Sewage Disposal Facilities Research Articles

Risk Factors of Infection and Transmission of Viral Hepatitis B and E

Viral hepatitis is a disease burden in Africa and globally. It can be caused by RNA or DNA virus, which is hepatotropic and can pose a financial burden on the individual, their family, and society. Hepatitis B virus (HBV) is a DNA virus that can be present in blood and body fluids, including saliva, semen, and vaginal secretion. It is par-enterally transmitted with horizontal and vertical transmission. The risk of infection and transmission of hepatitis B virus infection could be a result of occupational exposure, use of unsterilized blades for traditional and cultural practices in Africa like tribal marks, level of awareness on prevention and adherence to standard or universal precautions. The risk of infection and transmission of hepatitis B virus infection also includes individual sexual history, the availability and access to vaccines, the level of occupational hazards exposure, the level of vaccine acceptance and the vaccination status of individuals. Hepatitis E virus (HEV) is a single-stranded RNA virus that is transmitted through the faeco-oral route by consumption of contaminated food and water. Low socio-economic status, poor environmental sanitation, poor water supply, poor sewage disposal facilities, level of awareness on prevention, poor social condition and decreased personal hygiene are associated factors for the risk of hepatitis E virus infection. Knowledge and community-based awareness and practice of World Health Organization (WHO) preventive practices and treatments could reduce the burden of hepatitis B and E virus infections. Mediscope 2023;10(2): 89-92

Characteristics of nitrogen flow and its environmental effects in the Yellow River Basin, China

ABSTRACT In large river basins, the nitrogen (N) cycle is largely regulated by complicated interactions between human and natural elements. Nevertheless, the origins, fate and driving forces of reactive nitrogen (Nr) flows in the basins are still not clear. An estimation model of N flux was established for evaluating the Nr flow and its environmental effects in the Yellow River Basin of Henan Province (HYRB) by means of material flow analysis. Total N input and output of HYRB were calculated at 4090.9 and 3948.8 Gg N yr−1, causing 142.0 Gg yr−1 of N stored in the basin. Industry, cropland and residential activities, respectively occupied for 42.2%, 23.2% and 12.3% of the whole input, as well as 43.6%, 25.1% and 12.3% of the whole output, which were central to HYRB’s N cycle. Anthropogenic activities regulated above 95.0% of total inputs, and 49.5% of N outputs was emitted into the air and 4.5% into hydrosphere. High N input, energy intensive, imperfect sewage disposal facilities and low N utilization efficiency were the main reasons of contaminate. How to effectively regulate the input of high-strength N pollutant associated with insufficient N cycling and Nr elimination is the main issue in the Yellow River Basin. In present research also put forward corresponding control measures according to the evaluation of N flow and Nr release of HYRB. The research can supply science foundation for coordinating the human–environment relationship in large basins, and also has important reference significance for the formulation of Nr emission reduction strategies.

Assessment of Groundwater Quality and Hydrogeological Profiles within Odeda Local Government, Abeokuta, Southwest Nigeria

Groundwater quality can be affected by human activities such as agriculture and improper sewage disposal facilities currently in use by some homeowners within Odeda local government, Ogun State Nigeria. Sixty groundwatersamples collected from hand-dug wellswere analysed for physicochemical and bacteriological parameters using standard procedures. Results were integrated with multivariate and hydrogeochemical analyses to assess groundwater quality and hydrogeologycal facies within the study area. The range of values for the measured parameters include: pH (5.91 – 7.4), EC (101- 1142 μScm-1), TDS (50 - 581 mg L-1), NO3-(3 - 18 mg L-1), Cl- (25 – 234 mg L-1 ), BOD (0.1 – 17.9) and E. Coli (ND - 45×10cfu mL-1). The piper trilinear plot shows that the dominant hydrochemical facies in the study area is the Ca2+– Cl− type. A correlation analysis and a principal component analysis reflect dissolutions from basal rocks and contamination from biological wastes possibly arising from surrounding septic tanks or municipal waste disposal sites. There is need for a continuous monitoring of groundwater by relevant regulatory authorities to safeguard the human health and environment within the study area.

