The Mexican immigrant, a product of his background

Thesis (M.A.)--Boston University This item was digitized by the Internet Archive

Potentially Toxic Trace Element Contamination of the Little Akaki River of Addis Ababa, Ethiopia

In this study, river water samples taken from 26 different locations along the course of the Little Akaka River in Addis Ababa were analyzed to determine potentially toxic trace element concentrations. The mean concentrations in ?g L-1 for Mn 1540.04, Fe 1075.92, B 383.04, Sr 336.75, Ba 132.17, Cr 67.04, Sb 42.80, Zn 25.50, Ni 6.66, Cu 5.61, V 4.87, Pb 3.13, Co 2.62, As 1.46, Cd 0.06 and Hg <0.05. Overall metal concentration were in the order Mn > Fe > B > Sr > Ba > Cr > Sb > Zn > Ni > Cu > V > Pb > Co > As > Cd > Hg. A strong positive correlation was observed between several of the trace elements indicating common sources. The concentrations of Cr, Mn, Sb, B and Pb exceeded the permissible limits of the Ethiopian, European Community and WHO for drinking water quality guidelines. Fe and Sr exceeded the permissible limits of the Ethiopian drinking water guideline and Sr exceeded the WHO thresholds. The concentration of Cr, Zn, Cu and Pb exceeded the annual average thresholds for surface waters set in SI 272 of 2009. The concentration of Cr, Mn and Sr were also higher than the international guidelines value for irrigation water. The pollution of the river water is increasing alarmingly and poses serious threat to human health. Many of the concentrations were higher than previously reported. It is, thus, necessary to take serious and essential measures from the concerned bodies. Adoption of adequate measures to remove the heavy metal load from the industrial waste water and upgrading of sewage treatment plants are suggested to avoid further deterioration of the river water quality. Keywords: River water, Potential toxic elements, Heavy metal contamination, Drinking water standard

Assessment of Potentially Toxic Elements in Vegetables Grown along Akaki River in Addis Ababa and Potential Health Implications

The present study was carried out to assess contamination of vegetables from five farmlands in Addis Ababa with toxic and potentially toxic elements (Cd, Pb, As, Cu, Zn, Cr, Co, Ni, Ba, B, Sr, V, Fe and Mn) and health risk concerns to consumers of these vegetables as well as farm soils and water used to irrigate the vegetables. Pollution levels were varied with metals and vegetable types. The average total metal accumulation (mg kg-1) in the vegetables was potato (245.54) > carrot (202.20) > Swiss chard (52.42) > lettuce (47.43) > cabbage (38.04) > Ethiopian kale (30.17). Results also revealed that the average concentrations (mg kg-1) of all elements in the vegetables were found in order of Pb (744.10) > Fe (288.5) > Mn (51.66) > Sr (50.12) > Zn (38.81) > Ba (35.51) > B (21.65) > Cu (7.95) > Cr (1.97) > Ni (1.14) > V (0.54) > Co (0.20) > As (0.08) > Cd (0.08). Many of the concentrations were higher than previously reported. The average metal concentration (mg kg-1) of vegetables by farm was Burayu (136.58) > Akaki (125.00) > Kolfea (54.19) > Goffa (37.11) > Kera (29.40). The concentration of Cr, Cd, Pb and Fe in most vegetables surpassed the maximum recommended levels. From health standpoint consuming lettuce, Swiss chard, carrot and potato may cause serious health risk to consumers than cabbage and Ethiopia kale due to the high level of toxic metal accumulation. Elevated levels of some heavy metals were detected in the soil and irrigation water (Cd, Pb, As, Cu, Zn, Cr, Co, Ni, Ba, B, Sr, V, Fe and Mn) suggesting contamination from various the industrial and municipal discharges to the local river network. The present study highlights the immediate need for proper treatment and disposal of wide range of effluents and waste materials that currently enter the Akaki River and its tributary and farmlands as well as regular monitoring of potential contaminants in soil, water and vegetables and enforcement of standards. Keywords: Potentially toxic elements, contamination, plant uptake, health ris

Challenges in using hydrology and water quality models for assessing Freshwater Ecosystem Services:A Review

