Estimating Total Effective Dose Equivalents from Terrorist Use of Radiological Dispersion Devices

Radiological dispersion devices (RDDs), commonly called “dirty bombs,” utilize a conventional explosive to deliberately disperse non-fissile material as an aerosol. This analysis models total effective dose equivalent (Sv) at various locations down-wind from the detonation site subsequent to terrorists detonating a ²⁴¹Am, ¹³⁷Cs, ⁶⁰Co, ¹⁹²Ir, or⁹⁰Sr RDD. A source term for each isotope equaling 3.7 × 10¹³ Bq with an instantaneous release by either high explosives or low explosives at street level is assumed in order to evaluate total effective dose equivalent (TEDE) under various meteorological scenarios for intentional releases of non-fissile materials by terrorists. The inhalation pathway on average contributes most to TEDE. The inhalation pathway accounts for 96% (0.22 Sv) of the mean exposure estimate of 0.2321 Sv and occurs over an extremely short time frame (i.e., a few minutes). Ground shine, on average, contributes the second most to TEDE estimates accounting for approximately 4% (0.009 Sv) of the estimate. A cautionary note with regard to ground shine is warranted, however, because Hotspot estimates for this pathway are based on the assumption that a person is exposed for 4 days (96 hours). The TEDE for submersion (i.e., passing through the plume without inhaling particles) is negligible for the scenarios evaluated contributing less than 1% (5.2 × 10^?6 Sv) to the TEDE estimate averaged across all 140 model runs (5 nuclides × 2 rainfall scenarios × 2 explosive scenarios × 7 wind and atmospheric stability scenarios). The TEDE value for ²⁴¹Am from inhalation is much greater, on average, than the inhalation TEDE value for ⁶⁰Co, ¹³⁷Cs, ¹⁹²Ir, or ⁹⁰Sr. This underscores the potentially high risk to human health posed by exposure to ²⁴¹Am. Ground shine is the primary exposure pathway for ⁶⁰Co and ¹³⁷Cs due to the energetic and penetrating gamma rays those radionuclides emit. ¹⁹²Ir and ⁹⁰Sr have relatively low mean TEDE values for all of the pathways examined.     

Molecular docking and experimental investigation of new indole derivative cyclooxygenase inhibitor to probe its binding mechanism with bovine serum albumin

The indole derivative 2-(5-methoxy-2-methyl-1H-indol-3-yl)-N'-[(E)-(3-nitrophenyl) methylidene]acetohydrazide (IND) was synthesized for its therapeutic potential to inhibit cyclooxygenase (COX)-II. Binding if IND to bovine serum albumin (BSA) was investigated was because most drugs bind to serum albumin in-vivo. Fluorescence, UV–vis spectrophotometry and molecular modeling methodologies were employed for studying the interaction mechanism. The intrinsic fluorescence of BSA was quenched by BSA and the quenching mechanism involved was static quenching. The binding constants between IND and BSA at the three studied temperatures (298, 301 and 306 K) were 1.09 × 10⁵, 4.36 × 10⁴ and 1.23 × 10⁴ L mol⁻¹ respectively. The most likely site for binding IND to BSA was Site I (subdomain IIA). The analysis of thermodynamic parameter revealed the involvement of hydrogen bonding and van der Waals forces in the IND-BSA interaction. Synchronous fluorescence spectroscopic (SFS) and UV–vis spectrophotometric studies suggested conformational change in BSA molecule post interaction to IND. Molecular docking and the experimental results corroborated one another. The study can prove as an insight for future IND drug development.     

