Condition of Soils and Vegetation Along Roads Treated with Magnesium Chloride for Dust Suppression

Investigations of vegetation stress along non-paved roads treated with a range of magnesium chloride (MgCl₂) application rates utilized 60 roadside and 79 drainage plots on 15 and 18 roads, respectively. Evaluations were completed of foliar damage, plant health, biotic and abiotic damage incidence and severity, soil and foliar chemistry and other common site and stand characteristics of Pinus contorta, Populus tremuloides, Picea engelmannii, Abies lasiocarpa, and lower elevation plots dominated by shrubs and grasses. High concentrations of soil magnesium and chloride (400–500 ppm), high foliar chloride (2,000–16,000 ppm depending on species) and high incidence of foliar damage were measured in roadside plots along straight road segments in the first 3 to 6.1 m adjacent to treated roads. In drainage plots, where water is channeled off roads, high concentrations of both magnesium and chloride ions and associated foliar damage were measured between 3 and 98 m from the road. High incidence of foliar damage and elevated ion concentrations were not apparent in control plots along non-treated roads. Lodgepole pine appeared to be the most sensitive species, while aspen accumulated the most chloride and exhibited the least amount of damage. Foliar chloride concentrations strongly correlated with percent foliar damage for all species (r?=?0.53 to 0.74, p?<?0.0001) while the incidence of biotic damages did not correlate well. Positive relationships between foliar chloride and magnesium chloride application rates were strong and can be used to predict foliar concentrations and subsequent damage to roadside trees.     

Biological,chemical and physical responses of lakes to experimental acidification

Changes in physical, chemical and biological factors were observed during a 5-yr experimental acidification study in Lake 223 of the Experimental Lakes Area, and compared to a 2 yr pre-acidification period. Significant changes included increased transparency, rates of hypolimnion heating and rates of thermocline deepening; increased concentrations of Mn, Na, Zn, Al, and chlorophyll; decreased concentrations of suspended C, total dissolved N, Fe and chloride; increases in Chlorophyta but decreases in Chrysophyta; the disappearance of the opossum shrimpMysis relicta and the fathead minnowPimephales promelas; the appearance of epidemics of the filamentous algaMougeotea; decreased fitness and decline in numbers ofOrconectes virilis; and increased embryonic mortality of the lake troutSalvelinus namaycush. Sulfur budgets for two lakes experimentally acidified with sulfuric acid reveal that an average of 1/4 to 1/3 of added sulfate is sedimented, presumably as FeS, reducing the efficiency of acidification. The sedimentation occurs under both oxic and anoxic conditions. The utility of whole-ecosystem mass balance studies of S in ‘experimental’ and ‘observational’ mass balance studies is discussed.     

Comparison of mussels and crustacean plankton to monitor heavy metal pollution

The ability of freshwater organisms (mussels — Unio pictorum L. and crustacean plankton —Cladocera and Copepoda species) to monitor heavy metal pollution was compared under field conditions, near the effluent discharge of a sewage water treatment plant at Lake Balaton (Hungary). The mussels were transferred from their less polluted habitat to the study area. The crustacean plankton was collected at this site The concentrations of Hg Cd Cr Cut Pb, Zn, and Fe were measured m the gills of the transplanted mussels as well as the natural zooplankton in the summer period, using the AAS method. Both mussel gills and the zooplankton showed periodically high Fe-, Zn-, and Cu-concentrations. An elevated level of Hg was only observed in mussels, while high Pb- and Cr-concentrations were found only in crustacean plankton. Accordingly the zooplankton seems a more suitable model for monitoring heavy metal pollution under these field conditions.     

Temporal changes in metal levels of the lichens Parmotrema praesorediosum and Ramalina stenospora,Southwest Louisiana

Two species of lichen native to southwest Lousiana, Parmotrema praesorediosum (Nyl.) Hale and Ramalina stenospora, Mull. Arg. have been investigated as air pollution monitors. Over the period 1983–88 samples were collected at 18 stations in the Lake Charles/Westlake/Sulphur area. The samples were analyzed for A1, Fe, Cu, Pb, Cd, Hg, Cr, and Zn. When metal concentrations in lichens were plotted vs year for certain representative stations, a dramatic reduction in the concentrations of certain metals was seen after 1983. When the most recent data are compared with those previously obtained, the effects of the industrial zone, which was previously demonstrated, have now all but disappeared.     

