Arsenate and perchlorate toxicity, growth effects, and thyroid histopathology in hypothyroid zebrafish Danio rerio

Exposure to perchlorate or other thyrotoxic compounds can cause hypothyroidism in most vertebrates, and this may affect levels of endogenous antioxidants and cause oxidative stress. Arsenic also induces oxidative stress in animals by modifying the antioxidant capacity and may alter the thyroid homeostasis. Therefore, hypothyroidism may affect the toxicity of arsenate. In order to test this hypothesis, zebrafish (Danio rerio) were made hypothyroid by exposure to perchlorate, and toxicity of arsenate in hypothyroid and euthyroid fish was compared. The endpoints were LC50 and thyroid histopathology. Additionally, the recovery of thyroid histopathological indices after cessation of perchlorate exposure was determined. The current study showed that 96 h LC50 of perchlorate anion and arsenate ion to juveniles fish (37 day post-fertilization) were 2532 and 56 mg l(-1), respectively. In addition, hypothyroid fish were more sensitive to arsenate, with a 96 h LC50 of 43 mg l(-1). Growth rates were also significantly retarded by perchlorate exposure. After cessation of perchlorate exposure, there was recovery of thyroid histopathology in terms of epithelial cell height, but not colloid area or growth rate. In conclusion, perchlorate enhances arsenate toxicity to juvenile zebrafish, and the rate of thyroid recovery after cessation of perchlorate exposure depends on the endpoints examined.     

Consolidation in an Individual Transferable Quota Regime: Lessons from New Zealand, 1986–1999

Market-based approaches to environmental regulation (such as tradable permits or transferable quotas) are frequently offered as innovative solutions to many environmental problems. Globally, one of the most well-established forms of this approach is individual transferable quotas (or ITQs) in fisheries management. Within the natural resource management community, there is considerable debate over the effects ITQs have on the fishing industry and fisher behavior although this approach is not well-established in the United States. The previously imposed moratorium on ITQs in the United States has expired and the 2006 reauthorization of the Magnuson-Stevens Act explicitly provides for limited access privileges (LAPs). A variety of fishers, regulators, and conservation organizations are enthusiastically seeking to introduce ITQ management. With debate over whether and how ITQs should be used in American fisheries reinvigorated, it is timely to examine the evidence on the social and economic effects of ITQs in other nations’ fisheries. After briefly summarizing the debate on ITQs, we examine the case of New Zealand, one of the earliest and longest-lived ITQ-based fisheries regimes. We use multiple data sources and methods to analyze the extent to which industry consolidation and aggregation has occurred, including surveys of industry participants, expert interviews, reviews of academic reports and analyses, analysis of trade publications, and direct analysis of quota ownership patterns. This analysis shows a more complex outcome than recent debates in the ITQ literature would predict. These findings suggest that policy makers considering ITQs can learn from the experiences of other countries related to key issues such as quota allocation, aggregation limits, transferability, cost recovery, and resource sustainability when designing ITQ and other LAP systems. It is also important to explicitly identify economic and social objectives and then carefully design ITQ regimes to meet these objectives.     

A Template for Integrated Community Sustainability Planning

This article describes a template for implementing an integrated community sustainability plan. The template emphasizes community engagement and outlines the components of a basic framework for integrating ecological, social and economic dynamics into a community plan. The framework is a series of steps that support a sustainable community development process. While it reflects the Canadian experience, the tools and techniques have applied value for a range of environmental planning contexts around the world. The research is case study based and draws from a diverse range of communities representing many types of infrastructure, demographics and ecological and geographical contexts. A critical path for moving local governments to sustainable community development is the creation and implementation of integrated planning approaches. To be effective and to be implemented, a requisite shift to sustainability requires active community engagement processes, political will, and a commitment to political and administrative accountability, and measurement.     