Freshwater ecosystems contribute to many ecosystem services, many of which are being threatened by human activities such as land use change, river morphological changes and climate change. Many disciplines have studied the processes underlying freshwater ecosystem functions, ranging from hydrology to ecology, including water quality, and a panoply of models are available to simulate their behaviour. This understanding is useful for the prediction of ecosystem services, but the model outputs must go beyond the production of time-series of biophysical variables, to include notions of value and accessibility to the ecosystems? beneficiaries. This article analyses the literature of ad hoc approaches that aim at quantifying one or more freshwater ecosystem services. It identifies the strategies used to use disciplinary-specific models for the prediction of the services. This review identifies that hydrological, water quality, and ecological models form a valuable knowledge base to predict changes in ecosystem conditions, but challenges remain to make proper and useful use of these models. In particular, considerations of temporal and spatial scales could be given more attention in order to provide better justifications for the choice of a particular model over another, including the uncertainty in their predictions.publishersversionPeer reviewe

The effect of nutrient concentrations and ratios on periphyton biomass in low conductivity streams: implications for determination of nutrient limitation

The purpose of this study was to experimentally evaluate the effects of nutrient ratios and nutrient concentration (NC) on periphyton biomass using water from 4 Irish streams. Stream water nitrogen to phosphorus (N:P) ratios were manipulated (high >50, medium 15–30, low <10) and crossed with 3 different NCs over a 2-week period. Algal biomass as chlorophyll a (Chl-a) showed variable response to the treatments compared to the control in 3 streams and no response to the treatments in the forth stream. The 3 streams showed significant interaction between N:P ratio and NC. Periphyton response to the NC treatments and N:P ratio was varied; 2 streams had a significant response to both NC treatments and N:P ratios. In these 2 streams Chl-a was positively correlated to dissolved inorganic N but not to soluble reactive P, indicating N limitations despite the high N:P ratio from the ambient stream water. The third stream showed a significant response to NC and was again co-limited by N and P. The results suggest that nutrient ratio has no real application in predicting nutrient limitation in flowing water. Furthermore, the results highlight the importance of considering N in the potential for eutrophication

A Water Framework Directive-compatible metric for assessing acidification in UK and Irish rivers using diatoms

Freshwater acidification continues to be a major problem affecting large areas of Europe, and while there is evidence for chemical recovery, similar evidence for biological recovery of freshwaters is sparse. The need for a methodology to identify waterbodies impacted acidification and to assess the extent of biological recovery is relevant to the EUWater Framework Directive, which requires methods to quantify differences in biology between impacted and unimpacted or reference sites. This study presents a newWFD-compliant metric based on diatoms Diatom Acidification Metric: DAM) for assessing the acidification status of rivers. A database of 558 benthic diatom samples and associated water chemistry data was assembled. Diatom taxa were assigned to one of 5 indicator classes on the basis of their pH optimum, assessed using Gaussian logistic regression, and these indicator values used to calculate a DAM score for each site using weighted averaging. Reference sites were selected on the basis of their acid neutralising capacity (ANC) and calcium concentration, and a regression model developed to predict expected DAM for each site using pH and total organic carbon (TOC) concentration. Site-specific DAM scoreswere used to calculate ecological quality ratios ranging from≥1, where the diatom assemblage showed no impact, to (theoretically) 0, when the diatom assemblage was indicative of major anthropogenic activities. The boundary between ‘high’ and ‘good’ status was defined as the 25th percentile of Ecological Quality Ratios (EQRs) of all reference sites. The boundary between ‘good’ and ‘moderate’ status was set at the point at which nutrient sensitive and nutrient-tolerant taxa were present in equal relative abundance. The methodology was evaluated using long-term data from 11 sites from the UK UplandsWaters Monitoring Network and is shown to perform well in discriminating naturally acid from acidified sites

Hybridisation between two cyprinid fishes in a novel habitat: genetics, morphology and life-history traits

