Unlined Pits Research Articles

Evaluation of Sanitation Technologies Across Sanitation Service Chain in Kericho Town, Kenya

In 2020, over half of the world's population resided in cities, with projections indicating that by 2050, this figure will rise to 70%. Providing adequate sanitation services in urban and peri-urban areas presents significant challenges due to the dense concentration of people, particularly in low- and middle-income countries. Poor sanitation practices in these areas can lead to the spread of diseases with high morbidity and mortality rates. The focus of the study was on Kericho town, Kenya, facing a notable sanitation challenge due to dilapidated sewer system and inadequate sanitation facilities . The aim of this study was to evaluate the safety of sanitation technologies used in Kericho Town. Descriptive study design was adopted. Data collection methods included surveys, interviews, and observations, with a sample size of 409 households. The findings revealed that 66.5% of the population relies on pit latrines with slabs, 13.69% use pour/manual flush systems, 11.49% have ventilated improved pit latrines, 8.07% employ automatic cistern flush, and a minimal 0.24% practice open defecation. 25% of population discharged waste directly into the sewerage system whereby 5% were considered safely managed. Additionally, 4% of waste from user interfaces was discharged directly into open ground or open drains. 2% of population used septic tanks connected to soak pits, whereas 6% of population used septic tanks connected to open ground. Sludge from septic tanks, comprising 20%, was delivered to the WWTP by exhausters for further treatment, of which only 20% underwent treatment, with the remainder released untreated into the environment. 49% of the population used lined pits, while 14% used unlined pits. Approximately 20% of faecal sludge from the pits was exhausted, with only 20% of it considered safely treated, and the remainder released into the environment. Notably, open defecation accounted for less than 1% based on the survey findings. Consequently, the current trend in faecal sludge management in Kericho Town posed potential health hazards to the community unless measures such as rehabilitating the existing wastewater treatment plant are implemented.

Land-use interactions, Oil-Field infrastructure, and natural processes control hydrocarbon and arsenic concentrations in groundwater, Poso Creek Oil Field, California, USA

Like many hydrocarbon production areas in the U.S., the Poso Creek Oil Field in California includes and is adjacent to other land uses (agricultural and other developed lands) that affect the hydrology and geochemistry of the aquifer overlying and adjacent to oil development. We hypothesize that the distributions of hydrocarbons and arsenic in groundwater in such areas will be controlled by complex interactions between mixed land uses, oil-field infrastructure, and natural processes. In 2020–2021, samples of groundwater and surface water were collected and analyzed for a large suite of inorganic and organic chemicals and isotope and gas tracers to test this hypothesis. Those data are supplemented with ancillary data on historical geochemistry, hydrology, geology, and oil-field infrastructure. Hydrocarbons in groundwater (e.g., methane through pentane gases and benzene) are associated with natural processes (e.g., fault offsets or transition in sediment depositional environment) and oil-field infrastructure (e.g., fluid-migration pathways associated with uncemented annulus in oil wells or unlined pits). Arsenic concentrations >10 μg per liter (μg/L; maximum concentration 12.9 μg/L) are associated with natural processes in old, high-pH groundwater, and more recent recharge of water from natural and/or engineered recharge processes. Along the southwest margin of the oil field, pumping for drinking-water and irrigation supplies in combination with engineered groundwater recharge produce a depression in groundwater elevations where groundwater with elevated sulfate concentrations from agricultural areas and groundwater with hydrocarbons from the oil field mix to produce a zone of sulfate reduction that removes hydrocarbons and arsenic from groundwater but produces elevated sulfide (S2-) concentrations (maximum concentration 29 mg per liter, mg/L). In this study, multiple approaches were required to resolve the overlapping effects of land uses, oil-field infrastructure, and natural processes on the distributions of hydrocarbons and arsenic in groundwater. The combined use of geographic, historical, physical, chemical, isotopic, and other information to constrain processes could be a useful approach for studies in other hydrocarbon-production areas. This is particularly important where land uses affect aquifer hydrology to an extent that causes mixing of groundwaters with different chemical compositions.