Building recycling rates through the informal sector

Many developing country cities aspire to modern waste management systems, which are associated with relatively high recycling rates of clean, source separated materials. Most already have informal sector recycling systems, which are driven solely by the revenues derived from selling recovered materials, even though they are saving the formal sector money by reducing waste quantities. There is clear potential for 'win-win' co-operation between the formal and informal sectors, as providing support to the informal sector, to build recycling rates and to address some of the social issues could reduce the overall costs of waste management for the formal sector. This paper shows that recycling rates already achieved by the informal sector can be quite high, typically in the range from 20% to 50%; often up to half of this is in the form of clean, source separated materials collected directly from households and businesses by itinerant waste buyers. Four country case studies provide a number of lessons on how this solid foundation could be used to build high recycling rates of clean materials.     

Characterizing long-term hydrologic-response and sediment-transport for the R-5 catchment

Recently there have been several calls to establish long-term data collection networks to monitor near-surface hydrologic response and landscape evolution. The focus of this paper is a long-term dataset from the International Hydrologic Decade (1965-1974). The small upland catchment, known as R-5, located near Chickasha, Olahoma, has been the subject of considerable attention within the event-based hydrologic modeling community for more than 30 yr. Here, for the first time, 8 yr of continuous near-surface hydrologic-response and sediment-transport data are analyzed to show trends in the catchment's long-term behavior. The datasets include precipitation, temperature, solar radiation, soil-water content, infiltration, water discharge, and sediment discharge. Potential and actual evapotranspiration rates were estimated and used to calculate an average annual water balance for the catchment. Findings include, for example, that rainfall intensity rarely exceeds the threshold for Horton-type runoff, soil-water content is both spatially and temporally variable, and the water and sediment discharge rates are positively correlated. The R-5 data provide a unique opportunity to test (and refine) process-based models of continuous hydrologic response and sediment transport at the catchment scale for applications in the emerging fields of hydroecology and hydrogeomorphology.     

Science guides search and rescue after the 2006 Philippine landslide

A rockslide-debris avalanche destroyed the remote village of Guinsaugon in Southern Leyte, Philippines, on 17 February 2006. Although search and rescue procedures were implemented immediately, the scale of the landslide and a lack of information about its nature resulted in unfocused and imprecise efforts in the early days of the operation. Technical support was only introduced five days after the event, provided by a team of volunteer geologists, geophysicists, and meteorologists. By the time search and rescue operations were transferred to specific target sites, however, the chances of finding survivors trapped under the rubble had diminished. In such critical situations, speed, accuracy, and the maximum appropriation of resources are crucial. We emphasise here the need for a systematic and technically informed approach to search and rescue missions in large-scale landslide disaster contexts, and the formulation of better disaster management policies in general. Standard procedures must be developed and enforced to improve how civil authorities respond to natural calamities.     

Nitrogen fluxes through unsaturated zones in five agricultural settings across the United States

The main physical and chemical controls on nitrogen (N) fluxes between the root zone and the water table were determined for agricultural sites in California, Indiana, Maryland, Nebraska, and Washington from 2004 to 2005. Sites included irrigated and nonirrigated fields; soil textures ranging from clay to sand; crops including corn, soybeans, almonds, and pasture; and unsaturated zone thicknesses ranging from 1 to 22 m. Chemical analyses of water from lysimeters and shallow wells indicate that advective transport of nitrate is the dominant process affecting the flux of N below the root zone. Vertical profiles of (i) nitrogen species, (ii) stable isotopes of nitrogen and oxygen, and (iii) oxygen, N, and argon in unsaturated zone air and correlations between N and other agricultural chemicals indicate that reactions do not greatly affect N concentrations between the root zone and the capillary fringe. As a result, physical factors, such as N application rate, water inputs, and evapotranspiration, control the differences in concentrations among the sites. Concentrations of N in shallow lysimeters exhibit seasonal variation, whereas concentrations in lysimeters deeper than a few meters are relatively stable. Based on concentration and recharge estimates, fluxes of N through the deep unsaturated zone range from 7 to 99 kg ha(-1) yr(-1). Vertical fluxes of N in ground water are lower due to spatial and historical changes in N inputs. High N fluxes are associated with coarse sediments and high N application rates.     