The experimental phytotoxicology of germanium in relation to silicon

The common belief that the sensitivity of plants to Ge is evidence for a Si requirement has been examined experimentally using barely, wheat, cucumber and radish cultivars. All 4 test plants were inhibited by Na₂GeO₃ (metagermanate) at 1 mM or less, including germination, shoot height, root length, and first leaf growth in barley and wheat. The application of Na₂SiO₃ (metasilicate) counteracted Ge-inhibition only in barley. Further, only barley growth was stimulated by the application of Na₂SiO₃. Necrotic lesions were characteristic of Ge-toxicity only in barley leaves, and were reduced when Na₂SiO₃ was supplied.     

The effect of pH,aluminum, and chelator manipulations on the growth of acidic and circumneutral species of Asterionella

The growth rates of two diatoms, acidophilic Asterionella ralfsii and circumneutral A. formosa, were differentially affected by varying pH, Al, and EDTA in chemically defined media. Free Al ion concentration increased as pH and EDTA concentration decreased. Free trace metal ion concentration decreased as EDTA levels increased but increased by orders of magnitude upon addition of Al. pH had an overriding species specific effect on growth rate; at low pH A. ralfsii had higher growth rates than A. formosa and vice versa at high pH. For both species higher EDTA levels depressed growth rates. Moderate additions of Al generally resulted in growth stimulation. The growth rate stimulations, especially at 200 and 400 μg L^?1 Al additions, correlate to increases in free trace metal ion concentrations. The EDTA-AI interaction effects on growth rate were both pH and concentration dependent: at pH 7 both species were stimulated by addition of Al at all EDTA levels (except A. ralfsii at 5.0 mM EDTA and A. formosa at 0.5 mNM EDTA); at pH 6 Al addition either stimulated or had no effect on the growth rates of both species (except at low EDTA and high Al levels); at pH 5 A. formosa did not grow and additions of 200 μg L^?1 Al stimulated growth of A. ralfsii. It is likely that the effect of pH, Al, and EDTA on speciation of essential or toxic trace metals affects growth rates of these diatoms in a species specific manner.     

Multi-element analysis of an english peat bog soil

Nineteen elements were quantitatively determined by atomic emission spectroscopy with inductively coupled plasma in peat profiles in Ringinglow Bog, Derbyshire, England. For the elements Ba, Ca, Cd, Co, Cr, Fe, La, Mn, Ni, Ti, and Zn an enrichment in the upper 5 cm of the peat bogs was found probably caused by anthropogenic influences. The elements Al, Be, Cu, and Pb showed a different distribution pattern with maximum concentration in the 5 to 15 cm layer. The elements Mg, Na, and Sr showed no enrichment in the upper 55 cm of the peat reflecting the constant input of these elements from the sea during the last few centuries. Upper parts (leaves and stems) of the plants investigated (Calluna vulgaris and Eriophorum vaginatum) only represent higher values of Pb compared with the normal element content in other plants. Compared with the results of peat profiles in a Norwegian bog, the concentrations of the comparable elements (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) are much higher in the English peat. Ringinglow Bog seem to be very suitable for further investigations within the scope of a global monitoring programme.     

Synergistic effects of heavy metal pollutants on senescence in submerged aquatic plants

The effects of many combinations of toxic concentrations of heavy metal pollutants, viz., mercuric chloride, lead acetate, cadmium chloride and cupric sulphate, on the senescence of isolated mature leaves of submerged aquatic plants, Potamogeton pectinatus L., Vallisneria spiralis L., and Hydrilla Verticillata (L.f) Royle were studied. All of the combinations of heavy metal pollutants caused senescence in all three species by decreasing chlorophyll, DNA, RNA, protein and dry wt, and increasing free amino acid, tissue permeability, the activities of protease and RNase, and the ratio of acid to alkaline pyrophosphatase activity over control values. The effects were highest in Potamogeton and lowest in Hydrilla. The degree of senescence in the three submerged plants by combinations of toxic concentrations of heavy metal pollutants is much higher due to synergism than that by individual heavy metal pollutants.     

