A data synthesis on the biochar properties and implications for air,soil, and water quality in Brazil

Biochar has been intensively researched worldwide. In Brazil, there is a variety of feedstock production that can be turned into soil amendments of high performance through biochar conversion, especially solid wastes. However, advances in biochar research in Brazil have not been systematically evaluated to indicate possible gaps and suggest future research for eco-friendly applications. Thus, in this work we evaluated biochar properties and effects on air, water, and soil quality based on data gathered from researches performed in Brazil. Biochar has been mainly evaluated as soil conditioner (37%), material characterization (17%), water treatment (12%), and greenhouse gases emissions (9%). Based on the data synthesis of 68 feedstocks used for biochar production, we observed that the pyrolysis temperature profoundly affects biochar properties. Meta-analysis indicated benefits of biochar addition to soils for chemical, physical, microbiological and biochemical attributes that have resulted in increases in root growth (+30%), and plant shoots (+45%). Pyrolysis temperature and feedstock are key choices to design biochar properties aiming to retain dyes, aromatic hydrocarbon, pesticides, and metals in water and wastewater treatment. It was also observed an increase in CO₂ and a decrease in N₂O emissions after biochar application to soils in short-term experiments. Although there is a growing interest in the development of electrochemical sensors and biochar-based fertilizers, technological applications of biochar are still incipient in Brazil. Future research should prioritize long-term and mechanistically evaluations of biochar under field conditions and the development of eco-friendly technological applications.     

Assessment of hydrochemical trends in the highly anthropised Guadalhorce River basin (southern Spain) in terms of compliance with the European groundwater directive for 2015

One of the key aspects introduced by the European Water Framework Directive 2000/60/EC (WFD) and developed by Groundwater Directive 2006/118/EC was the need to analyse pollution trends in groundwater bodies in order to meet the environmental objectives set in Article 4 WFD. According to this Directive, the main goal of “good status” should be achieved by the year 2015, and having reached this horizon, now is a suitable time to assess the changes that have taken place with the progressive implementation of the WFD. An extensive database is available for the Guadalhorce River basin, and this was used not only to identify in groundwater but also to draw real conclusions with respect to the degree of success in meeting the targets established for this main deadline (2015) The geographic and climate context of the Guadalhorce basin has facilitated the development of a variety of economic activities, but the one affecting the largest surface area is agriculture (which is practised on over 50 % of the river basin). The main environmental impacts identified in the basin aquifers arise from the widespread use of fertilisers and manures, together with the input of sewage from population centres. In consequence, some of the groundwater bodies located in the basin have historically had very high nitrate concentrations, often exceeding 200 mg/L. In addition, return flows, the use of fertilisers and other pressures promote the entry of other pollutants into the groundwater, as well as the salinisation of the main aquifers in the basin. In order to assess the hydrochemical changes that have taken place since the entry into force of the WFD, we performed a detailed trends analysis, based on data from the official sampling networks. In some cases, over 35 years of water quality data are available, but these statistics also present significant limitations, due to some deficiencies in the design or management; thus, data are missing for many years, the results are subject to seasonality effects, there are gaps in the historical records obtained by the monitoring networks and other shortcomings. The results obtained were analysed with the non-parametric Mann-Kendall test and revealed a general upward trend of pollutants in the areas affected by major pressures. In this analysis, we evaluated not only the increase or decrease in pollutants but also the different processes detected and the sources of pollution within the basin area. Our evaluation shows that robust measures should be taken in order to prevent further major degradation of groundwater quality and to enable “good quality” status to be achieved in future extensions of the WFD.     

Effects of experience with access regimes on stewardship behaviors of small-scale fishers

Governance regimes that assign exclusive access to support collective action are increasingly promoted to manage common-pool resources under the premise that they foster environmental stewardship. However, experimental evidence linked to existing policies that support this premise is lacking. Overlapping access policies in small-scale fisheries provide a unique opportunity to test the effects of access regimes on users’ stewardship behaviors. We performed a lab-in-the-field experiment to assess how fishers’ previous experience with access regimes relates to compliance and peer enforcement (n = 120). Fishers’ compliance and peer-enforcement decisions were compared in a common-pool-resource game. Treatments differed in framing to represent exclusive access and pseudo-open access regimes, both of which fishers face in real life. To contrast behavior in the game with real-life observations, we compared fishers’ associations that have shown relatively high and low management performance under exclusive access policies. Compliance and peer enforcement were higher under the exclusive access treatment than under the pseudo-open access treatment only for fishers’ associations with high management performance in real life. Behaviors in the game reflected differences between associations in real life. Our results support previous research on ocean governance by experimentally assessing the role of access regimes in determining users’ stewardship and suggest potential mechanisms for stewardship internalization.     

