Although many previous studies have reported the soil pH and organic matter to be the most critical factors that affect the transfer of Cd in soil-crop systems in temperate zones, the behavior of Cd transfer is different in the Pearl River Delta (PRD), which is located in a subtropical zone with different climate and soil conditions. Therefore, we must determine the critical environmental factors that influence the transfer of Cd in the soil-vegetable system in the PRD region. Such knowledge can improve the safety of vegetables. In this study, the soil geochemical properties are investigated to explore the key soil factors that control the uptake of Cd by flowering cabbage, a popular leaf vegetable in China, from soils in the PRD region. The Cd contents in vegetables were most positively correlated to soil oxalate-Cd (p < 0.01), which indicates that amorphous Cd is the most available form for uptake into the cabbages. With the characteristics of rich in Fe oxide and Al oxide in the PRD soils, soil Fe and Al oxides were found to be the most relevant to the transfer factors of Cd from the soils to the cabbages. Soil secondary minerals are the key factor that affects the transfer of Cd, thereby influencing the migration and fate of Cd in soil-cabbage systems, with DCB-Fe significantly decreasing the Cd accumulation in cabbages. Additionally, models were developed to predict the enrichment of Cd in flowering cabbages, in which oxalate-Cd, DCB-Fe, and NaOAc-Al in soils were determined to be the most important factors that affect the Cd enrichment in flowering cabbages. In this study, we determine the important role of soil secondary minerals in affecting the transfer of Cd in soil-cabbage systems in the PRD. These observations are important to evaluate the accumulation of Cd in vegetables in subtropical zones.

Persistent pollutants such as organochlorine compounds (OCs) have been highlighted as a cause of population decline in avian predators. Understanding patterns of OCs contamination can be crucial for the conservation of affected species, yet little is known on these threats to African raptors. Here we report on OC concentrations in an endangered predator endemic to southern Africa, the Black Harrier Circus maurus. Blood samples were collected in 2012–2014 from wild nestlings (n = 90) and adults (n = 23) in south-western South Africa, where agriculture and urbanization have developed rapidly since the 1950s. Polychlorinated biphenyl (ΣPCB) and dichlorodiphenyltrichloroethane (ΣDDT, for p,p’-DDT + p,p’-DDE) were detected in 79% and 84% of sampled individuals, respectively, with varying concentrations among demographic groups: nestlings had significantly higher ΣPCB and p,p’-DDT concentrations than adults, while adults had higher levels of p,p’-DDE than nestlings. Levels of ΣPCB significantly increased with an index of electric transformer density, a measure of the number and power of electric transformers around active nests. We propose this index as a useful tool for assessing ΣPCB exposure risk in other wildlife. Levels of p,p’-DDE significantly increased with the proportion of wetlands within the breeding territory, and also with the proportion of bird biomass in the diet. No association was found between OC levels and the protected area status of nesting sites. Physiological effects of contaminants were also manifest in increased white blood cell counts with higher p,p’-DDT levels. Heterophil to lymphocyte ratio increased with higher ΣPCB levels, suggesting increased physiological stress and reduced immunity in contaminated individuals. Our results suggest that OCs are still a current cause of concern for endangered Black Harriers, as well as other sympatric predators.

Passive air samplers (PAS) were evaluated for measuring indoor concentrations of phthalates, novel brominated flame retardants (N-BFRs), polybrominated diphenyl ethers (PBDEs), and organophosphate esters (OPEs). Sampling rates were obtained from a 50-day calibration study for two newly introduced PAS, polydimethylsiloxane (PDMS) or silicone rubber PAS (one with and one without a coating of styrene divinyl benzene co-polymer, XAD) and the commonly used polyurethane foam (PUF) PAS. Average sampling rates normalized to PAS surface area were 1.5 ± 1.1 m³ day⁻¹ dm⁻² for both unsheltered PDMS and XAD-PDMS, and 0.90 m³ ± 0.6 day⁻¹dm⁻² for partially sheltered PUF. These values were derived based on the compound-specific sampling rates measured here and in the literature for the PAS tested, to reasonably account for site-specific variability of sampling rates.PDMS and PUF were co-deployed for three weeks in 51 homes located in Ottawa and Toronto, Canada. Duplicate PUF and PDMS samplers gave concentrations within 10% of each other. PDMS and PUF-derived air concentrations were not statistically different for gas-phase compounds. PUF had a higher detection of particle-phase compounds such as some OPEs. Phthalate and OPE air concentrations were ∼100 times higher than those of N-BFRs and PBDEs. Concentrations were not systematically related to PM₁₀, temperature or relative humidity.We conclude that both PAS provide replicable estimates of indoor concentrations of these targeted semi-volatile organic compounds (SVOCs) over a three-week deployment period. However, PUF is advantageous for collecting a wider range of compounds including those in the particle phase.

