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481.
Abstract:  Rapid evolution caused by human exploitation of wildlife is not usually addressed in studies of the impacts of such exploitation despite its direct relevance to population persistence. Japanese mamushi ( Gloydius blomhoffii ), an endemic venomous snake of the Japanese archipelago, has been heavily hunted by humans, and many populations appear to be declining or are already extirpated. We compared local populations that have been hunted regularly with populations that have not been hunted. Mamushi in hunted populations were smaller, had fewer vertebrae, produced more and smaller offspring, had increased reproductive effort among smaller females, and in nature fled at greater distances from an approaching human and were less defensive than mamushi in unhunted populations, as predicted from life-history theory. Heritability estimates for body size, number of vertebrae, and antipredator behavior were statistically significant, and neonates from hunted sites showed the same distribution of altered characters (compared with those from unhunted sites) as adults. Thus, distribution of the divergent trait between hunted and unhunted sites appeared in part to be genetically based, which suggests rapid evolution to human predation pressures. Trait distributions in hunted populations probably deviate from naturally (as opposed to anthropogenically) selected optima and, therefore, may have long-term negative repercussions on population persistence. Because rapid evolution affects a suite of parameters that characterize exploited populations, accurate understanding of the impacts of exploitation and effective resource management and conservation can only be achieved if evolutionary consequences are considered explicitly.  相似文献   
482.
为探究金属矿井下粉尘孔粒径特征,以阜山金矿为例,系统研究其进风巷粉尘(IAD)、回风巷粉尘(RAD)的孔粒径分布(PSD)情况.首先,利用激光粒度分析仪与扫描电子显微镜(SEM)、低温液氮吸附仪分别测试粉尘粒径与孔参数,然后利用分形理论计算并分析其粒度分形维数与孔分形维数.结果 表明:RAD粒径比IAD粒径小,两者最可...  相似文献   
483.
不同粒度锡采矿废石重金属淋溶规律及影响机制   总被引:1,自引:0,他引:1       下载免费PDF全文
采用广西某锡矿不同粒度采矿废石进行模拟酸雨动态淋溶试验,研究了不同粒度锡采矿废石的淋溶规律,结果表明,淋溶前期,废石溶出重金属浓度呈上升趋势,Pb、Zn溶出浓度表现出中粒度>细粒度>粗粒度,As溶出浓度最高为0.12mg/L,表现为细粒度>中粒度>粗粒度;淋溶中后期,废石溶出重金属浓度呈平缓甚至缓慢下降趋势,3种重金属溶出规律均表现为细粒度>中粒度>粗粒度, Pb、Zn、As最高溶出浓度分别为0.91,1.05,0.12mg/L.研究了重金属溶出动力学并运用X射线衍射、扫描电镜、能谱仪、比表面积及孔径分布仪和化学测试等手段分析得出了锡采矿废石淋溶影响机制,淋溶前期主要受粒度影响,溶质以对流运移为主;淋溶后期受粒度、空隙率、比表面积、表面结构和形态分布等多重因素影响,溶质以对流运移和分子扩散综合影响为主.本研究方法及结论可为废石重金属防控和监管提供理论依据.  相似文献   
484.
李海燕  石安邦 《生态环境》2014,(11):1852-1860
城市地表颗粒物作为重金属的重要载体,严重危害城市人群和水体,已成为城市环境的重要研究对象。阐述了对地表颗粒物重金属的空间、粒径、赋存形态等分布特征及其影响因素进行系统分析的意义。通过对国内不同城市不同功能区的重金属(主要为:Zn、Cu、Cd、Pb)数据进行对比分析,各功能区重金属污染情况为:Cu、Pb:工业区〉商业区〉交通区〉居民区〉休闲区;Zn:工业区〉交通区〉商业区〉居民区〉休闲区;Cd:交通区〉工业区〉商业区〉居民区〉休闲区,同时各功能区中Zn、Pb含量波动性较大。整体上国内工业区、交通区和商业区地表颗粒物重金属污染严重。与我国的土壤重金属背景值相比,4种金属中Cd污染程度最为严重。探讨了与国外部分城市地表颗粒重金属污染特征之间的差异,指出国内城市重金属含量均值整体上低于欧美发达城市,而国内一线城市重金属含量明显偏高。系统分析了颗粒物重金属的粒级效应,赋存形态以及生物有效性。综述了城市交通活动(主要为交通流量、车辆行驶速度、变速频率、车辆类型、道路特征等)、降雨冲刷事件、雨前干燥期、大气风力作用、和其他因素对地表颗粒物重金属分布特征的影响。某种程度上,道路车辆的行驶速度和变速对颗粒物重金属累积的影响作用大于交通流量。不同降雨事件和雨前干燥期对重金属分布特征影响的研究结论不一,但地表颗粒对大气PM2.5重金属贡献较大。今后应在以下方面进一步加强对城市地表颗粒物重金属的研究:建立颗粒物粒径划分标准;加强重金属在降雨冲刷过程变化规律的分析;探讨地表颗粒物与大气颗粒物重金属转换关系;还应开展中小型城市,城乡结合部(城中村)地表颗粒物重金属污染特性研究。  相似文献   
485.
