Micropollutant content of Sargassum drifted ashore: arsenic and chlordecone threat assessment and management recommendations for the Caribbean

Environmental Science and Pollution Research - Massive Sargassum beachings occurred since 2011 on Caribbean shores. Sargassum inundation events currently involve two species, namely S. fluitans and...     

A Simulation-Based Assessment of Alternative Explanations for Apparent Confounding in “PM Decomposition” Studies

Environmental Modeling & Assessment - Determining whether there is a causal link between chronic exposure to PM2.5 (atmospheric particulate matter with a diameter of 2.5 µm or...     

Vascular plant extinction in the continental United States and Canada

Extinction rates are expected to increase during the Anthropocene. Current extinction rates of plants and many animals remain unknown. We quantified extinctions among the vascular flora of the continental United States and Canada since European settlement. We compiled data on apparently extinct species by querying plant conservation databases, searching the literature, and vetting the resulting list with botanical experts. Because taxonomic opinion varies widely, we developed an index of taxonomic uncertainty (ITU). The ITU ranges from A to F, with A indicating unanimous taxonomic recognition and F indicating taxonomic recognition by only a single author. The ITU allowed us to rigorously evaluate extinction rates. Our data suggest that 51 species and 14 infraspecific taxa, representing 33 families and 49 genera of vascular plants, have become extinct in our study area since European settlement. Seven of these taxa exist in cultivation but are extinct in the wild. Most extinctions occurred in the west, but this outcome may reflect the timing of botanical exploration relative to settlement. Sixty-four percent of extinct plants were single-site endemics, and many occurred outside recognized biodiversity hotspots. Given the paucity of plant surveys in many areas, particularly prior to European settlement, the actual extinction rate of vascular plants is undoubtedly much higher than indicated here.     

Occupational risk of exposure to methicillin-resistant Staphylococcus aureus (MRSA) and the quality of infection hygiene in nursing homes

• Staff members were not colonised with MRSA. • But staff were exposed to MRSA from air, sedimented dust and surfaces. • MRSA was found in the rooms of MRSA-colonised residents but not in common areas. • Staff worry about MRSA and spreading it to other residents, family, and acquaintances. • The use of protective eyewear and facemasks could be improved. Methicillin-resistant Staphylococcus aureus (MRSA) is an increasing health concern across the globe and is often prevalent at long-term care facilities, such as nursing homes. However, we know little of whether nursing home staff is exposed to MRSA via air and surfaces. We investigated whether staff members at nursing homes are colonised with and exposed to culturable MRSA, and assessed staff members’ self-reported knowledge of MRSA and compliance with infection hygiene guidelines. Five nursing homes with MRSA positive residents were visited in Copenhagen, Denmark. Personal bioaerosol exposure samples and environmental samples from surfaces, sedimented dust and bioaerosols were examined for MRSA and methicillin-susceptible S. aureus (MSSA) to determine occupational exposure. Swabs were taken from staffs’ nose, throat, and hands to determine whether they were colonised with MRSA. An online questionnaire about MRSA and infection control was distributed. No staff members were colonised with MRSA, but MRSA was detected in the rooms of the colonised residents in two out of the five nursing homes. MRSA was observed in air (n = 4 out of 42, ranging from 2.9–7.9 CFU/m³), sedimented dust (n = 1 out of 58, 1.1 × 10³ CFU/m²/d), and on surfaces (n = 9 out of 113, 0.04–70.8 CFU/m²). The questionnaire revealed that half of the staff members worry about spreading MRSA to others. Identified aspects for improvement were improved availability and use of protective equipment, not transferring cleaning supplies (e.g., vacuum cleaners) between residents’ rooms and to reduce worry of MRSA, e.g., through education.     

A Precautionary Approach to Genetically Modified Organisms: Challenges and Implications for Policy and Science

The commercial introduction of genetically modified organisms (GMOs) has revealed a broad range of views among scientists and other stakeholders on perspectives of genetic engineering (GE) and if and how GMOs should be regulated. Within this controversy, the precautionary principle has become a contentious issue with high support from skeptical groups but resisted by GMO advocates. How to handle lack of scientific understanding and scientific disagreement are core issues within these debates. This article examines some of the key issues affecting precaution as a legal standard and as an approach to the use of science in decision-making processes. It is pointed out that there is a need for reflection over the level of scientific evidence required for applying the precautionary principle as well as who should have the burden of proof when there are uncertainties. Further, an awareness of the broader scientific uncertainties found in GMO risk assessment implies that a precautionary approach must be elaborated: both for acknowledging uncertainties and for identification of scientific responses. Since precaution is an important issue within the sustainable development framework, it is suggested that sustainability can provide a normative standard that can help to reveal the influence and negotiate the importance of the various forms of uncertainty. Wise management of uncertainties and inclusion of normative aspects in risk assessment and management may help to ensure sustainable and socially robust GMO innovations at present and in the future.     