Nickel oxide hollow microsphere for the chemiluminescence determination of tuberculostatic drug isoniazid

In this article, nickel(II) oxide (NiO) hollow microspheres (HMSs) were fabricated and used to catalyze chemiluminescence (CL) reaction. The studied CL reaction is the luminol-oxygen reaction that was used as a sensitive analytical tool for measuring tuberculostatic drug isoniazid (IND) in pharmaceutical formulations and water samples. The CL method was established based on the suppression impact of IND on the CL reaction. The NiO HMSs were produced by a simple hydrothermal method and characterized by several spectroscopic techniques. The result of essential parameters on the analytical performance of the CL method, including concentrations of sodium hydroxide (NaOH), luminol, and NiO HMSs were investigated. At the optimum conditions, the calibration curve for IND was linear in the range of 8.00 × 10⁻⁷ to 1.00 × 10⁻⁴ mol L⁻¹ (R² = 0.99). A detection limit (3S) of 2.00 × 10⁻⁷ mol L⁻¹ was obtained for this method. The acceptable relative standard deviation (RSD) was obtained for the proposed CL method (2.63%, n = 10) for a 5.00 × 10⁻⁶ mol L⁻¹ IND solution. The mechanism of the CL reaction was also discussed.     

Using the RESRAD Code to Assess Human Exposure Risk to 226Ra, 232Th,and 40K in Soil

This article evaluates the health risk raised by exposure to naturally occurring radionuclides in soil around Khak-Sefid, Ramsar, Iran, which is an area of high natural background radiation. A high purity germanium detector was used to determine levels of radionuclides in soil samples and the cancer morbidity risk for a hypothetical resident farmer was evaluated using the RESidual RADioactivity (RESRAD) code. The average activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K were found to be 13,201 ± 391, 27.9 ± 2.4, and 415.5 ± 16 Bq/kg, respectively. The maximum assessed cancer morbidity risks were calculated from external and internal exposure pathways as 4.73 × 10^?2 and 3.40 × 10^?2 for ²²⁶Ra, 1.41 × 10^?4 and 7.88 × 10^?5 for ²³²Th, and 1.3 × 10^?4 and 4.233 × 10^?4 for ⁴⁰K. The RESRAD calculations also showed total cancer morbidity risks from external gamma and plant ingestion pathways were more important than from other exposure pathways. A sensitivity analysis was also performed to determine the input parameter values in the risk assessment process. In general, due to the high calculated risk of ²²⁶Ra compared with ²³²Th and ⁴⁰K it can be the major source of concern for human heath in the study area.     

Risk assessment for recrudescence of avian influenza in caged layer houses following depopulation: the effect of cleansing,disinfection and dismantling of equipment

Following an outbreak of highly pathogenic avian influenza virus (HPAIV) in a poultry house, control measures are put in place to prevent further spread. An essential part of the control measures based on the European Commission Avian Influenza Directive 2005/94/EC is the cleansing and disinfection (C&D) of infected premises. Cleansing and disinfection includes both preliminary and secondary C&D, and the dismantling of complex equipment during secondary C&D is also required, which is costly to the owner and also delays the secondary cleansing process, hence increasing the risk for onward spread. In this study, a quantitative risk assessment is presented to assess the risk of re-infection (recrudescence) occurring in an enriched colony-caged layer poultry house on restocking with chickens after different C&D scenarios. The risk is expressed as the number of restocked poultry houses expected before recrudescence occurs. Three C&D scenarios were considered, namely (i) preliminary C&D alone, (ii) preliminary C&D plus secondary C&D without dismantling and (iii) preliminary C&D plus secondary C&D with dismantling. The source-pathway-receptor framework was used to construct the model, and parameterisation was based on the three C&D scenarios. Two key operational variables in the model are (i) the time between depopulation of infected birds and restocking with new birds (TbDR) and (ii) the proportion of infected material that bypasses C&D, enabling virus to survive the process. Probability distributions were used to describe these two parameters for which there was recognised variability between premises in TbDR or uncertainty due to lack of information in the fraction of bypass. The risk assessment estimates that the median (95% credible intervals) number of repopulated poultry houses before recrudescence are 1.2 × 10⁴ (50 to 2.8 × 10⁶), 1.9 × 10⁵ (780 to 5.7 × 10⁷) and 1.1 × 10⁶ (4.2 × 10³ to 2.9 × 10⁸) under C&D scenarios (i), (ii) and (iii), respectively. Thus for HPAIV in caged layers, undertaking secondary C&D without dismantling reduces the risk by 16-fold compared to preliminary C&D alone. Dismantling has an additional, although smaller, impact, reducing the risk by a further 6-fold and thus around 90-fold compared to preliminary C&D alone. On the basis of the 95% credible intervals, the model demonstrates the importance of secondary C&D (with or without dismantling) over preliminary C&D alone. However, the extra protection afforded by dismantling may not be cost beneficial in the context of reduced risk of onward spread.     

