Surface runoff losses of copper and zinc in sandy soils

Increased anthropogenic inputs of Cu and Zn in soils have caused considerable concern relative to their effect on water contamination. Copper and Zn contents in surface soil directly influence the movement of Cu and Zn. However, minimal information is available on runoff losses of Cu and Zn in agricultural soils, and soil-extractable Cu and Zn in relation to runoff water quality. Field experiments were conducted in 2001 to study dissolved Cu and Zn losses in runoff in Florida sandy soils under commercial citrus and vegetable production and the relationship between soil-extractable Cu and Zn forms and dissolved Cu and Zn concentrations in runoff water. Five extraction methods were compared for extracting soil available Cu and Zn. Concentrations of dissolved Cu and Zn in runoff were measured and runoff discharge was monitored. Mean dissolved Cu in field runoff water was significantly correlated with the extractable Cu obtained only by 0.01 mol L(-1) CaCl2, Mehlich 1, or DTPA-TEA methods. Dissolved Zn in runoff water was only significantly correlated with extractable Zn by 0.01 mol L(-1) CaCl2. The highest correlations to dissolved Cu in runoff were obtained when soil-available Cu was extracted by 0.01 mol L(-1) CaCl2. The results indicate that 0.01 mol L(-1) CaCl2-extractable Cu and Zn are the best soil indexes for predicting readily released Cu and Zn in the sandy soils. Both runoff discharge and 0.01 mol L(-1) CaCl2-extractable Cu and Zn levels had significant influences on Cu and Zn loads in surface runoff.     

Chemical extraction methods to assess bioavailable arsenic in soil and solid media

Soil ingestion by children is an important pathway in assessing public health risks associated with exposure to arsenic-contaminated soils. Soil chemical methods are available to extract various pools of soil arsenic, but their ability to measure bioavailable arsenic from soil ingestion is unknown. Arsenic extracted by five commonly used soil extractants was compared with bioavailable arsenic measured in vivo by immature swine (Sus scrofa) dosing trials. Fifteen contaminated soils that contained 233 to 17 500 mg kg(-1) arsenic were studied. Soil extractants were selected to dissolve surficially adsorbed and/or readily soluble arsenic (water, 1 M sodium acetate, 0.1 M Na2HPO4/0.1 M NaH2PO4) and arsenic in Fe and Mn oxide minerals (hydroxylamine hydrochloride, ammonium oxalate). The mean percent of total arsenic extracted was: ammonium oxalate (53.6%) > or = hydroxylamine hydrochloride (51.7%) > phosphate (10.5%), acetate (7.16%) > water (0.15%). The strongest relationship between arsenic determined by soil chemical extraction and in vivo bioavailable arsenic was found for hydroxylamine hydrochloride extractant (r = 0.88, significant at the 0.01 probability level). Comparison of the amount of arsenic extracted by soil methods with bioavailable arsenic showed the following trend: ammonium oxalate, hydroxylamine hydrochloride > in vivo > phosphate, acetate > water. The amount of arsenic dissolved in the stomach (potentially bioavailable) is between surficially adsorbed (extracted by phosphate or acetate) and surficially adsorbed + nonsurficial forms in Fe and Mn oxides (extracted by hydroxylamine hydrochloride or ammonium oxalate). Soil extraction methods that dissolve some of the amorphous Fe, such as hydroxylamine hydrochloride, can be designed to provide closer estimates of bioavailable arsenic.     

Impact of busy roads on breeding success in pied flycatchers Ficedula hypoleuca

The impact of dense traffic on the breeding success in pied flycatchers (Ficedula hypoleuca) was studied using roadside nest-boxes. Nest site selection and breeding success of flycatchers were observed in relation to the distance from the road. The number of occupied territories was no higher closer to the road than it was deeper inside the forest. The distance to the road had no effect on the laying date, clutch size, or brood size. However, nests closer to the road were more likely to fail at the chick stage. The number of broods that were closer to roads and were lost completely was significantly higher than those further away. As a consequence, the number of fledglings per breeding attempt decreased closer to roads. The nestlings typically died as older chicks when the parent birds were providing them with maximum quantities of food. A possible reason for the declining reproductive success was the traffic-related mortality of parent birds, as weather conditions were not especially adverse for raising healthy offspring.     

