221-240 of 328 Results

Article

Nomadism  

Philip Carl Salzman

Nomadism is a technique of population movement used to accomplish a variety of goals. It is used for primary production when the resources to be tapped are distributed thinly over a wide space, or are located in different places in a large region. Commonly nomadism is a technique used in a spatially extensive adaptation. Pastoralists raising domestic animals on natural pasture move from grazed areas to areas with fresh pasture, and from dry areas to those with water. Nomadism follows regular patterns where the resources tapped are reliable and thus predictable. This is common in macro-environmental adaptations to factors such as seasons and altitude. Some pastoralists have mountain adaptations, migrating to high altitudes in summer and low altitudes in winter, an adaptation called transhumance in Europe. Nomadic patterns are more irregular when rainfall patterns, and thus pasturage, are erratic and unpredictable, as is common in desert areas with low rainfall. Among some pastoral peoples, all of the households in the community move together. Among other pastoral peoples, a sector of the populations is nomadic; young and/or mature men migrate with the livestock, while women, children, and elders remain in a stationary home settlement. This is also the pattern in European transhumance. Many pastoral peoples produce primarily for their own subsistence; it is common that they have multi-resource or mixed economies, engaging also in hunting and gathering, horticulture, agriculture, and arboriculture. Economic activities are not limited to primary production; patterns of predation, including raiding and extortion, against other pastoralists, farmers, and traders are widespread. Other pastoral peoples are heavily market-oriented, producing for sale, or have symbiotic relations with hunters or cultivators; it is normal that they are more specialized in their production. But pastoralists can be found at all points on a continuum between subsistence- and market-oriented.

Article

Nutrient Pollution and Wastewater Treatment Systems  

Archis R. Ambulkar

Since the industrial revolution, societies across the globe have observed significant urbanization and population growth. Newer technologies, industries, and manufacturing plants have evolved over the period to develop sophisticated infrastructures and amenities for mankind. To achieve this, communities have utilized and exploited natural resources, resulting in sustained environmental degradation and pollution. Among various adverse ecological effects, nutrient contamination in water is posing serious problems for the water bodies worldwide. Nitrogen and phosphorus are the basic constituents for the growth and reproduction of living organisms and occur naturally in the soil, air, and water. However, human activities are affecting their natural cycles and causing excessive dumping into the surface and groundwater systems. Higher concentrations of nitrogen and phosphorus-based nutrients in water resources lead to eutrophication, reduction in sunlight, lower dissolved oxygen levels, changing rates of plant growth, reproduction patterns, and overall deterioration of water quality. Economically, this pollution can impact the fishing industry, recreational businesses, property values, and tourism. Also, using nutrient-polluted lakes or rivers as potable water sources may result in excess nitrates in drinking water, production of disinfection by-products, and associated health effects. Nutrients contamination in water commonly originates from point and non-point sources. Point sources are the specific discharge locations, like wastewater treatment plants (WWTP), industries, and municipal waste systems; whereas, non-point sources are discrete dischargers, like agricultural lands and storm water runoffs. Compared to non-point sources, point sources are easier to identify, regulate, and treat. WWTPs receive sewage from domestic, business, and industrial settings. With growing pollution concerns, nutrients removal and recovery at treatment plants is gaining significant attention. Newer chemical and biological nutrient removal processes are emerging to treat wastewater. Nitrogen removal mainly involves nitrification-denitrification processes; whereas, phosphorus removal includes biological uptake, chemical precipitation, or filtration. In regards to non-point sources, authorities are encouraging best management practices to control pollution loads to waterways. Governments are opting for novel strategies like source nutrient reduction schemes, bioremediation processes, stringent effluent limits, and nutrient trading programs. Source nutrient reduction strategies such as discouraging or banning use of phosphorus-rich detergents and selective chemicals, industrial pretreatment programs, and stormwater management programs can be effective by reducing nutrient loads to WWTPs. Bioremediation techniques such as riparian areas, natural and constructed wetlands, and treatment ponds can capture nutrients from agricultural lands or sewage treatment plant effluents. Nutrient trading programs allow purchase/sale of equivalent environmental credits between point and non-point nutrient dischargers to manage overall nutrient discharges in watersheds at lower costs. Nutrient pollution impacts are quite evident and documented in many parts of the world. Governments and environmental organizations are undertaking several waterways remediation projects to improve water quality and restore aquatic ecosystems. Shrinking freshwater reserves and rising water demands are compelling communities to make efficient use of the available water resources. With smarter choices and useful strategies, nutrient pollution in the water can be contained to a reasonable extent. As responsible members of the community, it is important for us to understand this key environmental issue as well as to learn the current and future needs to alleviate this problem.

