Characterization of soil physico-chemical parameters and limitations for revegetation in serpentine quarry soils (NW Spain)

Purpose

Quarrying activities in areas with serpentinized rocks may have a negative impact on plant growth. Quarry soils generally offer hostile environments for plant growth due to their low-nutrient availability, low organic matter, and high-trace metal content.

Materials and methods

In order to determine the factors that can limit plant revegetation, this study was carried out in two serpentine quarries in Galicia (NW Spain): one abandoned in 1999 and the other still active.

Results and discussion

The results show that in soils developed in the abandoned quarry, the limitations for revegetation were: moderate alkaline pH (7.87–8.05), strong Ca/Mg (<1) imbalance, low N (<0.42 mg kg^?1) and P (<2 mg kg^?1) content, and high total heavy-metal content (Co 76–147 mg kg^?1; Cr 1370–2600 mg kg^?1; and Ni 1340–2040 mg kg^?1). The limitations were much less intense in the soils developed in the substratum in the active quarry, which were incipient soils poorly developed and permanently affected by the quarrying activity.

Conclusions

Restoration work should be geared toward establishing a stable diverse vegetation cover, including serpentinophile species, which would provide the necessary modifications to correct nutritive imbalances and improve soil quality.

     

Solid-Solution Metal Partitioning for the Upper Mero River Basin (NW Spain)

This study determines the seasonal variability of metal partition coefficients [aluminium (Al), iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn)] and analyses the importance of suspended sediments (SS), dissolved organic carbon (DOC) concentrations, pH, and discharge (Q) on the seasonal variability of metal partition coefficients (K_Ds) in the headwaters of the Mero River catchment, which drains an agroforestry area in northwestern Spain. Metal partition coefficients were used as an approach to relate dissolved and particulate fractions. Water samples were collected over 3 years (2005–2008) at the catchment outlet. The mean metal dissolved concentrations were: Fe (43.5 μg L^?1) > Al (23.3 μg L^?1) > Zn (1.8 μg L^?1) > Mn (1.2 μg L^?1) > Cu (0.3 μg L^?1). Partition coefficients followed the order Mn > Al > Fe > Zn > Cu, and their values exhibited low variability. Al, Cu, and Zn partition coefficients presented the greatest values in summer, except during 2007–2008, when the greatest K_Ds value was observed in autumn, whereas the K_Ds of Fe showed the greatest values in winter. The K_D of Mn has no seasonality. For Al, Cu, and Zn, the seasonal SS concentrations were closely related to Kd. For Fe, Kd was more closely related to DOC concentration than to SS concentration.     

Aluminium Toxicity Risk for Pinus pinaster in Acid Soils (Galicia,NW Spain)

The influence of bedrock on aluminium toxicity and aluminium speciation in the soil solution was studied in four Pinus pinaster plots. Growth and biomass parameters in the acidic soils were also evaluated in relation to different Al toxicity indices. The plots were developed over slate, biotitic schist, mica schist and granite. Samples of rhizospheric and non‐rhizospheric soil, 1‐year‐old needles and roots were collected in each study plot. Total Al, reactive Al, acid‐soluble Al, non‐labile and labile Al and Al species (Al³⁺, Al‐OH, Al‐F and Al‐SO₄) were determined in soil solution. Reactive Al dominated over the acid‐soluble Al, and the non‐labile Al predominated over the labile Al in all soils, but particularly over mica schist. In the biotitic schist soil, the Al forms and total Al were lower, whereas concentrations were always higher over mica schist. The Al forms considered most toxic were Al³⁺ and Al‐OH, and Al concentrations were highest over slate and mica schist. Al toxicity indices in soil, needle and roots showed a risk of toxicity in mica schist, slate and granite. The stand site indices over slate and mica schist were lower, consistent with the high labile Al and Al³⁺ + Al‐OH in soil solution. Despite the high stand site index over granite, the growth efficiency was low, in accordance with very low ratios of Ca/Al in needles or fine roots. This confirmed the adaptation of maritime pine to granitic substrates. Copyright © 2016 John Wiley & Sons, Ltd.     

