不同粒度锡采矿废石重金属淋溶规律及影响机制

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.     

Risk aversion and adaptive management: Insights from a multi-armed bandit model of invasive species risk

This article explores adaptive management (AM) for decision-making under environmental uncertainty. In the context of targeting invasive species inspections of agricultural imports, I find that risk aversion increases the relative value of AM and can increase the rate of exploratory action. While calls for AM in natural resource management are common, many analyses have identified modest gains from this approach. I analytically and numerically examine the distribution of outcomes from AM under risk neutrality and risk aversion. The inspection decision is framed as a multi-armed bandit problem and solved using the Lagrangian decomposition method. Results show that even when expected gains are modest, asymmetry in the distribution of outcomes has important implications. Notably, AM can serve to buffer against large losses, even if the most likely outcome is a small loss.     

好氧-厌氧两相堆肥过程中抗生素耐药基因的变化特征及影响因素研究

针对堆肥处理过程中抗生素耐药基因（antibiotic resistance genes,ARGs）去除效率不高、诱导潜在致病菌传播扩散等环境安全问题,采用好氧-厌氧两相堆肥处理猪粪、秸秆,探讨ARGs丰度及微生物群落的变化特征,并明确影响ARGs相对丰度变化的关键因子.结果表明:与单一好氧相比,好氧-厌氧两相堆肥能更有效地降低部分ARGs及潜在致病菌的相对丰度,其中ermB、tetK的相对丰度分别降低了39.68%、72.19%,假单胞菌属（Pseudomonas）、梭菌属（Clostridium_sensu_stricto_1）的相对丰度分别降低了96.09%、90.07%.主成分分析（Principal Component Analysis,PCA）及冗余分析（Redundancy analysis,RDA）得出,微生物群落和环境因子均显著影响ARGs相对丰度的变化（P < 0.05）,贡献率分别为82.0%、71.2%.其中,梭菌属（Clostridium_sense_stricto_1）、黄杆菌属（Flavobacterium）、尿素芽孢杆菌属（Ureibacillus）和海洋杆菌属（Oceanobacillus）是影响ARGs相对丰度变化的主要微生物菌属;温度、电导率、含水率和pH是影响ARGs相对丰度变化的关键环境因子,贡献率分别为22.0%、16.7%、16.2%和15.0%.研究显示:与好氧堆肥相比,好氧-厌氧两相堆肥能更有效地去除ARGs,并抑制潜在致病菌的繁殖扩散,从而减少环境风险;然而部分ARGs和潜在致病菌仍存在增殖现象,因此亟需进一步优化好氧-厌氧两相堆肥工艺.      

Identifying fishing trip behaviour and estimating fishing effort from VMS data using Bayesian Hidden Markov Models

Recent advances in technologies have lead to a vast influx of data on movements, based on discrete recorded position of animals or fishing boats, opening new horizons for future analyses. However, most of the potential interest of tracking data depends on the ability to develop suitable modelling strategies to analyze trajectories from discrete recorded positions. A serious modelling challenge is to infer the evolution of the true position and the associated spatio-temporal distribution of behavioural states using discrete, error-prone and incomplete observations. In this paper, a Bayesian Hierarchical Model (HBM) using Hidden Markov Process (HMP) is proposed as a template for analyzing fishing boats trajectories based on data available from satellite-based vessel monitoring systems (VMS). The analysis seeks to enhance the definition of the fishing pressure exerted on fish stocks, by discriminating between the different behavioural states of a fishing trip, and also by quantifying the relative importance of each of these states during a fishing trip. The HBM approach is tested to analyse the behaviour of pelagic trawlers in the Bay of Biscay. A hidden Markov chain with a regular discrete time step is used to model transitions between successive behavioural states (e.g., fishing, steaming, stopping (at Port or at sea)) of each vessel. The parameters of the movement process (speed and turning angles) are defined conditionally upon the behavioural states. Bayesian methods are used to integrate the available data (typically VMS position recorded at discrete time) and to draw inferences on any unknown parameters of the model. The model is first tested on simulated data with different parameters structures. Results provide insights on the potential of HBM with HMP to analyze VMS data. They show that if VMS positions are recorded synchronously with the instants at which the process switch from one behavioural state to another, the estimation method provides unbiased and precise inferences on behavioural states and on associated movement parameters. However, if the observations are not gathered with a sufficiently high frequency, the performance of the estimation method could be drastically impacted when the discrete observations are not synchronous with the switching instants. The model is then applied to real pathways to estimate variables of interest such as the number of operations per trip, time and distance spent fishing or travelling.     

Determining the community structure of the coral Seriatopora hystrix from hydrodynamic and genetic networks

The exchange of genetic information between coral reefs through the transport of larvae can be described in terms of networks that capture the linkages between distant populations. A key question arising from these networks is the determination of the highly connected modules (communities). Communities can be defined using genetic similarity or distance statistics between multiple samples but due to limited specimen sampling capacity the boundaries of the communities for the known coral reefs in the seascape remain unresolved. In this study we use the microsatellite composition of individual corals to compare sample populations using a genetic dissimilarity measure (F_ST) which is then used to create a complex network. This network involved sampling 1025 colonies from 22 collection sites and examining 10 microsatellites loci. The links between each sampling site were given a strength that was created from the pair wise F_ST values. The result is an undirected weighted network describing the genetic dissimilarity between each sampled population. From this network we then determined the community structure using a leading eigenvector algorithm within graph theory. However, given the relatively limited sampling conducted, the representation of the regional genetic structure was incomplete. To assist with defining the boundaries of the genetically based communities we also integrated the communities derived from a hydrodynamic and distance based networks. The hydrodynamic network, though more comprehensive, was of smaller spatial extent than our genetic sampling. A Bayesian Belief network was developed to integrate the overlapping communities. The results indicate the genetic population structure of the Great Barrier Reef and provide guidance on where future genetic sampling should take place to complete the genetic diversity mapping.     