Article

Oats and Other Forage Crops  

Daren Redfearn

This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Environmental Science. Please check back later for the full article. Oats and the other small grains have been “rediscovered” with the drive towards intensifying agricultural production, integrating crops and livestock into diversified systems, and increasing environmental stewardship. Globally, oats and other winter annual small grains such as wheat, cereal rye, triticale, and barley, have been used primarily for grain production. The secondary market following grain production has been restricted to straw, used mainly as livestock bedding. In regions where livestock are economically important, oats and the other annual small grain crops can be used as a grazed forage or fodder crop, hay, or silage. There are several characteristics that make oats and other small grains suitable for multiple agricultural uses. All the small grains are fairly easy to establish, have rapid growth, can be productive, and have a high nutritional value for livestock. Recent improvements in cultivar development have allowed oats and wheat to be grown across a broader range of stressful environmental conditions. Similarly, cultivar development in oats and wheat has improved grazing tolerance, which is important in dual-purpose systems that emphasize both grazing and grain production. On a worldwide scale, oats and other annual small grains are economically and environmentally important forage crops, especially when used as focused components within intensified agricultural systems. Challenges include development of improved cultivars of oats and other small grains for use in intensified agricultural systems, including both grazing and no grazing, that serve as short rotation crops, dual-purpose crops, or are designed to mitigate a specific environmental issue.

Article

The Oceans and Human Health  

Lora Fleming, Michael Depledge, Niall McDonough, Mathew White, Sabine Pahl, Melanie Austen, Anders Goksoyr, Helena Solo-Gabriele, and John Stegeman

The interdisciplinary study of oceans and human health is an area of increasing global importance. There is a growing body of evidence that the health of the oceans and that of humans are inextricably linked and that how we interact with and affect our oceans and seas will significantly influence our future on earth. Since the emergence of modern humans, the oceans have served as a source of culture, livelihood, expansion, trade, food, and other resources. However, the rapidly rising global population and the continuing alterations of the coastal environment are placing greater pressure on coastal seas and oceans. Negative human impacts, including pollution (chemical, microbial, material), habitat destruction (e.g., bottom trawling, dredging), and overfishing, affect not only ecosystem health, but also human health. Conversely, there is potential to promote human health and well-being through sustainable interactions with the coasts and oceans, such as the restoration and preservation of coastal and marine ecosystems. The study of oceans and human health is inherently interdisciplinary, bringing together the natural and social sciences as well as diverse stakeholder communities (including fishers, recreational users, private enterprise, and policymakers). Reviewing history and policy with regard to oceans and human health, in addition to known and potential risks and benefits, provides insights into new areas and avenues of global cooperation, with the possibility for collaboratively addressing the local and global challenges of our interactions with the oceans, both now and in the future.