Compliance with regulations by "swim-with-dolphins" operations in Port Phillip Bay,Victoria, Australia

Managing the activities of commercial wildlife viewing tends to involve either restricting the number of industry participants and/or regulating the activities or industry participants. We report on operator compliance with regulations regarding humans swimming with free-ranging bottlenose dolphins ( Tursiops sp.) in Port Phillip Bay, Victoria, Australia. A total of 128 commercial dolphin-swim trips was studied between September 1998 and April 2000. Four permit conditions were investigated: approach type, swim time, time in proximity of dolphins, and presence of "fetal fold" calves. Results demonstrate noncompliance by operators to all of the four permit conditions studied. Compliance with temporal conditions was poorer than with other conditions. When conducting studies on the extent to which tourism affects cetaceans, investigators should consider whether tourist operations comply with existing regulations or guidelines.     

Codling moth males do not discriminate between pheromone and a pheromone/antagonist blend during upwind flight

Discrimination between conspecific and heterospecific signals is a key element in the evolution of pheromone-mediated communication in insects. Pheromone antagonists prevent heterospecific attraction. They are typically pheromone synergists in other species and enable specific communication in closely related species, using partly the same chemicals. In codling moth, Cydia pomonella, as in other moths, upwind flights to a pheromone/antagonist blend were slower and more convoluted than to pheromone. However, this deteriorated flight behaviour did not account for the strong decrease in male attraction. The pheromone/antagonist blend blocked instead the onset of upwind flight. This was corroborated by placing a separate source of pheromone close by, which restored male attraction. Males flying upwind did not discriminate between pheromone and the adjacent pheromone/antagonist blend, and landed on either source. This indicates differences in the neural regulation for initiating and maintaining a behavioural response to pheromone.     

The role of grazing by the lysianassid amphipod<Emphasis Type="Italic"> Orchomenella aahu</Emphasis> in dieback of the kelp<Emphasis Type="Italic"> Ecklonia radiata</Emphasis> in north-eastern New Zealand

The lysianassid amphipod Orchomenella aahu was associated with small-scale mass mortality of Ecklonia radiata, the dominant laminarian alga in north-eastern New Zealand. O. aahu burrowed into and hollowed out stipes with severe bleaching, accelerating mortality by 12–14 months. Meristoderm tissue of bleached plants contained approximately one-third of the phlorotannin content (~4% dry mass) present in unbleached, apparently healthier, sporophytes (~12% dry mass). Unbleached stages consistently lacked amphipod damage. O. aahu also colonised plants when non-lethal storm damage afforded entry into the cortical layers of the primary lamina, and ultimately the stipe. O. aahu typically consumed both medullary and cortical tissue of the stipes, forming networked brood-chambers within them, with increasing populations often reducing the plant to the holdfast. There was synchronised mortality across sites and between depths over spatial scales of metres. Following loss of the mature canopy, recruitment of E. radiata was generally within 2 months at most study sites where mortality had occurred.Communicated by G.F. Humphrey, Sydney     

Field testing of particulate matter continuous emission monitors at the DOE Oak Ridge TSCA incinerator. Toxic Substances Control Act