不同气候变化情景下2070-2099年中国潜在植被及其敏感性

潜在植被作为当前气候条件、无人类干扰下,所能发育演替形成的最稳定、最成熟的一种顶极植被类型,能够反映立地植被发展的趋势。潜在植被的研究有助于人类了解植被与气候系统的作用机制,可为区域植被恢复工程和生态建设提供参考依据。基于综合顺序分类系统,利用A1B、A2及B1情景下2070-2099年气象数据对中国潜在植被进行了模拟,在不同气候变化情景下分析了未来中国潜在植被的空间分布和潜在植被对不同气候变化的敏感性。结果表明:(1)不同气候变化背景下中国潜在植被分布的规律具有相似性,但潜在植被类在总数和各情景下分布的面积存在差异性;(2)比较发现,中国的气候条件在20世纪和21世纪均不适宜炎热极干热带荒漠类(ⅦA)的发育;(3)中国潜在植被在3种气候变化情景下表现为敏感性的区域占到国土总面积的64.10%,在西北地区、北方地区、南方地区及青藏地区不同自然区敏感性地区所占各区的比例不同,分别为68.20%、70.82%、49.94%及66.59%。     

Bioaccessibility-Based Risk Assessment of PAHs in Soils from Sites of Different Anthropogenic Activities in Lagos,Nigeria Using the Fed Organic Estimation Human Simulation Test Method

The aim of this study was to carry out a bioaccessibility-based risk assessment of polycyclic aromatic hydrocarbons (PAHs) in soils from sites of different anthropogenic activities in Lagos, Nigeria. Using an in vitro gastrointestinal model—Fed Organic Estimation Human Simulation Test method (FOREShT), the concentration of bioaccessible 16 priority US Environmental Protection Agency (USEPA) PAHs in soils were determined. Total concentration of 16 priority USEPA PAHs was also determined. The concentration range was 702–253,922 ng g^?1 and 92–760 ng g^?1 for total and bioaccessible PAHs, respectively. For persons involved with activities at these sites no health risks were observed, based on bioaccessibility values of PAHs. Mean daily intake of PAHs from these soils were below the oral mean daily intake threshold for PAHs in food. Also, overall estimated theoretical cancer risk (2.5 × 10^?09, 6.5 × 10^?07, 5.5 × 10^?10, 2.7 × 10^?09, 6.5 × 10^?10, 9.5 × 10^?10, 2.0 × 10^?09, and 4.1 × 10^?07 for the eight sites based on their bioaccessible concentration) for exposure to PAHs in surface soils were below the health guidelines for extreme (1 × 10^?04) and normal (1 × 10^?06) exposures.     

Using probability of occurrence to assess potential interaction between wind farms and a residual population of golden eagle Aquila chrysaetos in NW Spain

We evaluate the areas with potential negative impacts in a golden eagle population derived of the development of wind farms. At present, the entire golden eagle Galician population (5–6 pairs) is located within an area of about 2,000 km². Grid squares of 10 × 10 km UTM in the province were scored for current and future wind turbine density and probability of occurrence of golden eagle. This probability was obtained using cartographic models of habitat selection for two different historic periods. Potential risk index (PRI) was calculated for each grid square by multiplying the wind turbine density score by the probability of occurrence score. With the PRIs obtained a cartographic model of potential impact of wind farms on the golden eagle population was constructed. No significant correlation was observed between current wind turbine density and the probability of occurrence of golden eagle. A significant positive correlation was observed between current and future wind turbine density and the probability of occurrence of golden eagle. The areas with highest potential risk are eastern and the central mountains of Ourense where the species breeds. The risk model presented could be applied to future wind farm proposals and monitor potential interactions of golden eagles with wind farms in the Province of Ourense.     

