Chapter 12. BIOGEOCHEMICAL WEATHERING OF SILICATE MINERALS

Barker, William; Welch, Susan A.; Banfield, Jillian F.

doi:10.1515/9781501509247-014

Cited by 130 publications

(111 citation statements)

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“…The pH range of the experiment (pH 4-7 for input to output solution pH) is in the range for which both geochemical and plant-induced weathering can occur (Barker et al, 1997;Drever, 1994;Drever and Stillings, 1997) and is suggested to represent realistic field conditions (Welch and Ullman, 1993). The data showed comparable trends for all three treatments over time (vessels with or without plants).…”

Section: Experimental Conditionsmentioning

confidence: 89%

“…However, verifications in a series of pilot studies revealed that the pH (after addition of the nutrient solution of pH 4 or 3 into the vessels) rapidly increased in contact with the minerals and changed to final values of pH 5 to 7. This means that the range of pH in which most of the solution was in contact with the minerals, corresponds to the range in which organic acids can be most reactive for weathering (Barker et al, 1997;Drever, 1994;Drever and Stillings, 1997;Welch and Ullman, 1993). The geochemical contribution to weathering would thus be lower than was expected on the basis of the initial pH alone.…”

Section: Impact Of Ph On the Leaching Dynamicsmentioning

confidence: 98%

“…As a result, weathering rates in the rhizosphere -the soil volume surrounding roots containing high densities of microbionts -are often considerably higher than those in the bulk soil (Arocena and Glowa, 2000). Weathering rates showed a tenfold increase in the presence of oxalic acids (Welch and Ullman, 1993), however below pH 4.5 to 5 and above pH 8, the pure pH effect (acidity, geochemical weathering) is preponderant and weathering rates increase linearly with decreasing pH (< pH 5), or increasing pH (> pH 8), respectively (Barker et al, 1997;Drever and Stillings, 1997;Welch and Ullman, 1993). Between pH 4 and 7 plant effects -e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Between pH 4 and 7 plant effects -e.g. excretion of organic acidscan be relatively more important (Barker et al, 1997;Drever, 1994;Drever and Stillings, 1997). In fact, direct weathering and dissolution have been observed in many studies including roots and or isolated fungi and microbia.…”

Section: Introductionmentioning

confidence: 99%

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Impact of Douglas-fir and Scots pine seedlings on plagioclase weathering under acidic conditions

et al. 2005

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The weathering of soil minerals in forest ecosystems increases nutrient availability for the trees. The rate of such weathering and its relative contribution to forest tree nutrition, is a major issue when evaluating present and potential forest stand productivity and sustainability. The current paper examines the weathering rate of plagioclase with and without Douglas-fir or Scots pine seedlings, in a laboratory experiment at pH 3-4 and 25 • C. All nutrients, with the exception of Ca, were supplied in sufficient amounts in a nutrient solution. The objective of the experiment was to evaluate the potential of trees to mobilise Ca from the mineral plagioclase that contained 12% of Ca. Amounts of nutrients supplied in the nutrient solution, amounts accumulated in the living tissue of the seedlings and amounts leached from the experimental vessels, were measured. A weathering balance, accounting for leached + accumulated -supplied amounts, was established. Bio-induced weathering, defined as the weathering increase in the presence of trees, relative to the weathering rate without trees (geochemical weathering; control vessels), under the present experimental conditions, explained on average, 40% of total weathering (biological + geochemical). These conditions appeared more beneficial to Scots pine (higher relative growth rate, higher Ca incorporation) than to Douglas-fir.

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Section: Experimental Conditionsmentioning

confidence: 89%

Section: Impact Of Ph On the Leaching Dynamicsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Impact of Douglas-fir and Scots pine seedlings on plagioclase weathering under acidic conditions

et al. 2005

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“…It is known that vascular plants and associated microbial communities increase soil mineral weathering and mineral-derived nutrient availability through physical and chemical processes (Leyval and Berthelin 1991;Barker et al 1997;Bormann et al 1998;Kelly et al 1998;Banfield et al 1999;Landeweert et al 2001;Marschner 2002). Maintenance of soil fertility and long-term productivity of terrestrial ecosystems require that rates of chemical denudation-the transport of weathered elements in solution to groundwater, rivers, and the oceans-do not exceed weathering rates and internal cycling of cations.…”

