Recycled concrete aggregates (RCA) are a widely used recycled building material. RCA materials have many uses such as a road base or backfilling trenches. Our study investigated the potential water-contamination risks of water exposed to RCA materials. We recirculated water for 60min through four different treatments. Two treatments were a PVC gutter filled with different size grades of RCA material (20mm and 45mm), the third treatment was a clean PVC gutter and the fourth and final treatment was an unused concrete water pipe. Results showed that RCA material exposed to water released a suite of contaminants that could be ecologically hazardous to aquatic species. RCA leached metals over the 60-min recirculation (aluminium, arsenic, barium, chromium, lead, manganese, molybdenum, titanium, lithium and strontium). Water exposed to RCA material exceeded aquatic ecosystem guidelines for aluminium by 50 times and lead by up to 12 times. RCA materials increased pH by up to 4.35 pH units and electrical conductivity (EC) by up to 11 times the starting EC (mean 27.9 µs cm–1). We suggest that RCA materials need to be used with caution in settings that could be exposed to water and flow to waterways of conservation value.

Throughout the world, concrete is used extensively in urban development. Due to its convenience and durability, most paths, carparks, dams, and even drainage systems are constructed from concrete. However, recent studies indicate that concrete significantly affects water chemistry and that concrete infrastructure may have a major effect on the chemistry of nearby streams. This is particularly relevant for sensitive waterways such as those in the Blue Mountains region in Sydney, Australia. This study aimed to investigate the chemical changes associated with concrete exposure by conducting water recirculation experiments. Water collected from a pristine Blue Mountains Upland Swamp (BMUS) was mildly acidic (average pH of 4.65) with a low electrical conductivity (EC of 57.99μS/cm) before concrete exposure. After the water was continuously recirculated through a concrete pipe for 120 minutes, pH and EC increased significantly, to 7.87 and 137.72μS/cm respectively. Significant increases in concentrations of ions such as bicarbonate, calcium and sulphate were also observed. Results verify previous findings that concrete significantly and rapidly affects water chemistry and support the hypothesis that concrete plays a significant role in the chemical differences seen between urban and non-urban waterways. Results also indicate that concrete is a source of metals such as copper, chromium, strontium, titanium, and lithium. Furthermore, this study aimed to investigate whether these metals have the potential to affect ecosystems more broadly. Salix babylonica, a common invasive plant species in the Sydney region, was grown in pristine BMUS water and concrete-recirculated BMUS water. Plants grown in concrete-recirculated water had significantly greater new growth and the tissue of these plants was significantly higher in concentrations of barium, copper, lead, manganese, and strontium. As metals in the water appear to be moving into plant tissue, results suggest that these metals are bioavailable and thus have the potential to move into higher trophic levels and the ecosystem more generally. Further investigation is required to determine how far these metals may permeate the food chain.

Much of the literature on wombat diet is concerned only with the broad categories of consumed matter, and there is little about their specific nutritional requirements despite diet playing a major role in health. This study gathered information by surveying zoological parks and wildlife carers about current feeding regime, diet and the prevalence of nutritional or dental disorders of wombats held in captivity, with the aim of improving the diets of captive wombats, thus their health and welfare outcomes. Data on the composition, variation and basis of diets for 31 bare-nosed or common wombats (Vombatus ursinus) and 19 southern hairy-nosed wombats (Lasiorhinus latifrons) were gathered from 13 facilities. The nutritional values of diets fed to wombats in captivity were calculated and compared with known dietary requirements for bare-nosed wombats. Results demonstrate that the current diet of wombats held in captivity often consists of a high portion of fruits, vegetables and livestock feed, with the fruit and vegetable portions providing higher levels of simple carbohydrates and starch compared with natural grass diets. Generally, the facilities are providing diets that are exceeding reported maintenance energy and nitrogen requirements. Due to a lack of details provided regarding quantity and species of grasses fed, we could not provide an accurate ration calculation for the proportion of grasses in the diets. Some of the health concerns noted included insufficient weight gain, endoparasites, malocclusion and insufficient tooth wear. Further research is required to assess the requirements of reproductive, lactating and juvenile wombats; however, it is clear that wombats in captivity need to be fed larger volumes and varieties of grasses, forbs and sedges than they are currently being fed to maintain good health.

Riparian vegetation along urban streams and wetlands is frequently dominated by invasive weeds. Elevated nitrogen and phosphorous in urban waters and soils are well-known to encourage invasive urban weeds, but this research demonstrates that other urban geochemical contaminants may also be influential. Previous studies have demonstrated that the dissolution of urban concrete is a poorly recognised source of modified water and soil geochemistry, which may enhance the growth of some invasive weeds. This study investigated the relationship between urban water quality and the growth of an invasive urban riparian weed, willow (Salix spp.) to examine the contribution of concrete materials. The study used water from a wetland in the Greater Blue Mountains World Heritage Area. These wetlands have a unique biodiversity but are fragile and susceptible to degradation from human activity. Many are in urban catchments and are frequently dominated by invasive weeds, including Salix spp. In this study, willow cuttings were grown in a laboratory using four water treatments: pristine, urban, and pristine water exposed to two different concrete materials. The urban and concrete water treatments had higher pH, salinity, calcium, potassium, and higher concentration of several metals and were associated with increased growth of Salix spp. We suggest that the modification of urban water and riparian soil chemistry by urban concrete materials may contribute to the success of invasive species in urban wetlands and riparian zones. Some metals (barium, strontium) were present in urban water and in pristine water exposed to concrete and bioaccumulated in plant tissue.