Waste Disposal Area Research Articles

Technosol made from coal waste as a strategy to plant growth and environmental control

Coal waste disposal areas demand proper rehabilitation activities because several environmental impacts are related to them, such as acid mine drainage, loss of biohabitats, water pollution, and soil degradation. The most common strategy is to cover them with an impermeable layer followed by a new soil layer as soon as possible, while maximizing plant growth and avoiding water and wind erosion. This study examines the possibility of transforming coal waste itself into a substrate for plant growth, namely technosol, assuming its own use for progressive rehabilitation and revegetation of waste deposits. The coal waste is amended with other residues in an integrated waste management approach: rice husk ash, steel slag, and sewage sludge to adjust physical structure, pH, and nutrient availability, respectively. The raw material composition, fertility, metals bioavailability, plant growth, and nutrients in plant tissue are analyzed after successive growth of lopsided oats (Avena strigosa) and maize (Zea mays). The results show that coal waste allows a fertile plant substrate after being amended in accordance to experimental conditions. The soil metal concentration is found to fall within the limits of natural variation for soils in the study area and nutrients in plant tissue are found to be consistent with lopsided oats and maize standards. The proposed waste mixture results in a technosol capable of adequately promoting plant growth, that is, it is a potential resource to accelerate revegetation and natural succession in coal waste disposal areas.

Landfill Site Selection Using Geographic Information System and Fuzzy-AHP Model: A Case Study of Ilam Township, Iran

Introduction: Landfill siting is a difficult, complex, and protracted process, which requires evaluating different criteria. A suitable site should be located to dispose the municipal solid wastes hygienically (sanitary landfill), which is one of the fundamental subjects related to the environmental stability of the human settlements. The aim was to select a suitable waste disposal area using fuzzy-Analytic Hierarchy Process (AHP) models. Materials and Methods: To conduct this study, the information about elevation, slope, soil, drainage, vegetation, land use, population, and roads were produced and corrected in layers called shape files using the Geographic Information System (GIS) software. Finally, weights were applied in expert choice software by combining and overlapping information layers in GIS. Results: Based on the fuzzy-AHP model, 6 sites were identified as suitable areas for municipal waste disposal. Among the selected sites, one site was highly suitable, two were suitable, and three sites were moderately suitable. These areas with an area of 83.8 km2 are located along the west part of the city adjacent to the Iraqi border. The unsuitable sites for municipal waste disposal were located in the eastern and northeastern areas. Conclusion: However, applying fuzzy-AHP model provides the necessary conditions for assessing effective relationships among discrete criteria. In the end, combining these models and their findings represented advantages of this kind of modeling and improved scoring in all of these pixels.

Anaerobic digestion performance and microbial community structures in biogas production from whiskey distillers organic by-products

By-product and residue management are significant economic and environmental considerations in whiskey production. Incorporation of sustainable production methods in the industry can reduce costs in the areas of energy consumption and waste disposal and lessen environmental impacts via reduced greenhouse gas emissions. Circular economy opportunities for waste valorisation are possible also, such as anaerobic digestion of process effluents with high organic loads to produce high quality biogas for use in generation of thermal energy, electricity and transport biofuel. In this study lab-scale anaerobic digestion of whiskey distillery waste streams was trialled at mesophilic and thermophilic temperatures. Biogas production was assessed while monitoring process parameters and the microbial communities at different stages of reactor operation were described. Syntrophic acetate-oxidation appeared to be a significant process at mesophilic temperatures but not at thermophilic operation. Both hydrogenotrophic methanogenesis and acetoclastic methanogenesis appear to be important methanation processes under both temperature regimes.

