Biochar and vegetation effects on discharge water quality from organic-substrate green roofs

Green roofs have been increasingly used to improve stormwater management, but poor vegetation performance on roof systems, varying with vegetation type, can degrade discharge quality. Biochar has been suggested as an effective substrate additive for green roofs to improve plant performance and discharge quality. However, research on the effects of biochar and vegetation on discharge quality in the long term is lacking and the underlying mechanisms involved are unclear. We examined the effects of biochar amendment and vegetation on discharge quality on organic-substrate green roofs with pre-grown sedum mats and direct-seeded native plants for three years and investigated the key factors influencing discharge quality. Sedum mats reduced the leaching of nutrients and particulate matter by 6-64% relative to native plants, largely due to the higher initial vegetation cover of the former. Biochar addition to sedum mat green roofs resulted in the best integrated water quality due to enhanced plant cover and sorption effects. Structural equation modeling revealed that nutrient leaching was primarily influenced by rainfall depth, time, vegetation cover, and substrate pH. Although biochar-amended sedum mats showed better discharge quality from organic-substrate green roofs, additional ecosystem services may be provided by native plants, suggesting future research to optimize plant composition and cover and biochar properties for sustainable green roofs.

Year-round monitoring of chloride releases from three zero-exfiltration permeable pavements and an asphalt parking lot

Winter deicers, though essential for maintaining safe pavement conditions in winter, increase chloride (Cl^-) concentrations in receiving water bodies above recommended environmental guidelines. Zero-exfiltration or lined permeable pavement is an important technological innovation for controlling particulate-bound pollutants at the source. As stormwater does not infiltrate into the ground, soluble pollutants like Cl^- are ultimately discharged into receiving water bodies. Our aim was to examine Cl^- concentrations in effluents from three zero-exfiltration permeable pavement cells (Permeable Interlocking Concrete Pavement (PICP), Pervious Concrete (PC), Porous Asphalt (PA)) and compare them with runoff from a Conventional Asphalt (ASH) cell. The study conducted at a parking lot in St. Catharines, Ontario, Canada, from January 2016 to May 2017 observed that the permeable pavements provided only temporary attenuation of Cl^- during winter but exhibited a quick release during spring melt. Cl^- concentrations and loadings were different for each permeable pavement system in terms of timing and magnitude. Cl^- concentration in ASH runoff frequently had very high spikes (21,780 mg/L); however, the median winter Cl^- concentration in ASH runoff was lower than Cl^- levels in the permeable pavements' effluents and later declined drastically after spring melt, but in few instances, was above the chronic water quality guideline (120 mg/L). The average event mean concentration (EMC) of Cl^- was 1600 and 120 mg/L in the permeable pavements' effluents during salting and non-salting season, respectively. In one year, each permeable pavement system released approximately 67-81 kg of Cl^- with significant differences being observed in Cl^- loads between the 2016 and 2017 seasons. Therefore, a multi-year data collection and monitoring plan captured the variability in winter conditions. The study provided insights into the behaviour, retention and release of Cl^- from traditional and permeable hardscape surfaces and possible avenues for Cl^- attenuation, source control and aquatic habitat conservation.

Community response to a sustainable restoration plan for a superfund site

Large-scale copper (Cu) mining activities in Michigan's Upper Peninsula produced millions of metric tons of mining wastes also known as stamp sands. The stamp sands containing high concentrations of Cu were disposed of into several lakes connected to the Lake Superior. Eventually, as aquatic organisms in these lakes started to exhibit toxicity symptoms, the stamp sands were dredged and discarded on the lake shores. Consequently, these areas turned into degraded, marginal lands and were collectively classified as a Torch Lake Superfund site by the US EPA. Due to the lack of vegetative cover, the Cu-rich stamp sands eroded into the lakes, affecting the aquatic life. To alleviate this issue, a sustainable restoration plan (SRP) was developed and tested in a greenhouse environment prior to field implementation. Cold-tolerant oilseed crops, camelina (Camelina sativa) and field pennycress (Thlaspi arvense), were grown on compost-fertilized stamp sands, which reduced soil erosion by acting as a vegetative cap. Oilseed plants produced normal yield, demonstrating their potential utilization as biofuel feedstock. Prior to implementing the SRP in field-scale in the Torch Lake Superfund site, a public opinion survey of the local community was conducted to understand the views of residents. Door-to-door survey was performed in July-August 2015, which yielded a response rate of 68.1%. Results showed that residents were generally concerned with stamp sand erosion into the Torch Lake and were overwhelmingly supportive of the SRP, which would not only provide environmental benefits but could boost the local economy via biofuel production. To gauge the general environmental awareness of the respondents, the survey included questions on climate change. Most of the respondents acknowledged that climate change is real and anthropogenically mediated. Having college education and a relatively high annual household income showed a positive and significant correlation with climate change awareness.

