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Mehrad Bastani, Nurcin Celik, and Danielle Coogan
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.
The volume of municipal solid waste produced in the United States has increased by 68% since 1980, up from 151 million to over 254 million tons per year. As the output of municipal waste has grown, more attention has been placed on the occupations associated with waste management. In 2014, the occupation of refuse and recyclable material collection was ranked as the 6th most dangerous job in the United States, with a rate of 27.1 deaths per 100,000 workers. With the revelation of reported exposure statistics among solid waste workers in the United States, the problem of the identification and assessment of occupational health risks among solid waste workers is receiving more consideration.
From the generation of waste to its disposal, solid waste workers are exposed to substantial levels of physical, chemical, and biological toxins. Current waste management systems in the United States involve significant risk of contact with waste hazards, highlighting that prevention methods such as monitoring exposures, personal protection, engineering controls, job education and training, and other interventions are under-utilized. To recognize and address occupational hazards encountered by solid waste workers, it is necessary to discern potential safety concerns and their causes, as well as their direct and/or indirect impacts on the various types of workers. In solid waste management, the major industries processing solid waste are introduced as recycling, incineration, landfill, and composting. Thus, the reported exposures and potential occupational health risks need to be identified for workers in each of the aforementioned industries. Then, by acquiring data on reported exposure among solid waste workers, multiple county-level and state-level quantitative assessments for major occupational risks can be conducted using statistical assessment methods. To assess health risks among solid waste workers, the following questions must be answered: How can the methods of solid waste management be categorized? Which are the predominant occupational health risks among solid waste workers, and how can they be identified? Which practical and robust assessment methods are useful for evaluating occupational health risks among solid waste workers? What are possible solutions that can be implemented to reduce the occupational health hazard rates among solid waste workers?
James B. London
Coastal zone management (CZM) has evolved since the enactment of the U.S. Coastal Zone Management Act of 1972, which was the first comprehensive program of its type. The newer iteration of Integrated Coastal Zone Management (ICZM), as applied to the European Union (2000, 2002), establishes priorities and a comprehensive strategy framework. While coastal management was established in large part to address issues of both development and resource protection in the coastal zone, conditions have changed. Accelerated rates of sea level rise (SLR) as well as continued rapid development along the coasts have increased vulnerability. The article examines changing conditions over time and the role of CZM and ICZM in addressing increased climate related vulnerabilities along the coast.
The article argues that effective adaptation strategies will require a sound information base and an institutional framework that appropriately addresses the risk of development in the coastal zone. The information base has improved through recent advances in technology and geospatial data quality. Critical for decision-makers will be sound information to identify vulnerabilities, formulate options, and assess the viability of a set of adaptation alternatives. The institutional framework must include the political will to act decisively and send the right signals to encourage responsible development patterns. At the same time, as communities are likely to bear higher costs for adaptation, it is important that they are given appropriate tools to effectively weigh alternatives, including the cost avoidance associated with corrective action. Adaptation strategies must be pro-active and anticipatory. Failure to act strategically will be fiscally irresponsible.
Maria Cristina Fossi and Cristina Panti
A vigorous effort to identify and study sentinel species of marine ecosystem in the world’s oceans has developed over the past 50 years. The One Health concept recognizes that the health of humans is connected to the health of animals and the environment. Species ranging from invertebrate to large marine vertebrates have acted as “sentinels” of the exposure to environmental stressors and health impacts on the environment that may also affect human health. Sentinel species can signal warnings, at different levels, about the potential impacts on a specific ecosystem. These warnings can help manage the abiotic and anthropogenic stressors (e.g., climate change, chemical and microbial pollutants, marine litter) affecting ecosystems, biota, and human health.
The effects of exposure to multiple stressors, including pollutants, in the marine environment may be seen at multiple trophic levels of the ecosystem. Attention has focused on the large marine vertebrates, for several reasons. In the past, the use of large marine vertebrates in monitoring and assessing the marine ecosystem has been criticized. The fact that these species are pelagic and highly mobile has led to the suggestion that they are not useful indicators or sentinel species. In recent years, however, an alternative view has emerged: when we have a sufficient understanding of differences in species distribution and behavior in space and time, these species can be extremely valuable sentinels of environmental quality.