Geochemical characteristics for the soil deposits within the municipal waste disposal areas by the environment study results

As a result of the analytical research and result of the previous stages of study it was found the significant contamination of the soil layer by the heavy metals (HMs) within the Landfill area No 5 for the municipal solid waste (MSW) disposal and the surrounding areas. It was revealed also the negative its effect on the contents of these pollutants in the soil of adjacent buffer zone, which is under the influence of north-eastern, northern, and north-western parts of the Landfill. This is a result of 34 years of the operation of the MSW disposal facility, when there were operating troubles. That caused by the breach of operating procedures of the covering the garbage storages by the isolating layers of dirt, intermittent work of the leachate treatment system, capacity exceeded, etc. Therefore, the soils within the Landfill’s boundaries and also in the buffer its zone have been contaminated by the different toxic substances, in particular by the HMs. So, soil deposits of the Landfill have got the maximum exceed of background contents for cooper, lead, nickel, and tin by from several to ten times, at the same time, beyond its contour – by 2–3 times. The negative changes of physical-chemical properties of soils of the humus horizon is revealed by the comparison with the proper indications for the soil samples collected in the sites adjacent to the Landfill and directly on its territory. The buffer coefficient of soil of this horizon (Cb) is twice as lower for the technogenic polluted soils within the MSW disposal facility than for the background sites for their is equal to the value of Cb=55. The contents of mobile forms for the HMs in the soil formations of the Landfill No 5 in the comparison with the background values increase 2 times for cooper and zinc, as well 8 times for lead. It is the content of the mobile forms that affects the migration of the HMs in the trophic chain “soil – solution – biota”.

Experimental evaluation of geosynthetics interface friction with a new procedure by using inclined plane

One of the important applications of geosynthetics in the slopes, such as landfills and waste disposal areas, is to use them as lining systems. To create the above conditions, most geosynthetics are placed in multilayer systems in the slopes. In these cases, the interaction between the geosynthetic–geosynthetic composite system interfaces should be controlled. To characterize the friction at the geosynthetic interface, a European Standard describes the test with an inclined plane apparatus under low stress. Many studies have shown that this procedure is not able to determine the friction for many interfaces. In 2011, the “Force Procedure” was proposed to better characterize the friction angle at the geosynthetic interface. This new procedure still requires validations to be proposed to replace the existing European standard. Two new inclined planes have been developed to compare the force procedure with the displacement procedure on many geosynthetic interfaces and to confirm the interest to revise the European Standard.

INTEGRATED AGRICULTURE BASED AGROTOURISM MODELWITH ECO-FRIENDLY ENVIRONMENTAL ON CARIK INJEMAN LAND IN CIBODAS VILLAGE

An integrated agriculture-based agrotourism model needs to be implemented in the Carik Injeman area of Cibodas village. To date, Carik Land, with an area of 30 hectares to date, has not been optimally used. Cibodas villagers mostly work as farmers and ranchers. More than 50% of the workforce does not have permanent employment. Some previous researchers have said that with integrated agriculture, independent communities could increase their land resources and farmers would prosper in a sustainable manner. The aim of this study was (1) to identify the factors that determine agrotourism planning in Carik land, (2) study integrated farming systems as support for agrotourism, (3) inventory the various opinions of village groups and community leaders related to agrotourism development (4) formulate an agrotourism model in integrated agriculture. This research uses descriptive, qualitative, observational, and quantitative methods, in particular Likert scales. Data collection uses questionnaires through purposive sampling. The results show that the community response supported by the FGD results on agrotourism planning was very good. SWOT analysis was made to study the agrotourism planning factor. The sustainable agrotourism plan to be located on Carik Injeman’s land must have four zones, namely an: 1) integrated farming system area, 2) integrated waste disposal area, 3) environmental area, 4) and recreation and sports area. The study results can be used as a recommendation for agrotourism planning in Carik Injeman land, Cibodas village, Bandung.

