Gerty Gielen

Contamination and remediation of phthalic acid esters in agricultural soils in China: a review

Phthalic acid esters have been used as plasticizers in numerous products and classified as endocrine-disrupting compounds. As China is one of the largest consumers of phthalic acid esters, some human activities may lead to the accumulation of phthalic acid esters in soil and result in contamination. Therefore, it is necessary for us to understand the current contamination status and to identify appropriate remediation technologies. Here, we reviewed the potential sources, distribution, and contamination status of phthalic acid esters in soil. We then described the ecological effect and human risk of phthalic acid esters and finally provided technologies to remediate phthalic acid esters. We found that (1) the application of plastic agricultural films, municipal biosolids, agricultural chemicals, and wastewater irrigation have been identified as the main sources for phthalic acid ester contamination in agricultural soil; (2) the distribution of phthalic acid esters in soils is determined by factors such as anthropogenic behaviors, soil type, properties of phthalic acid esters, seasonal variation, etc.; (3) the concentrations of phthalic acid esters in soil in most regions of China are exceeding the recommended values of soil cleanup guidelines used by the US Environmental Protection Agency (US EPA), causing phthalic acid ester in soils to contaminate vegetables; (4) phthalic acid esters are toxic to soil microbes and enzymes; and (5) phthalic acid ester-contaminated soil can be remedied by degradation, phytoremediation, and adsorption.

Factors impacting on pharmaceutical leaching following sewage application to land.

Sewage effluent application to land is a treatment technology that requires appropriate consideration of various design factors. Soil type, level of sewage pre-treatment and irrigation rate were assessed for their influence on the success of soil treatment in removing pharmaceuticals remaining after conventional sewage treatment. A large scale experimental site was built to assess treatment performance in a realistic environment. Of the factors investigated, soil type had the biggest impact on treatment performance. In particular, carbamazepine was very efficiently removed (>99%) when irrigated onto a volcanic sandy loam soil. This was in contrast to irrigation onto a sandy soil where no carbamazepine removal occurred after irrigation. Differences were likely caused by the presence of allophane in the volcanic soil which is able to accumulate a high level of organic matter. Carbamazepine apparent adsorption distribution coefficients (K(d)) for both soils when irrigated with treated sewage effluent were determined as 25 L kg(-1) for the volcanic soil and 0.08 L kg(-1) for the sandy soil. Overall, a volcanic soil was reasonably efficient in removing carbamazepine while soil type was not a major factor for caffeine removal. Removal of caffeine, however, was more efficient when a partially treated rather than fully treated effluent was applied. Based on the investigated pharmaceuticals and given an appropriate design, effluent irrigation onto land, in conjunction with conventional sewage treatment may be considered a beneficial treatment for pharmaceutical removal.

Rice ( Oryza sativa L ) plantation affects the stability of biochar in paddy soil

Conversion of rice straw into biochar for soil amendment appears to be a promising method to increase long-term carbon sequestration and reduce greenhouse gas (GHG) emissions. The stability of biochar in paddy soil, which is the major determining factor of carbon sequestration effect, depends mainly on soil properties and plant functions. However, the influence of plants on biochar stability in paddy soil remains unclear. In this study, bulk and surface characteristics of the biochars incubated without rice plants were compared with those incubated with rice plants using a suite of analytical techniques. Results showed that although rice plants had no significant influence on the bulk characteristics and decomposition rates of the biochar, the surface oxidation of biochar particles was enhanced by rice plants. Using 13C labeling we observed that rice plants could significantly increase carbon incorporation from biochar into soil microbial biomass. About 0.047% of the carbon in biochar was incorporated into the rice plants during the whole rice growing cycle. These results inferred that root exudates and transportation of biochar particles into rice plants might decrease the stability of biochar in paddy soil. Impact of plants should be considered when predicting carbon sequestration potential of biochar in soil systems.

Influence of sewage and pharmaceuticals on soil microbial function

Although sewage effluent application to land is a common approach to recycle water and provide nutrients to plants, bioactive pharmaceuticals contained in sewage may change soil quality by affecting soil microbial communities. Establishing causal effects, however, is difficult, because trace levels of pharmaceuticals are confounded with other effluent constituents. Therefore, two originally similar soil microbial communities, one irrigated in situ with sewage effluent for 12 years and another nonirrigated, were exposed to high levels of acetaminophen, aspirin, carbamazepine, chlorpromazine, and tetracycline. The objectives of the current study were to determine the influence of high levels of pharmaceuticals on several soil microbial properties, the effect that prolonged effluent irrigation with ambient levels of pharmaceuticals had on soil microbial function, and how this effect would change in response to pharmaceutical exposure. Several pharmaceuticals, at high exposure levels, imposed stress on the soil microbial community as judged by increased CO(2) respiration, decreased biomass carbon, and altered substrate utilization affinities. Prolonged effluent irrigation, which altered the genetic fingerprint of the microbial community, also mitigated the response that exposure to pharmaceuticals had on the microbial community and enabled degradation of the antimicrobial salicylic acid after aspirin exposure. In conclusion, prolonged irrigation with sewage effluent containing pharmaceuticals at ambient levels influenced the microbial community so that they were able to better cope with sudden exposure to high levels of pharmaceuticals.

Ecological impacts of long-term application of biosolids to a radiata pine plantation.

