Lixiviation of Open-Coast Dumping Site and Pollution of Water and Soils of Edea Industrial Zone（Littoral-Cameroon）

The nexus between water, food and energy is one of the most fundamental relationships and challenges for society. Indeed, seepage of wastes stored into dumping sites of Edea township, favor their lixiviation. Soluble components of matter are slowly dissolves, drained by meteoric water and flowed into tail bay vicinity. Knowledge of trace and toxic metal concentrations in the biotic matrices is important for assessing the effects of pollutants and the risk of exposure. In this study, A1, Mn, Cd, Cr, Cu, Pb and Zn were quantified respectively in 33 samples of soil and water, using ICP-MS （Inductively Coupled Plasma Mass Spectrometry）, Pb were found between 1.38-88.28 mg/L. Higher concentrations of Al were found in Alucam industrial wastes （315,502.33 mg/kg）, and in Hysacam domestic wastes （54,126.93 mg/kg）. Concentrations of Cd （1.955 mg/kg）, Pb （469.00 mg/kg） and Zn （853.00 rng/kg） are higher in domestic wastes. The ones of Mn （696.96 mg/kg） and Cu （1,320.10 mg/kg） are higher in industrial wastes. Higher concentrations of Pb and Cu let assume that it is a risk of poisoning relative to these elements around this area. These findings illustrate that lixiviation of dumping wastes has great influence on water and soils pollutions of the study ecosystem.

An ensemble machine learning model to uncover potential sites of hazardous waste illegal dumping based on limited supervision experience

With the soaring generation of hazardous waste(HW)during industrialization and urbanization,HW illegal dumping continues to be an intractable global issue.Particularly in developing regions with lax regulations,it has become a major source of soil and groundwater contamination.One dominant challenge for HW illegal dumping supervision is the invisibility of dumping sites,which makes HW illegal dumping difficult to be found,thereby causing a long-term adverse impact on the environment.How to utilize the limited historic supervision records to screen the potential dumping sites in the whole region is a key challenge to be addressed.In this study,a novel machine learning model based on the positive-unlabeled(PU)learning algorithm was proposed to resolve this problem through the ensemble method which could iteratively mine the features of limited historic cases.Validation of the random forest-based PU model showed that the predicted top 30%of high-risk areas could cover 68.1%of newly reported cases in the studied region,indicating the reliability of the model prediction.This novel framework will also be promising in other environmental management scenarios to deal with numerous unknown samples based on limited prior experience.

Comparison of Soil Samples from Selected Anthropogenic Sites within Enugu Metropolis for Physicochemical Parameters and Heavy Metal Levels Determination

This study compared the physicochemical parameters and heavy metal levels in soil samples from selected anthropogenic sites within Enugu metropolis, Enugu State, Nigeria using standard analytical methods. Soil samples at depths (0 - 20 cm) and (20 - 40 cm) were collected from waste dump sites, metal scrap dumps, fuel filling stations and auto-mechanic workshops and analyzed for physicochemical characteristics and heavy metal levels. Atomic absorption spectrophotometer was used for heavy metal determination while conventional analytical methods were employed for physicochemical parameters evaluation of the soil samples. At soil depths 0 - 20 cm and 20 - 40 cm the respective mean range of pH, electrical conductivity, organic matter and organic carbon contents in the soil samples were, 6.33 - 6.74, 101.46 - 123.21 μS/cm, 6.41% - 8.35% and 13.73% - 16.14% for auto-mechanic workshops;6.92 - 7.43, 56.46 - 60.02 μS/cm, 1.53% - 2.20% and 11.93% - 12.60% for fuel filling stations;7.14 - 7.84, 70.81 - 77.71 μS/cm, 3.81% - 4.12% and 8.57% - 9.24% for metal scrap dumps;6.54 - 6.81, 94.40 - 100.71 μS/cm, 8.83% - 10.75% and 18.26% - 20.81% for waste dump sites. The pH of the top soil samples from auto-mechanical workshop was below the WHO recommended limits for agricultural purposes. The physic-chemical characteristics of the soil samples decreased with soil depths indicating therefore that anthropogenic activities greatly influence the soil characteristics at the top soils than the sub-soils. The electrical conductivity values of top and sub-soil samples from the studied auto-mechanical workshops were above the recommended limits. At soil depths 0 - 20 cm and 20 - 40 cm, the respective mean range of Zn, Pb and Cd in the soil samples were 17.29 - 19.16 μg/g, 0.704 - 0.96 μg/g and 0.26 - 0.33 μg/g for auto-mechanic workshops;4.13 - 4.88 μg/g, 0.21 - 0.32 μg/g and 0.03 - 0.11 μg/g for fuel filling stations;30.02 - 36.11 μg/g, 0.43 - 0.48 μg/g and 0.15 - 0.19 μg/g for metal scrap dumps;9.30 - 10.84 μg/g, 0.53 - 0.60 μg/g and 0.38 - 0.45 μg/g for waste dump sites. The mean levels of Pb in soil samples from mechanic workshops and waste dump sites were above the recommended permissible limits for agricultural purposes. The study therefore indicated that these sites (auto-mechanic workshops and waste dump sites) could be major sources of Pb pollution to nearby farmlands, streams and the general environment. Plants grown on or around these sites may not produce high yields and could be severely contaminated with heavy metals which portend health danger to food consumers within the environment.