Article

Optimal and Real-Time Control of Water Infrastructures  

Ronald van Nooijen, Demetris Koutsoyiannis, and Alla Kolechkina

Humanity has been modifying the natural water cycle by building large-scale water infrastructure for millennia. For most of that time, the principles of hydraulics and control theory were only imperfectly known. Moreover, the feedback from the artificial system to the natural system was not taken into account, either because it was too small to notice or took too long to appear. In the 21st century, humanity is all too aware of the effects of our adaptation of the environment to our needs on the planetary system as a whole. It is necessary to see the environment, both natural and hman-made as one integrated system. Moreover, due to the legacy of the past, the behaviour of the man-madeparts of this system needs to be adapted in a way that leads to a sustainable ecosystem. The water cycle plays a central role in that ecosystem. It is therefore essential that the behaviour of existing and planned water infrastructure fits into the natural system and contributes to its well-being. At the same time, it must serve the purpose for which it was constructed. As there are no natural feedbacks to govern its behaviour, it will be necessary to create such feedbacks, possibly in the form of real-time control systems. To do so, it would be beneficial if all persons involved in the decision process that establishes the desired system behaviour understand the basics of control systems in general and their application to different water systems in particular. This article contains a discussion of the prerequisites for and early development of automatic control of water systems, an introduction to the basics of control theory with examples, a short description of optimal control theory in general, a discussion of model predictive control in water resource management, an overview of key aspects of automatic control in water resource management, and different types of applications. Finally, some challenges faced by practitioners are mentioned.

Article

Organic Farming  

Theodore J. K. Radovich

Organic farming occupies a unique position among the world’s agricultural systems. While not the only available model for sustainable food production, organic farmers and their supporters have been the most vocal advocates for a fully integrated agriculture that recognizes a link between the health of the land, the food it produces, and those that consume it. Advocacy for the biological basis of agriculture and the deliberate restriction or prohibition of many agricultural inputs arose in response to potential and observed negative environmental impacts of new agricultural technologies introduced in the 20th century. A primary focus of organic farming is to enhance soil ecological function by building soil organic matter that in turn enhances the biota that soil health and the health of the agroecosystem depends on. The rapid growth in demand for organic products in the late 20th and early 21st centuries is based on consumer perception that organically grown food is better for the environment and human health. Although there have been some documented trends in chemical quality differences between organic and non-organic products, the meaningful impact of the magnitude of these differences is unclear. There is stronger evidence to suggest that organic systems pose less risk to the environment, particularly with regard to water quality; however, as intensity of management in organic farming increases, the potential risk to the environment is expected to also increase. In the early 21st century there has been much discussion centered on the apparent bifurcation of organic farming into two approaches: “input substitution” and “system redesign.” The former approach is a more recent phenomenon associated with pragmatic considerations of scaling up the size of operations and long distance shipping to take advantage of distant markets. Critics argue that this approach represents a “conventionalization” of organic agriculture that will erode potential benefits of organic farming to the environment, human health, and social welfare. A current challenge of organic farming systems is to reconcile the different views among organic producers regarding issues arising from the rapid growth of organic farming.

Article

Origin and Development of Agriculture in New Guinea, Island Melanesia, and Polynesia  

Tim Denham

Early agricultural and arboricultural practices in the Pacific are based on vegetative principles, namely, the asexual propagation and transplantation of plants. A vegetative orientation is reflected in the exploitation of underground storage organs (USOs) within Near Oceania, as well as Island Southeast Asia, during the Pleistocene. During the early Holocene, people in the New Guinea region (including Near Oceania) began to intensify the management of plant resources in different landscapes. The increased degree of plant management, as well as associated environmental transformation, is most clearly manifest in the agricultural chronology at Kuk Swamp in the highlands of Papua New Guinea. At Kuk, shifting cultivation was potentially practiced during the early Holocene, with mounded cultivation by c. 7000–6400 cal BP and ditched drainage of wetlands for cultivation by c. 4400–4000 cal BP. Comparable agricultural records are lacking for other regions of Near Oceania; lowland sites indicate a range of arboricultural practices focused on fruit- and nut-bearing trees during the Terminal Pleistocene and throughout the Holocene, as well as potentially sago during the late Holocene. By c. 4000–3000 cal BP, indigenous agricultural and arboricultural elements were integrated with new cultural traits from Southeast Asia, including domestic animals, pottery and potentially new varieties of traditional crops. From c. 3250 to 2800 cal BP, different elements of agricultural and arboricultural practices from lowland New Guinea and Island Melanesia were taken by Lapita pottery–bearing colonists into the western Pacific. A later period of agricultural expansion occurred around c. 1000–750 cal BP with the colonization of eastern Polynesia. Agricultural practices and crops were variably taken and adapted to different islands and island groups across the Pacific. Additional transformations to agriculture occurred with the Polynesian adoption of the sweet potato (Ipomoea batatas), a South American domesticate, as well as following protohistoric and historic encounters.