DDT and HCH (Organochlorine Pesticides) in Residential Soils and Health Assessment for Human Populations in Korba,India

Dichlorodiphenyltrichloroethane (DDT), hexachlorocyclohexane (HCH), and their isomers’ levels in residential soils were determined for the assessment of health risk in Korba, India. Observed concentrations of total HCH and total DDT in soils were more or less comparable with other parts of India and the world. ΣHCH and ΣDDT concentrations ranged between 0.9–20 μg kg^?1 and 2–315 μg kg^?1, respectively, which were lower than recommended soil quality guidelines indicating low ecotoxicological risk. Carcinogenic and non-carcinogenic impacts of HCH and DDT on human populations through soil ingestion were evaluated and presented. The incremental lifetime cancer risk (ILCR) for adults and children ranged between 7.8 × 10^?10–1.6 × 10^?7 and 4.1 × 10^?9–8.2 × 10^?7, respectively. Non-cancer health hazard quotient (HQ) ranged between 5.9 × 10^?7–1.8 × 10^?3 and 3.1 × 10^?6–9.4 × 10^?3, respectively, for adults and children. The estimated ILCR and HQ were within the safe acceptable limits of 10^?6–10^?4 and ≤1.0, respectively, indicating low risk to human populations from exposure to organochlorine pesticides (HCH and DDT) in the study area.     

Thermal and Ionic Factors in the Ultraviolet Photolysis of Plant Cell Membranes

The exposure of red beet root tissue to ultraviolet (254 nm) at 2 × 10⁶ erg × cm^?2× min^?1 (0.2 J × cm^?2× min^?1) causes release of betacyanin after a 20 minute induction period. Ultraviolet-photolysis is temperature-sensitive having a thermal threshold at about 10°C. Reduction in pigment release was effected by chlorides of Mg, Ca and Sr, but not by Li, Na or K. This effect was marked but not complete, even at 40 mM concentration. It is concluded that photolysis is indirect, and involves a lytic factor, possibly an oxidant, derived from an original photochemical product.     

耕地占补面积时空变化对碳储量的影响测度——以湖北省为例

基于InVEST模型定量评估湖北省2000-2020年耕地占补面积时空变化对陆地生态系统碳储量的影响,在县级行政单元尺度探究由耕地占补导致的碳储量变化量在空间上的集聚程度,并运用PLUS模型模拟区域未来四种发展情景下的土地利用格局及碳储量变化趋势。结果表明：（1）2000年至2020年,湖北省耕地面积净变化率为-3.89%,耕地面积略微下降,基本实现耕地占补数量平衡。（2）2000-2005年、2005-2010年、2010-2015年、2015-2020年耕地占用和补偿导致的碳储量变化值占该时段碳储量变化值的比例分别为68.45%、59.45%、57.86%、55.46%,二十年整体占比为61.38%。耕地碳储量的变化对陆地生态系统碳储量的影响巨大。碳固持的地块面积为1.29×10⁵ hm²,碳损失的地块面积为3.88×10⁵ hm²。（3）2000-2020年,湖北省耕地占补导致的碳储量变化值具有明显的空间集聚性,"高高聚集"区主要分布在西部和西南部山区,"低低聚集"区分布在中南部的江汉平原。（4）2020-2030年,湖北省陆地生态系统碳储量在自然发展情景下减少5.50×10⁶ t,在耕地保护情景下减少1.22×10⁶ t,在城镇开发情景下减少8.89×10⁶ t,在生态保护情景下增加2.43×10⁶ t。与其他三种情景相比,生态保护情景是未来发展的最优情景。研究通过定量评估耕地占补平衡背景下湖北省耕地面积时空变化对区域碳储量的影响为未来的国土空间规划以及增汇政策的制定提供决策依据和科学参考,对于实现土地资源的可持续利用和生态环境保护具有重要意义。     

Parameterizing Potential Exposure to Sulfur Mustard (HD) Using Mixed Model Regression