Design of modular constructed wetland and its effect on rural domestic sewage treatment

According to the characteristics of large amount and scattered discharge of domestic sewage in rural residential environment, a rural domestic sewage treatment system based on modular constructed wetland was designed. The wetland is composed of three modules with a treatment scale of 30 m3/d. The plants are Arundo donax and Typha, and three kinds of filter media are selected to fill the substrate. The treatment capacity and treatment effect of the modular constructed wetland were studied through experiments. The results showed that the modular constructed wetland had a good treatment effect on sewage, and the average removal rates of BOD5, COD, SS, NH3-N, TN and TP were 83.3%, 83.5%, 90.5%, 70%, 66.9% and 68.3%, respectively. The treated water quality can meet the first class standard of water pollutants discharge standard for rural domestic sewage treatment and disposal facilities (DB37/3693-2019) of Shandong Province. The modular constructed wetland can be used to treat rural scattered domestic sewage with strong applicability, flexibility and feasibility.

Faeco-orally transmitted viral hepatitis in african children

The faeco-orally transmitted hepatotropic viruses – hepatitis A and hepatitis E viruses- are endemic in Africa. While transmission has reduced remarkbly in Europe and North America in the past decades, it has remained unchanged in Africa with hepatitis A prevalence remaining at above 50% and hepatitis E more than 7%. Much of this transmission occurs during childhood with the important drivers/predictors being poor water supply, poor sewage disposal facilities, low socioeconomic class, crowding, and poor social conditions arising from conflict. Initial clinical features in children are difficult to distinguish from malaria which is also endemic in the region. Commercially available ELISA kits present the best option for laboratory diagnosis of both viruses in Africa. While effective vaccines suitable for the African situation have been developed recently, improved water supply and sanitation are sine qua non for the prevention of transmission of both viruses among African children. Interventional studies are needed in the region.

Kesehatan Lingkungan Sekolah Dasar Negeri Mlilir di Kecamatan Dolopo Kabupaten Madiun tahun 2017

ABSTRACTSchool is one of public places, where the public places have potency as a place of disease transmission occurrence, environmental pollution or other health problems. Based on preliminary survey conducted in Mlilir State Elementary School on Dolopo District Madiun Regency which the number of school was 2 schools, it was known that both of schools were located in Mlilir Community Health Centre area which the incidence rate of diarrhea was the highest in Madiun Regency area in 2015 – 2016. Mlilir State Elementary School was located on the edge of the highway which had potency of air contamination either in form of gas/fume or dust particles. Moreover, the environmental cleanliness of Mlilir State Elementary School was still less good. The aim of this study is to determine the environmental health of Mlilir State Elementary School on Dolopo District Madiun regency in 2017.This study was a descriptive study in form of survey. The object that studied in this study include school location, school yard, building construction (roof and gutters, ceilings, walls, floor, and doors), room building (classrooms, teacher rooms, School Health Unit room, library and place of worship, air quality (measurement of dust concentration in front of classrooms), illumination, ventilation, sanitation facilities (clean water supply, toilets, sewage disposal facilities and garbage disposal facilities). The instruments used were interview forms, assessment forms, lux meter, sound level meter, high volume dust sampler, measuring tape, pH indicator strip paper. Data were analyzed descriptively.The results of study showed that the environmental health of Mlilir State Elementary School on Dolopo District Madiun Regency in 2017 was categorized as Enough. All people of Mlilir State Elementary School must always keep the cleanliness of school environment and repair school facilities and infrastructures which do not meet the requirements.Keywords : Environmental Health, Elementary School.

Transmission of Urinary Schistosomiasis among School Aged Children in Owena, Kajola and Baiken Communities Bordering Owena Reservoir/Dam, Ondo East Local Area, Ondo State, Southwest, Nigeria