Section: Introductionmentioning

confidence: 99%

The effect of bacteria and fungi on chemical weathering and chemical denudation fluxes in pine growth experiments

et al. 2008

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Vascular plants and associated microbial communities affect the nutrient resources of terrestrial ecosystems by impacting chemical weathering that transfers elements from primary minerals to other ecosystem pools, and chemical denudation that transports weathered elements out of the system in solution. We performed a year-long replicated flowthrough column growth experiment to isolate the effects of vascular plants, ectomycorrhiza-forming fungi and associated bacteria on chemical weathering and chemical denudation. The study focused on Ca 2+ , K + and Mg 2+ , for which the sole sources were biotite and anorthite mixed into silica sand. Concentrations of the cations were measured in input and output solutions, and three times during the year in plant biomass and on exchangeable cation sites of the growth medium. Weathering and denudation fluxes were estimated by mass balance, and mineral surface changes, biofilm and microbial attachments to surfaces were investigated with scanning electron microscopy. Both bacteria and fungi increased weathering fluxes compared to abiotic controls. Without a host plant denudation rates were as large as weathering rates i.e. the weathering to denudation ratio was about one. Based on whole year fluxes, ectomycorrhizal seedlings produced the greatest weathering to denudation ratios (1.5). Non-ectomycorrhizal seedlings also showed a high ratio of 1.3. Both ectomycorrhizal hyphal networks and root hairs of non-ectomycorrhizal trees, embedded in biofilm (microorganisms surrounded by extracellular polymers), transferred nutrients to the host while drainage losses were minimized. These results suggest that biofilms localize both weathering and plant nutrient uptake, isolating the root-hypha-mineral interface from bulk soil solution.

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Biogeomorphological disturbance regimes: progress in linking ecological and geomorphological systems

Viles

Naylor

Carter

et al. 2008

Earth Surf Processes Landf

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Understanding the complex, non-linear ways in which linked ecological and geomorphological systems respond to disturbance is important to improving both theoretical understanding and practical environmental management. Some simple conceptual models have been proposed to describe biogeomorphological responses to disturbance within fluvial and aeolian environments, and are reviewed here. Recent research on the interactions between ecological and geomorphological processes in rock breakdown, aeolian, hillslope, fluvial and coastal wetland process regimes indicates a number of additional factors which need to be considered by such models in order to provide a more realistic representation. In particular, many empirical studies point to complex interactions between vegetation, microphytic crusts and animal action (bioturbation and grazing) in a wide range of sediment systems, which act as intrinsic feedback factors complicating the response of these systems to disturbances such as climate change and human action. Improved understanding of these interactions will help effective environmental management, as exemplified by salt marsh restoration schemes. Furthermore, better specification of biogeomorphological interactions can provide insights into large-scale, long-term Earth systems dynamics problems such as the long-term carbon cycle.A simple model representing how geomorphological systems respond to disturbance (e.g. storm events, climate change, human activities) is shown in Figure 1. This model illustrates that geomorphological systems do not respond in a simple, linear fashion to disturbance, but that there are both lags and different response rate characteristics to forcing factors. One factor group (often described as feedback or intrinsic factors, e.g. Allen, 2000) which influences lag times and response rates is ecological change, such as vegetation growth and decay. All biotic influences on geomorphological processes can be seen to have either a stabilizing effect (i.e. reducing erosion and other processes through what some workers call 'bioprotection') or a destabilizing effect (i.e. enhancing erosion and other geomorphological processes) as shown in Table I. Biotic stabilization effects lead to negative feedbacks within geomorphological systems, whereas destabilization through biotic processes produces positive feedbacks. Understanding the operation of such stabilizing and destabilizing effects and how they interact with abiotic processes is vital for a fuller understanding of the response of geomorphological systems to disturbance.Looking at things from an ecological systems point of view, geomorphological processes can be seen to produce positive and negative feedbacks on ecosystem response to disturbance as illustrated in Table II. In some cases, geomorphological processes have stabilizing or destabilizing roles depending on their rate relative to the rate of plant growth, or animal activity. However, the picture is further complicated by interactions within ecological systems, e.g. grazing impacts on ve...

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Chapter 12. BIOGEOCHEMICAL WEATHERING OF SILICATE MINERALS

Cited by 130 publications

References 0 publications

Impact of Douglas-fir and Scots pine seedlings on plagioclase weathering under acidic conditions

Impact of Douglas-fir and Scots pine seedlings on plagioclase weathering under acidic conditions

The effect of bacteria and fungi on chemical weathering and chemical denudation fluxes in pine growth experiments

Biogeomorphological disturbance regimes: progress in linking ecological and geomorphological systems

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