Governing Change: Land-Use Change and the Prevention of Nonpoint Source Pollution in the North Coastal Basin of California

Many rural areas in the United States and throughout much of the postindustrial world are undergoing significant ecological, socioeconomic, and political transformations. The migration of urban and suburban dwellers into rural areas has led to the subdivision of large tracts of land into smaller parcels, which can complicate efforts to govern human–environmental problems. Non-point source (NPS) pollution from private rural lands is a particularly pressing human–environmental challenge that may be aggravated by changing land tenure. In this article, I report on a study of the governance and management of sediment (a common NPS pollutant) in the North Coastal basin of California, a region undergoing a transition from traditional extractive and agricultural land uses to rural residential and other alternative land uses. I focus on the differences in the governance and management across private timber, ranch, residential, vacation, and other lands in the region. I find that (1) the stringency and strength of sediment regulations differ by land use, (2) nonregulatory programs tend to target working landscapes, and (3) rural residential landowners have less knowledge of sediment control and report using fewer sediment-control techniques than landowners using their land for timber production or ranching. I conclude with an exploration of the consequences of these differences on an evolving rural landscape.     

Methods for measuring denitrification: diverse approaches to a difficult problem.

Denitrification, the reduction of the nitrogen (N) oxides, nitrate (NO3-) and nitrite (NO2-), to the gases nitric oxide (NO), nitrous oxide (N2O), and dinitrogen (N2), is important to primary production, water quality, and the chemistry and physics of the atmosphere at ecosystem, landscape, regional, and global scales. Unfortunately, this process is very difficult to measure, and existing methods are problematic for different reasons in different places at different times. In this paper, we review the major approaches that have been taken to measure denitrification in terrestrial and aquatic environments and discuss the strengths, weaknesses, and future prospects for the different methods. Methodological approaches covered include (1) acetylene-based methods, (2) 15N tracers, (3) direct N2 quantification, (4) N2:Ar ratio quantification, (5) mass balance approaches, (6) stoichiometric approaches, (7) methods based on stable isotopes, (8) in situ gradients with atmospheric environmental tracers, and (9) molecular approaches. Our review makes it clear that the prospects for improved quantification of denitrification vary greatly in different environments and at different scales. While current methodology allows for the production of accurate estimates of denitrification at scales relevant to water and air quality and ecosystem fertility questions in some systems (e.g., aquatic sediments, well-defined aquifers), methodology for other systems, especially upland terrestrial areas, still needs development. Comparison of mass balance and stoichiometric approaches that constrain estimates of denitrification at large scales with point measurements (made using multiple methods), in multiple systems, is likely to propel more improvement in denitrification methods over the next few years.     

模拟酸雨下自然红壤与污染红壤中Cd,Cu,Zn的释放特征

通过对2个自然红壤和2个污染红壤的模拟酸雨土柱淋溶试验,研究了酸雨作用下红壤中重金属Cd,Cu,Zn的释放特征与影响因素,比较了自然红壤与污染红壤重金属释放特征的差异,结果表明,自然红壤中Cd,Cu,Zn的释放量均随酸雨淋溶量增加而线性增加,累积释放量有Zn＞Cu＞Cd的规律,并且随酸雨酸度增加而增加,3种重金属释放量之间存在显著的线性关系,在污染红壤中,Cd的释放随着酸雨淋溶量的增加呈现对数型增长,Cu的释放模式仍为直线型增长,而Zn的释放在弱酸性酸雨作用下为直线型增长,在强酸性酸雨作用下则为对数型增长,3种重金属释放鼍之间存在非线性关系,污染红壤中重金属释放量顺序为Cd＞Zn＞＞Cu,大约26%-76%的外源Cd和11%-68%的外源Zn被酸雨淋溶释放,但99%以上的外源Cu被土壤吸附,同时,3种重金属累积释放量均与淋出液中H+离子累积量呈现显著的对数关系;Cd和Zn与TOC累积释放量之间呈现显著的对数关系,Cu与TOC呈现显著的乘幂关系,在酸雨作用下,自然红壤由于重金属释放最很小,出现重金属污染的可能性较小;但污染红壤中大量Cd和zn的释放可能导致土壤,水体系统发生重金属污染.     

Remediation of chloroform in fine-textured soil using zero-valent iron

Chloroform, a probable human carcinogen, is mainly produced anthropogenically for industrial use and may be released to the environment from a large number of sources related to its manufacture and use, including pulp and paper mills, hazardous waste sites, and sanitary landfills. Remediation of chloroform through conventional technologies has been met with limited success due to the conditions required and the formation of hazardous substances such as dichloromethane. The objective of this study was to investigate chloroform reduction in multicontaminated fine-textured soil using zero-valent iron (Fe⁰) in anaerobic microcosms. Four amended matrices were tested: simple matrix control (glass beads), soil matrix control (glass beads + soil), Fe⁰ in a simple matrix (glass beads + Fe⁰), and Fe⁰ in a soil matrix (soil + Fe⁰). Headspace chloroform and its transformation products dichloromethane, chloromethane, and methane were measured over 230 days and during short intervals in the initial 3 days. Chloroform (~0.3 mM initial mass) persisted in both control microcosms but was completely transformed in microcosms containing soil + Fe⁰ by 12 h and glass beads + Fe⁰ by 48 h. Reductive dechlorination of chloroform occurred with simultaneous production of dichloromethane (~0.11 to 0.14 mM mass) and chloromethane (~0.02 to 0.13 mM mass). Little methane (~0.07 to 0.26 μM mass) production as an end product of chloroform reduction was observed in microcosms amended with Fe⁰. Produced dichloromethane and chloroform almost disappeared by 230 days. The results showed a complete chloroform transformation pathway that has good potential for the remediation of chlorinated compounds in fine-textured soil. The role of soil clay minerals in redox reactions can be further investigated to improve the reductive dechlorination of chlorinated compounds in contaminated environments.