Effects of biosolids and compost amendment on chemistry of soils contaminated with copper from mining activities

Several million metric tons of mining wastes, called stamp sands, were generated in the Upper Peninsula of Michigan during extensive copper (Cu) mining activities in the past. These materials, containing large amounts of Cu, were discharged into various offshoots of Lake Superior. Due to evidences of Cu toxicity on aquatic organisms, in due course, the materials were dredged and dumped on lake shores, thus converting these areas into vast, fallow lands. Erosion of these Cu-contaminated stamp sands back to the lakes is severely affecting aquatic life. A lack of uniform vegetation cover on stamp sands is facilitating this erosion. Understanding the fact that unless the stamp sands are fertilized to the point of sustaining vegetation growth, the problem with erosion and water quality degradation will continue, amending the stamp sands with locally available biosolids and composts, was considered. The purpose of the reported study was to assess potential effects of such organic fertilizer amendments on soil quality. As the first step of a combined laboratory and greenhouse study, a 2-month-long incubation experiment was performed to investigate the effects of biosolids and compost addition on the soil nutrient profile of stamp sands and organic matter content. Results showed that both biosolids and compost amendments resulted in significant increase in nitrogen and phosphorus concentrations and organic matter contents of stamp sands. Sequential extraction data demonstrated that Cu was mostly present as bound forms in stamp sands, and there was no significant increase in the plant available fraction of Cu because of fertilizer application.

Effect of cadmium-contaminated soils on dry matter yield and mineral composition of raya (Brassica juncea) and spinach (Spinacia oleracea)

Raya (Brassica juncea) and spinach (Spinacia oleracea), grown as leafy vegetables, are known to accumulate large amounts of heavy metals in their shoots and roots because of their high biomass and root proliferation. In a pot experiment, a sandy loam soil was polluted with cadmium (Cd) at rates of 0, 5, 10, 20, 40 and 80 mg kg−1 soil to assess the accumulation pattern and its effect on the dry matter yield and mineral composition of these vegetables. There was a decrease in dry matter yield due to the phytotoxic effect of Cd. The rate of Cd application at which a significant decline in root and shoot dry matter yield occurred varied depending on the vegetable. It was 20 mg Cd kg−1 soil in the shoots for both crops. However, the roots of raya were found to be more tolerant of Cd toxicity than those of spinach, as is evident from the fact that a significant decline in dry matter yield occurred at 20 and 10 mg Cd kg−1 soil, respectively. Since no visual toxic symptoms were observed on the leaves of raya in any of the treatments, it is clear that the metal may accumulate in this vegetable without visual evidence of its presence. However, at application levels beyond 40 mg kg−1 soil, toxicity symptoms, in the form of interveinal chlorosis of the leaf lamina followed by necrosis and leaf rolling, were clearly evident in the case of spinach. The reduction in root and shoot growth corresponded with the amounts of extractable Cd in the soils. The total content of Cd in the crops increased gradually as the rate of applied Cd rose and the roots accumulated much higher amounts than the shoots. The relationship of Cd with Zn and Fe was synergistic in both roots and shoots at the lower rates, but antagonistic at higher Cd application rates for both the crops, while in the case of Mn and Cu, the relationship was negative and antagonistic.

Atypical anaphylactic reaction to Patent Blue during sentinel lymph node biopsy for breast cancer

INTRODUCTION

We present an unusual case of severe anaphylaxis to Patent Blue dye with atypical clinical features during sentinel lymph node biopsy (SLNB). The medical personnel involved with sentinel node biopsies should be alert, and familiar with this unusual entity. We also present current data from the literature.

CASE REPORT

During a wide local excision for primary breast cancer and SLNB, and early during the operation, the patient became severely tachycardic and hypotensive without any signs of urticaria, rash, oedema, or bronchospasm. Resuscitation required the addition of noradrenaline infusion followed by an overnight admission to the intensive care unit. Raised serum tryptase levels supported the diagnosis of anaphylactic shock while skin tests showed a severe reaction to Patent Blue dye.

CONCLUSIONS

Severe, life-threatening anaphylaxis to Patent Blue dye may present without obvious previous exposure to the dye and without the cardinal signs of oedema, urticaria and bronchospasm making the diagnosis and management of such cases challenging. Correct diagnosis and identification of the causative factor is important and requires a specific set of laboratory tests that are not commonly requested in every-day medical practice. It is not clear from the literature whether the condition is common enough to justify pre-operative prophylactic or diagnostic measures.