The possible threat posed by terrorists using chemical warfare agents (CWAs) against civilian targets is a major concern, reflecting the fact that CWAs are highly toxic to unprotected populations, with releases as vapors or aerosols likely to produce mass casualties on a highly localized basis within minutes or hours after an incident. A conceptual site model is developed and mixed model regression is used to estimate concentration values for the vesicant sulfur mustard (HD) based on the output from computational fluid dynamics (CFD) simulation following wind tunnel experimentation. The analysis provides a first-approximation of the spatial and temporal distribution of potential exposures within a set of 50 m × 50 m × 2 m grids across a 1000 m width by 300 m height by 2250 m length domain in a geographic information system (GIS) environment. The HD concentration values are calculated as log-averaged mean and the 95% confidence intervals for each grid at 1.9 d and 6.0 d after initial release. The technique offers a statistically valid means for rapidly generating unbiased first-approximations of concentration values subsequent to an initial release as an alternative to extensive monitoring or multiple runs of CFD models to parameterize potential exposure to HD spatially and temporally.     

Risk Assessment of Aflatoxin B1 from Food Consumption in the Korean General Population

Levels were evaluated of Aflatoxin B₁ (AFB1) exposure through the intake of AFB1-contaminated foods among Koreans. Average daily intake, excess cancer risk, and population risk of AFB1 from food intake were calculated from Koreans with age greater than 20 years. Average daily intake of AFB1 by food ingestion was 0.064 ～ 0.361 ng/kg bw/ day. Excess cancer risk of AFB1 in food with the surface antigen of the hepatitis B-virus negative (HBsAg^?) and positive (HBsAg⁺) population was 5.76 × 10^{? 7}～ 3.25 × 10^{? 6} and 1.47 × 10^{? 5}～ 8.31 × 10^{? 5}, respectively. Application of JECFA's two tentative maximum levels (MLs) (10 μ g/kg and 20 μ g/kg) resulted in the population risk of 0.0009 ～ 0.0075 and 0.0014 ～ 0.0079 cancers/year/100,000 people, respectively, indicating that lower ML does not give a significant reduction of the risk. However, because Korea has a high incidence of HBsAg⁺ individuals, adoption of lower ML may be a reasonable decision to protect a high risk group. This is the first report on the risk assessment of AFB1 in food among the Korean population. Our study will contribute to providing the solid basis of establishing the maximum levels of AFB1 exposure through food ingestion in Korea as well as other countries.     

1980-2030年石羊河流域生态系统碳储存服务对土地利用变化的响应

陆地生态系统碳储量是表征碳储存服务的重要指标,其变化与土地利用变化存在着密不可分的关系。预测未来土地利用变化对认识区域生态系统服务及其变化具有重要的意义。利用石羊河流域1980—2020年土地利用数据,运用InVEST模型和FLUS模型,探究了石羊河流域在过去40年间和未来自然变化、生态保护、耕地保护3种情景下的土地利用变化对碳储量的影响。结果表明：石羊河流域在1980—2020年间耕地、草地、建设用地呈增加趋势,林地、水域、未利用地呈减少的趋势。40年间石羊河流域碳储量增加了7.98×10⁶t,增幅为1.44%。石羊河流域碳储量呈现明显的空间分异,碳储量较高的地区主要分布在上游祁连山区和中下游绿洲地区,这种分布格局与流域内土地利用类型的空间分布密切相关。至2030年,自然变化、生态保护、耕地保护情景下石羊河流域碳储量分别为563×10⁶t、563.43×10⁶t、564.98×10⁶t,较2020年分别增加了0.45%、0.53%和0.80%,其中生态保护情景与其他两种情景相比既保护了生态环境还保...     

Microbial Ecosystem in Sunderban Mangrove Forest Sediment,North-East Coast of Bay of Bengal,India