Ratio of turbidity and TSS (Tur/TSS) was used to characterize PSD of stormwater particles. Pb and Zn preferred to accumulate in finer RDS, while Cu, Cr and Ni in coarser RDS. HMs pollution in stormwater particles increased linearly with Tur/TSS. Dissolvability of HMs and PSD variations contribute to the differences between RDS and stormwater. Stormwater runoff, derived from the wash-off of road-deposited sediments (RDS), contains elevated heavy metal (HM) concentrations and, thus, imposes an increasing threat to urban aquatic ecosystems. In-depth understanding of the variations of HMs pollution from RDS to stormwater during transport processes facilitates the development of effective RDS and stormwater control strategies. Toward this end, the distribution of HMs (Cu, Pb, Zn, Cr, and Ni) in RDS and stormwater were investigated simultaneously. The results show a preferential accumulation of Pb and Zn in the finer (<38.5 μm) RDS, and Cu, Cr and Ni in the coarser (38.5–150 μm) RDS. For stormwater, n.d.~48.6% of HMs fractionated into the dissolved phase, and stormwater particles constitute the primary carriers of HMs. Furthermore, the accumulation of HMs in stormwater particles increased linearly with finer particle size distributions (PSD). Geoaccumulation index (Igeo) highlighted the predominant pollution of both RDS and stormwater particles by Cu, Pb and Zn. Nonetheless, Cu, Pb, and Ni mostly contributed the potential ecological risk of RDS, whereas Cu, Pb, and Zn mainly contributed that of stormwater particles. Moreover, contamination by Cu, Pb and Zn was significantly higher in stormwater particles than that in RDS. These differences are attributable to the solubility and size-dependent accumulation of HMs in RDS, as well as the PSD variations during transport processes. The study outcomes highlight the importance of very fine (nano- and submicron- scale) RDS in stormwater pollution and the necessity of control.  相似文献   
486.
Over the past 1000 years New Zealand has lost 40–50% of its bird species, and over half of these extinctions are attributable to predation by introduced mammals. Populations of many extant forest bird species continue to be depredated by mammals, especially rats, possums, and mustelids. The management history of New Zealand's forests over the past 50 years presents a unique opportunity because a varied program of mammalian predator control has created a replicated management experiment. We conducted a meta-analysis of population-level responses of forest birds to different levels of mammal control recorded across New Zealand. We collected data from 32 uniquely treated sites and 20 extant bird species representing a total of 247 population responses to 3 intensities of invasive mammal control (zero, low, and high). The treatments varied from eradication of invasive mammals via ground-based techniques to periodic suppression of mammals via aerially sown toxin. We modeled population-level responses of birds according to key life history attributes to determine the biological processes that influence species’ responses to management. Large endemic species, such as the Kaka (Nestor meridionalis) and New Zealand Pigeon (Hemiphaga novaeseelandiae), responded positively at the population level to mammal control in 61 of 77 cases for species ≥20 g compared with 31 positive responses from 78 cases for species <20 g. The Fantail (Rhipidura fuliginosa) and Grey Warbler (Gerygone igata), both shallow endemic species, and 4 nonendemic species (Blackbird [Turdus merula], Chaffinch [Fringilla coelebs], Dunnock [Prunella modularis], and Silvereye [Zosterops lateralis]) that arrived in New Zealand in the last 200 years tended to have slight negative or neutral responses to mammal control (59 of 77 cases). Our results suggest that large, deeply endemic forest birds, especially cavity nesters, are most at risk of further decline in the absence of mammal control and, conversely suggest that 6 species apparently tolerate the presence of invasive mammals and may be sensitive to competition from larger endemic birds.  相似文献   
487.
Long-term population declines have elevated recovery of grassland avifauna to among the highest conservation priorities in North America. Because most of the Great Plains is privately owned, recovery of grassland bird populations depends on voluntary conservation with strong partnerships between private landowners and resource professionals. Despite large areas enrolled in voluntary practices through U.S. Department of Agriculture's Lesser Prairie-chicken (Tympanuchus pallidicinctus) Initiative (LPCI), the effectiveness of Farm Bill investments for meeting wildlife conservation goals remains an open question. Our objectives were to evaluate extents to which Conservation Reserve Program (CRP) and LPCI-grazing practices influence population densities of grassland birds; estimate relative contributions of practices to regional bird populations; and evaluate percentages of populations conserved relative to vulnerability of species. We designed a large-scale impact-reference study and used the Integrated Monitoring in Bird Conservation Regions program to evaluate bird population targets of the Playa Lakes Joint Venture. We used point transect distance sampling to estimate density and population size for 35 species of grassland birds on private lands enrolled in native or introduced CRP plantings and LPCI-prescribed grazing. Treatment effects indicated CRP plantings increased densities of three grassland obligates vulnerable to habitat loss, and LPCI grazing increased densities of four species requiring heterogeneity in dense, tall-grass structure (α = 0.1). Population estimates in 2016 indicated the practices conserved breeding habitat for 4.5 million birds (90% CI: 4.0–5.1), and increased population sizes of 16 species , totaling 1.8 million birds (CI: 1.4–2.4). Conservation practices on private land benefited the most vulnerable grassland obligate species (AICc weight = 0.53). By addressing habitat loss and degradation in agricultural landscapes, conservation on private land provides a solution to declining avifauna of North America and scales up to meet population recovery goals for the most imperiled grassland birds.  相似文献   
488.