Resprouting as a persistence strategy of tropical forest trees: relations with carbohydrate storage and shade tolerance

Resprouting is an important persistence strategy for woody species and represents a dominant pathway of regeneration in many plant communities, with potentially large consequences for vegetation dynamics, community composition, and species coexistence. Most of our knowledge of resprouting strategies comes from fire-prone systems, but this cannot be readily applied to other systems where disturbances are less intense. In this study we evaluated sapling responses to stem snapping for 49 moist-forest species and 36 dry-forest species from two Bolivian tropical forests. To this end we compared in a field experiment the survival and height growth of clipped and control saplings for a two-year period, and related this to the shade tolerance, carbohydrate reserves, and the morphological traits (wood density, leaf size) of the species. Nearly all saplings resprouted readily after stem damage, although dry-forest species realized, on average, a better survival and growth after stem damage compared to moist-forest species. Shade-tolerant species were better at resprouting than light-demanding species in moist forest. This resprouting ability is an important prerequisite for successful regeneration in the shaded understory, where saplings frequently suffer damage from falling debris. Survival after stem damage was, surprisingly, only modestly related to stem reserves, and much more strongly related to wood density, possibly because a high wood density enables plants to resist fungi and pathogens and to reduce stem decay. Correlations between sampling performance and functional traits were similar for the two forest types, and for phylogenetically independent contrasts and for cross-species analyses. The consistency of these results suggests that tropical forest species face similar trade-offs in different sites and converge on similar sets of solutions. A high resprouting ability, as well as investments in stem defense and storage reserves, form part of a suite of co-evolved traits that underlies the growth-survival trade-off, and contributes to light gradient partitioning and species coexistence. These links with shade tolerance are important in the moist evergreen forest, which casts a deep, more persistent shade, but tend to diminish in dry deciduous forest where light is a less limiting resource.     

Local and regional genetic connectivity in a Caribbean coral reef fish

Coupled bio-physical models of larval dispersal predict that the Costa Rica–Panama (CR–PAN) reefs should constitute a demographically isolated region in the western Caribbean. We tested the hypothesis that CR–PAN coral reef fish populations would be isolated from Mesoamerican Barrier Reef System (MBRS) populations. To test that, we assessed population genetic structure in bicolor damselfish (Stegastes partitus) from both regions. Adult fish were genotyped from five reefs in CR–PAN and from four reefs along the MBRS at 12 microsatellite loci. Between-region F _ST (F _ST = 0.0030, P < 0.005) and exact test (x ² = 74.34, df = 18, P < 0.0001) results indicated that there is weak but significant genetic differentiation between regions, suggesting some restriction in connectivity along the Central American coastline, as predicted by bio-oceanographic models. Additionally, there is among-site genetic structure in the CR–PAN region, relative to the MBRS and between regions, suggesting higher self-recruitment within CR–PAN. This finding may be explained by differences in habitat characteristics.     

Assessment of the effects of a port expansion on algae appearance in a costal bay through mathematical modelling. Application to San Lorenzo Bay (North Spain)

In the last years several episodes of algae appearance affecting bathing areas have been observed in San Lorenzo Bay (north of Spain). The analysis of the collected algae revealed that they might come from near intertidal or shallow subtidal zones due to eutrophication processes or through drift algae movement by the action of marine currents. In the vicinity of this area, the expansion of the Port of Gijón (now under construction) supposes a significant modification of the coastal geometry. The magnitude of such an expansion could cause changes in the patterns of currents in the bay, with the consequent alteration of the observed algal appearance phenomena. A mathematical modelling study to evaluate the risk of generation of eutrophication processes in the San Lorenzo Bay area and the transport of drift algae from near sea bed areas was developed. This study required the use of different hydrodynamic models in order to characterize the currents caused by tides, winds and waves. The eutrophication processes in the bay were analyzed with a depth-averaged two-dimensional eutrophication model which deals with eight water quality variables. Calibration of model parameters with the observed data from a field survey was performed. A reasonable agreement with the field measurements was achieved. Model results showed that the maximum phytoplankton concentrations were below eutrophic conditions. Although, the port expansion has led to an increment of phytoplankton concentrations, chlorophyll a levels were not representative of eutrophic conditions. To analyse the transport of drift algae, a methodology based on the utilization of a two-dimensional model which solves the depth-averaged advection-diffusion equation considering seaweed as a conservative tracer was developed and applied. Numerical modelling allowed the identification of the coastal areas that seems to be the source of the seaweed found on the beach. It was also proven that port expansion does not significantly affect drift algae transport in the area.     