Impact assessment of faecal sludge on groundwater and river water quality in Lucknow environs, Uttar Pradesh, India

The present study aims at Faecal Sludge (FS) characterization and assessing water quality impacted due to waste dumping in one of the India's most polluted cities, Lucknow. In order to accomplish the objective; FS, groundwater and river water were sampled from the study area in the post monsoon season.Ground water and river water data were assessed by using Piper diagram, Gibbs' diagram, Water Quality Index (WQI), Wilcox's diagram, US Salinity Laboratory's(USSL) diagram and multivariate statistical analysis.The study reveals that FS sample contains considerable amounts of electrical conductivity, cations and anions.Piper diagram demonstrates that dominance of the anions is mainly HCO3in groundwater and river water. Whereas, Gibbs' diagram depicts that the chief source of soluble ions is weathering of rocks over which water flows. The ground water samples were grouped into excellent, good and poor while river water samples were grouped as good, poor, very poor and unsuitable for drinking as per WQI. Wilcox and USSL diagram indicated the majority of the samples are suitable for irrigation in groundwater and river water. Major Principal Components (PCs) have been identified by principal component analysis for groundwater and river water that explained 76% and 85% of the total variance in the dataset, respectively.PC1, PC2, PC3 and PC4 reflect the weathering, weathering along with anthropogenic, geochemical and anthropogenic component in groundwater, respectively. While for river water, PC1, PC2 and PC3 indicate mineral, anthropogenic and hardness component, respectively. Hierarchical cluster analysis depicts three types of cluster for groundwater and two types of cluster for river water samples based on the similarities in chemical composition. The study signifies that open dumping of waste is influencing the groundwater quality in solid waste disposal &slum area while pollution load of river water in downstream is increasing due to discharge of effluent.

Remediation of old subsurface repositories of radioactive waste, Russia: efficiency analysis

Boundaries of densely populated areas can approach with time to old subsurface repositories of radioactive waste due to growth of settlement territories. Protective isolation of the repositories was sometimes insufficient. Penetration of groundwater into the repository and discharge of the polluted water into neighboring rivers can lead to radioactive pollution of water resources of the region. Special rehabilitation measures at the repository sites are required to prevent this. Their efficiency is considered on example of former repositories of an atomic research center in Moscow (Russia). Radioactive materials were extracted from the subsurface burials for consequent disposal in a safer repository. A limited volume of polluted enclosing sedimentary rocks was also extracted and placed back after flushing with water. Analysis of rock pollution shows that these rehabilitation measures cannot enhance substantially a forecast of radioactive pollution. Moreover, loosening of the sedimentary rocks at the site of the earthwork leads to focusing of meteoric water from the surface in the domain of the most severe pollution of the underground medium. Elevated concentration of humic and fulvic acids in the surface water could intensify highly mobile colloidal form of actinide migration after the rehabilitation procedure. Place of polluted water discharge at a river bank and time of colloid-facilitated migration of radionuclides from the repository to the discharge place were estimated by computer simulation. Sampling of river sediments after approximately this time showed that concentration of uranium in the sediments at the calculated point exceeded about twice its values at neighboring sampling points up- and downstream (bottom sediments, which were polluted before remediation, were eliminated by a foregoing channel-cleaning of the river). Distributions of uranium in the sampled columns of the bottom sediments evidence that pollution of the sediments is caused by groundwater discharge. A comparison with the results of the mathematical modeling shows that this is in good agreement with the assumption of fast colloid-facilitated migration of uranium from the repository site. Along with the analysis of limited conditioning of the polluted rocks, these results indicate that the considered remediation method is less effective than hydraulic isolation of waste disposal area like it was performed at Oak Ridge National Laboratory.

Bioconversion of chitin and concomitant production of chitinase and N-acetylglucosamine by novel Achromobacter xylosoxidans isolated from shrimp waste disposal area

