Environmental aspects of storm runoff discharge from a timber port, Tauranga, New Zealand

An investigation was undertaken into storm runoff water quantity and quality, contaminant input to the receiving tidal waters from the Mt. Maunganui wharf, accumulation of potentially toxic resin acids in adjacent sediments, and the dilution of the wharf runoff in the receiving tidal waters, in order to assess the possible adverse environmental impact associated with the log operation at the Port of Tauranga Ltd. Based upon field data and rainfall records, about a half of the annual precipitation over the log handling areas is converted to surface runoff (117,000 m³a⁻¹). Annual runoff volume per hectare of wharf surface is estimated as 7,500 m³ha⁻¹a⁻¹ for the sealed area and 3,700 m³ha⁻¹a⁻¹ for the gravelled area. The optical quality of the wharf runoff is degraded due to addition of bark and soil particles. The black disk visual clarity (0.01-0.02 m) was only 0.5-1.0% of that in the receiving tidal waters. The wharf runoff appears very dark gray to yellowish brown in apparent colour (10YR1/3 to 10YR5/6 Munsell colour chart) and has a soluble yellow substance concentration of about 25 m⁻¹. Power relationships between the traditionally used parameters, for example, suspended solids and turbidity, were identified. The wharf surface pavement types had a significant influence on visual clarity, but little influence on yellow substance concentration. The potentially toxic resin acids in the wharf runoff have been determined with SIM GC-MS. The average total resin acid level (1,030 ppb) is comparable to that of 1,000 ppb reported at which acute toxicity is likely to be exhibited. A relationship of resin acids against volatile suspended solids was established. Tests undertaken suggest that conventional treatment methods of natural sedimentation and flocculation-sedimentation are able to remove the resin acids effectively. The levels of biological oxygen demand (BOD), total phosphorus and nitrogen in the wharf runoff are considerably higher than those of common urban runoff. However, the wharf runoff contributes little nitrate nitrogen and oil and grease to the receiving environment. About 87,500 kg of suspended solids, 43,000 kg of volatile suspended solids, 14,200 kg of BOD, 500 kg of phosphorus, and 103 kg of resin acids are discharged to the Tauranga Harbour annually from runoff from the Mt. Maunganui wharf. Analyses show that the impact on adjacent sediments from the storm runoff is limited to a distance of about 100 m from the discharge points and the resin acid levels in the sediments within this distance are not significantly higher compared to that of the storm runoff. The net resin acid accumulation rate in the shipping channel (Stella Passage) beside the log handling areas was estimated to be in the range of 300 to 370 ppb per year. Based on field investigation and numerical simulations, the findings on dispersion and dilution of the wharf runoff in the receiving tidal waters are as follows: (i) the sea water around Stella Passage experiences an obvious natural salinity stratification, the extent of which depends greatly on the weather conditions; (ii) the wind drag stress and the pressure gradient caused by the addition of runoff had the greatest influence on the plume dynamics during the flood tide. The plumes basically remain within the top 2-3 m of the water column under different winds; (iii) the plume is unlikely to advect to the Whareroa Marae under strong (30-40 knots) easterly or northeasterly winds for a storm with a 5-year return period. However, there is an obvious influence on the Whareroa Marae under 30- 40 knot northerly winds; and (iv) the short duration and restricted region of the low dilution pulse of effluent around slack water may explain why there has been no reports of acute toxic events. Sealing the gravel covered wharf area, improving the sweeping efficiency, and extending the present outfalls to the sea floor might be potential options for mitigating the environmental impact associated with discharge of the wharf runoff

Multidrug-resistant Pseudomonas aeruginosa is predisposed to lasR mutation through up-regulated activity of efflux pumps in non-cystic fibrosis bronchiectasis patients

BackgroundMultidrug-resistant (MDR) Pseudomonas aeruginosa is a frequent opportunistic pathogen that causes significant mortality in patients with non-cystic fibrosis bronchiectasis (NCFB). Although the quorum sensing (QS) system is a potential target for treatment, lasR mutants that present with a QS-deficient phenotype have been frequently reported among clinical P. aeruginosa isolates. We aimed to investigate whether antibiotic resistance would select for lasR mutants during chronic P. aeruginosa lung infection and determine the mechanism underlying the phenomenon.MethodsWe prospectively evaluated episodes of chronic P. aeruginosa lung infections in NCFB patients over a 2-year period at two centers of our institution. QS phenotypic assessments and whole-genome sequencing (WGS) of P. aeruginosa isolates were performed. Evolution experiments were conducted to confirm the emergence of lasR mutants in clinical MDR P. aeruginosa cultures.ResultsWe analyzed episodes of P. aeruginosa infection among 97 NCFB patients and found only prior carbapenem exposure independently predictive of the isolation of MDR P. aeruginosa strains. Compared with non-MDR isolates, MDR isolates presented significantly QS-deficient phenotypes, which could not be complemented by the exogenous addition of 3OC12-HSL. The paired isolates showed that their QS-phenotype deficiency occurred after MDR was developed. Whole-genome sequencing analysis revealed that lasR nonsynonymous mutations were significantly more frequent in MDR isolates, and positive correlations of mutation frequencies were observed between genes of lasR and negative-efflux-pump regulators (nalC and mexZ). The addition of the efflux pump inhibitor PAβN could not only promote QS phenotypes of these MDR isolates but also delay the early emergence of lasR mutants in evolution experiments.ConclusionsOur data indicated that MDR P. aeruginosa was predisposed to lasR mutation through the upregulated activity of efflux pumps. These findings suggest that anti-QS therapy combined with efflux pump inhibitors might be a potential strategy for NCFB patients in the challenge of MDR P. aeruginosa infections

