius species (i.e. their predators) had to be identified. At the collection sites examined these were the earwigLabidura riparia, the antCataglyphis bicolor, the flyLispe candicans, different carabids of the generaPogonus, Dichirotrichus, Dyschirius, Bembidion andCalathus and the wading birdsHaematopus ostralegus andCalidris alba. The secretion of the abdominal glands contains the toxin ptoluquinone dissolved in either-dodecalactone and 1-undecene (B. furcatus andB. spectabilis) or in octanoic acid and octyloctanoate (B. arenarius). The ratio of these solvents is species-specific. Application experiments using some of the natural insect predators (L. riparia, C. bicolor, Pogonus, Di. gustavii, Dyschirius) revealed that these solvent ratios provided a more effective deterrent than other possible ratios. Thus by combining the solvents in certain ratios, the capability of cuticular penetration and therefore the effectiveness of the defensive secretions are adapted to their natural targets.  相似文献   

14.
The politics of development includes subtexts of choice, as underpinned by community consensus (or lack of it), against the larger backdrop of a liberal democracy, with its intricate power structures that influence the choice of concepts and often lead to complicity rather than consent. A dilemma exists between the understanding of field-level practitioners and that of academics, whose understandings of progress differ. Progress can (and often does) imply long-term change across generations whereas development is often more a matter of crisis management and delivering tangible results to end-users. This makes it a bone of contention across political systems, irrespective of local or global dynamics. Development can emerge as a tool to be wielded for power and further political mileage at the expense of progress. Progress cannot be studied as a counterpoint to development as the sense of history is often missing in development interventions. Development tends to be piecemeal as its very logic often stems from the rationale of power. This is not to suggest, however, that development is only about politics; it is definitely more than the politics of everyday life and involves all of civil society that requires its critical and immediate attention. In this sense, it has become a priority for politicians with an underlying agenda designed to out-manouevre dissent and all statements of protest.  相似文献   

15.
As landscapes continue to fall under human influence through habitat loss and fragmentation, fencing is increasingly being used to mitigate anthropogenic threats and enhance the commercial value of wildlife. Subsequent intensification of management potentially erodes wildness by disembodying populations from landscape-level processes, thereby disconnecting species from natural selection. Tools are needed to measure the degree to which populations of large vertebrate species in formally protected and privately owned wildlife areas are self-sustaining and free to adapt. We devised a framework to measure such wildness based on 6 attributes relating to the evolutionary and ecological dynamics of vertebrates (space, disease and parasite resistance, exposure to predation, exposure to limitations and fluctuations of food and water supply, and reproduction). For each attribute, we set empirical, species-specific thresholds between 5 wildness states based on quantifiable management interventions. We analysed data from 205 private wildlife properties with management objectives spanning ecotourism to consumptive utilization to test the framework on 6 herbivore species representing a range of conservation statuses and commercial values. Wildness scores among species differed significantly, and the proportion of populations identified as wild ranged from 12% to 84%, which indicates the tool detected site-scale differences both among populations of different species and populations of the same species under different management regimes. By quantifying wildness, this framework provides practitioners with standardized measurement units that link biodiversity with the sustainable use of wildlife. Applications include informing species management plans at local scales; standardizing the inclusion of managed populations in red-list assessments; and providing a platform for certification and regulation of wildlife-based economies. Applying this framework may help embed wildness as a normative value in policy and mitigate the shifting baseline of what it means to truly conserve a species.  相似文献   

16.
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.  相似文献   

17.
Abstract: In the United States, as elsewhere, a growing debate pits national energy policy and homeland security against biological conservation. In rural communities the extraction of fossil fuels is often encouraged because of the employment opportunities it offers, although the concomitant itinerant workforce is often associated with increased wildlife poaching. We explored possible positive and negative factors associated with energy extraction in the Greater Yellowstone Ecosystem (GYE), an area known for its national parks, intact biological diversity, and some of the New World's longest terrestrial migrations. Specifically, we asked whether counties with different economies—recreation (ski), agrarian (ranching or farming), and energy extractive (petroleum)—differed in healthcare (gauged by the abundance of hospital beds) and in the frequency of sexual predators. The absolute and relative frequency of registered sex offenders grew approximately two to three times faster in areas reliant on energy extraction. Healthcare among counties did not differ. The strong conflation of community dishevel, as reflected by in‐migrant sexual predators, and ecological decay in Greater Yellowstone is consistent with patterns seen in similar systems from Ecuador to northern Canada, where social and environmental disarray exist around energy boomtowns. In our case, that groups (albeit with different aims) mobilized campaigns to help maintain the quality of rural livelihoods by protecting open space is a positive sign that conservation can matter, especially in the face of rampant and poorly executed energy extraction projects. Our findings further suggest that the public and industry need stronger regulatory action to instill greater vigilance when and where social factors and land conversion impact biological systems.  相似文献   

18.
Summary Acanthoscelides obtectus (Say) is one of the most damaging pests of kidney beans,Phaseolus vulgaris L. worldwide. However, aromatic plants from the families Lamiaceae, Lauraceae, Myrtaceae and Poaceae can protect kidney beans by direct or delayed insecticidal effect, through increased adult mortality and inhibition of beetle reproduction (both oviposition and adult emergence). The efficiency of hydrodistillated and intact plants fromThymus vulgaris andT. serpyllum, Mentha piperata, Rosmarinus officinalis, Satureia hortensis, Eucalyptus globulus, Laurus nobilis, Origanum vulgare, andCymbopogon nardus was compared. For both extracts,Origanum vulgare had the best effect. The insecticidal effect was induced by more than the essential oils because no significant difference was noticed between distilled and intact plants extract. Inhibition of reproduction was particularly important. These results suggest that lipidic as well as non lipidic, allelochemicals, such as phenolics, or non-protein amino-acids, or flavonoids may be involved in the toxicity of aromatic plants to this beetle.  相似文献   

19.
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.  相似文献   

20.
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.  相似文献   

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