There is a special reason for reviewing this book at this time: it is the 50th edition of a compendium that is known and used frequently in most chemical and physical laboratories in many parts of the world. Surely, a publication that has been published for 56 years, withstanding the vagaries of science in this century, must have had something to offer. There is another reason: while the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice). I believe that the Handbook can be useful in those laboratories. One of the reasons, among others, is that the various basic items of information it offers may be helpful in new tests, either physical or chemical, which are continuously being published. The basic information may relate

Handbook of Chemistry and Physics

In this article we review the biological effects of Al, primarily with respect to the chemical factors controlling Al bioavailability and toxicity, and how its biological effects are best predicted. Our intent is not to duplicate recent reviews on Al chemistry or toxicity, but rather to update the literature since these reviews were published, and to focus on Al speciation and other external chemical influences on Al bioavailability to freshwater biota. Briefly, we first review Al chemistry, with a specific focus on understanding, as well as measuring, Al chemical species of importance to aquatic biota. Next we more comprehensively review Al toxicity and bioavailability to freshwater algae, with a thorough analysis of the relationships between speciation and toxicity, the role of important chemical complexing agents such as P, Si, and organic carbon, as well as the potential for Al to impact algal community structure. A third section reviews the more sparse literature on aquatic higher plants; the fourth ...

The Bioavailability and Toxicity of Aluminum in Aquatic Environments

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Treatment Wetlands, Second Edition

Introduction to Soil Microbiology

The use constructed wetlands with horizontal sub-surface flow for various types of wastewater

Effects of vegetation, wastewater drawdown, hydraulic retention time (HRT), and media depth on removal of nitrogen, phosphorous, and organic carbon in microcosms were investigated. Synthetic wastewater was added daily to 28 microcosms, and effluent was sampled every 12 days for 132 days. Effluent was analyzed for ammonium (NH4

 +-N), nitrate (NO3

 −-N), orthophosphate (PO4

 3−-P), and total organic carbon (TOC). Average percent removal of NH4

 +-N was significantly greater in microcosms containing plants (67%) than in those without plants (29%). Percent removal of PO4

 3−-P was also significantly greater in microcosms with plants (42%) than in microcosms without plants (20%), but no significant difference was found for TOC removal between microcosms with plants (67%) and those without plants (74%). Average removal was significantly lower in microcosms with wastewater drawdown than in those without wastewater fluctuation for both NH4

 +-N (51% versus 83%) and PO4

 3−-P (14% versus 71%). Percent NH4

 +-N removal was significantly greater in microcosms with a 6-day retention time (80%) than in those with a 2-day retention (53%), and PO4

 3−-P removal was also significantly greater with a 6-day retention time (55%) than a 2-day retention (29%). No differences were seen in TOC removal due to any of the treatments but HRT, where removal was greater microcosms with a 2-day HRT (76%) than in those with a 6-day HRT (60%). Media depth did not have a significant effect on nutrient removal. Results of this study demonstrate that required design parameters are different depending on the nutrient being removed in systems simulated by these microcosms.

Nitrogen, phosphorous, and organic carbon removal in simulated wetland treatment systems.

The increased use of pesticides by container nurseries demands that practices for removal of these potential contaminants from runoff water be examined. Constructed wetlands may be designed to clean runoff water from agricultural production sites, including container nurseries. This study evaluated 14 constructed wetlands cells (1.2 by 4.9 m or 2.4 by 4.9 m, and 30 or 45 cm deep) that collected pesticide runoff from a 465-m2 gravel bed containerized nursery in Baxter, TN. One-half of the cells were vegetated with bulrush, Scirpus validus. The cells were loaded at three rates or flows of 0.240, 0.120, and 0.060 m3 d(-1). Herbicides-simazine (Princep) [2-chloro-4,6-bis(ethylamino)-s-triazine] and metolachlor (Pennant) [2-chloro-N-(2-ethyl-6-methylphenyl)-N-2-methoxy-1-methylethyl-acetamide] -were applied to the gravel portion of the container nursery at rates of 4.78 and 239 kg ha(-1), respectively, 9 July 1998, and at rates of 2.39 and 1.19 kg ha(-1), respectively, 17 May 1999. Pesticides entering the wetland and wetland cell water samples were analyzed daily to determine pesticide removal. At the slower flow rate, which corresponds to lower mass loading and greater hydraulic retention times (HRTs), a greater percentage of pesticides was removed. During the 2-yr period, cells with plants removed 82.4% metolachlor and 77.1% simazine compared with cells without plants, which removed 63.2% metolachlor and 64.3% simazine. At the lowest flow rate and mass loading, wetland cells removed 90.2% metolachlor and 83% simazine. Gravel subsurface flow constructed wetlands removed most of the pesticides in runoff water with the greatest removal occurring at lower flow rates in vegetated cells.