A field study to evaluate the performance of three commercially available particulate matter (PM) continuous emission monitors (CEMs) was conducted in 1999-2000 at the US Department of Energy (DOE) Toxic Substances Control Act (TSCA) Incinerator. This study offers unique features that are believed to enhance the collective US experience with PM CEMs. The TSCA Incinerator is permitted to treat PCB-contaminated RCRA hazardous low-level radioactive wastes. The air pollution control system utilizes MACT control technology and is comprised of a rapid quench, venturi scrubber, packed bed scrubber, and two ionizing wet scrubbers in series, which create a saturated flue gas that must be conditioned by the CEMs prior to measurement. The incinerator routinely treats a wide variety of wastes including high and low BTU organic liquids, aqueous, and solid wastes. The various possible combinations for treating liquid and solid wastes may present a challenge in establishing a single, acceptable correlation relationship for individual CEMs. The effect of low-level radioactive material present in the waste is a unique site-specific factor not evaluated in previous tests. The three systems chosen for evaluation were two beta gauge devices and a light scattering device. The performance of the CEMs was evaluated using the requirements in draft Environmental Protection Agency (EPA) Performance Specification 11 (PS11) and Procedure 2. The results of Reference Method 5i stack tests for establishing statistical correlations between the reference method data and the CEMs responses are discussed.     

Impact of cadmium on food utilization of the Indian major carp,Catla catla (Ham)

Catla catla, under the sublethal stress of cadmium exhibited depletion in food utilization parameters and it was concentration dependent. Heavy metal intoxication was found to exhibit reduction in biomass.     

Human impacts on the stream-groundwater exchange zone

Active exchanges of water and dissolved material between the stream and groundwater in many porous sand- and gravel-bed rivers create a dynamic ecotone called the hyporheic zone. Because it lies between two heavily exploited freshwater resources—rivers and groundwater—the hyporheic zone is vulnerable to impacts coming to it through both of these habitats. This review focuses on the direct and indirect effects of human activity on ecosystem functions of the hyporheic zone. River regulation, mining, agriculture, urban, and industrial activities all have the potential to impair interstitial bacterial and invertebrate biota and disrupt the hydrological connections between the hyporheic zone and stream, groundwater, riparian, and floodplain ecosystems. Until recently, our scientific ignorance of hyporheic processes has perhaps excused the inclusion of this ecotone in river management policy. However, this no longer is the case as we become increasingly aware of the central role that the hyporheic zone plays in the maintenance of water quality and as a habitat and refuge for fauna. To fully understand the impacts of human activity on the hyporheic zone, river managers need to work with scientists to conduct long-term studies over large stretches of river. River rehabilitation and protection strategies need to prevent the degradation of linkages between the hyporheic zone and surrounding habitats while ensuring that it remains isolated from toxicants. Strategies that prevent anthropogenic restriction of exchanges may include the periodic release of environmental flows to flush silt and reoxygenate sediments, maintenance of riparian buffers, effective land use practices, and suitable groundwater and surface water extraction policies.     

Relationships between bacterial tolerance levels and forms of copper and zinc in soils

The effects of various fractions of copper (Cu) and zinc (Zn) on soil bacteria were evaluated by the heavy metal tolerance level of the bacterial community (IC50) in soil samples collected near a mine. The IC50 values had no relationship with the total concentrations of Zn and Cu in the soils, but were weakly correlated with the 0.05 M CaCl2-extractable form of each metal in the soils (Cu: R2 = 0.670, p < 0.01; Zn: R2 = 0.453, p < 0.05). It was found that the IC50 correlated strongly with the total concentration of each metal in the extracts from water-saturated soil samples, described below as "soil solution" (Cu: R2 = 0.789, p < 0.01; Zn: R2 = 0.617, p < 0.01). The speciation of these metals in the soil solutions was estimated using an equilibrium thermodynamic computer model, SOILCHEM. Simulated free Cu ion ranged from 18 to 98% of total Cu, and organic complexes of Cu ranged from < 1 to 56%. In all samples, Zn existing as the free ion was estimated to be more than 80% of total Zn in the soil solutions. The IC50 values were also correlated with the estimated free metal ion activities, but with slightly lower correlation coefficients than found for total concentration in the soil solutions (Cu: R2 = 0.735, p < 0.01; Zn: R2 = 0.610, p < 0.01). The results suggest that not only high metal ion activities, but also total dissolved metal concentrations in soil solutions may affect the bacterial community.