Soil fertility dynamics in runoff-capture agriculture, Canary Islands, Spain

In the extremely arid (∼150 mm yr⁻¹) eastern Canary Islands of Lanzarote, Fuerteventura and La Graciosa, agriculture has been sustained for decades by a traditional runoff-capture (RC) farming system known as “gavias”. Although the main goal of these systems is to increase water supply for crops, making unnecessary conventional irrigation, a secondary and equally important factor is that this system allows for sustainable agricultural production without addition of chemical or organic fertilizers. A field study was conducted to assess the impact of long-term agriculture (>50 yr) on soil fertility and to evaluate key factors affecting the nutrient sustainability of RC agricultural production. Soil fertility and nutrient dynamics were studied through chemical characterization of the arable layer (0-25 cm) of RC agricultural plots, adjacent natural soils (control) not affected by runoff and cultivation, and sediments contributed by a series of RC events. Results showed that RC soils have enhanced fertility status, particularly because they are less affected by salinity and sodicity (mean electrical conductivity = 1.8 dS m⁻¹ vs. 51.0 dS m⁻¹ in control soils; mean exchangeable sodium percentage = 11.1% vs. 30.6% in control soils), and have higher water and nutrient holding capacities (mean clay plus silt contents ≈87% vs. 69% in control soils). In general, sediments transported with the runoff and deposited in RC plots (average sediment yield ≈ 46 ton ha⁻¹ yr⁻¹), contain sufficient nutrients to prevent a progressive reduction of essential plant nutrients below natural levels in spite of nutrient uptake and removal by the harvested crop. Average additions of nitrogen, phosphorus and potassium with the runoff sediments were 33.6, 35.3 and 48.8 kg ha⁻¹ yr⁻¹, respectively. Results of this study show how a crop production system can be sustained in the long term by natural hydrological and biogeochemical catchment processes. This system maintains a nutrient balance that is not based on energy-intensive inputs of fertilizers, but is integrated in natural nutrient cycling processes, unlike other tropical farming agroecosystems.     

ISO 14001 certification and financial performance: selection-effect versus treatment-effect

The paper explores the bi-directional relationship between ISO 14001 certification and financial performance with the aim of shedding light on whether better performance is due to the beneficial effects of ISO 14001 or due to selection-effects where better performance precedes accreditation. The study uses a five year longitudinal analysis to compare the financial performance of firms in Spain before and after certification. The results of a multivariate panel data analysis find that firms with better than average performance have a greater propensity to pursue accreditation but there is no evidence that improvements in performance follow certification. This suggests that the inference that environmental variables cause improved financial performance may be unwise in research studies that can only measure association.     

Trace element levels in foetus-mother pairs of short-beaked common dolphins (Delphinus delphis) stranded along the French coasts

Tissues of foetus-mother pairs of common dolphins (Delphinus delphis) stranded along the French coasts (Bay of Biscay and English Channel) were analysed for their Cd, Cu, Hg, Se and Zn contents. In the kidneys, foetal Cd levels were extremely low, and strong relationships between Cu and Zn suggested the involvement of metallothioneins since early foetal life. The results also indicated a limited maternal transfer of Hg during pregnancy since levels in the tissues of foetuses were below 1 microg g(-1) w.wt. However, hepatic Hg levels in foetuses increased with body length, and were also proportionate to maternal hepatic, renal and muscular Hg levels. Lastly, affinities between Hg and Se in tissues would participate in Hg neutralisation in both mothers--through tiemannite granules--and fetuses--through reduced glutathione--counteracting the toxic effects linked to the particularly high quantities of methyl-Hg to which marine mammals are naturally exposed.     

Variation of the distribution coefficient (Kd) of selenium in soils under various microbial states

This study aimed to (i) evaluate whether the K(d) value of selenium is dependent upon the soil microbial activity and (ii) define the limitation of the use of the K(d) concept to describe selenium behaviour in soils when assessing the long-term radiological waste disposal risk. K(d) coefficients, as well as information on selenite speciation in the soil-solution, were derived from short- and long-term batch experiments with a calcareous silty clay soil in various microbial states. Soil microbial activity induced (i) an increase of the K(d) value from 16 l kg(-1) in sterile conditions to 130 l kg(-1) when the soil was amended with glucose and nitrate, and (ii) changes in selenium speciation both in the solution (presence of seleno-species other than free Se(IV)) and in the solid phase (Se linked to microorganisms). Although the K(d) coefficient adequately reflects the initial fractionation between soil-solid and soil-solution, it does not allow for speciation and microbial processes, which could affect reversibility, mobility and the long-term accumulation and uptake into crops.     