Baiji genomes reveal low genetic variability and new insights into secondary aquatic adaptations

The baiji, or Yangtze River dolphin (Lipotes vexillifer), is a flagship species for the conservation of aquatic animals and ecosystems in the Yangtze River of China; however, this species has now been recognized as functionally extinct. Here we report a high-quality draft genome and three re-sequenced genomes of L. vexillifer using Illumina short-read sequencing technology. Comparative genomic analyses reveal that cetaceans have a slow molecular clock and molecular adaptations to their aquatic lifestyle. We also find a significantly lower number of heterozygous single nucleotide polymorphisms in the baiji compared to all other mammalian genomes reported thus far. A reconstruction of the demographic history of the baiji indicates that a bottleneck occurred near the end of the last deglaciation, a time coinciding with a rapid decrease in temperature and the rise of eustatic sea level

Plasma Depolymerization of Chitosan in the Presence of Hydrogen Peroxide

Abstract: The depolymerization of chitosan by plasma in the presence of hydrogen peroxide (H2O2) was investigated. The efficiency of the depolymerization was demonstrated by means of determination of viscosity-average molecular weight and gel permeation chromatography (GPC). The structure of the depolymerized chitosan was characterized by Fourier-transform infrared spectra (FT-IR), ultraviolet spectra (UV) and X-ray diffraction (XRD). The results showed that chitosan can be effectively degradated by plasma in the presence of H2O2. The chemical structure of the depolymerized chitosan was not obviously modified. The combined plasma/H2O2 method is significantly efficient for scale-up manufacturing of low molecular weight chitosan

Advances on Corrosion-Resistant Concrete for Sewers

This chapter discusses the advances on corrosion-resistant concrete for sewers from the viewpoint of binder materials, aggregates and additives. For binder materials, alkaline activated materials (AAM) and calcium aluminate cement (CAC) are not included, as they are presented in Chaps. 10 and 11. The performance of several other binder materials, including sulfate resistant cement, the use of supplementary cementitious materials, polymer modified cements, and sulfur binder, under (sulfuric) acidic conditions and sewers conditions are summarized. The possible benefits and limitations of each binder material are critically discussed. The importance of aggregate in corrosion resistant concrete is highlighted primarily due to the high-volume fraction (e.g. \u3e 60%). Aggregates studied include siliceous and calcareous aggregates, crushed CAC clicker aggregate and polyethylene terephthalate (PET) aggregate. Additives may play a significant role in improving the corrosion resistance of concrete. The effects and limitations of using antimicrobial agents and novel corrosion-resistant bioconcrete are also discussed

Antarctic Surface Ice Velocity Retrieval from MODIS-Based Mosaic of Antarctica (MOA)

The velocity of ice flow in the Antarctic is a crucial factor to determine ice discharge and thus future sea level rise. Feature tracking has been widely used in optical and radar imagery with fine resolution to retrieve flow parameters, although the primitive result may be contaminated by noise. In this paper, we present a series of modified post-processing steps, such as SNR thresholding by residual, complex Butterworth filters, and triple standard deviation truncation, to improve the performance of primitive results, and apply it to MODIS-based Mosaic of Antarctica (MOA) datasets. The final velocity field result displays the general flow pattern of the peripheral Antarctic. Seventy-eight out of 97 streamlines starting from seed points are smooth and continuous. The RMSE with 178 manually selected tie points is within 60 m·a−1. The systematic comparison with Making Earth System Data Records for Use in Research Environments (MEaSUREs) datasets in seven drainages shows that the results regarding high magnitude and large-scale ice shelf are highly reliable; absolute mean and median difference are less than 18 m·a−1, while the result of localized drainage suffered from too much tracking error. The relative differences from manually selected and random points are controlled within 8% when speed is beyond 500 m·a−1, but bias and uncertainty are pronounced when speed is lower than that. The result through our accuracy control strategy highlights that coarse remote-sensed images such as Moderate Resolution Imaging Spectrophotometer (MODIS) can still offer the capability for comprehensive and long-term continental ice sheet surface velocity mapping

Large-Aperture Real-Time Compensated Collimating Wavefront Error Detection Method

This paper proposes a real-time compensated pentaprism scanning wavefront detection method to achieve real-time compensation for scanning errors occurring during prism movement along a guide rail. The method is based on existing pentaprism scanning wavefront detection technology and it is realized by applying self-collimation-based three-dimensional error compensation. Using theoretical and data analyses of a detection experiment, the reliability of the optimized pentaprism scanning detection method is verified, thus effectively ensuring the reasonable estimation of the interferometry surface measurement uncertainty