Nitrogen Discharge from Livestock Wastes Thrown in Unlined Pit and Denitrification around the Pit

Numerous groundwater problems involving nitrate contamination, mainly derived from fertilizer and livestock waste, are reported worldwide. In Japan, although livestock wastes thrown in unlined pits has been banned by a law established in 1999, unlined pits still remain, causing high nitrogen discharges into groundwater. At the Tsukuba Plateau Ibaraki Pref., groundwater with more than 100 mgNO3−/L is observed just below an old unlined pit with 4.1 kgN/year of nitrogen estimated to be released from the pit. In addition, a large part of the released nitrogen is denitrified in a percolation process through a clay layer beneath the pit.

Development of an Inclusive City-Wide Faecal Sludge Management Business Model for Kabwe Town, Zambia

Investment in sanitation solutions reduce disease burdens and is a huge market for public and private businesses since billons of people in the world do not have access to safely managed sanitation services. However, there remains much to be done to develop, pilot and scale up business models and technologies that work to fully understand the nature and quantities of faecal sludge needing collection and treatment. In Kabwe, the lack of a comprehensive business model informed by market research has contributed to faecal sludge not reaching designated treatment sites. Private operators charge unregulated fees for emptying and use unhealthy emptying methods that risk public health and groundwater resource. This research aimed at developing an inclusive city-wide FSM business model for Kabwe Town was conducted using mixed qualitative and quantitative approaches at 172 households and institutions spread across 20 wards. The results showed that 41 percent of the containments were unlined pits which could not be desludged easily. Atleast 84 percent of households could not afford to pay $42 for emptying services, but 96 percent were willing to contribute a monthly staggered tariff for emptying service which would make the service affordable regardless of socioeconomic status. It was estimated that at least 8,882m3/year of sludge would be available for emptying. With minimal overhead costs, utilising existing infrastructure and charging an emptying fee of $1 – $3 or $3 – $9/m3, the business would make a positive net profit in the first year of operations and offset a loan amount of upto to $28,400. The model demonstrated that in as much as financial resources are required, minimal start-up capital coupled with prudent planning, utilisation of readily available resources are key success factors. The study brought out key areas of attention which includes the need for awareness creation, pro-poor diverse payment schemes to increase demand and concerted stakeholders efforts on issues of policy, enforcement and capacity strengthening.

Vouchers for Improving Sanitation: A Step toward Stopping Open Defecation.

Vouchers for Improving Sanitation: A Step toward Stopping Open Defecation.

Risk assessment of unlined oil pits leaking into groundwater in the Ecuadorian Amazon: A modified GIS-DRASTIC approach

This study evaluates the risk of groundwater contamination from unlined oil pits, in the Northern Ecuadorian Amazon (NEA). Applying spatial analysis, several maps were provided for its integration in land use planning, public health improvement and future site-specific investigations. Two main maps were produced: (1) a vulnerability indexed map using a modified DRASTIC model and (2) a hazard map based on the past (1995–1997) and present (2018) contamination using a weighted density equation. The hazard was derived from hydrocarbon contained in oil pits associated with a cost-distance analysis to obtain different maximum distance ranges (MDR), to model the surface of potentially impacted groundwater. The results indicate a total calculated hydrocarbons of 39 052 tons. A MDR from 500–10 000 km was retained to map aquifers at risk, the maximum surface potentially at risk covers 13% of the NEA, while 83% of the area represents low to medium-low vulnerability. This study led to several recommendations, such as the level of suitability of the available information, and what gaps should be filled to improve future research. A surface of 271–766.5 km in the 500-2000-m distance range should be prioritised for finer scale risk assessment.