Specific features of the growth of Scots pine vegetative organs in the forest-steppe zone of Cisbaikalia

The dependence of the annual increment of vegetative organs on air temperature and humidity and the amount of precipitation per phenophase, as well as the period of their growth in Scots pine, were studied in the forest-steppe zone of Cisbaikalia. The multiple effect of variation in environmental conditions on the annual increment of organs increased when precipitation in September of the previous year was taken into account. These factors proved to have a stronger effect on variation in the annual increment of needles (R ² = 0.59, p = 0.00005) than that in the annual ring width (R ² = 0.38, p = 0.0002).     

Impacts of wastewater sludge amendments in restoring nitrogen cycle in p-nitrophenol contaminated soil

The possible impacts on nitrogen-cycle in a p-nitrophenol (PNP) polluted soil and the e ectiveness of wastewater sludge amendments in restoring nitrification potential and urease activity were evaluated by an incubation study. The results indicated that PNP at 250 mg/kg soil inhibited urease activity, nitrification potential, arginine ammonification rate and heterotrophic bacteria counts to some extents. After exposure to PNP, the nitrification potential of the tested soil was dramatically reduced to zero over a period of 30 days. Based on the findings, nitrification potential was postulated as a simple biochemical indicator for PNP pollution in soils. Nitrogen-cycling processes in soils responded positively to the applications of wastewater sludges. A sludge application rate of 200 tons/ha was su cient for successful biostimulation of these nitrogen processes. The microbial activities in sludge-amended, heavy PNP-polluted soils seemed to recover after 30–45 days, indicating the e ectiveness of sludge as a useful soil amendment.     

Factors affecting the direct mineralization of CO2 with olivine

Olivine, one of the most abundant minerals existing in nature, is explored as a CO2 carbonation agent for direct carbonation of CO2 in flue gas. Olivine based CO2 capture is thermodynamically favorable and can form a stable carbonate for long-term storage. Experimental results have shown that water vapor plays an important role in improving CO2 carbonation rate and capacities. Other operation conditions including reaction temperature, initial CO2 concentration, residence time corresponding to the flow rate of CO2 gas stream, and water vapor concentration also considerably affect the performance of the technology.     

Production of new concrete with leather tannery waste used as partial replacement of the natural sand

Journal of Material Cycles and Waste Management - Leather production is a technology that boosts the economy because of its versatility and durability. However, the wastes generated throughout the...     

Face mask and medical waste generation in the City of Baguio,Philippines: its current management and GHG footprint

Journal of Material Cycles and Waste Management - The daily use of facemask to prevent virus transmission increases the negative effect on the environment because of improper waste disposal. Due to...     

Backwater Confluences of the Ohio River: Organic and Inorganic Fingerprints Explain Sediment Dynamics in Wetlands and Marinas

In the Ohio River (OR), backwater confluence sedimentation dynamics are understudied, however, these river features are expected to be influential on the system’s ecological and economic function when integrated along the river’s length. In the following paper, we test the efficacy of organic and inorganic tracers for sediment fingerprinting in backwater confluences; we use fingerprinting results to evidence sediment dynamics controlling deposition patterns in confluences used for wetland and marina functions; and we quantify the spatial extent of tributary drainages with wetland and marina features in OR confluences. Both organic and inorganic tracers statistically differentiate sediment from stream and river end‐members. Carbon and nitrogen stable isotopes produce greater uncertainty in fingerprinting results than inorganic elemental tracers. Uncertainty analysis of the nonconservative tracer term in the organic matter fingerprinting application estimates an apparent enrichment of the carbon stable isotopes during instream residence, and the nonconservativeness is quantified with a statistical approach unique to the fingerprinting literature. Wetland and marina features in OR confluences impact 42% and 11% of tributary drainage areas, respectively. Sediment dynamics show wetland and marina confluences experience deposition from river backwaters with longitudinally linear and nonlinear patterns, respectively, from sediment sources.