Mobility of sulphate in experimentally acidified soils from Galicia (NW Spain)

Retention of S0₄ ^2? was investigated in Galician soils throughout an intense regime of acidification. Experiments consisted of the addition of an H2SO4 solution (pH 2.7) to columns of 6 soils of contrasting properties over 1, 2, or 5 months. Leachates were obtained continuously throughout the experiment for analysis, and analysis made of the solid fractions after 1, 2 or 5 months. The greatest capacities for retention of S0₄ ^2? were found in soil developed from serpentine and micaschist; the lowest in soils from granite, slate and sandy sediments. The surface horizons, especially those rich in organic matter, displayed low retention of 5042-. The amount of S0₄ ^2? adsorbed throughout the experiment depended on the content of crystalline forms of Fe and with the Fe and Al extracted with dithionite-citrate.The low retention of S0₄ ^2? in the organic horizons and the slightly negative relation with the organic matter suggest an inhibitory effect of the organic matter on the S0₄ ^2? retention process. Results of the study show, that under conditions of moderate acidity, SO₄ ^2? retention occurs in the form of adsorption; in strongly acidic conditions, the precipitation of aluminium-sulphate minerals may provide an additional retention mechanism.     

Pedological and geomorphological cycles in a catena of Galicia (NW Spain)

A catena developed on gabbro in Galicia, N.W. Spain, was studied. The methods utilized, consisting of macro- and microscopic mineralogical and morphological observation, allowed the identification of different features produced by the action of pedological and geomorphological processes. The application of Butler's K cycle concept allows a relative sequence of events to be established in which pedogenetic processes are integrated within the general framework of the evolutionary history of the slope. Five K cycles could be recognized, beginning with a phase of deep weathering and ending with the present phase of incipient soil formation. In between feature a.o. phases of solifluxion, the formation of an argillic horizon and the development of a stoneline.     

Smectite formation produced by weathering in a coarse granite saprolite in Galicia (NW Spain)

Weathering of a calcalkaline granite was studied in the south of Galicia (NW Spain) where the average annual precipitation is 1400 mm and the average annual temperature is 12°C. The original rock contains perthitic K-feldspars, plagioclases with inclusions of muscovite and opaque minerals, quartz and chloritized biotite, with apatite, zircon, sphene and opaques as accessories. In the saprolite the structure of the rock is preserved, the plagioclases show up to grade 4 weathering and the biotites, between 2 and 3. Weathering in quartz and potassium feldspar crystals is manifested only by fracturing. Biotite changes following the parallel linear model and its weathering products are interstratified biotite–vermiculite and iron oxyhydroxides. The plagioclases change to a microgranular material by pseudomorphic transformation. This material, which substitutes the plagioclase, includes small clearly delimited units which retain zones with the optic characteristics of muscovite. X-ray diffraction analyses of microsamples show that they are formed by 1:1 diocthaedral phyllosilicate, smectite and a small quantity of mica. From these facts we concluded that smectite is formed inside the plagioclase crystals, and probably originates from the inclusions of muscovite contained in these crystals, as it is suggested by the microscopic study which shows the increase in volume which occurs when the crystals of muscovite are transformed.     

Copper distribution and acid-base mobilization in vineyard soils and sediments from Galicia (NW Spain)

In northern Spain and elsewhere in the world, many vineyards are located on steep slopes and are susceptible to accelerated soil erosion. Contaminants, notably Cu, originating from repeated application of copper‐based fungicides to the vines to prevent mildew, are transported and stored in the sediments deposited close to valley bottoms. In this study, the contents and distribution of Cu in 17 soil samples and 21 sediment samples collected from vineyard stands were determined. In addition, the effect of pH on Cu release from vineyard soils and sediments was quantified. The total Cu content (Cu_T) in the soils varied between 96 and 583 mg kg^?1, and was between 1.2 and 5.6 times greater in sediment samples. The mean concentration of potentially bioavailable Cu (Cu_EDTA) in the sediments was 199 mg kg^?1 (46% of Cu_T), and was 80 mg kg^?1 (36% of Cu_T) in the soils. Copper bound to soil organic matter (Cu_OM) was the dominant fraction in the soils (on average, 53% of the Cu_T), while in sediment samples Cu_OM values varied between 37 and 712 mg kg^?1 and were significantly greater (P < 0.01) than in the soils. Copper associated with non‐crystalline inorganic components (Cu_IA) was the second most important fraction in the sediments, in which it was 3.4 times greater than in the soils. Release of Cu due to changes in the pH followed a U‐shaped pattern in soils and sediments. The release of Cu increased when the pH decreased below 5.5 due to the increased solubility of the metal at this pH. When the pH increased above 7.5, Cu and organic matter were released simultaneously.     