Knowledge of the status of large vertebrate populations is crucial for understanding the health of the ecosystem and instigating mitigation measures for the conservation of large vertebrates. For example, it is well known that the various cetacean species exhibit different home ranges and occupy different habitats. This knowledge can be used in “hot spot” areas, such as the Mediterranean Basin, where different species can serve as sentinels of marine environmental quality. Organisms that have relatively long life spans (such as cetaceans) allow for the study of chronic diseases, including reproductive alterations, abnormalities in growth and development, and cancer. As apex predators, marine mammals feed at or near the top of the food chain. As the result of biomagnification, the levels of anthropogenic contaminants found in the tissues of top predators and long-living species are typically high. Finally, the application of consistent examination procedures and biochemical, immunological, and microbiological techniques, combined with pathological examination and behavioral analysis, has led to the development of health assessment methods at the individual and population levels in wild marine mammals. With these tools in hand, investigators have begun to explore and understand the relationships between exposures to environmental stressors and a range of disease end points in sentinel species (ranging from invertebrates to marine mammals) as an indicator of ecosystem health and a harbinger of human health and well-being.
Jean-François Bissonnette and Rodolphe De Koninck
Plantation farming emerged as a large-scale system of specialized agriculture in the tropics under European colonialism, in opposition to smallholding subsistence agriculture. Despite large-scale plantations in the tropics, smallholdings have consistently formed the backbone of rural economies, to the extent that they have become the main producers of some of the former plantation crops. In the early 21st century, oil palm has become the third most important cash crop in the world in terms of area cultivated, largely due to the expansion of this crop in Malaysia and Indonesia. Although in these countries, oil palm is primarily cultivated in large plantations, smallholders cultivate a large share of the territory devoted to this crop. This is related to the programs set up by governments of Malaysia and Indonesia during the second half of the 20th century, to provide smallholders with land plots in capital intensive large-scale oil palm schemes. Despite the relative success encountered by these programs in both countries, policymakers have continued to insist on the development of private centrally managed large-scale plantations. Yet, smallholding family farming has remained the most resilient economic activity in rural areas of the tropics. This system has proven adaptive to environmental change and, given proper access to markets and capital, particularly responsive to market signals. Today, many small-holdings are still characterized by the diversity of crops cultivated, low use of chemical inputs, reliance on family labor, and high levels of ecological knowledge. These are some of the main factors explaining why small family farms have proven more efficient than large plantations and, in the long term, more economically and ecologically resilient. Yet, large-scale land acquisitions for monocrop production remain a current issue, highlighting the paradox of the latest stage of agrarian capitalism and of its persistent built-in disregard for environmental deterioration.
Soils, the earth’s skin, are at the intersection of the lithosphere, hydrosphere, atmosphere, and biosphere. The persistence of life on our planet depends on the maintenance of soils as they constitute the biological engines of earth. Human population has increased exponentially in recent decades, along with the demand for food, materials, and energy, which have caused a shift from low-yield and subsistence agriculture to a more productive, high-cost, and intensive agriculture. However, soils are very fragile ecosystems and require centuries for their development, thus within the human timescale they are not renewable resources. Modern and intensive agriculture implies serious concern about the conservation of soil as living organism, i.e., of its capacity to perform the vast number of biochemical processes needed to complete the biogeochemical cycles of plant nutrients, such as nitrogen and phosphorus, crucial for crop primary production. Most practices related to intensive agriculture determine a deterioration even in the short-middle term of their physical, chemical, and biological properties, which all together contribute to soil quality, along with an overexploitation of soils as living organisms. Recent trends are turning toward styles of agriculture management that are more sustainable or conservative for soil quality.
Usually, use of soils for agricultural purposes deflect them at various degrees from the “natural” soil development processes (pedogenesis), and this shift may be assumed as a divergence from soil sustainability principles. For decades, the misuse of land due to intensive crop management has deteriorated soil health and quality. A huge plethora of microorganisms inhabits soils, thus acting as “the biological engine of the earth”; indeed, this microbiota serves the soil ecosystem, performing several fundamental functions. Therefore, management practices might be planned looking at the safeguard of soil microbial diversity and resilience. In addition, each unexpected alteration in numberless soil biochemical processes, being regulated by microbial communities, may represent an early and sensible signal of soil homeostasis weakening and, consequently, warn about soil conservation. Within the vast number of soil biochemical processes and connected features (bioindicators) virtually effective to measure the sustainable soil exploitation, those related to the mineralization or immobilization of the main nutrients (C and N), including enzyme activity (functioning) and composition (diversity) of microbial communities, exert a fundamental role because of their involvement in soil metabolism. Comparing the influence of many cropping factors (tillage, mulching and cover crops, rotations, mineral and organic fertilization) under both intensive and sustainable managements on soil microbial diversity and functioning, through both chemical and biological soil quality indicators, makes it possible to identify the most hazardous diversions from soil sustainability principles.