This is the first documentation of seasonal and spatial fluctuation of the culturable microbial population collected from different zones in the sediment of the Sunderban mangrove forest. The population of cellulose degrading bacteria, [mean value of CFU 6.189 ± 1.025 × 10⁶ (g dry weight of sediment)^?1] was found to be maximum during post monsoon in the deep forest region, whereas, the fungal population [mean value of CFU 3.424 ± 0.886 × 10⁶ (g dry weight of sediment)^?1] was found to be maximum during pre-monsoon in the rooted region. The abundances of microbes, in decreasing order, studied from different zones are nitrifying bacteria [mean value of CFU 1.125 ± 0.359 × 10⁶ (g dry weight of sediment)^?1], phosphorous solubilizing bacteria (PSB) [mean value of CFU 0.805 ± 0.322 × 10⁶ (g dry weight of sediment)^?1], free living nitrogen fixing bacteria [mean value of CFU 0.417 ± 0.120 × 10⁶ (g dry weight of sediment)^?1] and sulfur reducing bacteria (SRB) [mean value of CFU 0.356 ± 0.125 × 10⁶ (g dry weight of sediment)^?1]. The content of organic carbon in the soil decreased from the deep forest region to the rooted and unrooted region but a reverse profile was found for soil salinity and soil silicate concentration. The results from the present study indicate that the monsoon cycle has a pronounced effect on the microbially dominated biogeochemistry in the sediment and consequently on the ecology of the Sundarban mangrove forest.     

Development of human health damage factors related to CO<Subscript>2</Subscript> emissions by considering future socioeconomic scenarios

Purpose

Global warming is exerting a damaging effect on human health. This damage is not only influenced by future climate conditions but also projected economic development and population growth. That being said, there are no health damage factors related to CO₂ emissions which take into account future socioeconomic scenarios in life cycle impact assessment (LCIA). Thus, the purpose of the current research is to calculate human health damage factors based on the Special Report on Emission Scenarios (SRESs) developed by the Intergovernmental Panel on Climate Change (IPCC).

Methods

The procedure used to calculate the SRES-based damage factors is as follows. First, a framework was developed to calculate damage factors based on multiple parameters: rise in temperature, relative risk increase, mortality rate increase, rise in number of deaths, and disability-adjusted life year (DALY) increase. Secondly, these parameters were calculated for each individual SRES based on the relationship among the parameters and CO₂ emissions, GDP, and population values of each scenario. Finally, the damage factor for each SRES was calculated by multiplying all the parameters that had been calculated based on the CO₂ emission, GDP, and population data in the corresponding scenarios.

Results and discussion

Using this method, the human health damage factors for four SRESs (A1B, A2, B1, and B2) were calculated. The damage factors consisted of six different items: malaria, diarrhea, cardiovascular disease, malnutrition, coastal flooding, and inland flooding. The calculated results by scenario were 2.0?×?10^?7, 6.2?×?10^?7, 2.1?×?10^?7, and 4.2?×?10^?7 DALY/kg CO₂, respectively. The damage caused by malnutrition is the greatest, followed by diarrhea. Regions of Southeast Asia, Africa, and the Middle East showed the highest damages due to their high damage from malnutrition and diarrhea. With regard to the differences among the four damage factors, the difference between the projected future mortality rate and DALY per death based on the future GDP per capita is greater than the difference between the increases in temperature among scenarios dependent on future CO₂ emission.

Conclusions

The human health damage factors related to CO₂ emissions for four SRESs were estimated. As a result of differences between future socioeconomic scenarios, the largest amount of damage per CO₂ emission unit was three times greater than the smallest amount. Therefore, sensitive analysis is highly recommended when seeking to compare damage caused by global warming and other impact categories.

     

IgE-mediated 14C-serotonin release from rat mast cells modulated by morphine and endorphins

The formaldehyde method was used to examine the interaction of PGE₁ with morphine, β-endorphin and Met-enkephalin on rat mast cells by their effects on IgE-mediated ¹⁴C-serotonin release. PGE₁ (2×10^?8?2×10^?5 M) caused a dose-related inhibition of the mediator release 1 min after an antigen challenge, and morphine (3×10^?7?3×10^?5 M) reversed this PGE₁ effect dose-dependently and stereospecifically; naloxone (2×10^?4 M) antagonized this action of morphine. β-Endorphin (3×10^?7?10^?5 M) and Met-enkephalin (3×10^?6?10^?4 M) mimicked this morphine action dose-dependently and were antagonized by naloxone (2×10^?4 M). These results suggest that morphine and endorphins modulate immunological mediator release from rat mast cells through opioid receptors.     