Assessment of the ecological impact of applying biosolids is important for determining both the risks and benefits. This study investigated the impact on soil physical, chemical and biological properties, tree nutrition and growth of long-term biosolids applications to a radiata pine (Pinus radiata D. Don) plantation growing on a Sandy Raw Soil in New Zealand. Biosolids were applied to the trial site every 3 years from tree age 6 to 19 years at three application rates: 0 (Control), 300 (Standard) and 600 (High) kg nitrogen (N) ha(-1), equivalent to 0, 3 and 6 Mg ha(-1) of dry biosolids, respectively. Tree nutrition status and growth have been monitored annually. Soil samples were collected 13 years after the first biosolids application to assess the soil properties and functioning. Both the Standard and High biosolids treatments significantly increased soil (0-50 cm depth) total carbon (C), N, and phosphorus (P), Olsen P and cation exchange capacity (CEC), reduced soil pH, but had no significant effects on soil (0-20 cm depth) physical properties including bulk density, total porosity and unsaturated hydraulic conductivity. The High biosolids treatment also increased concentrations of soil total cadmium (Cd), chromium (Cr), copper (Cu) and lead (Pb) at 25-50 cm depth, but these concentrations were still considered very low for a soil. Ecotoxicological assessment showed no significant adverse effects of biosolids application on either the reproduction of springtails (Folsomia candida) or substrate utilisation ability of the soil microbial community, indicating no negative ecological impact of bisolids-derived heavy metals or triclosan. This study demonstrated that repeated application of biosolids to a plantation forest on a poor sandy soil could significantly improve soil fertility, tree nutrition and pine productivity. However, the long-term fate of biosolids-derived N, P and litter-retained heavy metals needs to be further monitored in the receiving environment.

Degradation of Tetracyclines in Pig Manure by Composting with Rice Straw.

A holistic approach was followed for utilizing tetracyclines (TCs)-contaminated pig manure, by composting this with rice straw in a greenhouse for CO2 fertilization and composted residue application. After composting, the composted residues can be applied to cropland as a supplemental source of synthetic fertilizers. The objective of this study was to determine the effect of pig manure-rice straw composting on the degradation of TCs in pig manure. The results showed that greenhouse composting significantly accelerated the degradation of TCs. Contents (150 mg·kg−1) of oxytetracycline (OTC), tetracycline (TC) and chlortetracycline (CTC) in the composting feedstock could be completely removed within 42 days for OTC and TC, and 14 days for CTC. However, in the control samples incubated at 25 °C in the dark, concentrations of OTC, TC and CTC only decreased 64.7%, 66.7% and 73.3%, respectively, after 49 days. The degradation rates of TCs in the composting feedstock were in the order of CTC > TC > OTC. During the composting process, CTC dissipated rapidly with the time required for 50% degradation (DT50) and 90% degradation (DT90) of 2.4 and 7.9 days, but OTC was more persistent with DT50 and DT90 values of 5.5 and 18.4 days. On the basis of the results obtained in this study, it could be concluded that pig manure-rice straw composting in a greenhouse can help to accelerate the degradation of TCs in pig manure and make composted residues safer for field application. This technology could be an acceptable practice for greenhouse farmers to utilize TCs-contaminated pig manure.

Assessing drivers of plantation forest productivity on eroded and non-eroded soils in hilly land, eastern North Island, New Zealand

BackgroundThe effect of soil erosion on New Zealand production forestry is not well known and there has been no research prior to our study into the relationship between soil nutrient status and planted forests growing in eroded soils in steeplands.MethodsThe impact of soil erosion by mass movement on forest productivity was investigated in a paired plot trial in a planted forest in a mainly hilly to steepland catchment (Pakuratahi) near Napier, eastern North Island, New Zealand. Tree growth and form were measured and soil properties analysed to compare productivity and productivity drivers in adjacent non-eroded and eroded plots.ResultsRegression analysis showed that the decreased soil total nitrogen, total carbon, total phosphorus, and soil organic matter content in eroded plots had a negative impact on tree volume, resulting in a 10% decrease in measured tree volume. Based on an assessment of log quality, trees in the eroded plots were forecast to produce 16% less volume from high-quality pruned logs (with associated reduction in revenue of around

Chemical properties of two soils irrigated with thermo-mechanical pulp mill effluent

4000 per hectare), than trees in non-eroded plots. The total recoverable volume (TRV), estimated (for a 25-year rotation) from the measured Pinus radiata D. Don trees growing on the eroded sites, was valued at

Effect of bamboo and rice straw biochars on the mobility and redistribution of heavy metals (Cd, Cu, Pb and Zn) in contaminated soil.

68,500, about 9% less than the estimated TRV from trees measured on non-eroded plots (

Effect of temperature on phosphorus sorption to sediments from shallow eutrophic lakes

76,000). Tree form and mean tree height in eroded and non-eroded plots were not significantly different.ConclusionsSoil erosion impacts production in planted forests. Afforestation of erodible land provides a valuable ecosystem service through land and soil stabilisation but this service is currently not reflected in the market prices for timber in New Zealand. Maintaining the productive capacity of erodible soils through practices such as fertilisation or continuous-cover forestry can add further costs to production forestry. To ensure that sustainable forest practices are carried out to protect the productivity of soils, financial incentives may be justified.