Article

Payments for Ecosystem Services: Program Design and Participation  

Natasha James and Erin Sills

Payments for ecosystem or environmental services (PES) are broadly defined as payments (in kind or in cash) to participants (often landowners) who volunteer to provide the services either to a specific user or to society at large. Payments are typically conditional on agreed rules of natural resource management rather than on delivery of the services. The rules range from protection of native ecosystems to installation of conservation practices. The earliest proponents of PES were economists who argued that they are a cost-effective way to conserve forests, manage watersheds, and protect biodiversity. Political support for PES rests on the claim that these programs can alleviate poverty among participants as well as protect the environment. More recent literature and experience with PES reveals barriers to achieving cost-effectiveness and poverty alleviation, including many related to the distribution of participation. The Costa Rican experience illustrates the choices that must be made and the potential for innovation in the design of PES programs.

Article

Payments versus Direct Controls for Environmental Externalities in Agriculture  

Alfons Weersink and David Pannell

The production of food, fiber, and fuel often results in negative externalities due to impacts on soil, water, air, or habitat. There are two broad ways to incentivize farmers to alter their land use or management practices on that land to benefit the environment: (1) provide payments to farmers who adopt environmentally beneficial actions and (2) introduce direct controls or regulations that require farmers to undertake certain actions, backed up with penalties for noncompliance. Both the provision of payments for environmentally beneficial management practices (BMPs) and a regulatory requirement for use of a BMP alter the incentives faced by farmers, but they do so in different ways, with different implications and consequences for farmers, for the policy, for politics, and consequently for the environment. These two incentive-based mechanisms are recommended where the private incentives conflict with the public interest, and only where the private incentives are not so strong as to outweigh the public benefits. The biggest differences between them probably relate to equity/distributional outcomes and politics rather than efficiency. Governments often seem to prefer to employ beneficiary-pays mechanisms in cases where they seek to alter farmers’ existing practices, and polluter-pays mechanisms when they seek to prevent farmers from changing from their current practices to something worse for the environment. The digital revolution has the potential to help farmers produce more food on less land and with fewer inputs. In addition to reducing input levels and identifying unprofitable management zones to set aside, the technology could also alter the transaction costs of the policy options.

Article

Performance Bonding for Environmental Protection  

Olli-Pekka Kuusela

Performance bonds are a widely used enforcement and assurance mechanism in extractive activities and large-scale projects that are associated with clearly defined environmental liabilities. They are especially effective and useful in conditions where the judgment-proof problem is a pervasive challenge. Bonds provide an assurance for the regulator that funds are available to complete the decommissioning activities and the termination of operations under contingencies where the operator fails to follow the contractual obligations or becomes insolvent. Applications of bonding are found in oil and gas drilling, surface mining, renewable energy projects, and timber concessions. However, real bonding systems are not without issues and limitations. Defining a sufficiently high enough bond has been especially challenging in conditions with limited information about costs and environmental risks and where smaller operators may not be able to secure access to required funds or financial services for posting the bond. The use of surety companies, bond pools, and blanket bonds provides a solution to these problems, albeit not without issues of their own. Furthermore, to keep up with the technological developments in extractive industries and with the inescapable uncertainties related to reclamation costs and environmental damages, the regulator should continually review and update bonding instruments based on new available information. Regulatory rules and statistical models that have been developed to adjust the required bonds, based on observable risk factors, provide some encouraging examples for how to design more responsive and effective bonding systems.

