Assessing germination characteristics of Australian native plant species in metal/metalloid solution.

This study investigated tolerance of Australian native grass species Astrebla lappacea, Themeda australis, and Austrostipa scabra and a tree species Acacia harpophylla to different concentrations of arsenic As(V) (13.34-667.36 µM), Cu2+ (0.5-200 µM), Zn2+ (9-500 µM), Mn2+ (8-10240 µM) and Pb2+ (240-9600 µM) in single solutions in germination experiments. Metal/loid tolerance indicators used were maximum germination percentage (Gmax), mean germination time (MGT), radicle and shoot tolerance indexes (RTI & STI). Radicle tolerance index was the most sensitive indicator of metal tolerance in germinating seeds. All native species were highly tolerant to the metal/loids tested, however, they showed different metal toxicity thresholds and levels of tolerance based on RTI as a metal tolerance indicator during germination. Overall, all four species could be classified as metallophytes, confirming their current suitability for and established use in mine site rehabilitation. This work may also serve as a basis for future studies on metal/loid tolerance of other plant species during germination.

A new conceptual framework for plant responses to soil metals based on metal transporter kinetic parameters.

Based on a review of the literature, we have developed a functional conceptual framework of plant metal uptake in relation to plant available metal concentration in the soil. This framework applies to all plant parts and plant available metal levels in soils, and was validated using independent datasets from field surveys and the literature. This is the first framework based on metal transporter kinetic parameters and combining Michaelis-Menten (hyperbolic) kinetics facilitated by the High Affinity Transport System (HATS) for soil concentrations below the transition concentration between transport systems, and linear metal uptake facilitated by the Low Affinity Transport System (LATS) for higher soil available metal concentrations. We propose a new terminology for metal tolerant plants, i.e. metal tolerators, based on this framework. Depending on the plant available metal levels in the soil, tolerator responses to metals can be described best by either Vmax and Km for soil concentrations below the transition concentration between metal transport systems (HATS), or by the slope for greater soil concentrations (LATS). This conceptual framework may be a useful tool for selecting suitable metal tolerators for specific phytoremediation purposes, and may be also applied to non-metal elements or ions.

Metal-binding hydrogel particles alleviate soil toxicity and facilitate healthy plant establishment of the native metallophyte grass Astrebla lappacea in mine waste rock and tailings.

Soil contaminants are potentially a major threat to human and ecosystem health and sustainable production of food and energy where mineral processing wastes are discharged into the environment. In extreme conditions, metal concentrations in wastes often exceed even the metal tolerance thresholds of metallophytes (metal-tolerant plants) and sites remain barren with high risks of contaminant leaching and dispersion into the environment via erosion. A novel soil amendment based on micron-size thiol functional cross-linked acrylamide polymer hydrogel particles (X3) binds toxic soluble metals irreversibly and significantly reduces their concentrations in the soil solution to below the phytotoxicity thresholds. X3 mixed into the top 50mm of phytotoxic mine waste materials in pots in glasshouse conditions reduced total soluble concentrations of toxic contaminants by 90.3-98.7% in waste rock, and 88.6-96.4% in tailings immediately after application. After 61 days, quality of unamended bottom layer of X3-treated pots was also significantly improved in both wastes. Combination of X3 and metallophytes was more efficient at improving soil solution quality than X3 alone. Addition of X3 to substrates increased substrate water retention and water availability to plants by up to 108% and 98% for waste rock and tailings respectively. Soil quality improvement by X3 allowed successful early establishment of the native metallophyte grass Astrebla lappacea on both wastes where plants failed to establish otherwise.

Micron-size metal-binding hydrogel particles improve germination and radicle elongation of Australian metallophyte grasses in mine waste rock and tailings.

Metal contamination of landscapes as a result of mining and other industrial activities is a pervasive problem worldwide. Metal contaminated soils often lack effective vegetation cover and are prone to contaminant leaching and dispersion through erosion, leading to contamination of the environment. Metal-binding hydrogel particle amendments could ameliorate mine wastes prior to planting and enhance seedling emergence. In this study, micron-size thiol functional cross-linked acrylamide polymer hydrogel particles (X3) were synthesised and tested in laboratory-scale experiments on phytotoxic mine wastes to determine their capacity to: (i) increase substrate water holding capacity (WHC); (ii) reduce metal availability to plants to below the phytotoxicity threshold; and (iii) enhance germination characteristics and early radicle development of two Australian metallophyte grasses under limiting and non-limiting water conditions. Addition of X3 to mine wastes significantly increased their WHC and lowered toxic soluble metal concentrations in mine waste leachates. Germination percentages and radicle elongation of both grasses in wastes were significantly increased. Highest germination percentages and greater radicle development recorded in X3 amended wastes under water limited conditions suggests that X3 was able to ameliorate metal toxicity to radicles, and provide moisture, which improved the imbibition and consequent germination of the seeds.

Hand-assisted laparoscopic nephrectomy versus transperitoneal anterior approach in living donors for renal transplantation.

The objective of this study was to compare two surgical approaches for living donor nephrectomy: transperitoneal anterior approach and the hand-assisted laparoscopic nephrectomy. Between January 2001 and October 2003 we performed 63 kidney transplantations from living donors. The transperitoneal anterior approach was used in 36 cases and the hand-assisted laparoscopic nephrectomy in 27. Outcomes were compared in terms of hospital stay, postoperative analgesia, and graft quality. Mean hospital stay was 4.7 days in the transperitoneal anterior approach group and 3.7 days in the hand-assisted laparoscopic group (P < .005). Postoperative analgesia dosage was significantly lower in the hand-assisted laparoscopic group (P < .001). Surgical complications and graft quality were similar. We concluded that hand-assisted laparoscopic nephrectomy patients had shorter hospital stays and less pain in the postoperative period, with better cosmetic results and equivalent graft quality compared to transperitoneal anterior approach patients.

Renal artery aneurysm in hand-assisted laparoscopic donor nephrectomy: case report.

We report a living donor who underwent laparoscopic nephrectomy using a hand-assisted device (HALD). At preoperative arteriography the donor showed a renal artery aneurysm. The patient was a 37-year-old female, 166 cm height, white, weighing 87 kg, HLA identical to the recipient. HALD was indicated due to the better visualization of renal pedicle and greater security in an obese patient. Renal artery aneurysm is a rare condition, with many possible complications. The method proved to be adequate and safe for donor nephrectomy, despite a renal artery aneurysm.