Elemental concentrations in fishes from the Salton Sea,Southeastern California

The Salton Sea is a 93 000 ha saline lake fed by drainage water from more than 283 000 ha of irrigated lands in the Imperial and Coachella valleys of California. A total of 21 composite samples of four recreationally important fish species — bairdiella (Bairdiella icistia), orangemouth corvina (Cynoscion xanthulus), sargo (Anisotremus davidsoni), and Mozambique tilapia (Tilapia mossambica) —collected there were analyzed for 14 elements. Twelve of these elements were detected in one or more of the samples: As, B, Co, Cu, Fe, Hg, Mo, Ni, Pb, Se, V, and Zn. Cadmium and Tl were not detected. The ranges in concentrations of elements in the skinless fillets of bairdiella, corvina, and sargo, and in whole bodies of all four fishes were comparable to levels that are typically measured in saltwater fishes. Only Se concentrations were elevated (as much as 14 µg g^?1 dry weight in both fillets and whole bodies) in this series of samples. Elevated concentrations of Se have already led to public health advisories concerning the consumption of fish and might eventually cause the demise of fish populations from toxic effects.     

Micromycetes in podzolic and bog-podzolic soils in the middle taiga subzone of northeastern European Russia

The qualitative and quantitative characteristics of the mycobiota in podzolic and bog-podzolic soils were studied in the middle taiga subzone (the Republic of Komi). The complex of micromycetes was found to include 73 species of 18 genera from the Zygomycota and Ascomycota orders and from the formal class of anamorphic fungi. The latter has the following specific features: many forms of sterile mycelium, the predominance of Penicillium species (25), the constant presence of Mucor and Trichoderma species, and single Aspergillus species. With increasing moisture in the sequence of the podzolic, surface-gleyic podzolic, peaty podzolic-gleyic, and peat podzolic-gley soils, the dominant soil fungi are preserved, but the species composition of the micromycete complexes becomes poorer due to the removal of rare species. In the podzolic and bog-podzolic soils, fungi absolutely predominate in the microbial biomass. They accounted for more than 99% of the total biomass, 1–6% of the latter is the biomass of spores, and more than 94% falls on mycelium. In these soils, the reserves of bacterial biomass, as compared to those of fungi, are lower by two orders of magnitude.     

Amoebae in a waste stabilization pond system in Mexico

A protozoological survey was performed to analyze the organisms of the subphylum Sarcodina Schmarda, present in waste stabilization ponds located at Santo Tomás Atzingo, México, from March to December 1981. The amoebae isolated were identified and counted. Several physicochemical parameters were also determined and correlated with the biological data. Thirteen amoebic species were isolated and identified: one definite pathogen, Entamoeba histolytica Schaudinn; three species that have shown pathogenic strains for humans: Acanthamoeba polyphaga Page, Acanthamoeba castellanii Douglas, and Naegleria sp. (Alexeieff) Calkins; two opportunist species: Entamoeba coli (Grassi) Casagrandi and Barbagallo, and Iodamoeba bühschlii (Von Prowazek) Dobell; and seven free-living amoebae: Acanthamoeba astronyxis Ray and Hayes, Amoeba proteus (Pallas) Leidy, Hartmannella exundans Page, Hartmannella vermiformis Page, Pelomyxa palustris Leidy, Vahlkampfia avara Page, and Vahlkampfia russelli Singh. A clear correlation between the number of amoebae and the temperature and alkalinity of the system was found. The removal capacity of the ponds for E. histolytica varied from 30 to 100% during the survey. The amoebae showed a succession in space and time in the system studied.     

Concentration and deposition of trace metals in Ontario-1982

Results of trace metal concentrations in air and precipitation and the corresponding wet and dry deposition in Ontario in 1982 arc reported. In terms of the spatial patterns, in general, there was a decreasing gradient from south-to-north in both concentration and deposition. Patterns differed with each parameter although certain groups of metals (e.g., Fe and Al; Pb, Zn, and Mn) displayed similar patterns. In general, wet deposition was greater than dry deposition at all sites. Geographically, the variability in the wet to dry deposition ratio for coarse particles (MMD > 2.5 μm) was small. However, it increased from the south to the north for fine particles (MMD < 2.5 μm), being higher away from the source areas. Scavenging ratios (W) have been derived from the precipitation and air concentrations of trace metals. The scatter in W is quite large for all trace metals, up to 2 orders of magnitude. There was little seasonal variability in W for fine particles (Pb, Mn, Zn, and Cd). However, coarse particles (Fe, Al, and Cu) were more efficiently scavenged by snow than by rain.     