Article

Pesticides and Human Health  

Pierluigi Cocco

The fight against agricultural and household pests accompanies the history of humanity, and a total ban on the use of pesticides seems unlikely to happen in the foreseeable future. Currently, about 100,000 different chemicals, inorganic and organic, are currently in the market, grouped according to their function as insecticides, herbicides, fungicides, fumigants, rodenticides, fertilizers, growth regulators, etc. against specific pests, such as snails or human parasites, or their chemical structure—organochlorines, organophosphates, pyrethroids, carbamates, dithiocarbamates, organotin compounds, phthalimides, phenoxy acids, heterocyclic azole compounds, coumarins, etc. Runoff from agricultural land and rain precipitation and dry deposition from the atmosphere can extend exposure to the general environment through the transport of pesticides to streams and ground-water. Also, the prolonged bio-persistence of organochlorines generates their accumulation in the food chain, and their atmospheric drift toward remote geographical areas is mentioned as the cause of elevated fat contents in Arctic mammals. Current regulation in the developed world and the phasing out of more toxic pesticides have greatly reduced the frequency of acute intoxications, although less stringent regulations in the developing world contribute to a complex pattern of exposure circumstances worldwide. Nonetheless, evidence is growing about long-term health effects following high-level, long-lasting exposure to specific pesticides, including asthma and other allergic diseases, immunotoxicity, endocrine disruption, cancer, and central and peripheral nervous system effects. Major reasons for uncertainty in interpreting epidemiological findings of pesticide effects include the complex pattern of overlapping exposure due to multiple treatments applied to different crops and their frequent changes over time to overcome pest resistance. Further research will have to address specific agrochemicals with well-characterized exposure patterns.

Article

Philosophy of the Anthropocene  

Sébastien Dutreuil and Pierre Charbonnier

The Anthropocene was proposed in 2000 as the name of a new geological epoch, succeeding to the Holocene, and marked by the influence of humanity as a biological species on its geological environment. It has resonated differently in three major epistemological domains, where the configurations of the debate has varied. For Earth system science, within which the term emerged, the Anthropocene was a keyword encompassing and stimulating large research programs which stimulated original and new scientific investigations and synthesis. The term had a more specific and evidential meaning for the geological community, which seized it after 2008. Documenting empirically the Anthropocene meant different things for these two scientific communities: tracking down every single impact humanity has on the environment on which humanity depends upon to survive for the former; analyzing how this influence can be documented in Earth’s strata for the latter. These two different epistemological regimes are intertwined with two different normative registers. Earth system science assumed from the very start a normative position: international experts elaborate normative concepts and produce scientific synthesis meant to define the conceptual space, quantitatively delimited, within which political decisions related to global environmental issues ought to be taken. By contrast, geologists were more cautious, and for some, reluctant, to engage in normative issues; but political issues unavoidably emerged when the starting date was discussed. This politicization of the debate was accompanied by human and social sciences, seizing up the debate at the same time as geologists and lay public did, toward the end of the 2000s.

Article

Planning for Resilient and Sustainable Coastal Shorelands and Communities in the Face of Global Climate Change  

Richard K. Norton

Coastal shorelands and communities are among the most beautiful, vital, remunerative, popular, inequitable, and hazardous of places to live, work, and play. Because of the varied and intensive uses of them combined with climate-related impacts to them, they increasingly experience threats from coastal hazards, suffer ecological degradation, and engender contentious conflicts. Although some coastal shorelands are publicly owned, many are privately owned. Coastal states and communities confront many challenges as they plan for and manage the use of privately owned coastal shorelands. Coastal shorelands encompass the near-shore beaches, dunes, wetlands, and other transitional areas within dynamic coastal zones, whether developed or natural. Sustainability suggests the ability of natural and social coastal systems to persist, whereas resilience speaks to the sustainability of those systems when subject to substantial disruptions such as flooding from extreme storms. In addition to promoting sustainable and resilient coastal shorelands in general, advocates also call for redressing the heightened risks and other inequities experienced by historically marginalized communities. Most of the challenges prompting calls for enhanced coastal resilience, sustainability, and equity are not unique to coastal settings, but coastal communities especially need to attend to them given the heightened risks and development pressures they face. Broadly, they include increasingly frequent and fierce storms, floods, drought, fires, and heatwaves. Coastal communities also face unique challenges, including accelerating rates of shoreline recession and increasing near-shore flooding. Further complicating these natural dynamics are complex and poorly adapted property right, public interest, and related legal/administrative institutional arrangements shaping both private and public expectations in coastal settings. Community planning, if well executed, offers the promise of facilitating and advancing the kinds of nuanced and adaptive resiliency and sustainability goals needed everywhere, especially in coastal settings. Toward that end, researchers and advocates promote a range of planning principles, such as recognizing that coastal economies are nested within and dependent upon coastal ecosystems; promoting culturally aware, place-based, and infrastructure-efficient development policies; adopting no- to low-regrets climate adaptation policies; and encouraging ongoing learning and adaptative management. They similarly promote a variety of planning methods to support those policies, such as land suitability, infrastructure capacity, hazard vulnerability, and social vulnerability analyses, best engaged through scenario-based planning given climate-related uncertainties. Coastal communities experiencing aggressive shoreline recession face difficult choices as well—such as whether to armor receding shores or withdraw—most of which will require acknowledging and working through unavoidable trade-offs. Finally, providing knowledge about natural coastal dynamics and management systems is necessary but not by itself sufficient. Also needed are enhanced local capacity to conduct the analyses required to identify policies and programs that will effectively and equitably advance coastal sustainability and the firm commitment of local residents and officials to adopt those policies—challenges that are daunting but not insurmountable.