Wildfires influence on soil organic matter in an Atlantic mountainous region (NW of Spain)

The principal aim of this research was to determine the influence of wildfires on soil organic matter (SOM) content and composition in soils located on the northern slope of the Cantabrian Cordillera, an Atlantic mountainous region in the North West of Spain, where wildfires are frequent. Samples from soils with similar aspect, slope, elevation and vegetation characteristics, but with different wildfires histories were collected. Total organic carbon and total nitrogen contents were determined as well as the C/N ratio. Furthermore, a qualitative characterization of the soil organic carbon (SOC) was carried out by ¹³C variable amplitude cross polarization magic angle spinning (VACP/MAS) Nuclear Magnetic Resonance (NMR) spectroscopy. Our results show that, on the one hand, all the sampled soils can be considered important pools of carbon in this Atlantic mountainous region, especially in the heath areas. On the other hand, the fire-affected soils present higher SOM contents than their unburnt counterparts. This could be attributed to an important reaccumulation of fresh vegetal material, which is probably a consequence of the decrease of SOM decomposition rates after fire. Moreover, charred organic compounds are not found in all the burnt soils, which could be due to the long time since the last fires events took place, to different fire severities, or to different post-fire erosion processes in the studied soils.     

微立地因子植被恢复法在汶川地震植被重建中的应用

“5·12”汶川大地震造成的滑坡、泥石流、崩塌等地质次生灾害使当地的植被毁坏严重,微立地因子植被恢复法适用于地震灾区复杂的立地条件植被重建。在研究灾区植被破坏类型的基础上,将损毁植被的坡面划分为岩质边坡、土质边坡、土石边坡3种类型,并对不同坡面进行微立地因子类型划分,针对不同立地条件选择适宜植被恢复技术,促使灾区尽快植被重建,并为微立地因子植被恢复法的完善提供重要依据。     

Comparison of indirect methods for the determination of percent exchangeable aluminium in acid soils of Galicia (NW Spain)

Abstract

Ten easily determined soil parameters related to soil acidity were evaluated for their potential to provide simple, indirect estimates of the exchangeable aluminium percentage (PAL). These parameters were correlated with the PAL in 0.6N BaCl₂ extracts of soils collected from lime trials on 4 different parent materials. Six rates of lime (0, 0.75, 1.5, 3, 6, 12 t/ha) were added 3–4 years prior to collection of the samples. The soil parameters examined were the pH of soil suspensions with SMP, Woodruff and New Woodruff buffer solutions; the pH of 1, 5 and 10mM CaCl₂ and 0.6N BaCl₂ soil extracts, and the aluminium content of 1, 5 and 10mM CaCl₂ soil extracts. The best correlations with the exchangeable aluminium percentage for all soils considered, were those based on the aluminium content of the 5mM CaCl₂ extract (r=0.976, n=24) followed by the pH of the 0.6N BaCl₂ extract (r=0.945, n= 24). Both these methods are suggested as reliable indirect estimates of soil exchangeable alumimium percentage where availability of staff or equipment restrict direct determinations.     

Expression of andic properties in soils from Galicia (NW Spain) under forest and agricultural use

The organic matter (OM) of soils with andic properties has long been considered highly stable because of the presence of Al–humus complexes and sorption of organic ligands onto amorphous compounds. In this study, we characterized soils under different land use regimes located within an amphibolitic massif close to Santiago de Compostela (Spain), where soils with andic properties are present. Slash and burn agriculture was a common practice in the area until the second half of the 20th century. Thereafter, modern agriculture was progressively introduced into the area (AGR soils), and the rest of the land was either reforested or abandoned (FOR soils). We found that the mean organic C content of AGR soils (48.7 g kg^?1) was ～ 50% that of FOR soils (94.2 g kg^?1). Mean soil pH was significantly greater (P < 0.05) in the AGR than in the FOR soils (4.95 compared with 4.63), which is attributed to liming and Ca‐phosphate fertilization of the former. Mean concentrations of the Al forms studied (extractable with CuCl₂, sodium pyrophosphate, ammonium oxalate, or NaOH) were significantly smaller (P < 0.01) in AGR (1.4, 4.9, 9.3, 11.0 g kg^?1, respectively) than in FOR soils (3.9, 10.2, 16.5, 17.9 g kg^?1, respectively). The results show the vulnerability of the OM and Al–humus complexes in these soils to modern agricultural practices, which has led to the attenuation – and in some cases even the disappearance – of andic soil properties in a relatively short time (< 30 years) following changes in land use/management. We propose the inclusion of the formative element ‘andic’ in the criteria for the definition of Umbrisol subunits; this would avoid the abrupt discontinuity observed in the current World Reference Base classification.     