A Review of Petroleum Waste Management and Environmental Quality Status of Niger Delta

This paper provides a review and assessment of many researches and documentaries on Niger delta petroleum waste management. What new strategy or operational techniques would be added to improve waste management and environmental quality of Niger delta is our concern. Poor waste management, lack of environmental impacts assessment (EIA) and remediation neglects in the three sectors of oil and gas operations (upstream, midstream and downstream) are responsible for environmental pollution in the Niger delta. There is need to adopt continuous, operational, and periodic EIA with immediate remediation in the three operational sectors. This will end the old method of remediation only after a crisis. Application of Remove, Reduce, and Reuse to petroleum waste water should be considered. Avoidance of gas flaring near residential areas is obvious. Replacing unlined waste water pits with lined pits, solid waste dumps with sanitary landfills and partial waste treatment with full treatment are inevitable in sustainable management of petroleum wastes. Oil companies and the Nigeria National Petroleum Corporation (NNPC) could establish research grant for environmental studies to have the findings reported to them directly. Niger delta operational areas with maximum toxicity should be mapped out as brown fields and declared “no farm areas”.

Pit Latrine Fecal Sludge Resistance Using a Dynamic Cone Penetrometer in Low Income Areas in Mzuzu City, Malawi.

Pit latrines can provide improved household sanitation, but without effective and inexpensive emptying options, they are often abandoned once full and may pose a public health threat. Emptying techniques can be difficult, as the sludge contents of each pit latrine are different. The design of effective emptying techniques (e.g., pumps) is limited by a lack of data characterizing typical in situ latrine sludge resistance. This investigation aimed to better understand the community education and technical engineering needs necessary to improve pit latrine management. In low income areas within Mzuzu city, Malawi, 300 pit latrines from three distinct areas were assessed using a dynamic cone penetrometer to quantify fecal sludge strength, and household members were surveyed to determine their knowledge of desludging procedures and practices likely to impact fecal sludge characteristics. The results demonstrate that there is a significant difference in sludge strength between lined and unlined pits within a defined area, though sludge hardened with depth, regardless of the pit type or region. There was only limited association between cone penetration depth and household survey data. To promote the adoption of pit emptying, it is recommended that households be provided with information that supports pit emptying, such as latrine construction designs, local pit emptying options, and cost. This study indicates that the use of a penetrometer test in the field prior to pit latrine emptying may facilitate the selection of appropriate pit emptying technology.

Characterization of pit latrines to support the design and selection of emptying tools in peri-urban Mzuzu, Malawi

The urban areas of many low-income countries must balance a rising demand for pit latrines for household sanitation provision against limitations in space, resulting in a need for pit latrine emptying services. This study was undertaken in the peri-urban neighborhood of Area 1B in the city of Mzuzu, Malawi, to examine the characteristics of household pit latrines for designing and selecting pit latrine emptying tools. We used 150 structured household surveys and field observations. From this, a subset was selected and 30 manual cone penetrometer tests were conducted at full latrines. Chemical oxygen demand analysis was also performed for 14 pit latrines. The results indicated that in addition to serving as a disposal for fecal matter, 90% of households also used pit latrines for domestic waste. Only 10% of the studied pit latrines were lined. The filling rate in the study area is calculated to be about three years, and no respondents reported previous emptying. It is suggested pit latrine emptying technology development focuses on a maximum tool diameter of 10 cm to fit through the keyhole (squat hole) and height of 146 cm to fit inside the superstructure, as well as supporting unlined pits and the ability to pump trash.