This study systematically explored the effect of humic acid (HA) (as model of natural organic matter) on the kinetics, products and transformation pathway of triclosan (TCS) by laccase-catalyzed oxidation. It was found that TCS could be effectively transformed by laccase-catalysis, with the apparent second-order rate constant being 0.056 U⁻¹ mL min⁻¹. HA inhibited the removal rate of TCS. HA-induced inhibition was negatively correlated with HA concentration in the range of 0–10 mg L⁻¹ and pH-dependent from 3.5 to 9.5. FT-IR and ¹³C NMR spectra showed a decrease of aromatic hydroxyl (phenolic) groups and an increase of aromatic ether groups, indicating the cross-linking of HA via C-O-C and C-N-C bonds during enzyme-catalyzed oxidation. Ten principle oxidative products, including two quinone-like products (2-chlorohydroquinone, 2-chloro-5-(2,4-dichlodichlorophenoxy)-(1,4)benzoquinone), one chlorinated phenol (2,4-dichlorophenol (2,4-DCP)), three dimers, two trimmers and two tetramers, were detected by gas chromatograghy/mass spectrometry (GC-MS) and high performance liquid chromatography/quadrupole time-of-flight/mass spectrometry (HPLC/Q-TOF/MS). The presence of HA induced significantly lesser generation of self-polymers and enhanced cross-coupling between HA and self-polymers via C-O-C, C-N-C and C-C coupling pathways. A plausible transformation pathway was proposed as follows: TCS was initially oxidized to form reactive phenoxyl radicals, which self-coupled to each other subsequently by C-C and C-O pathway, yielding self-polymers. In addition, the scission of ether bond was also observed. The presence of HA can promote scission of ether bond and further oxidation of phenoxyl radicals, forming hydroxylated or quinone-like TCS. This study shed light on the behavior of TCS in natural environment and engineered processes, as well provided a perspective for the water/wastewater treatment using enzyme-catalyzed oxidation techniques.

Globally, millions of people who rely on groundwater for potable purposes and agriculture have been inadvertently exposed to toxic arsenic (As) because of its natural occurrence in groundwater in several countries of Asia, Europe and America. While the presence of As in groundwater and its impacts on human health have been documented in many countries, there is little information on As contamination in Pakistan. This review highlights, for the first time, the extent and severity of As-induced problems in Pakistan based on relevant published papers; discusses possible sources of As contamination of aquifers; and estimates As-induced potential health hazards in the country in relation to global data. Data from 43 studies (>9882 groundwater samples) were used to describe As variability in groundwater of Pakistan and for comparison with global data. The mean groundwater As content reported in these studies was 120 μg/L (range: 0.1–2090 μg/L; SD: ±307). About 73% of the values for mean As contents in the 43 studies were higher than the World Health Organization (WHO) permissible limit (10 μg/L) for drinking water, while 41% were higher than the permissible limit of As in Pakistan (50 μg/L). It was observed that groundwater samples in some areas of Punjab and Sindh provinces contained high As concentrations which were almost equal to concentrations reported in the most contaminated areas of the world. We predicted that the mean values of ADD, HQ and CR were 4.4 μg kg⁻¹day⁻¹ (range: 0–77 μg kg⁻¹day⁻¹), 14.7 (range: 0–256) and 0.0029 (range: 0–0.0512), respectively, based on mean As concentrations reported in Pakistan. In addition, this article proposes some integrated sustainable solutions and future perspectives keeping in view the regional and global context, as well as the on-ground reality of the population drinking As-contaminated water, planning issues, awareness among civil society and role of the government bodies. Based on available data, it is predicted that almost 47 million people in Pakistan are residing in areas where more than 50% of groundwater wells contain As concentrations above the WHO recommended limit of As in drinking water.