Throughfall,runoff and soil erosion after prescribed burning in gorse shrubland in Galicia (NW Spain)

The first‐year effect of two different prescribed burning treatments on throughfall, runoff and soil erosion was evaluated in gorse shrubland (Ulex europaeus L.) in Galicia (NW Spain). The treatments compared were: intense burn, light burn and control (no burn). Accumulated annual throughfall represented between the 81 and 87 per cent of total rainfall in intensely burned and lightly burned areas, respectively, whereas in the unburnt areas it was 60 per cent. No significant differences between burning treatments were found for the annual throughfall. However, runoff was significantly greater in intensely burned plots (1·5‐times) than in lightly burned plots. Burning also resulted in a significant increase in runoff (between 2·5 and 1·7‐times, respectively) compared with controls. Total soil losses were small in all treatments, but the intense burn caused significantly greater soil erosion (5·8‐times) compared with the unburned areas. Soil losses after the light burn did not significantly differ from the control although they were higher (2·3‐times). The relationships obtained between erosion and several rainfall parameters were significantly different in burned areas compared to the control. The same response was observed for runoff. Annual erosion losses showed a strong dependence on percentage of bare soil even for small values of this variable. Litter thickness was also a very important variable influencing on erosion rates. This study indicated that by combining ignition techniques and high litter moisture content to maintain the percentage of bare soil below 85 per cent, soil erosion was low. Nevertheless, this result was constrained by the low rainfall that occurred during the study. Copyright © 2005 John Wiley & Sons, Ltd.     

Response of some soils of Galicia (NW Spain) to H2SO4 acidification

This paper presents the results of an acidification experiment, consisting of seven consecutive equilibrations of repesentative soils of Galicia with a H₂SO₄ solution (pH 3). Different responses to soil acidification, such as SO₄ retention and cation release, were evaluated. In soils derived from gabbro and amphibolite, SO₄ retention and Al release were the principal acid neutralization mechanisms, whereas in soils derived from granite, schist, shale and sandstone Al release was the main process. The SO₄ retention was significantly correlated with Al and Fe extracted with dihionite-citrate-bicarbonate and crystalline Fe. The released base cations came mainly from exchange sites, though sometimes also from other sources, probably by mineral weathering. The major sources of Al in these soils were metalorganic complexes and weatherable minerals. Solutions with pHs close to 4 are in equilibrium with gibbsite, kaolinite, jurbanite and alunite; at lower pH values, with jurbanite and alunite.     

