Abua Ikem

Trace element content of fish feed and bluegill sunfish (Lepomis macrochirus) from aquaculture and wild source in Missouri

Trace element content of fish feed and bluegill sunfish muscles (Lepomis macrochirus) from aquaculture and natural pond in Missouri were determined using the inductively coupled-plasma optical emission spectrometer (ICP-OES) and the direct mercury analyzer (DMA). Dietary intake rates of trace elements were estimated. Dogfish muscle (DORM-2) and lobster hepatopancreas (TORT-2) reference standards were used in trace element recovery and method validations. The average elemental concentrations (mg/kg diet, dry wt.) of fish feed were: As 1.81, Cd 2.37, Co 0.10, Cr 1.42, Cu 8.0, Fe 404, Mn 35.9, Ni 0.51, Pb 9.16, Se 1.71, Sn 20.7, V 0.09, Zn 118 and Hg 0.07. The mean elemental concentrations (μg/kg wet wt.) in bluegill muscles from both aquaculture and wild (in parenthesis) sources were: As 0.36 (0.06), Cd 0.28 (0.01), Co 0.0 (0.0), Cr 0.52 (0.05), Cu 0.38 (0.18), Fe 17.5 (2.43), Mn 0.18 (0.24), Ni 0.18 (0.04), Pb 1.03 (0.04), Se 0.34 (0.30), Sn 0.66 (0.42), V 0.02 (0.01), Zn 6.97 (9.13) and Hg 0.06 (0.24). Kruskal-Wallis chi square indicated significant differences in As, Cd, Co, Cr, Cu, Fe, Ni, Pb, Sn, V, Zn and Hg (P<0.001), Se (P<0.01) and Mn (P<0.05) across the sampling locations. Dietary intake rates, estimated from weekly consumption of 228g of aquaculture and wild bluegills, posed no health risks for approximately 85% of all samples.

A comparison of forest and agricultural shallow groundwater chemical status a century after land use change.

Considering the increasing pace of global land use change and the importance of groundwater quality to humans and aquatic ecosystems, studies are needed that relate land use types to patterns of groundwater chemical composition. Piezometer grids were installed in a remnant bottomland hardwood forest (BHF) and a historic agricultural field (Ag) to compare groundwater chemical composition between sites with contrasting land use histories. Groundwater was sampled monthly from June 2011 to June 2013, and analyzed for 50 physiochemical metrics. Statistical tests indicated significant differences (p<0.05) between the study sites for 32 out of 50 parameters. Compared to the Ag site, BHF groundwater was characterized by significantly (p<0.05) lower pH, higher electrical conductivity, and higher concentrations of total dissolved solids and inorganic carbon. BHF groundwater contained significantly (p<0.05) higher concentrations of all nitrogen species except nitrate, which was higher in Ag groundwater. BHF groundwater contained significantly (p<0.05) higher concentrations of nutrients such as sulfur, potassium, magnesium, calcium, and sodium, relative to the Ag site. Ag groundwater was characterized by significantly (p<0.05) higher concentrations of trace elements such as arsenic, cadmium, cobalt, copper, molybdenum, nickel, and titanium. Comparison of shallow groundwater chemical composition with that of nearby receiving water suggests that subsurface concentration patterns are the result of contrasting site hydrology and vegetation. Results detail impacts of surface vegetation alteration on subsurface chemistry and groundwater quality, thereby illustrating land use impacts on the lithosphere and hydrosphere. This study is among the first to comprehensively characterize and compare shallow groundwater chemical composition at sites with contrasting land use histories.