Differential effect of ultraviolet exposure (UVR) in the stress response of the Dinophycea Gymnodinium sp. and the Chlorophyta Dunaliella tertiolecta: mortality versus survival

Dunaliella tertiolecta (Chlorophyta) and Gymnodinium sp. (Dinophyceae) cells were exposed to ultraviolet radiation (UVR) (PAR, UVA and UVB: PAB) for 6 days either continuously or during a photoperiod. Both UVR treatments were harmful to Gymnodinium but exposure to continuous PAB had the most dramatic effects. Although a number of lesions/damage could have happened during the first few hours of exposure to UVR, in less than 24 h, Gymnodinium lost its ability to detoxify ROS efficiently, photoinhibition occurred, thymine dimers formed in the DNA, caspase-like enzymatic activities DEVDase sharply increased and cells died as determined by SYTOX-green staining. Superoxide dismutase activity did not significantly change with time, and although the catalase activity augmented in both treatments, cells still suffered from the UVR stress. Clearly, UVR was fatal to the dinoflagellate. For the chlorophyte, however, cell numbers increased regardless of the UVR treatment and mortality remained low (<20 %). F _v/F _m showed an initial decrease but then remained constant for both light treatments. After 6 days of continuous PAB exposure, however, signs of stress (thymine dimers, oxidative stress) paralleled a drop in catalase activity. Results obtained here demonstrate that the dinoflagellate Gymnodinium was much more sensitive and was harmed more rapidly by UVR exposure than the chlorophyte D. tertiolecta. The increased tolerance to UVR exposure of the chlorophyte may provide advantages over other more sensitive phytoplankton species within the photic zone. We provide strong support in the present study for repair being an important component of UV resistance in this species.     

Arsenic and lead contamination in urban soils of Villa de la Paz (Mexico) affected by historical mine wastes and its effect on children’s health studied by micronucleated exfoliated cells assay

Environmental geochemical and health studies were carried out in urban areas of Villa de la Paz, S.L.P. (Mexico), where mining activities have been developed for more of 200 years, leading to the pollution of surface soil by arsenic and heavy metals (Pb, Cd, Cu, Zn). The analysis of urban soils to determine total and bioaccessibility concentrations of As and Pb, demonstrated a combined contribution of the natural and anthropogenic concentrations in the site, at levels higher than the environmental guideline values that provoke a human health risk. Contour soil mapping confirmed that historical mine waste deposits without environmental control measures, are the main source of pollution soil by As and Pb in the site. Exposure (Pb in blood and As in urine) and effect (micronucleated exfoliated cells assay) biological monitoring were then carried out in the childhood population of the site and in a control site. The exposure biological monitoring demonstrated that at least 20–30 % of children presented Pb and As exposure values higher than the national and international maximum intervention values. The effect biomonitoring by MEC assay confirmed that there is a genotoxic damage in local childhood population that could be associated with the arsenic exposure in the site.     

Genetic profile of overweight and obese school-age children

Obesity is associated with overproduction of free radicals that promotes genotoxicity and could be measured as micronuclei (MN) and nuclear abnormalities (NA) in buccal mucosa cells. The frequency of MN and NA in buccal mucosa cells from overweight and obesity school-age children was determined. In a cross-sectional study, four anthropometric parameters were obtained from each child and one buccal mucosa sample was collected from each child. The slides were stained with orcein and fast green and microscopically analyzed for MN and NA. Twenty overweight and obesity school-age children (7–11 years old) from three schools located at the metropolitan area of Guadalajara were selected to form three groups with 20 children each, according to the weight features as follows: (1) normal weight; (2) overweight; and (3) obesity. No marked differences were found between groups for frequency of MN and NA. Genotoxicity, as indicated by increase in binucleated (BN) cells, was found in children within both overweight and obese groups exposed to passive tobacco smoke. There was no evidence of genetic instability in overweight and obese school-age children and no associations between body weight and genotoxicity markers found.     

A new derivatization method for a determination of MX and related hydroxyfuranones in water

An extremely potent mutagen, 3‐chloro‐4(dichloromethyl)‐5‐hydroxy‐2(5/f)‐furanone (MX) is commonly present in chlorinated drinking water. Due to its high mutagenic activity and according to WHO guidelines its concentration should be controlled in drinking waters. Determination of MX is difficult due to ppt levels at which the compound usually exists in drinking waters. Derivatization with 2‐propanol is presented as a method which significantly lowers GC/MS detection level of MX. Suitability of 2‐propylation for derivatization of other hydroxyfuranones is also shown.