Distribution of dinoflagellate cysts in Yellow Sea sediments

To investigate the distribution, abundance, and species composition of dinoflagellate cysts in the Yellow Sea, surface sediment samples were collected at 37 sites, including the Korean dump site. Twenty-one di- noflagellate cyst taxa were identified, with the assemblages dominated mainly by Spiniferites bulloideus, Operculodinium centrocarpum, and cyst of Alexandrium catenella/tarnarense type. A high frequency of O. centrocarpum in the Yellow Sea was observed for the first time, and it is likely that this can be attributed to the dynamics of the Yellow Sea Cold Water Mass and the Changjiang （Yangtze） River runoff. Total cyst concentrations ranged from 23 to 48 442 cysts/g dry weight, and high cyst concentrations were recorded adjacent to the dumping site. This result suggests that anthropogenic activities such as ocean dumping s- timulate the growth of dinoflagellates in the Yellow Sea, which in turn leads to high levels of dinoflagellate cyst production.

Effects of artificial vegetation arrangement and structure on the colonization and development of biological soil crusts

The colonization and development of biological soil crusts （BSCs） are rarely discussed when investigating vegetation restoration with difference arrangement and structure of anthropogenically damaged areas in semi-arid regions. The present study analyzes the relationships among coverage, height and density of woody vegetation and coverage and thickness of BSCs on the surface mine dumpsite in Heidaigou, China. Results showed that PR （Prunus sibirica L.）, PT （Pinus tabulaeformis Carr.） and PPr （P. tabulaeformis Carr., P. sibirica L.） types had the highest coverage of total BSCs, which were 76.8%, 75.9% and 78.9%, respectively and PR showed the thickest BSCs of 4.41 mm. There was a significant correlation between coverage and thickness of BSCs and coverage and height of woody vegetation as a unimodal curve. Our findings suggest that a single woody plant species and low level coverage and height （no more than 30% and 300 cm, respectively） of woody plants may be able to create suitable conditions for facilitating BSCs restoration on the surface of mine dumpsites. The effects of vegetation arrangement and structure on BSCs colonization and development should be considered in reconstructing and managing woody vegetation in disturbed environments, such as surface mine dumpsites in semi-arid areas.

Impact of Municipal Solid Waste Disposal on Compaction Characteristics and Strength of Red Soil

The disposal of MSW （municipal solid waste）, in most of Indian cities, is to dump on nearby low laying lands. This investigation aims to characterize MSW and assess compaction characteristics and strength properties of contaminated soils at dumping sites in two cities Chickballapur and Kolar of Karnataka, India. Representative solid wastes from selected wards of the city were collected and analyzed. Substantial release of leachate form the dump yards occurred during past few years and the soil at the dump site experience extensive contamination. The test results of contaminated and uncontaminated soil show increase in optimum moisture content and decrease in maximum dry density. The unconfined compressive strength decreased considerably for soil samples obtained at 0.0 m, 0.5 m and 1.0 m depths below waste dump. At depths greater than 1.5 m, compaction characteristics and unconfined compressive strength closely match with the uncontaminated soil. Little variation in pH value, which makes soil slightly alkaline, was observed. From the study, it is inferred that, this investigation is very significant, as the foundation normally at these depths may be affected by this contamination.