温室气体光声光谱检测系统的建立及效果分析

“双碳”目标下,温室气体在线长期稳定监测技术是全面掌握温室气体排放及其环境、气候效应,并预测未来变化趋势的重要保障。为了实时在线监测工业生产现场等环境温室气体浓度及其变化趋势,及时采取相应措施,在分析光声光谱信号产生机理及多组分气体混合监测原理的基础上,根据温室气体的主要成分,分析其吸收光谱特性,基于光声光谱的多组分温室气体的定性和定量监测技术,搭建温室气体光声光谱在线监测实验平台,分析监测器内部噪声和环境温度、湿度等外部影响因素,并通过现场测试,分析试验数据,应用吸附法降低内外部因素的影响。结果表明,对称安装传声器和非共振式光声腔能有效削弱外部噪声对测试结果的影响;空气净化器能降低空气中水蒸气和其他气体对测试结果的影响;低、高浓度混合气体监测结果偏差均小于0.5,与GC测试结果偏差小于10%。应用光声光谱技术的环境温室气体监测技术监测范围宽,选择性好,且监测精度达10^-6,适用于环境温室气体浓度在线监测。     

Transboundary Issues in Wilderness Management

/ The management of lands adjacent to federally designated wilderness is increasingly seen to have the potential to negatively impact wilderness resources and management objectives. This paper first examines the numerous and often conflicting laws and regulations that influence how managers can mitigate transboundary issues. We then examine the various types of transboundary issues, and describe how they impact wilderness resources. Transboundary issues include recreational use, extractive activities, fire management, exotic species introductions, aircraft overflights and military operations, water diversion, urban encroachment, and transported pollutants. KEY WORDS: Adjacent lands; Buffer zones; Ecosystem management; Wilderness; Zones of influence     

三唑酮在水中的光化学降解及其影响因素

以太阳光和高压汞灯为光源，研究了水溶液中三唑酮光化学降解的影响因子。结果表明：在不同光源和透光介质下，三唑酮的降解能力从大到小依次为：石英试管＋高压汞灯、玻璃试管＋高压汞灯、石英试管＋太阳光、玻璃试管＋太阳光、暗室；水溶液中三唑酮初始浓度越高，其光降解率越低，呈负相关关系；丙酮对三唑酮在水中的光解有极显著的光敏作用，光敏效率与丙酮添加量有显著相关性；三唑酮的光解实质为光氧化作用，溶解氧含量对三唑酮光解有重大影响。     

大亚湾水体营养盐分布特征及其生态环境效应

2019年秋季和2020年春季在大亚湾海域开展了生态环境现状调查,调查要素包括水温、盐度、pH、溶解氧、化学需氧量(COD)、溶解无机氮(DIN)、磷酸盐(DIP)、叶绿素a等。秋季DIN和DIP平均浓度分别为(5.00±3.36)、(0.31±0.56) μmol/L,春季分别为(3.12±1.97)、(0.13±0.05) μmol/L,春季DIN和DIP含量低于秋季。秋、春季DIN和DIP高值区均位于淡澳河入海口、哑铃湾和范和港湾口以及渔业养殖和港口交汇海域,且呈现自湾顶至湾口逐渐减小趋势,主要受入海径流、外海水入侵、渔业养殖、污水排放等多重因素影响。大部分海域处于贫营养化状态,仅湾顶局部海域为中度富营养化水平。春季叶绿素a平均值为(2.10±1.07) μg/L,大于秋季[(0.83±0.54) μg/L],秋、春季叶绿素a空间分布大体与营养盐相同,即湾顶高,湾中和湾口逐渐降低,秋、春季N/P平均值分别为30.52±20.09和26.68±17.70,湾顶浮游植物繁殖的主要限制因子为磷,湾口的主要限制因子为氮。     

Dynamic risk analysis of offloading process in floating liquefied natural gas (FLNG) platform using Bayesian Network

The growing demand for natural gas has pushed oil and gas exploration to more isolated and previously untapped regions around the world where construction of LNG processing plants is not always a viable option. The development of FLNG will allow floating plants to be positioned in remote offshore areas and subsequently produce, liquefy, store and offload LNG in the one position. The offloading process from an FLNG platform to a gas tanker can be a high risk operation. It consists of LNG being transferred, in hostile environments, through loading arms or flexible cryogenic hoses into a carrier which then transports the LNG to onshore facilities. During the carrier's offloading process at onshore terminals, it again involves risk that may result in an accident such as collision, leakage and/or grounding. It is therefore critical to assess and monitor all risks associated with the offloading operation. This study is aimed at developing a novel methodology using Bayesian Network (BN) to conduct the dynamic safety analysis for the offloading process of an LNG carrier. It investigates different risk factors associated with LNG offloading procedures in order to predict the probability of undesirable accidents. Dynamic failure assessment using Bayesian theory can estimate the likelihood of the occurrence of an event. It can also estimate the failure probability of the safety system and thereby develop a dynamic failure assessment tool for the offloading process at a particular FLNG plant. The main objectives of this paper are: to understand the LNG offloading process, to identify hazardous events during offloading operation, and to perform failure analysis (modelling) of critical accidents and/or events. Most importantly, it is to evaluate and compare risks. A sensitivity analysis has been performed to validate the risk models and to study the behaviour of the most influential factors. The results have indicated that collision is the most probable accident to occur during the offloading process of an LNG carrier at berth, which may have catastrophic consequences.