Soil organic carbon stock for reclaimed minesoils in northeastern Ohio

Reclamation of disturbed soils is done with the primary objective of restoring the land for agronomic or forestry land use. Reclamation followed by sustainable management can restore the depleted soil organic carbon (SOC) stock over time. This study was designed to assess SOC stocks of reclaimed and undisturbed minesoils under different cropping systems in Dover Township, Tuscarawas County, Ohio (40°32·33′ N and 81°33·86′ W). Prior to reclamation, the soil was classified as Bethesda Soil Series (loamy‐skeletal, mixed, acid, mesic Typic Udorthent). The reclaimed and unmined sites were located side by side and were under forage (fescue—Festuca arundinacea Schreb. and alfa grass—Stipa tenacissima L.), and corn (Zea mays L.)—soybean (Glycine max (L.) Merr.) rotation. All fields were chisel plowed annually except unmined forage, and fertilized only when planted to corn. The manure was mostly applied on unmined fields planted to corn, and reclaimed fields planted to forage and corn. The variability in soil properties (i.e., soil bulk density, pH and soil organic carbon stock) ranged from moderate to low across all land uses in both reclaimed and unmined fields for 0–10 and 10–20 cm depths. The soil nitrogen stock ranged from low to moderate for unmined fields and moderate to high in some reclaimed fields. Soil pH was always less than 6·7 in both reclaimed and unmined fields. The mean soil bulk density was consistently lower in unmined (1·27 mg m⁻³ and 1·22 mg m⁻³) than reclaimed fields (1·39 mg m⁻³ and 1·34 mg m⁻³) planted to forage and corn, respectively. The SOC and total nitrogen (TN) concentrations were higher for reclaimed forage (33·30 g kg⁻¹; 3·23 g kg⁻¹) and cornfields (21·22 g kg⁻¹; 3·66 g kg⁻¹) than unmined forage (17·47 g kg⁻¹; 1·98 g kg⁻¹) and cornfield (17·70 g kg⁻¹; 2·76 g kg⁻¹). The SOC stocks in unmined soils did not differ among forage, corn or soybean fields but did so in reclaimed soils for 0–10 cm depth. The SOC stock for reclaimed forage (39·6 mg ha⁻¹ for 0–10 cm and 28·6 mg ha⁻¹ for 10–20 cm depths) and cornfields (28·3 mg ha⁻¹; 32·2 mg ha⁻¹) were higher than that for the unmined forage (22·7 mg ha⁻¹; 17·6 mg ha⁻¹) and corn (21·5 mg ha⁻¹; 26·8 mg ha⁻¹) fields for both depths. These results showed that the manure application increased SOC stocks in soil. Overall this study showed that if the reclamation is done properly, there is a large potential for SOC sequestration in reclaimed soils. Copyright © 2005 John Wiley & Sons, Ltd.     

Effect of management and climate on biochemical properties of grassland soils from Galicia (NW Spain)

Biochemical properties are considered to be the best indicators available at present for assessing soil quality. However, there are still many gaps in our knowledge about how these properties are affected by abiotic factors and how these factors interact with soil management. With the aim of understanding how climate and soil management affect soil biochemical properties in grasslands soils from a temperate-humid area (Galicia, NW Spain), a total of 60 soils were analyzed for several microbial and biochemical properties. Grasslands were divided into groups according to the type of management applied (native compared with intensive) and to the climate in the area where they were sampled (Mediterranean subhumid with centroeuropean drift climate compared with Atlantic climate). We found that management had a greater influence on soil biochemical properties than climate. Altitude, which strongly influences climate in the region where the soils were analyzed, was found to be a significant factor that affected most soil biochemical properties. In conclusion, the results show that microbially-mediated processes are greatly affected by both, management and abiotic factors and that, for some properties (like net N mineralization and cellulase and casein-protease activities), abiotic factors can have an important influence on soil biochemical properties.     

Excretion of lead,zinc and calcium by the earthworm Dendrobaen a rubida living in soil contaminated with zinc and lead

Higher concentrations and total amounts of Pb were found in faeces than urine and mucus or coelomic fluid. The highest concentration of Zn was present in coelomic fluid but the highest total amount of Zn was in earthworm faeces. Metal analysis of the contents of various sections of the alimentary tract showed the highest concentration and total amount of Pb in the contents of the posterior alimentary tract. Zn and Ca showed the opposite distribution and the highest concentrations were found in anterior gut contents while the highest total amounts of Zn and Ca were found in posterior gut contents. The results are discussed in relation to dry weight of material, excretory sites and the presence of water soluble salts.The terminal segments of D. rubida were analysed for Pb and Zn and it was concluded that self-amputation or autotomy of these segments is probably not involved in the elimination of these metals.     

Andosols developed from non-volcanic materials in Galicia, NW Spain

A set of well-drained soils in Galicia, formed from gabbros, amphibolites and schists, with udic moisture and mesic temperature regimes, are studied. All but one of the surface horizons show an'exchange complex dominated by amorphous material'(ECDAM); consequently, most soils are classified as Andosols (FAO) or as different subgroups of Dystrandepts (Soil Taxonomy). The soils on gabbros and amphibolites frequently have'andic properties'so, following the ICOMAND proposals, five of the 12 soils studied may be characterized as Andisols. Many of the five soils have properties comparable to those of soils from volcanic areas, especially to those called'non-allophanic Andosols', which have an abundance of active-Al, mainly in the form of Al-humus complexes.     

