Contribution for the derivation of a soil screening value (SSV) for uranium, using a natural reference soil

In order to regulate the management of contaminated land, many countries have been deriving soil screening values (SSV). However, the ecotoxicological data available for uranium is still insufficient and incapable to generate SSVs for European soils. In this sense, and so as to make up for this shortcoming, a battery of ecotoxicological assays focusing on soil functions and organisms, and a wide range of endpoints was carried out, using a natural soil artificially spiked with uranium. In terrestrial ecotoxicology, it is widely recognized that soils have different properties that can influence the bioavailability and the toxicity of chemicals. In this context, SSVs derived for artificial soils or for other types of natural soils, may lead to unfeasible environmental risk assessment. Hence, the use of natural regional representative soils is of great importance in the derivation of SSVs. A Portuguese natural reference soil PTRS1, from a granitic region, was thereby applied as test substrate. This study allowed the determination of NOEC, LOEC, EC20 and EC50 values for uranium. Dehydrogenase and urease enzymes displayed the lowest values (34.9 and ,134.5 mg U Kg, respectively). Eisenia andrei and Enchytraeus crypticus revealed to be more sensitive to uranium than Folsomia candida. EC50 values of 631.00, 518.65 and 851.64 mg U Kg were recorded for the three species, respectively. Concerning plants, only Lactuca sativa was affected by U at concentrations up to 1000 mg U kg1. The outcomes of the study may in part be constrained by physical and chemical characteristics of soils, hence contributing to the discrepancy between the toxicity data generated in this study and that available in the literature. Following the assessment factor method, a predicted no effect concentration (PNEC) value of 15.5 mg kg21dw was obtained for U. This PNEC value is proposed as a SSV for soils similar to the PTRS1

Natural capital, ecosystem services, and soil change: why soil science must embrace an ecosystems approach

Soil is part of the Earth's life support system, but how should we convey the value of this and of soil as a resource? Consideration of the ecosystem services and natural capital of soils offers a framework going beyond performance indicators of soil health and quality, and recognizes the broad value that soil contributes to human wellbeing. This approach provides links and synergies between soil science and other disciplines such as ecology, hydrology, and economics, recognizing the importance of soils alongside other natural resources in sustaining the functioning of the Earth system. We articulate why an ecosystems approach is important for soil science in the context of natural capital, ecosystem services, and soil change. Soil change is defined as change on anthropogenic time scales and is an important way of conveying dynamic changes occurring in soils that are relevant to current political decision-making time scales. We identify four important areas of research: (i) framework development; (ii) quantifying the soil resource, stocks, fluxes, transformations, and identifying indicators; (iii) valuing the soil resource for its ecosystem services; and (iv) developing decision-support tools. Furthermore, we propose contributions that soil science can make to address these research challenges

Ecosystem services: A useful concept for soil policy making!

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On the value of soil resources in the context of natural capital and ecosystem service delivery

The ecosystem services approach endeavors to incorporate the economic value of ecosystems into decision making. This is because many natural resources are subject to market failure. As a result, many economic decisions omit the impact that natural resource use has on the earth’s resources and the life support system it provides. Hence, one of the objectives of the ecosystem services approach is to employ economic valuation of natural resources in micro- and macroeconomic policy design, implementation, and evaluation. In this article we examine valuation concepts, and ask why we might attempt to economically value the contribution of soils to the provision of ecosystem services. We go on to examine economic valuation methods and review economic valuation of soils. By surveying prices of soils on the web we are able to make a first, limited global assessment of direct market value of topsoil prices. We then consider other research efforts to value soil. Finally, we consider how the valuation of soil can meaningfully be used in the introduction of improved resource management mechanisms such as decision support tools on which valuation can be based, within the UN’s System of Environmental and Economic Accounts (SEEA) and policy mechanisms like Payments for Ecosystem Services (PES)

Pedometric Valuation of the Soil Resource

Soil forms the thin skin of the Earth and is the site of many ecological processes, transformations, and fluxes. It forms the substrate for most of the activities that take place at the Earth’s surface, including almost all food production and human occupation, and underpins both natural and managed ecosystems. Soils differ in their structure, composition, and ability to function under a use. Soil is a multifunctional resource that affects human well-being both directly (e.g., food provision) and indirectly (e.g., surface and groundwater supplies) and that affects all near-land surface ecological processes. Clearly, soil is “valuable” as that term is understood in common language. The pedometric program as outlined in this book, i.e., the development of “quantitative methods for the study of soil distribution … as a sustainable resource,” should therefore include an attempt to quantify this value. Chapter 1 of the present book lists as the third of four items on the pedometric agenda “evaluating the utility and quality of soil,” and it is in this sense that we attempt in this chapter to define and quantify the value of the soil resource. This process is referred to as “valuation.

Nitrogen cycling from increased soil organic carbon contributes both positively and negatively to ecosystem services in wheat agro-ecosystems

Soil organic carbon (SOC) is an important and manageable property of soils that impacts on multiple ecosystem services through its effect on soil processes such as nitrogen (N) cycling and soil physical properties. There is considerable interest in increasing SOCconcentration in agro-ecosystems worldwide. In some agro-ecosystems, increased SOC has been found to enhance the provision of ecosystem services such as the provision of food. However, increased SOC may increase the environmental footprint of some agro-ecosystems, for example by increasing nitrous oxide emissions. Given this uncertainty, progress is needed in quantifying the impact of increased SOCconcentration on agro-ecosystems. Increased SOC concentration affects both N cycling and soil physical properties (i.e., water holding capacity). Thus, the aim of this study was to quantify the contribution, both positive and negative, of increased SOC concentration on ecosystem services provided by wheat agro-ecosystems. We used the Agricultural Production Systems sIMulator (APSIM) to represent the effect of increased SOC concentration on N cycling and soil physical properties, and used model outputs as proxies for multiple ecosystem services from wheat production agro-ecosystems at seven locations around the world. Under increased SOC, we found that N cycling had a larger effect on a range of ecosystem services (food provision, filtering of N, and nitrous oxide regulation) than soil physical properties. We predicted that food provision in thse agro-ecosystems could be significantly increased by increased SOCconcentration when N supply is limiting. Conversely, we predicted no significant benefit to food production from increasing SOC when soil N supply (from fertiliser and soil N stocks) is not limiting. The effect of increasing SOC on N cycling also led to significantly higher nitrous oxide emissions, although the relative increase was small. We also found that N losses via deepdrainage were minimally affectedby increasedSOCin the drylandagro-ecosystems studied, but increased in the irrigated agro-ecosystem. Therefore, we show that under increased SOC concentration, N cycling contributes both positively and negatively to ecosystem services depending on supply, while the effects on soil physical properties are negligible