Evaluation of sugar beet pulp efficiency for improving the retention of copper in stormwater basin

Purpose

Sugar beet pulp (SBP) has been shown to be a promising low-cost sorbent for the removal of metals from contaminated waters. The objective of this study was to investigate the impact of SBP addition to horizontal-flow gravel filters in increasing the copper (Cu) retention ability of stormwater basins.

Material and methods

Small-scale gravel filters filled with 6 kg of a sand–sediment mix (SS) were used to experimentally treat Cu-contaminated water under conditions that represented an intense storm event. Sugar beet pulp efficiency was assessed by adding 100 g of raw SBP. Two ways of applying SBP were tested: (1) mixed with SS into the gravel filter or (2) packed at the outlet in a PVC column. Eluates were characterized by their volume, pH, Cu and dissolved organic carbon (DOC) concentrations.

Results and discussion

When placed at the outlet, SBP fixed 73 % of the Cu remaining in solution and increased the overall retention capacity of the gravel filter to 99.4 %. Conversely, when SBP was mixed with SS, the outflowing water carried higher concentrations of Cu and DOC. Complementary batch experiments underlined the crucial role of DOC in the decline of Cu sorption ability observed when SS and SBP were mixed. Geochemical calculations suggested that DOC (assumed to be pectins) promotes the mobilisation of Cu from SS by complexing it in porewater.

Conclusions

Accompanied with careful guidance, SBP has the potential of removing dissolved Cu from contaminated water in gravel filters. Protocols for SBP preparation and conditions of use should be established so as to promote its sorption efficiency and decrease its release of Cu-complexing compounds like pectins.     

Simplified performance assessment methodology for addressing soil quality of nature-based solutions

Journal of Soils and Sediments - In urban areas, soil functions are deeply impacted by all human activities, e.g., water infiltration, carbon storage, and chemical substances degradation potential....     

Droplet size spectra and drift effect of two phenmedipham formulations and four adjuvants mixtures

The effect of 4 adjuvants on two formulations of phenmedipham (EC and SC) applied with three types of hydraulic nozzles (hollow cone, flat fan and air induction) was evaluated using a wind tunnel to determine spray drift potential (DP). The volume median diameter (VMD) and the percentage by volume of droplets less than 100 μm diameter was determined using a Malvern particle size analyser. In a wind tunnel DP was measured between 2 and 6 m downwind of the nozzle on glass fibre collectors using a fluorescent tracer. The EC formulation produced a smaller VMD and larger DP than the SC formulation irrespective of any effect due to adjuvants. DP increased as the proportion of small droplets increased.     

Improving in-row weed detection in multispectral stereoscopic images

Previous research has shown that plant height and spectral reflectance are relevant features to classify crop and weeds in organic carrots: classification based on height gave a classification accuracy (CA) of up to 83% while classification based on a combination of three multispectral bands gave a CA of 72%.The first goal of this study was to examine the simultaneous use of both height and multispectral parameters. It was found that classification rate was only slightly improved when using a feature set comprising both height and multispectral data (2%).The second goal of this study was to improve the detection method based on plant height by setting an automatic threshold between crop and weeds heights, in their early growth stage. This threshold was based on crop row determination and peak detection in plant height probability density function, corresponding to the homogeneous crop population. Using this method, the CA was 82% while the CA obtained with optimal plant height limits is only slightly higher at 86%.     

Spatial variability of trace elements in allotment gardens of four European cities: assessments at city,garden, and plot scale

Purpose

Urban allotment gardens (UAGs) are expanding worldwide, especially in large cities. Environmental pressures (direct and diffuse pollution, gardener practice, geogenic contamination) often result in the accumulation of potentially harmful trace elements in garden soils. The objectives of this study were to assess the spatial variability of trace element distribution in UAGs from city, garden, and plot scale in four European cities; to provide a baseline understanding and identify abnormal values under environmental pressures; and to evaluate the potential of portable X-ray fluorescence screening as a useful tool in soil management.

Materials and methods

The four cities (Ayr and Greenock (Scotland), Lisbon (Portugal), Nantes (France)) provided a wide range of environmental pressures on soils. The locations of the 14 allotment gardens were identified in consultation with the local municipality in each city to reflect various land uses or according to previous evaluation of soil quality. Soil sampling was carried out in 66 plots in total, from which 3 datasets were produced: (i) basic soil properties and trace element concentrations from a composite sample of topsoil for each plot (trace elements quantified by inductively coupled plasma–optical emission spectrometry/mass spectrometry (ICP-OES/MS) or using in-lab portable X-ray fluorescence (PXRF); (ii) in situ PXRF measurement on composite samples (263 plots in Nantes); and (iii) composite samples from 32 small areas within 4 plots in one garden of Nantes.