Article

Politics of Local Community Engagement in Transboundary Water Negotiations  

Isabela Espindola and Pilar Villar

The sharing of transboundary water resources, whether surface or groundwater, is a significant challenge, both in theory and practice. Countries in situations of sharing these natural resources are predisposed to interact with each other. These interactions, here called transboundary water interactions, are characterized by the coexistence of cooperation and conflict, which can arise at different governance levels. However, negotiations around transboundary water resources primarily occur between diplomats and high government members from riparian countries and river basin organization (RBO) managers. Transboundary water negotiations are usually considered high-level political discussions, given the complexity and scale of the water challenges. Consequently, decision-making processes incorporate only a limited number of participants, who make decisions capable of impacting the entire population that depend on the shared waters. Over the last 20 years, there has been a need for greater transparency and a participatory process in transboundary water negotiations, especially for local community engagement and collaboration in these processes. Many of the negotiation processes around transboundary water resources need the participation of municipalities and local populations, concomitant with the involvement of RBOs, to carry out decisions to manage transboundary waters in an integrated manner. There are several reasons for this demand, including negotiation effectiveness, contestation prevention, data sharing, ensuring continuing participation and collaboration, and promoting public awareness related to water resources. Discussing social participation, particularly in the management of transboundary water resources, requires attention to the historical context and its constraints. Considering the enormous challenge, the experiences of local community engagement in transboundary water negotiations in South America, especially from the Guarani Aquifer and the La Plata Basin, are good examples for improving this discussion around transboundary water interactions and local community engagement. The La Plata Basin is the second-largest transboundary basin in the continent, shared by Argentina, Bolivia, Brazil, Uruguay, and Paraguay, while the Guarani Aquifer is one of the largest reservoirs of freshwater worldwide, shared by Argentina, Brazil, Paraguay, and Uruguay. Even with both having cooperation agreements in place between the riparian states, there are still great difficulties with regard to the participation of local communities in transboundary water negotiations.

Article

Exploring the Politics of Institutional Fragmentation in Transboundary River Basins  

Christian Bréthaut and Laura Turley

Institutional fragmentation has been less addressed by research when considering the specific context of transboundary river basins, settings that are often characterized by multiple regulatory frameworks as well as by a great range of uses and users of the river that intervene at different institutional levels. Considering that such contexts represent fertile ground for reinforced use rivalries and exacerbated power relations, it is key to focus on the very nature and results of such institutional fragmentation; in other words, it is necessary to explore the politics of institutional fragmentation in transboundary rivers. Three main bodies of literature are suggested as insightful perspectives to provide enhanced understanding of such contexts: (a) institutional fit literature: challenges of fits between institutions and ecosystems, (b) legal pluralism: interplay and co-existence of different normative orders, (c) polycentric governance: coordination modalities between different and independent decision-making centers.