Mapping the global supply and demand structure of rice

Rice plays a major role in the global supply and demand for sustainable food production. The constraints of maintaining sustainable rice production are closely linked to the relationship between the distribution patterns of human activity on the planet and economic growth. Global patterns of rice production can be mapped by using various criteria linked to domestic income, population patterns, and associated satellite brightness data of rice-producing regions. Prosperous regions have more electric lighting, and there are documented correlations between gross domestic product (GDP) and nighttime light. We chose to examine global rice production patterns on a geographical basis. For the purposes of this study, each country is considered to be made up of regions, and rice production is discussed in terms of regional distribution. A region is delineated by its administrative boundaries; the number of regions where rice is produced is about 13,839. We used gridded spatial population distribution data overlain by nocturnal light imagery derived from satellite imagery. The resultant relationship revealed a correlation between regional income (nominal values of GDP were used) and rice production in the world. The following criteria were used to examine the supply and demand structure of rice. Global rice consumption = “caloric rice consumption per capita per day” multiplied by “regional population values”. Regional rice yields = “country-based production” divided by “harvested area” (multiple harvests are taken into account). Regional rice production = “regional harvested areas” multiplied by “rice yield values”. We compared regional rice consumption and production values according to these methods. Analysis of the data sets generated a map of rice supply and demand. Inter-regional shipping costs were not accounted for. This map can contribute to the understanding of food security issues in rice-producing regions and to estimating potential population values in such regions.     

Using multitemporal Landsat TM imagery to establish land use pressure induced trends in forest and woodland cover in sections of the Soutpansberg Mountains of Venda region, Limpopo Province, South Africa

Globally, tropical forests are being perturbed by human activity. Tropical vegetation constitutes some of the largest terrestrial carbon stocks against the build up of greenhouse gases. In this paper, a local-scale case study utilising remote sensing methodology in estimating forest loss is presented, for a section of tropical South Africa’s Soutpansberg Mountains where land use pressure threatens some of the last remaining indigenous forests. Landsat TM images from October 1990, August 2000 and September 2006 were used, together with municipality level demographic data. Hybrid image classification techniques distinguished forest cover on the images, which were classified into vegetation density categories. About 20% of forest and woodland cover was lost in the 16-year analysis period, mainly due to pine and eucalyptus plantation and residential housing expansions. The local-scale key drivers behind the deforestation are examined.     

Sources and deposition of reactive gaseous mercury in the marine atmosphere

Observations of reactive gaseous mercury (RGM) in marine air show a consistent diurnal cycle with minimum at night, rapid increase at sunrise, maximum at midday, and rapid decline in afternoon. We use a box model for the marine boundary layer (MBL) to interpret these observations in terms of RGM sources and sinks. The morning rise and midday maximum are consistent with oxidation of elemental mercury (Hg⁰) by Br atoms, requiring <2 ppt BrO in most conditions. Oxidation of Hg⁰ by Br accounts for 35–60% of the RGM source in our model MBL, with most of the remainder contributed by oxidation of Hg⁰ by ozone (5–20%) and entrainment of RGM-rich air from the free troposphere (25–40%). Oxidation of Hg⁰ by Cl is minor (3–7%), and oxidation by OH cannot reproduce the observed RGM diurnal cycle, suggesting that it is unimportant. Fitting the RGM observations could be achieved in the model without oxidation of Hg⁰ by ozone (leaving Br as the only significant oxidant) by increasing the entrainment flux from the free troposphere. The large relative diurnal amplitude of RGM concentrations implies rapid loss with a lifetime of only a few hours. We show that this can be quantitatively explained by rapid, mass-transfer-limited uptake of RGM into sea-salt aerosols as HgCl₃^? and HgCl₄^2?. Our results suggest that 80–95% of Hg^II in the MBL should be present in sea-salt aerosol rather than gas-phase, and that deposition of sea-salt aerosols is the major pathway delivering Hg^II to the ocean.