Marine pollution is a significant issue in recent decades, with the increase in industries and their waste harming the environment and ecosystems. Notably, the rise in shellfish industries contributes to tons of shellfish waste composed of up to 58% chitin. Chitin, the second most ample polymer next to cellulose, is insoluble and resistant to degradation. It requires chemical-based treatment or enzymatic hydrolysis to cleave the chitin polymers. The chemical-based treatment can lead to environmental pollution, so to solve this problem, enzymatic hydrolysis is the best option. Moreover, the resulting biopolymer by-products can be used to boost the fish immune system and also as drug delivery agents. Many marine microbial strains have chitinase producing ability. Nevertheless, we still lack an economical and highly stable chitinase enzyme for use in the industrial sector. So we isolate a novel marine bacterial strain Achromobacter xylosoxidans from the shrimp waste disposal site using chitin minimal medium. Placket–Burman and central composite design statistical models for culture condition optimisation predicted a 464.2 U/ml of chitinase production. The culture conditions were optimised for maximum chitinase production recording up to 467 U/ml. This chitinase from the A. xylosoxidans was 100% active at an optimum temperature of 45 °C (withstand up to 55 °C) and pH 8 with 80% stability. The HPLC analysis of chitinase degraded shellfish waste reveals a major amino acid profile composition—arginine, lysine, aspartic acid, alanine, threonine and low levels of isoleucine and methionine. These chitinase degraded products and by-products can be used as supplements in the aquaculture industry.

INDEX TO EVALUATE CLOSED LANDFILLS BASED ON LEACHATE PARAMETERS

After the end of their useful life, waste landfills and their surroundings should continue to be monitored constantly. The main concern is pollution of groundwater and surface water from leachate, posing a risk to public health. The effluent generated by closed landfills may have equal or greater potential for contamination compared to active landfills. The proposal of an index to evaluate the landfill conditions after closure was the main motivation for this work. The insufficiency of data on the waste entering these areas causes uncertainty as to how long the material will continue to degrade. In this article, the presence of polluting elements in the leachate of a deactivated landfill was evaluated through the characterization of the effluent during a ten-year monitoring period. From the study of existing indexes to evaluate the leachate of closed waste disposal areas, we verified the importance given to certain parameters that are not relevant for Brazilian landfills, in which the presence of organic matter is high. The present work contributes by generating information for a better understanding of the impacts caused by landfills in Brazil and in most countries of the Third Word, in which organic waste represents at least 50% of the waste discarded in landfills. With the application of the proposed Deactivated Landfill Assessment Index (DLAI), involving four-parameter analysis (pH, BOD, COD and ammoniacal nitrogen), possible threats of pollution can be detected, allowing prioritizing areas for remediation and better allocation of resources.

ANALISIS KADAR TIMBAL (Pb) PADA AIR SUMUR GALI DI KAWASAN TEMPAT PEMBUANGAN AKHIR SAMPAH BANJAR SUWUNG BATAN KENDAL DENPASAR SELATAN

AbstractFinal Waste Disposal Area at Suwung, Denpasar is one of the final waste disposal area that uses an open dumping system for the waste management techniques. These waste management techniques cause the lack of the groundwater quality. On the other hand, this groundwater is still being used as a main water source by the residents around the final waste disposal area. The aim of the study was to determine of the lead concentration in the well water at the Suwung Waste Disposal Area. This research uses descriptive method with observational approach while the analysis of lead was conducted by using atomic absorption spectrophotometry (AAS). Based on the results, it is proved that there is 1 sample contains of the lead concentration more than maximum allowable of lead according to the Minister of Health of Indonesia No. 416/MENKES/PER/IX/1990. The excess of lead concentration in the water samples may influenced by the distance of the dug wells from waste disposal area which does not meet the requirements, so the pollution occur easily.Keywords: Final waste disposal area, lead determination, atomic absorption spectrophotometry (AAS)

ANALISIS KADAR TIMBAL (Pb) PADA AIR SUMUR GALI DI KAWASAN TEMPAT PEMBUANGAN AKHIR SAMPAH BANJAR SUWUNG BATAN KENDAL DENPASAR SELATAN

AbstractFinal Waste Disposal Area at Suwung, Denpasar is one of the final waste disposal area that uses an open dumping system for the waste management techniques. These waste management techniques cause the lack of the groundwater quality. On the other hand, this groundwater is still being used as a main water source by the residents around the final waste disposal area. The aim of the study was to determine of the lead concentration in the well water at the Suwung Waste Disposal Area. This research uses descriptive method with observational approach while the analysis of lead was conducted by using atomic absorption spectrophotometry (AAS). Based on the results, it is proved that there is 1 sample contains of the lead concentration more than maximum allowable of lead according to the Minister of Health of Indonesia No. 416/MENKES/PER/IX/1990. The excess of lead concentration in the water samples may influenced by the distance of the dug wells from waste disposal area which does not meet the requirements, so the pollution occur easily.Keywords: Final waste disposal area, lead determination, atomic absorption spectrophotometry (AAS)