Polychlorinated biphenyl uptake and translation by Spartina alterniflora loisel

This paper presents the findings of initial investigation of the role of Spartina alterniora Loisel. in the movement of chlorinated hydrocarbons. ¹⁴C-polychlorinated biphenyls and technical Aroclor® 1254 were used for the determinations. The findings demonstrate that Spartina accumulates ¹⁴C-radioactivity from sand and organic mud soil systems treated with ¹⁴C-PCB's. These findings also demonstrate that this plant has the capacity to accumulate ¹⁴C-radioactivity to levels elevated above that in the treated soil. Other experiments with Aroclor® 1254 demonstrate that cogeners of Aroclor® 1254 are present in Spartina stem and root extracts. These experiments also suggest that the chlorinated hydrocarbon uptake process is modulated by the plant and that this results in selective cogener uptake. The selectivity appears to be for the lesser chlorinated components of the commercial mixture. Overall, this study suggests that Spartina may act as an initial vector for mobilization of sediment bound chlorinated hydrocarbons to the estuarine food chain.     

The effects of PCB's (Aroclors 1254 and 1016) on fertilization and morphology in Arbacia punctulata

This study examined the effects of exposing the eggs of the purple sea urchin (Arbacia punctulata) to two commercial polychlorinated biphenyl mixtures (PCB's), Aroclors 1254 and 1016, on fertilization through pluteus (larva) development. Eggs were exposed to various concentrations of the PCB's (0.5, 1.0, 5.0, and 10.0 mg L^?1) beginning 25 min prior to insemination, with continuous exposure post-insemination for the 72 hr observation period employed in this study. The PCB's were administered as a component of a filtered sea water (FSW) medium. A FSW control and a FSW-acetone conditioned control where used since acetone was utilized in a 49 : 1, acetone: PCB ratio, to emulsify the PCB's. Since Arbacia eggs cleave synchronously following insemination, the percentage of the eggs cleaving at 1.75 hr post-insemination was used to determine the fertilization efficiency. Pluteus development and morphology was assayed at 24 hr intervals. The results of the fertilization efficiency studies were tested using Chi square and Pearson's-Product-Moment-Correlation Coefficient (r) at a 95% level of confidence. The morphology data were treated with a two-tailed t-test (99% confidence level) and (r). Both PCB's affected fertilization efficiency with the Aroclor 1016 being an order of magnitude more toxic than the Aroclor 1254. Likewise, both Aroclors were toxic to the pluteus development process with Aroclor 1016 being the more toxic of the two mixtures. At the highest PCB level employed, Aroclor 1254 proved more lethally toxic than Aroclor 1016 although both treatment-groups exhibited more than 90% toxicity to the morphogenic process.     

Distribution of airborne heavy metals as measured in the lichens Ramalina stenospora and Parmotrema praesorediosum in Baton Rouge,Louisiana

The lichens Ramalina stenospora and Parmotrema praesorediosum were collected from 30 stations in the greater metropolitan area of Baton Rouge, Louisiana and analyzed for Al, Cu, Fe, Zn, and Pb content. A univariate analysis of the data showed a significant difference between metal concentrations and sampling stations. When the stations were separated into two groups representing those in the industrial and urban zones, a discriminant analysis was over 90% successful in correctly assigning stations based solely on metal concentrations. No significant differences in metal concentration with species could be observed. Average metal concentrations for the two lichen species were used to construct contours and three-dimensional plots of metal distribution across the study area which clearly demonstrate the effects of the industrial zone on airborne metal levels.     

Foliar Damage,Ion Content,and Mortality Rate of Five Common Roadside Tree Species Treated with Soil Applications of Magnesium Chloride

Sensitivity to magnesium chloride (MgCl₂) was assessed on five common roadside tree species by maintaining soil concentrations at 0-, 400-, 800-, or 1,600-ppm chloride via MgCl₂ solution over four growing seasons. Evaluations of growth, leaf retention, foliar damage, and ion concentrations were conducted. Water potentials were measured on two species. Foliar chloride and magnesium concentrations were positively correlated with foliar damage in all species. Conifers exhibited mild damage during the first growing season but moderate to severe damage during the first winter and second growing season. The two highest MgCl₂ treatments caused leaf loss, severe damage, or mortality of Douglas-fir, lodgepole, and ponderosa pines after two seasons of treatments and of limber pine after four seasons. Aspen also displayed foliar damage and crown loss but abscised damaged leaves and flushed asymptomatic leaves throughout the growing seasons. The highest treatment caused mortality of aspen in 4 years. Approximately 13,000–17,000-ppm foliar chloride was associated with severe damage in conifers but ranged from 13,000- to 33,000-ppm in fully necrotic leaves. Aspen foliage contained the highest concentrations of chloride (24,000–36,000-ppm), and limber pine leaves had the lowest (<14,200-ppm). Although MgCl₂ caused reductions in leaf water potential, aspen and ponderosa pine did not appear to be under substantial moisture stress and continued to take up ions. Mortality of common roadside tree species in 2 to 4 years can occur due to high MgCl₂ soil concentrations, and transportation officials should consider these implications in their management plans.     