English

Inadequate information on physiochemical properties of faecal sludge leads to inappropriate design of pit emptying devices and poor faecal sludge disposal contributing to environmental pollution. This study undertook a critical analysis of physiochemical properties of feacal sludge that influence design and performance of pit emptying devices and faecal sludge disposal for improved faecal sludge management in urban slums. The physiochemical properties determined were; Moisture content (MC), ash content (AC), total solids (TS), volatile solids (VS), nitrogen (N), phosphorous (P), potassium (K) and pH. Samples were collected from 55 unlined pits at depths of 0, 0.5, 1 and 1.5 m from pit surface. The unlined pits in this study were purposively selected from slums in Kampala. A sample of 300 g was sucked from each depth using a manual sampling tool and emptied into a plastic container. The container was then wrapped in a black plastic bag and transported in cooler boxes to the lab for analysis. The properties were subjected to Principal Component Analysis to isolate the critical parameters that affect pit emptying and faecal sludge disposal. The mean results were: MC of 86 ± 8.37%; TS of 0.14 ± 0.08 g/g wet sample; VS of 0.73 ± 0.32 g/g dry sample; pH of 8.0 ± 1.5; AC of 0.35± 0.18 g/g dry sample; TN of 3.5 ± 0.08%; K of 2.2± 0.13%  and P of 1.4± 0.05%. It was concluded that physiochemical properties in Ugandan pits are comparable to those of global pits except for the acidic conditions at top surface in some pits, and higher moisture content in pits due to the high water table. PCA results showed that moisture content and total solids affected pit emptying techniques while fractional content of N, P and pH affect most choice of faecal sludge disposal technique.   Key words: Pit latrine, faecal sludge management, developing countries, physiochemical properties, pit emptying.

Dewaterability of faecal sludge and its implications on faecal sludge management in urban slums

The current practices of faecal sludge management in urban slums pose risks to public health and environmental pollution. Given that faecal sludge contains high water content, dewatering it presents an important step of managing it effectively. This paper therefore explores the applicability of dewatering as the first step in decentralized treatment of faecal sludge (FS) generated from pit latrines, the commonest sanitation technology used in urban slums. A total of 22 and 10 FS samples were collected from lined and unlined pit latrines, respectively. The high moisture content of 92.4 and 83.4 % of FS from lined and unlined pit latrines, respectively, depicted a need for dewatering. Dewaterability extent and rate were measured in terms of per cent cake solids and capillary suction time, respectively. The average dewaterability extent of FS from unlined pit latrines (31.8 %) was significantly higher than that of lined latrines (18.6 %) (p = 0.000) while the dewaterability rate (1122 and 1485 s of FS from lined and unlined pits, respectively) was not significantly different (p = 0.104), although very low compared to sewage sludge. To obtain high dewaterability extent of FS from lined pit latrines, volatile solids should be reduced and sand content increased. To maintain high dewaterability extent of FS from unlined pit latrines, the particle sizes should be ≤1 mm. The results from this study suggest that FS from pit latrines in Kampala can be conveniently dewatered without thickening, thereby reducing costs of FS management.

Impact to Underground Sources of Drinking Water and Domestic Wells from Production Well Stimulation and Completion Practices in the Pavillion, Wyoming, Field.

A comprehensive analysis of all publicly available data and reports was conducted to evaluate impact to Underground Sources of Drinking Water (USDWs) as a result of acid stimulation and hydraulic fracturing in the Pavillion, WY, Field. Although injection of stimulation fluids into USDWs in the Pavillion Field was documented by EPA, potential impact to USDWs at the depths of stimulation as a result of this activity was not previously evaluated. Concentrations of major ions in produced water samples outside expected levels in the Wind River Formation, leakoff of stimulation fluids into formation media, and likely loss of zonal isolation during stimulation at several production wells, indicates that impact to USDWs has occurred. Detection of organic compounds used for well stimulation in samples from two monitoring wells installed by EPA, plus anomalies in major ion concentrations in water from one of these monitoring wells, provide additional evidence of impact to USDWs and indicate upward solute migration to depths of current groundwater use. Detections of diesel range organics and other organic compounds in domestic wells <600 m from unlined pits used prior to the mid-1990s to dispose diesel-fuel based drilling mud and production fluids suggest impact to domestic wells as a result of legacy pit disposal practices.