BACKGROUND: The potential role hybridisation in adaptive radiation and the evolution of new lineages has received much recent attention. Hybridisation between roach (Rutilus rutilus L.) and bream (Abramis brama L.) is well documented throughout Europe, however hybrids in Ireland occur at an unprecedented frequency, often exceeding that of both parental species. Utilising an integrated approach, which incorporates geometric morphometrics, life history and molecular genetic analyses we identify the levels and processes of hybridisation present, while also determining the direction of hybridisation, through the analysis of mitochondrial DNA. RESULTS: The presence of F2 hybrids was found to be unlikely from the studied populations, although significant levels of backcrossing, involving both parental taxa was observed in some lakes. Hybridisation represents a viable conduit for introgression of genes between roach and bream. The vast majority of hybrids in all populations studied exhibited bream mitochondrial DNA, indicating that bream are maternal in the majority of crosses. CONCLUSIONS: The success of roach × bream hybrids in Ireland is not due to a successful self reproducing lineage. The potential causes of widespread hybridisation between both species, along with the considerations regarding the role of hybridisation in evolution and conservation, are also discussed

Chronic nutrient inputs affect stream macroinvertebrate communities more than acute inputs: An experiment manipulating phosphorus, nitrogen and sediment

peer-reviewedFreshwaters worldwide are affected by multiple stressors. Timing of inputs and pathways of delivery can influence the impact stressors have on freshwater communities. In particular, effects of point versus diffuse nutrient inputs on stream macroinvertebrates are poorly understood. Point-source inputs tend to pose a chronic problem, whereas diffuse inputs tend to be acute with short concentration spikes. We manipulated three key agricultural stressors, phosphorus (ambient, chronic, acute), nitrogen (ambient, chronic, acute) and fine sediment (ambient, high), in 112 stream mesocosms (26 days colonisation, 18 days of manipulations) and determined the individual and combined effects of these stressors on stream macroinvertebrate communities (benthos and drift). Chronic nutrient treatments continuously received high concentrations of P and/or N. Acute channels received the same continuous enrichment, but concentrations were doubled during two 3-hour periods (day 6, day 13) to simulate acute nutrient inputs during rainstorms. Sediment was the most pervasive stressor in the benthos, reducing total macroinvertebrate abundance and richness, EPT (mayflies, stoneflies, caddisflies) abundance and richness. By contrast, N or P enrichment did not affect any of the six studied community-level metrics. In the drift assemblage, enrichment effects became more prevalent the longer the experiment went on. Sediment was the dominant driver of drift responses at the beginning of the experiment. After the first acute nutrient pulse, sediment remained the most influential stressor but its effects started to fade. After the second pulse, N became the dominant stressor. In general, impacts of either N or P on the drift were due to chronic exposure, with acute nutrient pulses having no additional effects. Overall, our findings imply that cost-effective management should focus on mitigating sediment inputs first and tackle chronic nutrient inputs second. Freshwater managers should also take into account the length of exposure to high nutrient concentrations, rather than merely the concentrations themselves

The Grizzly, April 18, 2002

From the B-52\u27s to the Beach Boys: Airband was a Huge Success • ProTheatre Stages History with Twilight: Los Angeles this Weekend • Students Rave About the Pat McGee Band in Concert • Adolph Reed to Deliver Pancoast Lecture • Fitness Week a Fitness Blast • Male Birth Control: Latest Medical Breakthrough? • Opinions: Greek Portrayal in Movies Demeaning, not True!; Parking Policy not Fun for Some Residents • Y100\u27s Caseyboy and his Crazy Stunts • The Letters and the Cane • Comparative Pricing Report: Self Tanners • Skin Cancer is not Your Friend • UC Women\u27s Rugby Making a Breakthrough in Women\u27s Sports • Workman\u27s Workouts Paying Off for Field Hockey • Baseball Team Winds Down Season Looking for Top Spot in Centennial Conference Playoffs • Erin Fitzgerald Named Centennial Conference Women\u27s Lacrosse Player of the Week • Dougherty Qualifies in 5000m for NCAA Championships • Another Flawless Season for Women\u27s Lacrosse to Lead Team to Second Consecutive Championship Title • UC Men\u27s LAX Stars: What are they up to Now? • Win, Loss, and Postponement for UC Softball as Season Winds Downhttps://digitalcommons.ursinus.edu/grizzlynews/1514/thumbnail.jp