Effects of waterproofing admixture on the compressive strength and permeability of recycled aggregate concrete

The recycling and reuse of demolished concrete aims to preserve the environment by reducing the waste disposal areas. Moreover, the replacement of virgin aggregates with aggregates obtained by crushing concrete waste can decrease the new quarries development rate. However, the application of recycled concrete aggregates (RCA) in new concretes is generally hindered by the loss of properties of produced concretes. Indeed, the addition of RCA normally affects the concrete properties due to their porosity and weakness. The effectiveness of waterproofing admixtures to improve the durability performance and increase the physical and mechanical properties of natural aggregate concrete (NAC) is well documented in the literature. Yet, the effect of this type of admixture on the properties of concrete incorporating recycled aggregates is not sufficiently studied. This paper investigates some properties of recycled aggregate concrete (RAC) containing waterproofing admixture. Concrete mixes with and without waterproofing admixture are tested in order to examine the slump, temperature, density, and air content of concrete at fresh state, and the compressive strength and permeability of concrete at hardened state. The permeability of concrete is assessed by determining its chloride ion penetration resistance using the rapid chloride permeability test and by measuring the depth of penetration of water under pressure. Test results have shown an improvement of the properties of RAC when waterproofing admixture is added; an improved compressive strength and a decreased permeability of RAC are tangible.

Compostagem: a importância da reutilização dos resíduos orgânicos para a sustentabilidade de uma instituição de ensino superior

O crescimento populacional, a urbanização, o desenvolvimento econômico e tecnológico ocasionaram mudanças no estilo de vida, alterando os modos de produção e consumo. Assim, resultaram em um aumento, tanto em quantidade como em diversidade, da geração dos resíduos sólidos. Consequentemente, surge a necessidade da promoção da disposição final adequada dos resíduos gerados. O presente estudo teve como objetivo propor diagnóstico de geração de resíduos orgânicos e recomendações para a melhoria do manejo desse tipo de resíduos em uma instituição de ensino superior da cidade de Salvador, Bahia, Brasil. Como resultado, pode-se destacar o local onde funciona o restaurante universitário, que apresentou o maior percentual de resíduos orgânicos: 84% do total (142.240g). Foi constatado que não há uma destinação correta dos resíduos orgânicos gerados. A compostagem é uma forma viável para a destinação ambientalmente apropriada, pois aproveita os resíduos na agricultura urbana e rural como adubo. Importante destacar que a simples implantação de um sistema de compostagem não resolve os graves problemas da destinação incorreta, que polui e apresenta risco ambiental. Dessa forma, foi necessário elaborar e apresentar recomendações, baseadas nos resultados encontrados, para serem implementadas na Instituição investigada.

Interaction type of tetrabromobisphenol A and copper manipulates ammonia-oxidizing archaea and bacteria communities in co-contaminated river sediments