Background: Schistosomiasis is a snail-borne, water-based parasitic infection caused by blood-dwelling (hence called blood-fluke) trematode worms of the genus Schistosoma. It is a disease of the poor and marginalized. Schistosomiasis remains an important public health problem globally with approximately 779 million estimated to be at risk. This study was carried out to ascertain the prevalence of the disease among school children in the three communities: Owena, Kajola and Baiken with a view to providing important parasitological information and boosting can sustainable control strategies of the disease.Methods: A school based cross-sectional technique was used to collect data on risk factors from 624 school children in March 2014 and 591 in April 2015. Urine samples were collected between the hours of 10:00 am 12:00 pm GMT in dry labeled wide mouthed. Plastic urine container (300-500 ml) each 10 ml was centrifuged and examined for the presence or absence of more nutobiuk eggs. Using X40 objectives of a light microscope. Infection intensity was recorded as number of eggs per 10 ml of urine sample. The intensity of infection was graded as heavy 500 eggs/10 ml urine, moderate (51-499 eggs/10 ml urine) or light (50 eggs/10 ml urine). Data obtained were analyzed using version 20.0 of the Statistical Package for The Social Sciences (SPSS) for windows Software Packages (SPSS on Chicag oil, 2013).Results: Our of the 624 pupils examined in 2014, 256 (41.0%) were positive for S. haematobium eggs in urine, while in 2015, 381 (64.5%) out of 591 were positive. Thus, there was a 23% increase in prevalence between the two genera. Individual intensity of infection varied from 1-6, 468 eggs/10 ml urine. Meaning the most heavily infected pupil in 2015 exceeded more than 68% infection in 2014. The arithmetic memory 2016 in moles was 0.65 in 2015 it was 0.09, while that of females in 2014 was 0.05 and 0.08 in 2015.Conclusion: This study area in Owena, Kajola and Baiken communities bordering Owena Reservoir/Dam, Ondo East Local Government Area, Ondo State, Nigeria show risk communities for urinary schistosomiasis. The overall pattern of S. haematobium eggs per 10 ml urine in the three communities in the two years (March 2014 and April 2015) study shows that it was sex and age dependent. The age-group with highest prevalence is 11-15 years in 2014 and 55.4% in 2015 with range infection for males was 43.6% in 2014 and 71.86 in 2015, while that of females was 37.0% in 2014 and 57.0% in 2015. Therefore, it is recommended that all school-age children especially those in 11-15 age-group should be treated using chemotherapy method. Pipe-borne water to prevent people having contact with the infected fresh water, sewage disposal facilities provided, mass educational therapy (societal sensitization/ health education) is required to reduce infection and transmission of urinary schistosomiasis.

Boron contamination in groundwater at a sewage waste disposal facility near Jeddah, Saudi Arabia

Shallow aquifers underlying sewage disposal facilities contain salts much higher than non-contaminated shallow aquifers of surrounding areas. This study focuses on the spatial distribution of boron in an alluvial aquifer subjected to sewage waste contamination. Nineteen groundwater samples were collected from the water wells present in the Wadi Bani Malik area known to have a history of sewage waste disposal. The sampling locations were carefully selected to cover an area upstream and downstream to the dam axis, within the boundary as well as around the lake perimeter. Prior to sampling, in situ field parameters such as top of the casing, depth to water table, temperature, salinity, electrical conductivity (EC) and the pH were measured. A total of 10 trace elements most commonly found in the groundwater contamination context were selected for the analysis which are: Li, Al, Cr, Mn, Fe, Ni, Ba, Hg, Pb and B. The results of this study indicate that concentrations of all the trace elements except boron are largely less than 1.0 mg/L. The concentration of boron varies between 3.70 and 44.98 mg/L with an average of 13.24 mg/L. The highest boron concentration is found in the cluster of wells located adjacent to a point source. The lowest concentration of boron is upgradient to this location. When compared with the EC data, the pattern of highs and lows of boron corresponds well with the EC. This pattern is consistent with the description of other plumes in sand and gravel of somewhat similar grain-size distributions. Also, the correlation coefficient analysis performed on the dataset indicates a strong correlation coefficient (r = 0.8) between the boron and EC. This suggests the possibility of using boron as an indicator for plumes originating from sewage waste disposal facilities.

Urogenital schistosomiasis and associated determinant factors among senior high school students in the Dutsin-Ma and Safana Local Government Areas of Katsina State, Nigeria

