MERCURY IN HOSPITAL CLEANING PRODUCTS

To enable wastewater treatment plant discharges to meet strict regulatory standards some agencies are beginning to regulate selected mercury-containing products at their sources. Hospitals, which on average contribute approximately 8 percent of the total influent mercury to wastewater treatment plants, could have great potential for achieving measurable reductions of mercury in wastewaters.

A mass balance approach was used to estimate the relative contribution of mercury in cleaning products to the total mercury load from hospitals. The mercury concentration in hospital wastewater is in the range 4 to 4.6 micrograms per liter (ug/L) and may include waste from broken equipment (where approximately 20 percent of the spilled mercury is reportedly discharged to wastewater), laboratory chemicals (e.g., Zenker’s Fluid, reported to contain mercury at 37.5 grams per liter), medicinal wastes (e.g., preservatives such as Thimerasol), amalgam from dental clinics (mercury load contribution of 138 g/dental office/day), human waste-amalgam (up to 67 ug/person/day), dietary waste (1.4 ug/person/day), cleaning products (0.108 to 0.258 ug/patient/day), dirt and dye from laundry processing and mercury settled in wastewater sumps and traps.

The total mass of laundry detergent, bleach, dishwashing detergent, shampoo, soap and drain cleaner contributes between 64.90 ug and 154.75 ug of mercury to the average hospital effluent per day. This is equivalent to 0.0032 - 0.0077 percent of the average total hospital wastewater mercury contribution. A conservative sensitivity analysis in which both the estimated mass and concentration of cleaning products used within hospitals were increased ten-fold indicated that the relative contribution of cleaning products to mercury in hospital wastewaters was 0.33-0.78 percent of the average total hospital wastewater mercury contribution.

Simultaneous nitrogen and phosphorus deficiency in natural phytoplankton assemblages: Theory, empirical evidence, and implications for lake management

The paper investigates the theory that phytoplankton communities experience non-equilibrium conditions. Simultaneous additions of NH₄⁺ and PO₄^3- were necessary to stimulate community photosynthesis - uptake of ¹⁴CO₂ - during summer stratification in a number of northern Rocky Mountain lakes and reservoirs, whereas adding one nutrient had no significant effect on community photosynthesis.

Role of nutrients and zooplankton in regulation of phytoplankton in Flathead Lake (Montana, U.S.A.), a large oligotrophic lake

In order to assess the importance of these two factors in regulating the phytoplankton community in Flathead Lake, zooplankton abundance and nutrient availability in a series of 5-day enclosure experiments were manipulated.

Chlorophyll a levels were stimulated by simultaneous addition of nitrogen and phosphorus.

These results suggest that the phytoplankton community in Flathead Lake is regulated primarily by bottom-up controls.

A conceptual model is presented illustrating the relative importance of top-down and bottom-up controls across a trophic gradient.

Evaluating eutrophication control alternatives for the Lower Neuse River, North Carolina

Larry G. Huffman, Jr.
A Thesis Presented to the faculty of the School of Engineering and Applied Science University of Virginia In Partial Fulfillment of the requirements for the Degree Master of Science (Civil Engineering)

In the past decade, advanced eutrophication has been observed in segments of the lower Neuse River between Goldsboro and New Bern, North Carolina. Eutrophication in the lower Neuse River is characterized by three major symptoms: 1) nitrogen and phosphorus concentrations in the water column that exceed levels required to sustain algal growth; 2) high rates of primary production; and 3) summer and fall blooms of Microcystis aeruginosa, a surface-dwelling, non-nitrogen fixing blue-green algae. Blooms occur most often during summers with below-average river flow following winters and springs with high runoff of nutrient-laden water.

Two existing water-quality models were used to evaluate the effectiveness of ten alternatives to control and limit eutrophication and algal growth in the lower Neuse River. Point-source control alternatives involved a stepwise reduction of effluent concentrations of total phosphorus from 6 mg/L to 0.2 mg/L and total nitrogen from 7 mg/L to 3 mg/L. Reductions of current non-point source nitrogen and phosphorus loads by 30% were evaluated both alone and in conjunction with point-source phosphorus and nitrogen controls. A hybrid annual flow scenario featuring high winter-spring flow and summer low-flow was used in the model evaluations to simulate optimum algal growth conditions. Low-flow augmentation was also examined as a method to limit bloom formation.

Model results indicate that a 38% reduction in maximum annual chlorophyll a concentrations may be achieved with stringent point-source phosphorus control. Non-point source nitrogen and phosphorus controls of 30% were effective in limiting growth only when used in conjunction with point-source phosphorus control. Flow control simulations suggest that periodic release of water from upstream reservoirs may arrest algal growth during low flows.

Surfactant Analysis for SDA Sediment Taskforce Study: Analysis of AE, AES and LAS in environmental media from the Trinity River (Texas, USA)

Analysis was carried out on surface water, pore water and sediment from the Trinity River (Texas, USA) for the presence of three specific surfactants; linear alkylbenzene sulphonates (LAS), alkyl ethoxysulphates (AES) and alcohol ethoxylates (AE). Total suspended solids data were also obtained for pore water samples. These analyses form part of a comprehensive study of the Trinity river which includes assessment of biological data and water quality. The surfactant analysis involved extraction and cleanup of samples using solid phase extraction cartridges followed by liquid chromatography-mass spectrometry. Specifically the surfactants for which levels were obtained are C_10-14 LAS, C_12-15 EO_0-6 AES and C_12-16+18 EO_0-18 AE. It is believed that this is the first study to provide such a comprehensive fingerprint of the levels of three surfactant types from a number of locations in a single river. Results were obtained from all samples allthough there is some doubt as to the levels at one sampling site (site 10). No obvious trends were observed allthough a few individual high and low concentrations were observed.