Results and discussion

The results were analyzed to assess the spatial variability of soil properties. At city and garden scale, the variability observed for basic soil properties and major elements is dominated by local geology/parent material (pH, CaCO₃, Fe) and gardening practice (OM, CaCO₃), which vary between each country. The range of trace element concentrations is similar between each city except for Greenock. Extreme values are observed for Cu, Pb, and Zn reflecting human disruption. In most situations, the trace element contamination was explained through the historical and environmental situations of the site. The PXRF screening method proved useful in providing detailed mapping for hot spot detection or delineation, providing support for soil management at plot and garden scale.

Conclusions

As anticipated, basic soil properties appear to be controlled by the parent material. At plot and garden scale, the trace element variability shows the influence of land use history and background and strong inputs from external factors (e.g., by industrial activity or traffic emission). The PXRF screening method appears to be an efficient solution for soil management as it can be used to discriminate zones which may require restriction on cultivation.

     

So near and yet so far: the specific case of Ralstonia Solanacearum populations from Côte d'Ivoire in Africa

The genetic and phenotypic diversity of C?te d'Ivoire Ralstonia solanacearum strains was assessed on a 168-strain collection sampled on Solanaceae both in the southern lowlands and western highlands. Phylotypes I, II, and III were prevalent, though at unexpected frequencies. Phylotype I strains (87.5%) were genetically diverse and overrepresented in all agroecological areas, including highlands (AEZ III). Phylotype II strains (10.7%) only belonged to one tropical lowland-adapted broad host range lineage (IIA-35), whereas no highland-adapted potato brown rot (IIB-1) or Moko strains were detected. African phylotype III strains were rare (1.8%). They originated from a single Burkina Faso lineage (III-23) and were only found in lowlands. Three phylotype I strains were found harboring pRSC35, a plasmid identified in phylotype III strains in Cameroon. From pathogenicity tests performed on commercial varieties and tomato/eggplant/pepper references, the virulence diversity observed was high, with five pathoprofiles described. Eggplant accessions MM152 and EG203 and tomato HW7996 displayed the largest resistance spectrum and highest level. Two highly virulent phylotype I strains were able to bypass resistance of HW7996 and the eggplant reference AG91-25. Collectively, these points lead to the conclusion that the situation in C?te d'Ivoire is specific towards other African countries, and specifically from the Cameroon reference, and that within phylotype I can exist a high virulence diversity. This calls for similar studies in neighboring West African countries, linking R. solanacearum pathogen genetic diversity to strain virulence at the regional level, for the rationalization of regional resistance deployment strategies and future resistance durability studies.     

The effect of surface orientation on spray retention

Research in precision spraying investigates the means to reduce the amount of herbicide applied by directing droplets more accurately towards the weeds. The trend in the development of spot spraying equipment is an increase of the spatial resolution and new actuators that are able to target very small areas. However, there is a lack of methods for assigning rates of herbicides relating target to optimal droplet features. A wide range of droplet impact angles occurs during the spray application process because of droplet trajectories and the variability of leaf orientation. In this study, laboratory experiments were conducted to highlight the effect of surface orientation on droplet impact outcomes (adhesion, rebound or splashing) on two very difficult-to-wet surfaces: an artificial surface with a regular roughness pattern and an excised black-grass leaf with an anisotropic roughness pattern. Measurements were performed for different surface orientations with a high-speed camera coupled with backlighting LED. Droplets of two formulations (distilled water and distilled water + a surfactant) were produced with a moving flat-fan hydraulic nozzle to obtain a wide range of droplet sizes and velocities, which were measured by image analysis. Increasing surface angle reduces surface area available for droplet capture. Droplet impact behaviors are then modified since surface tilt induces a tangential velocity component at impact and, consequently, a reduction of the normal component. Impact modifications have also been observed due to the anisotropic roughness pattern of a black-grass leaf. The integration of droplet-surface interaction information offers a significant way to further improve the precision spraying efficiency by considering the optimal droplet size, speed and ejection angle depending on the target surface and architecture.