BackgroundHuman schistosomiasis is a chronic parasitic disease of poverty caused by the cercariae of digenetic trematodes of the genus Schistosoma. The disease is a major source of morbidity and mortality in 77 low- and middle-income countries in the tropics where 700 million people are at risk. In a bid to provide relevant epidemiological information to boost control of urogenital schistosomiasis at the state level in Nigeria, we conducted this study with the aim of investigating the disease’s prevalence and intensity, and the determinant factors responsible for its endemicity.MethodsData on risk factors were obtained from a total of 645 students aged 12─25 years using well- designed questionnaires. Samples were collected between 09:45 and 14:00 in universal bottles. Each10μl centrifuged sample was examined for the eggs of S. haematobium using Motic® (Binocular) Light Microscope (model S-10-P) with a x10 objective. Average infection intensity was recorded as number of eggs per 10 ml of urine sample. Survey data were entered into Microsoft Excel 2010 and analyzed using Epi Info™ 7. Associations among variables were determined using the chi square test and bivariate and multivariate logistic regressions.ResultsPrevalence of urogenital schistosomiasis was 30.54 % among the study population, with a mean infection intensity of 30.27 eggs/10 ml of urine. Prevalence and average intensity were higher in males (28.37 % and 32.21 eggs/10 ml of urine respectively) than in females (2.17 % and 5 eggs/10 ml of urine respectively). Water contact activities (X2 = 29.031, P = 0.0000), sex (male) [X2 = 109.82; P<0.0001], location (Dutsin─Ma) [X2 = 7.19; P = 0.0073], age group 18-20 (X2 = 4.819, P = 0.0281), altitude (531─560 m) [X2 = 6.84, p = 0.0089], fathers doing other brown─collar jobs (X2 = 8.449, P = 0.0037) and mothers’ occupation (X2 = 9.470, P = 0.0021) were found to be significantly associated with urogenital schistosomiasis. Boys were six times more likely to be infected with the cercariae of S. haematobium compared to girls [AOR (95 % CI): 6.34 (4.89─8.22)].ConclusionsDutsin-Ma and Safana were classified as moderate-risk Local Government Areas for urogenital schistosomiasis. The strong association between the disease and mother’s occupation is of utmost importance and suggests a promising control measure: that is, directing health education as well as grassroots mass chemotherapeutic intervention with praziquantel at mothers. A good network including treated pipe-borne water, drainage system, and sewage disposal facilities available should be improved upon. Molluscicides should be provided at highly subsidized rate to help control the disease.Electronic supplementary materialThe online version of this article (doi:10.1186/s40249-016-0158-1) contains supplementary material, which is available to authorized users.

Development of Data-Flow Control Algorithm of Wireless Network for Sewage Disposal Facility

Recently, water sewage disposal facilities are able to manage real-time data collection and record management through compact broadband modem LAN switching technology. Therefore, it needs more stable and efficient facility management. So, we required practical use of environmental facilities convergence based on broadband integrated modem. In this paper, we proposed short distance wireless communication network of compact broadband modem for sewage disposal facilities. And it received data inside of water treatment facility using the two communication methods (IEEE802.11x and IEEE802.15.4x). Then, our proposed an data-flow control algorithm of wireless network technology will prioritize processing data when emergency happen through collecting data, analysis data and processing. Lastly, we proved usefulness by experiment and simulation analysis.

Fluctuations in bird numbers on sewage treatment ponds in an arid environment, South Africa

Regular twice-monthly counts of birds associated with water at the Prince Albert sewage disposal facility recorded 69 species, of which 16 species (23.5%) were waterbirds (ducks, Red-knobbed Coot Fulica cristata and Little Grebe Tachybaptus ruficollis) and 21 species were shorebirds (30.9%). The remainder of the species were birds of reed beds (11; 16.2%), weedy or shrubby habitats around the edges of the ponds (12; 17.6%) or that hawked prey over the ponds (9; 13.2%). The numbers of shorebirds and waterbirds were positively and significantly correlated and were highly variable over time. There were no movements to the sewage facility by waterfowl specifically to moult. The presence of both waterbirds and shorebirds showed an historic movement pattern, with peak numbers correlated with long-term average peak rainfall months.

Urbanization, housing and environmental quality indicators

The migration of human populations from rural to urban settlements known as urbanization in its most basic sense suggests an improvement in various facets of life. Urbanization ideally should also imply an enhancement of housing quality and other components of human settlements such as power supply, portable water, good roads, proper refuse and sewage disposal facilities, maintenance of ecological balance and a reduction in environmental pollution. Globally, the urbanization process has occurred in a disorganized and nearly uncontrollable manner. The spontaneity in growth of urban settlements has affected negatively several components of the urban fabric such that these components (previously mentioned) are either severely inadequate or non-existent in majority of instances where urbanization has taken place. Arguably, the success of any urbanization process can be measured by the quality of the environments produced and the housing stock found within such environments. This paper seeks to identify and evaluate the components of urban settlements that can be used as indices for establishing quality of our housing, environments and urban clusters particularly for the Nigerian context. The research methodology is a reconnaissance survey, field observation and comparison of four main areas within Ido Local Government Area of Ibadan, Oyo State, namely Apete, Elebu, Elenusonso and Ologuneru.Key words: Urbanization, Environmental quality indicators.

Periodontal disease and Helicobacter pylori infection: a community-based study using serology and rapid urease test.