Article

Politics of Water Flows: Water Supply, Sanitation, and Drainage  

Tatiana Acevedo Guerrero

Since the late 20th century, water and sanitation management has been deeply influenced by ideas from economics, specifically by the doctrine of neoliberalism. The resulting set of policy trends are usually referred to as market environmentalism, which in broad terms encourages specific types of water reforms aiming to employ markets as allocation mechanisms, establish private-property rights and full-cost pricing, reduce (or remove) subsidies, and promote private sector management to reduce government interference and avoid the politicization of water and sanitation management. Market environmentalism sees water as a resource that should be efficiently managed through economic reforms. Instead of seeing water as an external resource to be managed, alternative approaches like political ecology see water as a socio-nature. This means that water is studied as a historical-geographical process in which society and nature are inseparable, mutually produced, and transformable. Political ecological analyses understand processes of environmental change as deeply interrelated to socioeconomic dynamics. They also emphasize the impact of environmental dynamics on social relations and take seriously the question of how the physical properties of water may be sources of unpredictability, unruliness, and resistance from human intentions. As an alternative to the hydrologic cycle, political ecology proposes the concept of hydrosocial cycle, which emphasizes that water is deeply political and social. An analysis of the politics of water flows, drawing from political ecology explores the different relationships and histories reflected in access to (and exclusion from) water supply, sanitation, and drainage. It portrays how power inequalities are at the heart of differentiated levels of access to infrastructure.

Article

Pollen, Allergens, and Human Health  

Rachel N. McInnes

Allergenic pollen is produced by the flowers of a number of trees, grasses, and weeds found throughout the world. Human exposure to such pollen grains can exacerbate pollen-related asthma and allergenic conditions such as allergic rhinitis (hay fever). While allergenic pollen comes from three main groups of plants—certain trees, grasses, and weeds—many people are sensitive to pollen from one or a few taxa only. Weather, climate, and environmental conditions have a significant impact on the levels and varieties of pollen grains present in the air. These allergenic conditions significantly reduce the quality of life of affected individuals and have been shown to have a major economic impact. Pollen production depends on both the current meteorological conditions (including day length, temperature, irradiation, precipitation, and wind speed/direction), and the water availability and other environmental and meteorological conditions experienced in the previous year. The climate affects the types of vegetation and taxa that can grow in a particular location through availability of different habitats. Land-use or land management is also crucial, and so this field of study has implications for vegetation management practices and policy. Given the influential effects of weather and climate on pollen, and the significant health impacts globally, the total effect of any future environmental and climatic changes on aeroallergen production and spread will be significant. The overall impact of climate change on pollen production and spread remains highly uncertain, and there is a need for further understanding of pollen-related health impact information. There are a number of ways air quality interacts with the impact of pollen. Further understanding of the risks of co-exposure to both pollen and air pollutants is needed to better inform public health policy. Furthermore, thunderstorms have been linked to asthma epidemics, especially during the grass pollen seasons. It is thought that allergenic pollen plays a role in this “thunderstorm asthma.” To reduce the exposure to, or impact from, pollen grains in the air, a number of adaptation and mitigation options may be adopted. Many of these would need to be done either through policy changes, or at a local or regional level, although some can be done by individuals to minimize their exposure to pollen they are sensitive to. Improved aeroallergen forecast models could be developed to provide detailed taxon-specific, localized information to the public. One challenge will be combining the many different sources of aeroallergen data that are likely to become available in future into numerical forecast systems. Examples of these potential inputs are automated observations of aeroallergens, real-time phenological observations and remote sensing of vegetation, social sensing, DNA analysis of specific aeroallergens, and data from symptom trackers or personal monitors. All of these have the potential to improve the forecasts and information available to the public.