David A. Robinson, Fiona Seaton, Katrina Sharps, Amy Thomas, Francis Parry Roberts, Martine van der Ploeg, Laurence Jones, Jannes Stolte, Maria Puig de la Bellacasa, Paula Harrison, and Bridget Emmett
Soils provide important functions, which according to the European Commission include: biomass production (e.g., agriculture and forestry); storing, filtering, and transforming nutrients, substances, and water; harboring biodiversity (habitats, species, and genes); forming the physical and cultural environment for humans and their activities; providing raw materials; acting as a carbon pool; and forming an archive of geological and archaeological heritage, all of which support human society and planetary life. The basis of these functions is the soil natural capital, the stocks of soil material. Soil functions feed into a range of ecosystem services which in turn contribute to the United Nations sustainable development goals (SDGs). This overarching framework hides a range of complex, often nonlinear, biophysical interactions with feedbacks and perhaps yet to be discovered tipping points. Moreover, interwoven with this biophysical complexity are the interactions with human society and the socioeconomic system which often drives our attitudes toward, and the management and exploitation of, our environment.
Challenges abound, both social and environmental, in terms of how to feed an increasingly populous and material world, while maintaining some semblance of thriving ecosystems to pass on to future generations. How do we best steward the resources we have, keep them from degradation, and restore them where necessary as soils underpin life? How do we measure and quantify the soil resources we have, how are they changing in time and space, what can we predict about their future use and function? What is the value of soil resources, and how should we express it? This article explores how soil properties and processes underpin ecosystem services, how to measure and model them, and how to identify the wider benefits they provide to society. Furthermore, it considers value frameworks, including caring for our resources.
Beyond damage to rainfed agricultural and forestry ecosystems, soil erosion due to water affects surrounding environments. Large amounts of eroded soil are deposited in streams, lakes, and other ecosystems. The most costly off-site damages occur when eroded particles, transported along the hillslopes of a basin, arrive at the river network or are deposited in lakes. The negative effects of soil erosion include water pollution and siltation, organic matter loss, nutrient loss, and reduction in water storage capacity. Sediment deposition raises the bottom of waterways, making them more prone to overflowing and flooding. Sediments contaminate water ecosystems with soil particles and the fertilizer and pesticide chemicals they contain. Siltation of reservoirs and dams reduces water storage, increases the maintenance cost of dams, and shortens the lifetime of reservoirs. Sediment yield is the quantity of transported sediments, in a given time interval, from eroding sources through the hillslopes and river network to a basin outlet. Chemicals can also be transported together with the eroded sediments. Sediment deposition inside a reservoir reduces the water storage of a dam.
The prediction of sediment yield can be carried out by coupling an erosion model with a mathematical operator which expresses the sediment transport efficiency of the hillslopes and the channel network. The sediment lag between sediment yield and erosion can be simply represented by the sediment delivery ratio, which can be calculated at the outlet of the considered basin, or by using a distributed approach. The former procedure couples the evaluation of basin soil loss with an estimate of the sediment delivery ratio SDRW for the whole watershed. The latter procedure requires that the watershed be discretized into morphological units, areas having a constant steepness and a clearly defined length, for which the corresponding sediment delivery ratio is calculated. When rainfall reaches the surface horizon of the soil, some pollutants are desorbed and go into solution while others remain adsorbed and move with soil particles. The spatial distribution of the loading of nitrogen, phosphorous, and total organic carbon can be deduced using the spatial distribution of sediment yield and the pollutant content measured on soil samples. The enrichment concept is applied to clay, organic matter, and all pollutants adsorbed by soil particles, such as nitrogen and phosphorous. Knowledge of both the rate and pattern of sediment deposition in a reservoir is required to establish the remedial strategies which may be practicable. Repeated reservoir capacity surveys are used to determine the total volume occupied by sediment, the sedimentation pattern, and the shift in the stage-area and stage-storage curves. By converting the sedimentation volume to sediment mass, on the basis of estimated or measured bulk density, and correcting for trap efficiency, the sediment yield from the basin can be computed.
