Effect of dairy effluent on the biomass, transpiration, and elemental composition of Salix kinuyanagi Kimura

Introduction Available online at www.sciencedirect.com ht tp://www.elsevier.com/locate/biombioe b i o m a s s a n d b i o e n e r g y 3 7 ( 2 0 1 2 ) 2 8 2 e2 8 8 0961-9534/$ e see front matter

Natural and induced cadmium-accumulation in poplar and willow: implications for phytoremediation. Plant Soil 227

Abstract Potentially poplars and willows may be used for the in situ decontamination of soils polluted with Cd, such as pasturelands fertilised with Cd-rich superphosphate fertiliser. Poplar (Kawa and Argyle) and willow (Tangoio) clones were grown in soils containing a range (0.6-60.6 µg g −1 dry soil) of Cd concentrations. The willow clone accumulated significantly more Cd (9-167 µg g −1 dry matter) than the two poplar clones (6-75 µg g −1 ), which themselves were not significantly different. Poplar trees (Beaupré) sampled in situ from a contaminated site near the town of Auby, Northern France, were also found to accumulate significant quantities (up to 209 µg g −1 ) of Cd. The addition of chelating agents (0.5 and 2 g kg −1 EDTA, 0.5 g kg −1 DTPA and 0.5 g kg −1 NTA) to poplar (Kawa) clones caused a temporary increase in uptake of Cd. However, two of the chelating agents (2 g kg −1 EDTA and 0.5 g kg −1 NTA) also resulted in a significant reduction in growth, as well as abscission of leaves. If the results obtained in these pot experiments can be realised in the field, then a single crop of willows could remove over 100 years worth of fertiliser-induced Cd contamination from pasturelands

Seasonal variation of hydraulic properties of soils measured using a tension disk infiltrometer

For sound land management, it is important to understand the temporal changes that soil hydraulic properties undergo. Estimation of the unsaturated characteristics of the hydraulic conductivity, sorptivity, and mean pore radius was performed using tension-disk infiltrometers in two different soils of the Mediterranean region: a sandy soil (Xerochrept) and a heterogeneous, stony, and sandy soil (Alfisol). Both soils were cropped with maize (Zea mays L.) and underwent conventional tillage and different irrigation practices, namely furrow irrigation and gun irrigation. The mobile water content was also deduced from soil samples extracted underneath the disk following a period of infiltration with the tension infiltrometer filled with a Cl- tracer. Results are presented here of measurements made after plowing and again at the end of the growing season. During the growing season, the sandy soil under furrow irrigation showed a significant decrease in its hydraulic properties. This followed an increase in the hulk density and was a result of sealing of the small interconnected pores at the soil surface. Strong nonlinearity in the hydraulic conductivity was found for the stony soil, yet there was no significant change in this nonlinearity during the growing season. However, from the tracer results, it is stated that for this soil, the structure of the fine fraction changes from a well-interconnected microporous network to a poorly connected one. This results in an increase of the mobile water content during the growing season. It is shown that a good understanding of the porous network can be obtained from tension infiltrometers and can explain changes in both the hydraulic conductivity and the sorptivity. These changes were also partially corroborated by the mobile water content measurements obtained from tracer observations under the disk.Peer Reviewe

CCA transport in soil from treated-timber posts: pattern dynamics from the local to regional scale

Winegrape growing in many parts of the world, including Marlborough, New Zealand, uses treated-timber posts to act as supports for the grapevine's canopy. At a density of 580 posts per hectare, the H4-process treated supports result in an areal loading of CCA of: Copper (12 kg-Cu ha−1), Chromium (21 kg-Cr ha−1) and Arsenic (17 kg-As ha−1). Arsenic is the most mobile and toxic of the CCA-treatment cocktail. We describe experiments which indicate that about 4–6 mg-As month−1 post−1 is released from the subterranean part of the post. We have used SPASMO (Soil Plant Atmosphere System Model) to predict post-to-soil leakage, as well as the pattern dynamics of leaching and exchange around the post. Locally the pattern dynamics of transport and fate are controlled by the soil's chemical characteristics and the prevailing weather. Over its 20-year lifetime, the concentration of arsenic, both that adsorbed on the soil and in the soil solution, exceeds guideline values for soils (100 mg-As kg−1) and drinking water (10 μg-As L−1). Under a regime of 5% annual replacement of posts, the spatially averaged concentration of arsenic leaching through the soil is predicted to rise to 1.25 to 1.7 times the drinking water standard, depending only slightly on the soil type. The steady value is primarily controlled by the arsenic-release rate from the post. These steady values were used in a simple hydrogeological model of the major Marlborough aquifer systems to determine whether the subterranean flow of water could dilute the descending plumes of arsenic coming from above. Except for the sluggish aquifers of the southern valleys in Marlborough, most of the aquifer systems seem capable of diluting the leachate to between one tenth and one twentieth of the drinking water standard. The upscaling of our modelling of the local pattern dynamics spanned six orders of spatial magnitude, and four orders of time dimension.ISSN:1812-2116ISSN:1812-210