Microcalorimetric study of changes in the microbial activity in a humic Cambisol after reforestation with eucalyptus in Galicia (NW Spain)

The microcalorimetric technique was used to analyse the influence of successive reforestations with Eucalyptus globulus Labill, a fast growing species, on the microbial activity in soil. With this aim, samples of similar origin soils, humic-eutrophic Cambisol, were collected from two adjacent land plots. One of the plots, to be taken as the reference, was not subjected to man activities for the last 100 years. The other plot was subjected to two reforestations in the last 20 years. For collection of the two samples, 100 m² homogeneous and perfectly defined zones were chosen in each of the adjacent land plots to obtain final representative bulk samples of 400 g each.The study was carried out using the microbial population as a bioindicator of the productive potential in soil. The experiments were carried out using 1 g soil samples that were treated with 1.25 mg glucose and stored at 4 °C for 3 months. The analysis was complemented by the determination of physical, chemical, and biological properties and environmental parameters.The study was performed over 1 year and samples were seasonally collected (spring, summer, autumn and winter) in the same zone situated in Viveiro (Galicia, NW Spain) with the objective of checking the influence of environmental conditions on the microbial activity in the two soils studied.From the measured results, it can be observed that soils subjected to reforestations suffer not only important changes in physical structure, such as an increase in bulk density, from 600 to 660 kg m⁻³, a reduction in hydraulic conductivity, from 8.85×10⁻³ to 4.4×10⁻³ m s⁻¹, or a decrease in the C-to-N ratio, from 13 to 8, but also they have lower microbial activity, for example 2.84 J g⁻¹ in the reforested soil versus 6.14 J g⁻¹ in the reference soil, in spring, thus presenting a lower productive potential that suggests the use of both amendments and adequate management techniques to ensure a sustainable exploitation, thus avoiding future degradation of soil.     

Micromorphological evidence of black carbon in colluvial soils from NW Spain

Biomass burning produces a residue called black carbon (BC). Black C is generally considered to be highly resistant against biodegradation and has a potential role in the global C cycle, but is difficult to identify and quantify when subjected to prolonged degradation in terrestrial sediments. The colluvial soils from Campo Lameiro (NW Spain), also known as ‘Atlantic rankers’, are rich in organic matter (up to 140 g C kg^?1 soil). A micromorphological study was undertaken to test the hypothesis that a large proportion of the organic matter was derived from BC formed during Holocene wildfires (up to > 6000 years ago). As roughly estimated from image analysis of 12 thin sections, the volumetric BC contribution ranged between 10 and 60% (26% on average) of the organic matter. This is a conservative estimate as additional morphologically unrecognizable BC was present in the microgranular matrix of coalesced excrement. We conclude that (i) currently unknown quantities of BC are stored in Atlantic rankers and (ii) analysis of thin sections is an effective tool to identify BC.     

Dissolved and Particulate Metals in the Mero River (NW Spain): Factors affecting Concentrations and Load during Runoff Events

This article examines the metal [aluminum (Al), iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn)] runoff dynamics in the Mero River (northwestern Spain). At the catchment outlet, metal concentrations, suspended solids, dissolved organic carbon, pH, and discharge were determined during three runoff events. The river drains an agroforestry catchment of 65 km² with relatively high livestock density. Dissolved and particulate metal concentrations increased during the events with respect to pre-event concentrations, but the increase of the dissolved fraction is relatively small compared to that of the particulate fraction. The dissolved metal concentration peaks appeared after the hydrograph peak, suggesting transport associated with subsurface flow. For particulate metals, peaks usually occurred during the falling limb of hydrograph, implying distant-river source of metals. Particulate forms represented more than 90% of total Al, Fe, and Mn load, whereas for Cu and Zn its contributions were 52–76% and 31–56%, respectively. The high positive correlations of all particulate metals, except Zn, with suspended solid concentrations indicate that these constituents play a major role in transport of metals. Soil erosion is the main process responsible for causing elevated Al, Fe, and Mn concentrations in the river during rainfall–runoff events while Zn and Cu come mainly from the addition of slurries and manures to farmland.