Assessment of Selected Heavy Metal Concentrations in Selected Fresh Fruits in Eldoret Town, Kenya

This study assessed levels of selected heavy metals (Lead, Chromium and Cadmium) in oranges and mangoes sold in Eldoret town and their health implications to consumers. A total of one hundred and eighty (180) samples were collected for analysis from randomly selected market sites within Eldoret town. Samples were wet digested using a mixture of 1:3 (65% HCl: HNO3) and analyzed using Atomic Absorption Spectrophotometer version 200. One Way Analysis of Variance (ANOVA) was used to test the significance of selected heavy metal levels in consideration of market sites at 5% significance level. There was insignificant variance in mean chromium levels in mango fruits among market sites (f=2.1, f=3, p=0.10) with the highest mean level occurring at 2.43±0.24 mg/kg. Lead levels in orange fruits were significant (f=13.3, df=3, p=0.00) with the highest mean level occurring at 0.65±0.03 mg/kg. Cadmium levels were significant in mango fruits among market sites (f=6.5, df =3, p=0.00) with the highest level at 0.09±0.05 mg/kg. Risk Assessment in terms of values of Daily Intake of Metal (D.I.M) had chromium levels in mango fruits with the highest at 0.05mg/day, lead in orange fruits was at 0.02mg/day with the least D.I.M occurring in cadmium levels in mango fruits at 0.002mg/day. Mango and orange fruits sold in Eldoret town posed no health risks to consumers based on their D.I.M levels, as the values were within Provisional Daily Tolerable Intake standards of World Health Organization (WHO). The elevated chromium D.I.M levels in mango fruits in this study meant that environment in which mango fruits are grown were high in chromium content. There is need to initiate and sustain continued monitoring of heavy metals in fruits and food sold to consumers due to their different sources where contamination of heavy metals varies to ascertain food safety. Keywords: Daily Intake of Metal, Hazard Quotient and Heavy metal

Influence of Ammonium Sulphate from anaerobic pasteurization digester latrines (APDLs) effluent on soil pH

Improper disposal of human waste is one of the most serious health problems in developing countries due to pollution of the  environment. The use of chemical fertilizers for agriculture increase the plant growth to meet the food security of the world, but also causes environmental problems including lowering of soil pH. On the other hand, anaerobic pasteurization digester systems enable the recovery of nutrients from human faces and urine for the benefit of agriculture, thus helping to preserve soil fertility. Therefore, the present work aims to assess the potential of using ammonium sulphate processed from anaerobic pasteurization digesters latrines  (APDLS) effluent to stabilize soil pH. The experiment was laid out in a completely randomized design with four treatments replicated four times. The treatments were Ammonium sulphate, Compost manure, Di-ammonium Phosphate (DAP) and control. The results showed that soil pH increased significantly (p<0.05) from 4.7 -4.9 before planting to 5.6 - 5.7 after planting. The organic and inorganic fertilizers as well as the interaction between the fertilizer and time did not have significant effect on soil pH (p > 0.05). The Ammonium sulphate recovered from APDLs final effluent could act as effective as a chemical fertilizer without significant reduction in the yield

Global Patterns and Controls of Nutrient Immobilization On Decomposing Cellulose In Riverine Ecosystems

Microbes play a critical role in plant litter decomposition and influence the fate of carbon in rivers and riparian zones. When decomposing low-nutrient plant litter, microbes acquire nitrogen (N) and phosphorus (P) from the environment (i.e., nutrient immobilization), and this process is potentially sensitive to nutrient loading and changing climate. Nonetheless, environmental controls on immobilization are poorly understood because rates are also influenced by plant litter chemistry, which is coupled to the same environmental factors. Here we used a standardized, low-nutrient organic matter substrate (cotton strips) to quantify nutrient immobilization at 100 paired stream and riparian sites representing 11 biomes worldwide. Immobilization rates varied by three orders of magnitude, were greater in rivers than riparian zones, and were strongly correlated to decomposition rates. In rivers, P immobilization rates were controlled by surface water phosphate concentrations, but N immobilization rates were not related to inorganic N. The N:P of immobilized nutrients was tightly constrained to a molar ratio of 10:1 despite wide variation in surface water N:P. Immobilization rates were temperature-dependent in riparian zones but not related to temperature in rivers. However, in rivers nutrient supply ultimately controlled whether microbes could achieve the maximum expected decomposition rate at a given temperature

Child Exposure to Lead in the Vicinities of Informal Used Lead-Acid Battery Recycling Operations in Nairobi Slums, Kenya