The aims of the present study were to assess the prevalence of periodontal disease and Helicobacter pylori (H.pylori) infection and their associations within a predefined Indian population. A community-based cross-sectional study of 500 selected individuals using a questionnaire, oral examination, rapid urease testing of dental plaque, and serological examination for immunoglobulin G antibody to H.pylori was carried out. Periodontal disease and H.pylori infection were prevalent in more than 50% of the population. Age, smoking, and diabetic status of the individuals were risk factors for periodontal disease after multivariate analysis, and a lack of proper sewage and waste disposal facilities were found to increase the risk of H.pylori infection. Although there was no association between periodontal disease and H.pylori seropositivity in the community, a highly-significant association was found between periodontal disease and colonization of H.pylori in dental plaque. Because periodontal disease is associated with the increased colonization of H.pylori, new treatment modalities, such as plaque control measures, should be employed for the complete management of H.pylori-associated gastric disease.

Comment: Pilot-Scale Test for a Phosphate Treatment Using Sulfate-Coated Zeolite at a Sewage Disposal Facility by Jae-Woo Choi, Kyu-Sang Kwon, Soonjae Lee, Byungryul An, Seok-Won Hong, Sang-Hyup Lee

The article, Pilot-Scale Test for a Phosphate Treatment Using Sulfate-Coated Zeolite at a Sewage Disposal Facility by Jae-Woo Choi, Kyu-Sang Kwon, Soonjae Lee, Byungryul An, Seok-Won Hong, Sang-Hyup Lee, is replete with some fundamental scientific flaws which have the potential to misinform readers. This comment seek to correct these flaws.

Pilot-Scale Test for a Phosphate Treatment Using Sulfate-Coated Zeolite at a Sewage Disposal Facility

The objective of this research was to evaluate a zeolite ball coated with sulfate (ZBCS) for the removal of phosphate in a batch, lab-scale column, and pilot-scale plant. Phosphate adsorption in the batch studies satisfactorily fitted to the Langmuir isotherm with a maximum adsorption capacity of 15.13 mg/g and the pseudo-first-order model with the amount of phosphate sorbed at equilibrium of 6.98 mg/g. The breakthrough data were satisfactorily described using the empirical model by Thomas. Phosphate adsorbed on the ZBCS was effectively desorbed using 10 % sulfuric acid and the surface-modified mineral was regenerated as an adsorbent for thrice adsorption and desorption cycles by maintaining the adsorption capacity at the value before regeneration. In addition, since the regeneration solution used for recycling of the ZBCS in the pilot plant is enriched with sulfate ion, the enriched solution could be used for resource recovery by various methods, such as mineral-based and chemical-based methods. Our research suggests a complete system for removal and recovery of phosphate from sewage and wastewater using a novel adsorbent based on minerals.

Investigation of a community outbreak of typhoid fever associated with drinking water

BackgroundThis report is about the investigation of an outbreak of typhoid fever claimed three human lives and left more than 300 people suffered within one week. The aim of this report is to draw the attention of global health community towards the areas that are still far from basic human essentialities.MethodsA total of 250 suspected cases of typhoid fever were interviewed, out of which 100 were selected for sample collection on the basis of criteria included temperature > 38°C since the onset of outbreak, abdominal discomfort, diarrhea, vomiting and weakness. Food and water samples were also collected and analyzed microbiologically.ResultsInhabitants of village lived in poor and unhygienic conditions with no proper water supply or sewage disposal facilities and other basic necessities of life. They consumed water from a nearby well which was the only available source of drinking water. Epidemiological evidences revealed the gross contamination of well with dead and decaying animal bodies, their fecal material and garbage. Microbiological analysis of household and well water samples revealed the presence of heavy bacterial load with an average total aerobic count 106-109 CFU/ml. A number of Gram positive and Gram negative bacteria including Escherichia coli, Klebsiella, Bacillus species, Staphylococcus species, Enterobacter species, and Pseudomonas aeruginosa were isolated. Lab investigations confirmed the presence of multidrug resistant strain of Salmonella enterica serovar Typhi in 100% well water, 65% household water samples and 2% food items. 22% of clinical stool samples were tested positive with Salmonella enterica serover TyphiConclusionsThis study indicated the possible involvement of well water in outbreaks. In order to avoid such outbreaks in future, we contacted the local health authorities and urged them to immediately make arrangements for safe drinking water supply.