以具有致癌毒性的多环芳烃(polycyclic aromatic hydrocarbons,PAHs)为对象,本研究于2014年1月(冬季)在湖北恩施农村地区使用煤炭和薪柴的家庭中同步采集了室内外空气样品,分析了室内外空气中28种PAHs(∑PAH28)的浓度水平、成分谱和粒径分布,重点比较了不同燃料家庭的污染特征差异,并据此估算了暴露人群的健康风险。结果表明,在燃煤家庭,∑PAH28的室内和室外浓度分别是(507±449) ng·m~(-3)和(120±18) ng·m~(-3);而在燃柴家庭,其室内和室外∑PAH28浓度分别是(849±421) ng·m~(-3)和(268±44) ng·m~(-3)。受室内排放源影响,室内PAHs浓度显著高于室外,室内外∑PAH28浓度比值在2~13。颗粒态PAHs主要集中在细颗粒物上,PM1.0(空气动力学直径小于1.0μm)上的PAHs占到颗粒态PAHs的50%~80%。燃煤家庭的居民因PAHs呼吸暴露导致的终生致癌风险的中位数是1.8×10~(-5)(四分位距是1.2×10~(-5)~3.1×10~(-5)),使用薪柴的家庭人群暴露风险7.1×10~(-5)(6.5×10~(-5)~7.8×10~(-5))。无论是燃煤还是薪柴的家庭,居民因PAHs呼吸暴露导致的终生致癌风险均超过10-6的可接受风险水平,表明该地区的高浓度PAHs污染致使当地人群存在较高的致癌风险。  相似文献   
489.
采用实验室底盘测功机和全流定容稀释采样系统(CVS),搭载EEPS3090,开展了国三重型柴油车加装催化型颗粒物捕集器(CDPF)前后颗粒物排放因子和粒径分布比较,进一步分析了不同工况下CDPF对各模态颗粒物排放因子的影响.结果表明,重型柴油车加装CDPF前后基于单位里程的颗粒物数量排放因子分别为(2.7±1.1)×1015 km-1和7.9×1014 km-1,CDPF对颗粒物数量减排率为71.10%,其中对核模态和聚集态颗粒物数量减排率分别为28.70%和84.95%.随着车速的增加,CDPF对聚集态颗粒物数量减排效果良好,核模态颗粒物数量减排率急剧下降.高速工况下颗粒物在CDPF内部出现大粒径颗粒物向小粒径颗粒物转化的现象,导致核模态颗粒物数量排放因子的增加,应引起足够的重视.  相似文献   
490.
蛋白类有机质(pDOM)广泛存在于天然水体中,是非常重要的含氮消毒副产物前驱物.近年来,其在饮用水处理过程中的去除和控制逐渐受到广泛关注.本文以两个实际饮用水厂不同工段进出水为研究对象,通过高效尺寸排阻色谱联合紫外、荧光及有机碳检测器的分析方法,对水样中pDOM不同分子量组分的去除特性及变化规律进行探究.同时,选取混凝和活性炭吸附两种水处理技术进行小试实验,进一步探究pDOM组分在常规处理单元的去除规律.结果表明,pDOM在不同水处理单元具有不同的去除特性,预氧化能够有效分解类色氨酸和类酪氨酸型高分子组分,且随着氧化剂氧化作用增强,更多的高分子组分被氧化分解为小分子,但一些分子量较大的脂肪族蛋白等组分则难以被氧化分解;混凝沉淀对高分子组分有良好去除效果,尤其是类色氨酸型pDOM,且混凝过程可能存在一定量pDOM组分的释放,多为小分子及疏水性组分;活性炭过滤易去除分子量较低及疏水性较强的组分,但炭砂滤池长期运行可能存在微生物滋生,因此造成出水部分pDOM组分浓度增加;紫外消毒在一定程度上提高了小分子组分的去除效率.由于实际水厂运行过程中水质条件变化复杂且微生物活动不可控,故各处理单元对pDOM的去除并没有展现协同作用.且相比于腐殖质类物质,pDOM组分受水质变化影响较大,从整体工艺流程来看,去除效果有限.因此在水厂未来运行中,应加强进出水中pDOM各组分的监测,及时对各处理单元运行参数进行调整,同时考虑结合臭氧-生物活性炭工艺,或增加纳滤等膜过滤单元,严格控制pDOM组分的去除.  相似文献   
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