Pesticide Removal from Container Nursery Runoff in Constructed Wetland Cells

Alum sludges from ten water treatment plants throughout North America were subjected to a battery of toxicity tests which included the S. capricornutum growth test, the fathead minnow survival and growth test, a protozoan mortality test, and the Microtox® test. S. capricornutum was more sensitive than any other test species to sludge extracts. Algal growth inhibition was observed in extracts obtained at pH 5 but generally not in circumneutral solutions. Alum sludge extracts prepared with natural receiving waters were toxic to S. capricornutum at all extract pH levels tested if receiving water hardness was less than 35 mg CaCO3/L. These results indicate that water-soluble constituents from alum sludges discharged into receiving waters may affect algal growth.

Toxicity of alum sludge extracts to a freshwater alga, protozoan, fish, and marine bacterium

Research was conducted on pilot-scale, subsurface flow constructed wetland systems treating municipal wastewater. Increasing the hydraulic retention time (HRT) from 1.7 days to 4.3 days reduced the mean effluent NH 4 concentration by 2.7 mg N/L. Hydroperiod manipulation caused a 2.9-mg N/L decrease in effluent NH 4 . The influent NH 4 concentration for the 9-month study period averaged 21 mg N/L. The lowest average effluent NH 4 concentration observed in single-stage treatment cells was 13 mg N/L. The mean effluent NH 4 concentration from the second-stage cells of two wetland cells in series was 10 mg N/L. During the period from May through September, the second-stage cells produced an effluent NH 4 concentration of 6 mg N/L. A variable-order kinetic model for sizing the second-stage cells of a series system yielded a coefficient of determination, r 2 , of 0.94 for the summer NH4 removal data. The predicted HRT to reduce NH 4 from 20 mg N/L to 5 mg N/L was 3.9 days, if the cells were subjected to cyclic draw and fill.

https://www.jstor.org/stable/info/25044993

Subsurface flow constructed wetlands treating municipal wastewater for nitrogen transformation and removal

Factors affecting growth of softstem bulrush (Scirpus validus), an obligate wetland plant frequently used in subsurface-flow constructed wetlands in North America, were studied in a controlled environmental chamber. Effects of media depth (30-and 46-cm), hydraulic retention time (HRT) (2- and 6-day), and water-level drawdown (drawdown vs. no drawdown) on plant growth in 24 microcosms were investigated. Weekly root and stem growth was measured and stem health assessed to determine effects of treatments on plant vigor. Water-level drawdown was detrimental to plant growth, increasing the percentage of dead stems. Stem production was higher in microcosms with a 46-cm media depth than those with a 30-cm depth and also higher in microcosms that were permanently flooded than in those with fluctuating water levels. Root production was greater in microcosms with a 30-cm media depth than in those with a 46-cm depth, and root production was also greater in microcosms that were constantly flooded than in those drawn down. Scirpus validus is a robust plant that grows well in gravel media microcosms; however, problems are experienced when rhizomes and roots dry out during water drainage.

Dennis B. George

Papers

Nitrogen, phosphorous, and organic carbon removal in simulated wetland treatment systems.

Pesticide Removal from Container Nursery Runoff in Constructed Wetland Cells

Toxicity of alum sludge extracts to a freshwater alga, protozoan, fish, and marine bacterium

Subsurface flow constructed wetlands treating municipal wastewater for nitrogen transformation and removal

Growth of softstem bulrush (scirpus validus) in microcosms with different hydrologic regimes and media depths