Article

Pollution in Terrestrial and Aquatic Sediment  

Rodney Stevens

This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Environmental Science. Please check back later for the full article. Pollution problems in aquatic sediments and on land can be quite varied—from the widespread contamination of a coastal bay receiving untreated urban or industrial discharge to the local leakage from underground petroleum tanks or pipelines. Such problems are related to the range of sediment and soil in which they occur. Sediments and soil particles can be carriers, receptors, and sources for contaminants. The effectiveness of these roles is largely related to their adsorptive capacity and is governed mainly by particle size, mineralogy, and organic matter as well as site-specific geochemical conditions. Sustainable use of land and marine areas requires a source-to-sink system perspective in order to prescribe remedial actions. Measures can focus on preventing release from the source, spreading along selective pathways, stabilization, and isolation to protect the receptor. Therefore, many traditional scientific goals, such as provenance (sediment source) identification, the interpretation of sediment transport modes and directions, and post-depositional (diagenetic) changes, are applicable and complementary tools to increase predictability between sampled sites. The carrier function of aquatic sediments is emphasized when contaminates are transported to the site of accumulation. Ground pollution in terrestrial settings, on the other hand, is often due to more local sources. Nevertheless, retention and ecological exposure is dependent on the particle-solute interactions. The stratigraphic architecture of ground environments can also decisively influence the spread of contaminants, contrasting with the largely two-dimensional redistribution of eroded aquatic sediments. Diffuse pollution sources, including agriculture, urban, transportation, and industrial sources, contribute significantly to overall environmental stress. Quantitative modeling of contaminant fluxes is increasingly possible with database availability, but relative risk ranking is still a necessary simplification in many decision-support evaluations due to the complexity of sediment and ground environments.

Article

Potential Impacts of Deep-Sea Mining on Ecosystems  

Rahul Sharma

Deep-sea mining pertains to underwater minerals such as polymetallic nodules, ferromanganese crusts, and hydrothermal sulfides that are considered as alternative sources for metals such as Cu, Ni, Co, Pb, Zn, Cd, Mn, Fe, and rare earths that could be exploited in the future by developing suitable technologies. Many of these deposits occur in international waters in which several “contractors” have staked claims over large tracts of the seafloor under the United Nations Law of the Sea, whereas attempts are also being made to develop the deposits within the Exclusive Economic Zone of some countries. However, several concerns have emerged over potential impacts of mining these deposits, leading to regulations being framed as well as measures being devised for conserving the marine ecosystems. The likely sources of environmental impact of deep-sea mining include those from the mining ship where handling of ore, machinery, oil will take place; the lift mechanism that would transfer the minerals from the sea bottom to the surface through the entire water column; as well as the mining machine that would actually scrape the seafloor for minerals. This article describes the likely impacts that could be caused due to mining of three different types of deep-sea minerals, viz. polymetallic nodules, hydrothermal sulfides and ferromanganese crusts. It further shows the estimation of impacts in terms of mining area, volume and weight of associated substrates; and goes on to suggest mitigation measures to minimize the potential impacts of deep-sea mining. Finally, the national and international environmental regulations for deep-sea mining have been discussed.

Article

Prehistoric Agriculture in China: Food Globalization in Prehistory  

Giedrė Motuzaitė Matuzevičiūtė and Xinyi Liu

It is commonly recognised that farming activities initiated independently in different parts of the world between approximately 12,000 and 8,000 years ago. Two of such agricultural centres is situated in modern-day China, where systems based on the cultivation of plants and animal husbandry has developed. Recent investigations have shown that between 5000 and 1500 cal. bce, the Eurasian and African landmass underpinned a continental-scale process of food “globalisation of staple crops. In the narrative of food domestication and global food dispersal processes, China has played a particularly important role, contributing key staple food domesticates such as rice, broomcorn, and foxtail millet. The millets dispersed from China across Eurasia during the Bronze Age, becoming an essential food for many ancient communities. In counterpoise, southwest Asian crops, such as wheat or barley, found new habitats among the ancient populations of China, dramatically changing the course of its development. The processes of plant domestication and prehistoric agriculture in China have been a topic of extensive research, review, and discussion by many scholars around the world, and there is a great deal of literature on these topics. One of the consequences of these discoveries concerning the origins of agriculture in China has been to undermine the notion of a single centre of origin for civilisation, agriculture, and urbanism, which was a popular and widespread narrative in the past. It has become clear that agricultural centres of development in China were concurrent with, rather than after, the Fertile Crescent.