Establishment of lymphocytoid cell lines in relation to number of leukocytes,surface area of monolayer formation,and feeding procedures

Summary Twenty-eight lymphocytoid cell lines were established within 6 months from the peripheral blood of a single healthy donor. Establishment seemed independent of feeding regimens. Establishment occurred if cultures in 100-ml glass bottles (surface area of 46 cm²) were initiated with a leukocyte population between 4.9×10⁷ and 6.8×10⁷ cells, and if cultures in 16-ml test tubes (surface area of 1.8 cm²) were initiated with a total leukocyte population between 4.9×10⁶ and 2.2×10⁷ cells. It is concluded that establishment is related to a optimal relationship between number of leukocytes and the surface area for possible monolayer formation. When the surface area is decreased, the initial number of leukocytes must be reduced. Establishment of a cell line did not occur with an initial total population below 4.9×10⁶ leukocytes. There is a positive correlation between initial leukocyte number, initial growth velocity, and the determination of establishment by subculture. This work was supported in part with funds from the Mary B. and L. H. Marshall Foundation. Hans W. von Heyden is supported by a Fellowship from the Deutsche Forschungsgemeinschaft. After September 1, 1972, the authors will be at the Medizinische Universit?t Klinik II, Tübingen, West Germany.     

The migratory history of anadromous and non-anadromous tapertail anchovy Coilia nasus in the Yangtze River Estuary revealed by the otolith Sr:Ca ratio

The migratory history of tapertail anchovy Coilia nasus in the Yangtze River Estuary, China was investigated using otolith Sr:Ca ratios and two-dimensional images of the Sr level from an X-ray electron probe microanalyzer (EPMA). The results showed that 17 of the 22 young-of-the-year (YOY) specimens had low Sr:Ca ratios (1.2–2.4?×?10^?3;1.5?±?0.3?×?10^?3) at the central otolith area, indicating their riverine origin and initial freshwater residence. In addition, 11 of the 14 adult specimens had low Sr:Ca ratios (1.3–2.2?×?10^?3; 1.7?±?0.4?×?10^?3) at the central otolith area but showed alternating changes between high (>4.0?×?10^?3) and low (<2.5?×?10^?3) values outside of this region, reflecting their riverine origin and the migration between freshwater and estuarine habitats. These 28 specimens represented the anadromous population in this region. The other 5 YOY specimens had high Sr:Ca ratios (3.6–5.9?×?10^?3; 4.8?±?0.8?×?10^?3) throughout the life history. Similarly, the other 3 adult specimens had high Sr:Ca ratios (4.0–5.7?×?10^?3; 4.8?±?0.7?×?10^?3) at the central otolith area but showed alternating changes between low and high values outside this region, suggesting that estuarine-origin non-anadromous individuals occurred in this region. The average of the otolith Sr:Ca ratios and Sr level mapping along the life-history transects could be used as a scalar for charting the migratory history of the tapertail anchovy in the Yangtze River Estuary: <2.0?×?10^?3 for freshwater residence and 3.5–6.0?×?10^?3 for estuarine residence.     

基于景观结构的生态移民安置区生态风险评价——以宁夏红寺堡区为例

以宁夏自治区红寺堡区为例,以1995年、2000年、2005、2010年和2015年5期遥感影像为数据源,综合运用景观格局指数、生态风险指数、空间分析法以及地理探测器等多种研究方法,研究了移民安置区生态风险时空特征。结果表明:1995—2015年研究区景观格局发生了较大的变化,草地面积减少了2.97×10~4hm~2,耕地、林地、建设用地分别增加了1.90×10~4hm~2,0.42×10~4hm~2和0.43×10~4hm~2;在研究期间景观整体斑块数不断增加,其景观整体破碎度随之变大;研究区生态风险主要以较低风险和中风险为主,其中建设用地、沙地和未利用地生态风险值较高,在研究期间生态风险平均值由0.166降低至0.154,研究区生态风险值呈降低趋势。通过地理探测器诊断得出景观斑块数、景观破碎度、景观优势度、景观损失度、斑块密度等因素是安置区生态风险的主要影响因素。