Analysis of sewage sludge and cover soil by neutron activation analysis

The Korean government reported that in 2005, 4395 tons/day of sewage sludge were generated from sewage disposal facilities in Korea and only 11.03% of it was reused. In addition, as a direct landfill of sewage sludge was forbidden from June 2003, research for a relevant disposal technique has been increasing. In this study, the aims were to analyze the collected sewage sludge samples and to evaluate the possibility for their reuse by a comparison of the elemental contents from a sewage sludge and a cover soil. Sludge samples were collected from a sewage disposal plant in Daejeon city and the cover soil was produced by a dilution of a sewage sludge with quicklime. Instrumental neutron activation analysis was employed to determine the elemental contents in the samples. Twenty seven elements were analyzed and their concentrations were compared.

Intestinal parasitism, potable water availability and methods of sewage disposal in three communities in benue state, Nigeria: A survey

To assess the level of parasite burden in a village community and the predisposing factors. Two hundred subjects each were recruited from three communities- Tyogbenda, Jato-Aka and Adikpo during an episode of free medical outreach. A simple random sampling method was adopted and a questionnaire was interviewer administered on relevant aspects of basic hygiene such as- sources of water supply, methods of domestic sewage disposal and frequency of hand washing. Stool samples were collected and tested and findings analysed using appropriate statistical methods, p values < 0.05 were considered significant. The prevalence of intestinal parasites in Tyogbenda, Jato-Aka and Adikpo communities was found to be 71.5%, 65.5% and 40.5% respectively. Ascaris lumbricoides was the commonest parasite in the three centres (34.5%, 28.5% and 19.0% respectively for Tyogbenda, Jato-Aka and Adikpo communities). Other parasites identified were- Entamoeba histolytica, Entamoeba coli, Hookworm. Enterobius vermicularis, Strongyloides stercoralis, Schistosoma mansoni and Trichuris trichura. Multiple parasitic infestation was common in the communities where quality of water supply and methods of sewage disposal facilities were below standard. The prevalence of intestinal parasitism is still high in Nigerian rural communities. The present resolve by the federal ministry of water resources to supply potable water to all Nigerian rural communities should be sustained. Furthermore, a health education program should be properly constituted and integrated into the present primary health care policy for the country.

Severe malnutrition: epidemiological and clinical characteristics of children hospitalized in the Instituto Materno Infantil de Pernambuco (IMIP), Brazil

Ninety-nine children admitted to the Instituto Materno Infantil de Pernambuco with severe malnutrition from May 1999 to May 2000 were investigated in a cross-sectional study focusing on key epidemiological and clinical variables. The majority of the children (88.9%) were less than 6 months of age, 42.4% had a history of low birth weight, and 36.4% were premature. Some 19.2% had never been breastfed, and 49.5% had been breastfed for less than 2 months. Some 15.2% of the mothers were illiterate. Most of the families (86.1%) had incomes less than twice the minimum wage (approximately US$150/month), and 51.5% had migrated from rural areas. Only 26.3% of the homes had running water, and 40.4% lacked sewage disposal facilities. Diarrhea was the reason for hospital admission in 55.6% of the cases. Hospital mortality was 34.3% in this group.

Predicting Arsenic Solubility in Contaminated Soils Using Isotopic Dilution Techniques

An isotopic dilution assay was developed to measure radiolabile As concentration in a diverse range of soils (pH 3.30-7.62; % C = 1.00-6.55). Soils amended with 50 mg of As kg(-1) (as Na2HAsO4 x 7H2O) were incubated for over 800 d in an aerated "microcosm" experiment. After 818 d, radiolabile As ranged from 27 to 57% of total applied As and showed a pH-dependent increase above pH 6. The radiolabile assay was also applied to three sets of soils historically contaminated with sewage sludge or mine-spoil. Results reflected the various geochemical forms in which the arsenic was present. On soils from a sewage disposal facility, radiolabile arsenate ranged from 3 to 60% of total As; mean lability was lower than in the equivalent pH range of the microcosm soils, suggesting occlusion of As into calcium phosphate compounds in the sludge-amended soils. In soils from mining areas in the U.K. and Malaysia, radiolabile As accounted for 0.44-19% of total As. The lowest levels of lability were associated with extremely large As concentrations, up to 17,000 mg kg(-1), from arsenopyrite. Soil pore water was extracted from the microcosm experiment and speciated using "GEOCHEM". The solid<==>solution equilibria of As in the microcosm soils was described by a simple model based on competition between HAsO4(2-) and HPO4(2-) for "labile" adsorption sites.