The influence of the herbicide paraquat ‘Gramaxon’ on growth and metabolic activity of three chlorophytes

The acute toxicity of commercial herbicide, Paraquat was determined by 96-hr static bioassay on the freshwater chlorophytes Scenedesmus dimorphus (Trup.) Kuetz., Scenedesmus quadricauda (Trup.) de Brebisson and Ankistrodesmus falcatus (Cord) Ralfs. The 96-hr EC50 values of Paraquat for reducing growth and metabolic products of the three algae were determined. The number of days required for cell division increased with increasing Paraquat concentration. The three algae and their test parameters respond differently to Paraquat. Scenedesmus dimorphus was the most susceptible alga and the chlorophyll a was the most sensitive response parameter. On the other hand, the dry weight of the test algae was the most resistant parameter. It was observed that Paraquat has inhibitory effect on the primary producers.     

Antibiotic resistant coliform and faecal coliform bacteria in drinking water

Coliform and faccal coliform were isolated from drinking water samples obtained from tap water (TW) and storage tanks (ST) in Baghdad city. All isolates were identified and tested for their resistance to twelve antibiotics. Bacterial identification revealed that Ent. cloacae and Kl. pneumoniae were the predominant organisms from TW and ST water samples, respectively. Overall, 66% of the isolates from TW and 38% from ST were resistant to one or more of the drugs tested. Ampicillin, Carbenicillin, Cefalotin and Colistin resistance in particular were more frequent among bacterial isolates. The overall frequency of multiple antibiotic resistance among bacterial isolates in TW and ST samples were 47% and 33%, respectively. All bacterial strains isolated from drinking water were sensitive to Rifampicin. Results demonstrated the need for periodical bacteriological examination of drinking water and restriction in the use of antibiotics in this country.     

Influence of labelled food type on the accumulation and retention of 60Co by a freshwater fish,Cyprinus carpio L.

The study was carried out on 3 groups of 10 fish, each fed on a different natural labelled food. The preys selected were a crustacean (Gammarus pulex), a midge larvae (Chironomus sp.) and the soft tissues from a snail (Lymnaea stagnalis), which are usually consumed by carp in the natural environment. The contaminated food consumption by the fish resulted in a ⁶⁰Co maximum transfer factor ranging from 1.2 × 10^?2 to 5.1 × 10^?2 depending on the food type. These values, and the contamination kinetics indicate that the biomagnification of the radionuclides cannot occur, even over the long term. ⁶⁰Co depuration from fish was also influenced by the contaminated food type, previously ingested. The lower elimination rate correspond to the higher value of the transfer factor (Gammarus pulex) and inversely (Lymnaea stagnalis).     

Genetic diversity and structure of Munronia delavayi Franch. (Meliaceae), an endemic species in the dry-hot valley of Jinsha River,south-western China

Munronia delavayi Franch. (Meliaceae) is a vulnerable perennial species that is narrowly distributed and endemic to the dry-hot valley of the middle/lower Jinsha River. However, 12 hydropower stations are currently scheduled to be built in the middle and lower Jinsha River drainage and their distribution overlaps with the range of M. delavayi. The construction of these hydropower stations will cause flooding of the adjacent habitats that support M. delavayi and will change the local ecological environment, which may result in a new and dangerous situation for the survival of this species. Our aim was to evaluate the population structure and propose the most suitable conservation strategy for M. delavayi to support its adaptive potential. In this study, we collected 70 individuals from seven populations that covered most of the geographic range along the Jinsha River and investigated the population diversity, genetic structure and demographic history of this species by analyzing the variations in one mitochondrial marker (18sf-5sr), two non-coding chloroplast DNA regions (trnT-trnL, trnS-trnG), and one nuclear DNA marker (Gs687f-994r). As a result, three mitotypes, nine chlorotypes and six haplotypes with high genetic diversity (H _T = 0.580, 0.774 and 0.740) were detected based on mtDNA, cpDNA and nDNA and a strong genetic structure (F _ST = 0.855 and 0.545) was detected based on cpDNA and nDNA. Our study also indicated that habitat fragmentation and limited gene flow may result in the genetic differentiation of this species and that the population distributed in Qiaojia, Yongshan and Panzhihua should be proactively protected based on the conservation genetic analysis.