The combined contamination of brominated flame retardants (BFRs) and heavy metals in electronic waste (e-waste) recycling and disposal areas has been a serious concern owing to their environmental persistence and chronic toxicities. Ammonia oxidizers, e.g., ammonia-oxidizing archaea (AOA) and bacteria (AOB) play essential roles in nitrogen cycling and can serve as ideal indicators that reflect the changes in sediment health in response to environmental variables. There is currently very little information available on the combined toxic effects of BFRs and heavy metals on AOA and AOB communities. In this study, two typical e-waste pollutants, tetrabromobisphenol A (TBBPA) and copper (Cu), were selected as target contaminants to investigate the individual and combined effects of both pollutants on AOA and AOB communities in river sediments. Respective treatments of TBBPA (1, 10, and 20 mg/kg wet weight), Cu (100 mg/kg wet weight) and their combined treatments (weight ratios of 1:100, 1:10, and 1:5) were performed in laboratory experiments. High-throughput sequencing was applied to explore the response of ammonia oxidizers to TBBPA and Cu. The interaction types of TBBPA and Cu were calculated by the directional classification system to reveal the individual and combined toxicities of both contaminants to the ammonia oxidizers. On days 15 and 30, the dominant interaction type of TBBPA and Cu was synergistic (62.50%), and the combined contamination exacted selective pressure and inhibition on the AOB and AOA communities. On days 45 and 90, the interaction type shifted to be antagonistic (83.33%), with both the AOB and AOA communities gradually reaching stable population equilibria. The alteration of the interaction type is attributed to the elevated TBBPA/Cu tolerance as the incubation time increased. This study disclosed the interaction types of TBBPA and Cu in contaminated river sediments, and revealed that the combined effect could potentially manipulate AOB and AOA communities.

Valorisation of organic fraction municipal solid waste via anaerobic co-digestion of Malaysia tropical fruit for biogas production

The acceleration of MSW generation is one of the world’s critical challenge that contributed to the serious environmental and socio-economic problems involving pollutions and shortage of waste disposal area. The population growth, economic growth and urbanization are the key contributors to the MSW generation. Precisely, organic waste is the world highest contributor of MSW compared to other inorganic waste. This massive amount of putrescible waste consumption has a great global warming potential through the unutilized methane gas released from the landfill. In this regard, the waste treatment method through energy recovery Organic Fraction of Municipal Solid Waste (OFMSW) via Anaerobic Digestion (AD) has become the best way to utilize the high valuable energy (methane) resource potential and sustaining the environment. Moreover, AD process could be further enhanced through co-digestion process with various of substrates. Malaysia tropical fruit are among the potential of substrate for the anaerobic co-digestion that receiving extensive attention. This short article reviewed the potential of the selected Malaysia tropical fruit residues as substrates for anaerobic co-digestion with OFMSW.

Long-term geophysical monitoring of an abandoned dumpsite area in a Guarani Aquifer recharge zone

Even though attenuation processes in the subsurface are known to reduce the impacts of contaminant plumes, their importance is significantly dependent on geological and climatic characteristics, as well as on the leachate quality. The knowledge of attenuation processes linked to different geological formations is therefore fundamental in predicting the impacts of waste disposal areas. Geophysical methods are useful tools for assessing and delineating contaminant plumes, as well as their changes with time, which enables their lower-cost monitoring and association with geological and environmental properties. This paper shows the results of geophysical surveys conducted in the years of 1996, 2005 and 2018 in a waste disposal area located at a Guarani Aquifer recharge zone in Brazil. The objective of this study was to show the evolution of the contamination plume, as well as discuss some possible transport and attenuation processes that the contaminants may undergo in similar areas. Five geophysical sections surveyed within a time span of 20 years were compared, and the information was integrated with physicochemical data from monitoring wells. The results show a horizontal plume spreading, reaching about 200 m from the deposit and about 60 m of depth, 20 years after the ending of disposal activities. The measured resistivities in 2018 are similar to the ones found in 1996 and 2005 in the same surveyed areas, showing that a significant temporal attenuation did not occur. Moreover, samples collected close to anomaly zones and within a distance of 200 m from the deposit presented concentrations of some heavy metals above the screening values according to the Brazilian legislation, showing a metals mobility higher than previously expected, which can be possibly explained by the aquifer's acidic conditions. The estimated plume velocity was about 7 m/yr, a plume deepening was observed until about 50 m and changes in water flow direction and/or diffusion processes made the plume spread to areas previously regarded as upgradient. Therefore, the present paper shows that the rehabilitation of sites neighboring waste disposal sites (less than 200 m from it) did not seem to be feasible through natural attenuation in sandy soils and that the plume spreading is significant in this geological formation. Thus, abandoned disposal areas, constantly considered to be closed after the ending of disposal activities in developing countries, generate plumes which move silently and may reach areas of concern in the future.