Background. Child exposure to lead from informal used lead-acid battery (ULAB) recycling operations is a serious environmental health problem, particularly in developing countries. Objectives. We investigated child exposure to lead in the vicinities of ULAB recycling operations in the Dandora, Kariobangi and Mukuru slums in Nairobi between January and August 2015. Methods. Top soil (n = 232) and floor dust (n = 322) samples were collected from dwelling units (n = 120) and preparatory schools (n = 44) and analyzed using an inductively coupled plasma-optical emission spectrometer at the Mines and Geological Department Laboratory in the Ministry of Mining, Nairobi. From the obtained lead levels in soil and house dust, child blood lead levels were subsequently predicted using the Integrated Exposure Uptake Biokinetic Model for Lead in Children (IEUBK), Windows version. Results. Lead loadings in all the floor dust samples from the Dandora, Kariobangi and Mukuru slums exceeded the United States Environmental Protection Agency (USEPA) guidance value for lead on floors with a range of 65.2 – 58,194 μg/ft2. Control floor dust samples recorded lower lead loadings compared to the Dandora, Kariobangi and Mukuru slums. Lead concentration in 70.7% of the soil samples collected from waste dumps, industrial sites, residential areas, playgrounds and preparatory schools in Dandora, Kariobangi and Mukuru exceeded the respective USEPA guidance values for lead in soils. Lead concentration in 100% of control soil samples were below the respective USEPA limits. The IEUBK model predicted that nearly 99.9% of children ≤ 7 years old living near informal ULAB recycling operations in Dandora, Kariobangi and Mukuru were at risk of being lead poisoned, with predicted blood lead levels (BLL) above the Centers for Disease Control (CDC) reference value for blood lead. A total of 99.9% of exposed children living in the Mukuru slums are likely to have BLL above 34 μg/dL. Conclusions. There is a need for coordinated efforts to decrease lead emissions from informal battery recycling in Nairobi slums and to remediate existing soils, particularly around battery workplaces and dumpsites. The BLL of local children should be clinically tested and appropriate intervention measures taken. Competing Interests. The authors declare no competing financial interests

Global Patterns and Controls of Nutrient Immobilization on Decomposing Cellulose in Riverine Ecosystems

International audienceMicrobes play a critical role in plant litter decomposition and influence the fate of carbon in rivers and riparian zones. When decomposing low‐nutrient plant litter, microbes acquire nitrogen (N) and phosphorus (P) from the environment (i.e., nutrient immobilization), and this process is potentially sensitive to nutrient loading and changing climate. Nonetheless, environmental controls on immobilization arepoorly understood because rates are also influenced by plant litter chemistry, which is coupled to the same environmental factors. Here we used a standardized, low‐nutrient organic matter substrate (cotton strips) to quantify nutrient immobilization at 100 paired stream and riparian sites representing 11 biomes worldwide. Immobilization rates varied by three orders of magnitude, were greater in rivers than riparian zones, andwere strongly correlated to decomposition rates. In rivers, P immobilization rates were controlled by surface water phosphate concentrations, but N immobilization rates were not related to inorganic N. The N:P of immobilized nutrients was tightly constrained to a molar ratio of 10:1 despite wide variation in surface water N:P. Immobilization rates were temperature‐dependent in riparian zones but not related to temperature in rivers. However, in rivers nutrient supply ultimately controlled whether microbes could achieve the maximum expected decomposition rate at a given temperature. Collectively, we demonstrated that exogenous nutrient supply and immobilization are critical control points for decomposition of organic matter

Global patterns and controls of nutrient immobilization on decomposing cellulose in riverine ecosystems

Abstract Microbes play a critical role in plant litter decomposition and influence the fate of carbon in rivers and riparian zones. When decomposing low-nutrient plant litter, microbes acquire nitrogen (N) and phosphorus (P) from the environment (i.e., nutrient immobilization), and this process is potentially sensitive to nutrient loading and changing climate. Nonetheless, environmental controls on immobilization are poorly understood because rates are also influenced by plant litter chemistry, which is coupled to the same environmental factors. Here we used a standardized, low-nutrient organic matter substrate (cotton strips) to quantify nutrient immobilization at 100 paired stream and riparian sites representing 11 biomes worldwide. Immobilization rates varied by three orders of magnitude, were greater in rivers than riparian zones, and were strongly correlated to decomposition rates. In rivers, P immobilization rates were controlled by surface water phosphate concentrations, but N immobilization rates were not related to inorganic N. The N:P of immobilized nutrients was tightly constrained to a molar ratio of 10:1 despite wide variation in surface water N:P. Immobilization rates were temperature-dependent in riparian zones but not related to temperature in rivers. However, in rivers nutrient supply ultimately controlled whether microbes could achieve the maximum expected decomposition rate at a given temperature. Collectively, we demonstrated that exogenous nutrient supply and immobilization are critical control points for decomposition of organic matter

Global patterns and drivers of ecosystem functioning in rivers and riparian zones

Abstract River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to conduct a global-scale field experiment in greater than 1000 river and riparian sites. We found that Earth’s biomes have distinct carbon processing signatures. Slow processing is evident across latitudes, whereas rapid rates are restricted to lower latitudes. Both the mean rate and variability decline with latitude, suggesting temperature constraints toward the poles and greater roles for other environmental drivers (e.g., nutrient loading) toward the equator. These results and data set the stage for unprecedented “next-generation biomonitoring” by establishing baselines to help quantify environmental impacts to the functioning of ecosystems at a global scale