Soils are the complex, dynamic, spatially diverse, living, and environmentally sensitive foundations of terrestrial ecosystems as well as human civilizations. The modern, environmental study of soil is a truly young scientific discipline that emerged only in the late 19th century from foundations in agricultural chemistry, land resource mapping, and geology. Today, little more than a century later, soil science is a rigorously interdisciplinary field with a wide range of exciting applications in agronomy, ecology, environmental policy, geology, public health, and many other environmentally relevant disciplines. Soils form slowly, in response to five inter-related factors: climate, organisms, topography, parent material, and time. Consequently, many soils are chemically, biologically, and/or geologically unique. The profound importance of soil, combined with the threats of erosion, urban development, pollution, climate change, and other factors, are now prompting soil scientists to consider the application of endangered species concepts to rare or threatened soil around the world.
Gerrit de Rooij
Henry Darcy was an engineer who built the drinking water supply system of the French city of Dijon in the mid-19th century. In doing so, he developed an interest in the flow of water through sands, and, together with Charles Ritter, he experimented (in a hospital, for unclear reasons) with water flow in a vertical cylinder filled with different sands to determine the laws of flow of water through sand. The results were published in an appendix to Darcy’s report on his work on Dijon’s water supply. Darcy and Ritter installed mercury manometers at the bottom and near the top of the cylinder, and they observed that the water flux density through the sand was proportional to the difference between the mercury levels. After mercury levels are converted to equivalent water levels and recast in differential form, this relationship is known as Darcy’s Law, and until this day it is the cornerstone of the theory of water flow in porous media. The development of groundwater hydrology and soil water hydrology that originated with Darcy’s Law is tracked through seminal contributions over the past 160 years.
Darcy’s Law was quickly adopted for calculating groundwater flow, which blossomed after the introduction of a few very useful simplifying assumptions that permitted a host of analytical solutions to groundwater problems, including flows toward pumped drinking water wells and toward drain tubes. Computers have made possible ever more advanced numerical solutions based on Darcy’s Law, which have allowed tailor-made computations for specific areas. In soil hydrology, Darcy’s Law itself required modification to facilitate its application for different soil water contents. The understanding of the relationship between the potential energy of soil water and the soil water content emerged early in the 20th century. The mathematical formalization of the consequences for the flow rate and storage change of soil water was established in the 1930s, but only after the 1970s did computers become powerful enough to tackle unsaturated flows head-on. In combination with crop growth models, this allowed Darcy-based models to aid in the setup of irrigation practices and to optimize drainage designs. In the past decades, spatial variation of the hydraulic properties of aquifers and soils has been shown to affect the transfer of solutes from soils to groundwater and from groundwater to surface water. More recently, regional and continental-scale hydrology have been required to quantify the role of the terrestrial hydrological cycle in relation to climate change. Both developments may pose new areas of application, or show the limits of applicability, of a law derived from a few experiments on a cylinder filled with sand in the 1850s.
Gary Sands, Srinivasulu Ale, Laura Christianson, and Nathan Utt
Agricultural (tile) drainage enables agricultural production on millions of hectares of arable lands worldwide. Lands where drainage or irrigation (and sometimes both) are implemented, generate a disproportionately large share of global agricultural production compared to dry land or rain-fed agricultural lands and thus, these water management tools are vital for meeting the food demands of today and the future. Future food demands will likely require irrigation and drainage to be practiced on an even greater share of the world’s agricultural lands. The practice of agricultural drainage finds its roots in ancient societies and has evolved greatly to incorporate modern technologies and materials, including the modern drainage plow, plastic drainage pipe and tubing, laser and GPS-guided installation equipment, and computer-aided design tools. Although drainage brings important agricultural production and environmental benefits to poorly drained and salt-affected arable lands, it can also give rise to the transport of nutrients and other constituents to downstream waters. Other unwanted ecological and hydrologic environmental effects may also be associated with the practice. The goal of this article is to familiarize the reader with the practice of subsurface agricultural drainage, the history and extent of its application, and the benefits commonly associated with it. In addition, environmental effects associated with subsurface drainage including hydrologic and water quality effects are presented, and conservation practices for mitigating these unwanted effects are described. These conservation practices are categorized by whether they are implemented in-field (such as controlled drainage) versus edge-of-field (such as bioreactors). The literature cited and reviewed herein is not meant to be exhaustive, but seminal and key literary works are identified where possible.