Recovery of crude from OVL in joint operations, Wafra, Kuwait

ABSTRACTWeathered crude oils stored in open and unlined pits pose several environmental, safety, and health issues to the flora, fauna, and human population. The weathered crude oil could leach through the cracks and fissures in the ground surface contaminating the groundwater contribute to a higher concentration of VOCs and hazardous gases such as H2S in the atmosphere and render the soil unusable due to high concentration of petroleum hydrocarbons. Processing and recovery of clean oil is possible through the use of complex technologies involving the use of mechanical equipment, chemicals, and heat. By processing and recovering clean oil from weathered crude, it can be seen that the dangers of pollution posed to groundwater, atmosphere, and the soil can be greatly reduced and removed. In addition to reducing the dangers to the environment, substantial revenues are also being generated which keeps the clean-up process self-sustaining. The author describes the successful recovery of 905,900 barrels from large waste oil pit that was estimated to contain approximately 1,000,000 barrels of oily viscous liquid (OVL) of which approximately 600,000 barrels were estimated recoverable crude. The process not only recovered 50% more than estimated recovery, yet this has helped to remediate and mitigate negative environmental impact and generated revenues for WJO. Between June 2011 and July 2014, the footprint of that pit was reduced by approximately 60% due to the cleanup efforts.

Characterization and analysis of medical solid waste in Osun State, Nigeria

This paper reports the study of quantum and characterization of medica solid wastes generated by healthcare facilities in Osun State. The work involved administration of a questionnaire and detailed studies conducted on facilities selected on the basis of a combination of purposive and random sampling methods. The results show that the facilities are well spread among the 30 Local Government Areas; that the total quantity of medical waste generated in the state is 2672 kg/day and when domestic wastes are included the total is 5832 kg/day; that the medical wastes are not being properly disposed of as pathology wastes such as unclaimed dead bodies, placentas, umbilical cords are being dumped into unlined pits and other wastes in open dumps. A centralised system is proposed state–wide involving use of incinerators, landfills, aerobic lagoons, and reed beds. The Federal Ministry of Environment has responsibility to push for development of legislation and codes of practice that would guide facilities to achieve waste segregation, packaging in colour-coded and labeled bags, safe transportation and disposal of medical waste. Keywords : Medical solid wastes, pathological wastes, incinerators, landfills, aerobic lagoons, reed beds.

Brief of International Law Professors as Amici Curiae in Support of Defendants in Chevron versus Donziger

Between 1964 and 1990, Texaco dumped about 16 billion gallons of toxic substances into the surface water of the Amazon, relied upon by indigenous Amazon and remote farmers. Texaco also created hundreds of unlined pits in the jungle floor and filled them with toxic sludge. In 1993, the Amazon indigenous communities and remote farmers sued Texaco in the United States, its home jurisdiction, seeking redress for damages caused by Texaco’s operations. From 1993 to 2002 Texaco and later Chevron, when it acquired Texaco, fought to have the case dismissed and moved to Ecuador as the more appropriate forum to try the case. Ultimately, the U.S. action was dismissed in exchange for promises by Chevron to accept jurisdiction in Ecuador and satisfy any judgment rendered by an Ecuadorian court. The case was re-filed and tried in Ecuador. On February 14, 2011 the Provincial Court of Sucumbios awarded the Ecuadorian plaintiffs $8.6 billion in damages, with $5.6 billion going toward environmental remediation. Anticipating the worst, Chevron took preemptive action back in the United States. With the judgment not final and no attempt by the Ecuadorian plaintiffs to enforce in the U.S., Chevron filed a complaint against the Ecuadorians seeking declaratory relief for non-recognition of the Ecuadorian judgment and a preliminary injunction enjoining the Ecuadorians from seeking to have the Ecuadorian judgment recognized or enforced anywhere in the world. On March 7, 2011, the U.S. Federal District Court in the Southern District of New York granted the preliminary injunction in this Opinion. The Ecuadorian's have appealed and this amicus brief was filed on June 9, 2001 in support of the Ecuadorians. The brief seeks to show that the District Court erred in granting the injunction and that international legal obligations of the United States requires that the injunction be dissolved and the case dismissed.