Influence of Nutrient Source and Growing Environment on Tissue Elemental Concentration and Yield of Cos Lettuce in Hydroponic Culture

Complete fertilizers formulated for fertigation and soil application are commonly used in hydroponic production. However, these are unsuitable for hydroponic culture of many crops because of imbalances in mineral nutrient composition. Currently, research information about the effect of nonhydroponic fertilizers and the confounding effects of crop type and culture condition on crop yield is limited. The influence of mineral nutrient source (FERT) and growing environment (two controlled environment hydroponic greenhouses; CEHG) with different temperature and relative humidity (RH) regimes on mineral elemental concentration and yield of cos lettuce (Lactuca sativa L. var. longifolia Lam.), cv. Cimmaron, were determined in a nutrient film technique (NFT) hydroponic culture. With the exception of calcium, both CEHG and FERT had a significant effect on the tissue concentration of all the macronutrients, and the concentration of micronutrients in lettuce tissue were optimum, regardless of FERT and CEHG, except for Fe (APHN and CAMG) and Mo (APHN). However, low tissue concentration of macronutrients may have contributed to reducing the marketable yield, which was also significantly affected by FERT.

Evaluation of Surface Water Quality Impacted by Sewage Overflows from Animal and Residential Lagoon Systems using Principal Component Analysis

This study was conducted to: (1) evaluate the water quality of Gans Creek (Missouri, United States), (2) assess the physical and chemical characteristics of two sewage lagoon overflows (confined animal lot lagoon overflow: CALLO, and domestic sewage lagoon overflow: DSLO) discharged into Gans Creek, and (3) understand the most significant analytical variables and major controlling processes influencing Gans Creek water quality using principal component analysis (PCA). Monthly (May 2009-February 2010) sampling was conducted along Gans Creek and at lagoon overflow points. Ammonia-nitrogen (NH3-N) in Gans Creek and the overflows was monitored for another year (March 2010-July 2011) because of its potential toxicity to stream health. Thirty-one variables including pH, electrical conductivity (EC), elemental and anionic species, total nitrogen (TN) and total organic carbon (TOC) were measured in samples. We observed that DSLO samples had the highest level of NH3-N, total phosphorus (TP), TN, TOC and B compared to the corresponding levels in both CALLO and Gans Creek samples. Major stressors for this stream system were dissolved materials and ammonia. PCA showed that the first four rotated components (RC1, RC2, RC3 and RC4) accounted for approximately 60% of the total variability of the dataset. Mineralization (RC1: 20%), sewage overflows (RC2: 19%), diffuse pollution (RC3: 12%), and runoffs from cattle grazing areas (RC4: 9%) were the major controlling processes at the study area. Over twenty water quality determinands were significant in the rotated components. Overflows from the lagoon systems need consistent treatment and management for adequate protection of Gans Creek ecosystem.

Occurrence of enrofloxacin in overflows from animal lot and residential sewage lagoons and a receiving-stream

Enrofloxacin (ENRO), a fluoroquinolone, was quantified in overflows from an animal lot and residential sewage lagoons and in a receiving-stream (Gans Creek). The concentrations of ENRO in samples was determined by high-performance liquid chromatography − tandem mass spectrometry. In total, ninety samples including duplicates were analyzed during several monthly sampling campaigns. The samples collected represented the residential sewage lagoon overflow (RLO), animal lot lagoon overflow (ALLO), the combined overflows (RLO and ALLO), and Gans Creek (upstream, midstream and downstream positions). The frequency of detection of ENRO was 90% for RLO and 100% for both ALLO and Gans Creek. The highest concentration of ENRO (0.44 μg/L) was found in ALLO sample collected during high precipitation. ENRO levels found in RLO samples ranged from < LOQ to 259 ng/L and the highest value observed also coincided with high flow. The levels of ENRO found in Gans Creek ranged from 17–216 ng/L. A preliminary ecotoxicological assessment was conducted through calculation of the risk quotients (RQs) for organisms based on the ratio of the measured environmental concentrations in this study to the predicted-no-effect-concentrations (acute and chronic effect) data. From the RQs, high risks were observed for Microcystis aeruginosa (cyanobacteria; RQ = 4.4); Anabaena flosaquae (cyanobacteria; RQ = 1.3); and Lemna minor (aquatic vascular plant; RQ = 2.0). The long-term effects of mixtures of PHCs on Gans Creek watershed are probable.