Design of a Methane Monitoring System for Landfill and Duct Emissions

Methane is released from waste disposal areas as a result from anaerobic decay of food. Methane causes more greenhouse effects than carbon dioxide so a methane monitoring system is required to warn its release from gas emitting environments. The low explosive limit of methane is 5% in ambient air, so gas leakage is dangerous and can produce explosions. An entire head monitoring system was built around a MQ-4 methane gas sensor as it is cheap and reliable. The design proves to be flexible enough as it can measure CH4 emissions in ducts, CH4 in landfills at different depths and even in cattle barns. The measuring system head consists of a suction pump, solenoids, and a methane sensor. Measurements are taken 13 seconds after methane gas sucking. A timing of 100 seconds is required for purging the chamber before the second solenoid is turned-on. Devices temperature during operation was sampled with a thermal Flir-One camera and solenoid coil temperature was of 24.9˚C after a continuous operation of 30 seconds. As hoses for emission sampling become larger time for sampling increases as well as energy consumption.

The Dominance of Tramps Ants in The Settlement Area of Semarang, Central Java

The high rate of urbanization in Semarang have caused the land conversion from forest into various human need spaces. The land conversion is not only affect the life of humans but also the animals, including ants. The objectives of this study were to examine the dominance of tramp ants in the settlement area of Semarang City. The method used was the bait trap method using chicken intestine as a bait. Samples of ants were collected from four habitats, i.e., waste disposal area, traditional markets, house area, and urban parks. This study found four dominant ants, i.e., Anoplolepis gracilipes, Paratrechina longicornis, Solenopsis geminata and Monomorium pharaonis. Two of them were categorized as tramp ants (Anoplolepis gracillipes and Paratrechina longicornis). The highest diversity of ants was found in house (H'= 2.72). The waste area tends to be an ideal habitat for particular species, which was proved by the low value of Simpson's dominance index (iD = 0.06) and a high value of evenness index (E=0 0.89). This study provides new information about tramp ants population as pest in urban area. The findings would be beneficial for controlling the population of tramp ants, which are disturbing humans in the settlement area.

CHARACTERIZATION OF RHIZOBIA AND ARBUSCULAR MYCORRHIZAL FUNGI IN AREAS IMPACTED BY GRAVEL MINING IN BRAZIL

ABSTRACT On-shore oil exploration is one of the main economic activities in the semiarid region (Caatinga biome) of the state of Rio Grande do Norte (RN), Brazil. Gravel mining is an activity associated with oil exploration that causes environmental impacts. Gravel is a base-material for constructions, such as roads and pumpjack bases. The areas of gravel mining and other decommissioned areas where the gravel has been deposited must be revegetated with species native to the biome at end of the activity in the site. An efficient strategy for revegetation of degraded areas has been the planting of leguminous species that can associate with rhizobia and arbuscular mycorrhizal fungi (AMF). Nevertheless, the impact of mining activities on the autochthonous populations of these microorganisms is unknown. The objective of the present work is to characterize the density of rhizobia and AMF spores in four areas impacted by the oil exploration in RN when compared to non-impacted adjacent areas. Gravel samples were collected in dry and rainy seasons in two mining areas: one in a pumpjack base, and one in a waste disposal area. Surface soil (topsoil) samples were collected in adjacent areas with native Caatinga vegetation. Assays were carried out to evaluate the most probable number (MPN) of rhizobia and to identify the type and density of arbuscular mycorrhizal fungi (AMF), using rhizobia trap plants Mimosa tenuiflora (Mart.) Benth. and Mimosa caesalpiniifolia Benth. The MPN of rhizobia was low in all areas, but higher in the rainy season. The highest amount and diversity of AMF spores were found in the dry season. Among the symbiotic microorganisms studied, the AMF presented lower densities in the evaluated areas when compared to those in the adjcent native vegetation areas, denoting the impact of this activity.