Crude: The Real Price of Oil (review)

Crude: The Real Price of Oil (2009) Produced and Directed by Joe Berlinger Distributed by First Run Features www.firstrunfeatures.com 105 minutes Joe Berlinger's 2009 documentary, Crude: The Real Price of Oil, is a compelling and disturbing examination of efforts to seek environmental justice in Ecuador's section of the Amazon rainforest. In the 1960s, the Ecuadorian government opened the Amazon region to oil exploration, an opportunity quickly exploited by Texaco. After three decades of oil extraction, Texaco sold its operation to PetroEcuador, owned and operated by the Ecuadorian government. The following year, 1993, a class action suit was filed on behalf of the Amazon indigenous populations against Texaco. The case was originally slated for the United States, but the oil company fought to have it tried in Ecuador. The suit charges that the petroleum giant, by diverting its waste byproducts into streams, rivers, and unlined dumping pits, created a level of toxicity that resulted in abnormally high rates of cancer, leukemia, birth defects, and other health problems. Chevron (which inherited the lawsuit after merging with Texaco) blames PetroEcuador for the environmental damage and claims that, when the company was sold to PetroEcuador, an agreement with the Ecuadorian government granted impunity to Texaco for past and future environmental contamination. Although Crude presents both sides of this complex and still unfolding legal drama, contrasting positions are depicted in stylistically different ways, possibly the result of Chevron's initial reluctance to provide access to Berlinger. Chevron's arguments are generally told through interviews with company lawyers and scientists. The interviews, however, are essentially predictable talking points with no interaction between the interlocutor and interviewee. In contrast, the plaintiffs' position is revealed through footage of American lawyer Steven Donziger and Ecuadorian lawyer Pablo Fajardo interacting with the local population and developing their legal strategy. The most notable - and most disturbing - moments include personal stories of the victims: a father recalls losing his young son after he drank water with a high concentration of oil; a young mother attempts to sell a few chickens to raise money for her daughter's cancer treatments, but soon sees the chickens succumb to the toxic environment. Other segments of Crude are implicitly disquieting. For example, Donziger was exhilarated when rock musician Sting and his wife became involved in the case. Although the couple generated much needed publicity to the plight of the indigenous populations, the viewer is left to ponder why it is necessary to utilize celebrities to achieve justice. …

Impact of land disposal of reject brine from desalination plants on soil and groundwater

The impact of reject brine chemical composition and disposal from inland desalination plants on soil and groundwater in the eastern region of Abu Dhabi Emirate, namely Al Wagan, Al Quaa and Um Al Zumool, was evaluated. Twenty five inland BWRO desalination plants (11 at Al Wagan, 12 at Al Quaa, and 2 at Um Al Zumool) have been investigated. The study indicated that average capacity of these plants varied between 26,400 G/d (99.93 m 3/d) to 61,000 G/d (230.91 m 3/d). The recovery rate varied from 60 to 70% and the reject brine accounted for about 30–40% of the total water production. The electrical conductivity of feed water and rejects brine varied from 4.61 to 14.70 and 12.90–30.30 (mS/cm), respectively. The reject brine is disposed directly into surface impoundment (unlined pits) in a permeable soil with low clay content, cation exchange capacity and organic matter content. The groundwater table lies at a depth of 100–150 m. The average distance between feed water intake and the disposal site is approximately 5 km. A survey has been conducted to gather basic information, determine the type of chemicals used, and determine if there is any current and previous monitoring program. The chemical compositions of the feed, product, reject, and pond water have been analyzed for major, minor and trace constituents. Most of the water samples (feed, product, reject and pond water) showed the presence of major, minor and trace constituents. Some of these constituents are above the Gulf Cooperation Council (GCC) and Abu-Dhabi National Oil Company (ADNOC) Standards for drinking water and effluents discharged into the desert. Total Petroleum Hydrocarbon (TPH) was also analyzed and found to be present, even in product water samples, in amount that exceed the GCC standards for organic chemical constituents in drinking water (0.01 mg/l).

Using Multimedia Modeling to Expedite Site Characterization

This paper uses two case studies of U.S. Department of Energy nuclear weapons complex installations to illustrate the integration of expedited site characterization (ESC) and multimedia modeling in the remedial action decision making process. CONCEPTUAL SITE MODELS, MULTIMEDIA MODELS, AND EXPEDITED SITE CHARACTERIZATION: Conceptual site models outline assumptions about contaminates and the spatial/temporal distribution of potential receptors. Multimedia models simulate contaminant transport and fate through multiple environmental media, estimate potential human exposure via specific exposure pathways, and estimate the risk of cancer and non-cancer health outcomes. ESC relies on using monitoring data to quantify the key components of an initial conceptual site model that is modified iteratively using the multimedia model. Two case studies are presented that used the ESC approach: Los Alamos National Laboratory (LANL) and Pantex. LANL released radionuclides, metals, and organic compounds, into canyons surrounding the facility. The Pantex Plant has past waste management operations which included burning chemical wastes in unlined pits, burying wastes in unlined landfills, and discharging plant wastewaters into on-site surface waters. The case studies indicate that using multimedia models with the ESC approach can inform assessors about what, where, and how much site characterization data needs to be collected to reduce the uncertainty associated with risk assessment. Lowering the degree of uncertainty reduces the time and cost associated with assessing potential risk and increases the confidence that decision makers have in the assessments performed.

Aquatic ecotoxicity due to oil pollution in the Ecuadorian Amazon

One of the major environmental impacts of oil exploration in the Ecuadorian Amazon region is the contamination of the aquatic environment. In addition to occasional major oil spills, there are several minor sources. This study investigates aquatic toxicity due to seepage from production pits and oiled road run-off. Water and sediment samples were collected and acute toxicity was determined in Daphnia magna and Hyalella azteca bioassays. Because exposure to ultra-violet radiation may enhance the toxicity of several polycyclic aromatic hydrocarbons in crude oil, toxicity was studied before and after exposure to natural sunlight in the field using a microbiotest or solar-simulating ultra-violet light in the laboratory using cultured organisms. Total petroleum hydrocarbon concentrations of analyzed sediments ranged from 4.9 to 6980 mg kg−1 dry weight (dw). Immobility and lethality ranged from 0 to 100% in Daphnia magna and from 0 to 40% in Hyalella azteca. The micro-biotest results were generally confirmed by the tests on cultured Daphnia. A river exposed to oiled road run-off and a pond used for drinking water, 100-m from a production pit, had the highest total petroleum hydrocarbon concentrations. These samples were toxic compared to reference sites. The response increased upon light exposure, suggesting polycyclic aromatic hydrocarbon availability. Minor water phototoxicity was also observed in the drinking water pond (having ten times the total petroleum hydrocarbon concentration nationally allowed in drinking water). Thus, the seepage from unlined production pits and the practice to use oil for dust control on roads in the area pose environmental and human health hazards.

Effects of wall linings on moisture ingress into traditional grain storage pits.

Increasing climate variability, resulting in frequent years of poor rainfall, has recently subjected the traditional subsistence farmers in the Central Clay Plain of the Sudan to longer periods of food shortage. However, excess production in years of good rainfall could bridge the gap of years with poor rainfall if the grain is properly stored. Resource-poor farmers have tried several linings to improve the traditional underground pit ("matmura") they use for storage of sorghum. In the experimental study described here, pits with two types of lining: (i) a mixture of mud, cow dung and straw and (ii) sorghum chaff, were compared with unlined pits. Six closed pits were used, two for each type, and temperature and moisture content were monitored. It was found that the temperature increased in all pits and at all positions within the pits, with few differences between the linings. Moisture levels also increased everywhere but the sources of moisture were at the sides and bottoms of the pits. The chaff-lined pits were superior to the others because they showed smaller increases in moisture content at all positions and thus maintained a better quality of sorghum. Joint traditional assessments with local farmers after the pits were opened supported these findings.