To further assess the human being's exposure to polycyclic aromatic hydrocarbons (PAHs) through the dietary pathway, understanding the partitioning of these chemicals co-existed with nanomaterials in edible vegetable systems deserves specific consideration. In this study, the fiber-optic fluorimetry was applied to in situ examine the effects of graphene (GNS) and graphene oxide (GO) nanosheets on the quantification and depuration of three-ringed phenanthrene (Phe) and four-ringed fluoranthene (Fla) adsorbed individually onto the living spinach (Spinacia oleracea L.) surfaces. When the GNS and GO dosages separately increased to the maximum values: a respective red-shift of 4–5 nm and blue-shift of 2–3 nm occurred for the optimal detection emission wavelengths (λem) of the two PAHs, indicating that individual GNS and GO resulted in different changes to the epicuticular wax (ECW) polarity; GNS-inducing fluorescence quenching for the PAHs was about two times greater than GO, owing to the stronger π-π interactions between PAH molecules and GNS relative to GO; the volatilization coefficients (kC1) were reduced by 31.1% versus 26.7% for Phe, and 51.6% versus 34.4% for Fla, mainly via providing an additional adsorbent and promoting the accessibility of the leaf cuticle; respective photolysis coefficients (kP2) of Phe and Fla decreased by 42.9% and 50.0% with GNS, primarily owing to the enhancement of the ECW light-adsorption capacity, but increased by 33.3% and 40.0% with GO due to its photocatalytic activities; overall, total depuration coefficients (kT1, kT2) of the two PAHs decreased by 11.1–55.6%. These findings demonstrate that GNS and GO significantly alter the depuration behavior of PAHs in vegetable systems, potentially posing a threat to the safety of edible vegetables.

Pollution of marine environments with microplastic particles (i.e. plastic fragments <5 mm) has increased rapidly during the last decades. As these particles are mainly of terrestrial origin, coastal ecosystems such as coral reefs are particularly threatened. Recent studies revealed that microplastic ingestion can have adverse effects on marine invertebrates. However, little is known about its effects on small-polyp stony corals that are the main framework builders in coral reefs. The goal of this study is to characterise how different coral species I) respond to microplastic particles and whether the exposure might II) lead to health effects. Therefore, six small-polyp stony coral species belonging to the genera Acropora, Pocillopora, and Porites were exposed to microplastics (polyethylene, size 37–163 μm, concentration ca. 4000 particles L−1) over four weeks, and responses and effects on health were documented.The study showed that the corals responded differentially to microplastics. Cleaning mechanisms (direct interaction, mucus production) but also feeding interactions (i.e. interaction with mesenterial filaments, ingestion, and egestion) were observed. Additionally, passive contact through overgrowth was documented. In five of the six studied species, negative effects on health (i.e. bleaching and tissue necrosis) were reported.We here provide preliminary knowledge about coral-microplastic-interactions. The results call for further investigations of the effects of realistic microplastic concentrations on growth, reproduction, and survival of stony corals. This might lead to a better understanding of resilience capacities in coral reef ecosystems.

Chemical pollution is considered a factor that may threaten marine protected areas (MPAs), and recent studies have found contamination and associated biological effects in some MPAs. However, organized data on this topic are lacking. This study reviewed the literature on pollution in MPAs in order to compile data, determine whether MPAs are influenced by pollution and, whenever possible, describe how they are being affected by contaminants. The results show that the pollution status is unknown in most MPAs worldwide. When any information is available, it is often insufficient to diagnose the threats to biodiversity or to support further actions. More robust and extensive information is available on a small number of MPAs, and much less information is available regarding the negative effects of pollution. More than 80% of the areas studied exhibited evidence of contamination at potentially toxic concentrations or were found to have a status that produced toxic effects on the biota. The scientific community is encouraged to study pollution in MPAs worldwide.

Pesticide contamination is more often found as a mixture of different pesticides in water bodies rather than individual compounds. However, regulatory risk evaluation is mostly based on the effects of individual pesticides. In the present study, we aimed to investigate the individual and joint toxicities of triazophos (TRI) and imidacloprid (IMI) to the zebrafish (Danio rerio) using acute indices and various sublethal endpoints. Results from 96-h semi-static test indicated that the LC₅₀ values of TRI to D. rerio at multiple life stages (embryonic, larval, juvenile and adult stages) ranged from 0.49 (0.36–0.71) to 4.99 (2.06–6.81) mg a.i. L⁻¹, which were higher than those of IMI ranging from 26.39 (19.04–38.01) to 128.9 (68.47–173.6) mg a.i. L⁻¹. Pesticide mixtures of TRI and IMI displayed synergistic response to zebrafish embryos. Activities of carboxylesterase (CarE) and catalase (CAT) were significantly changed in most of the individual and joint exposures of pesticides compared with the control group. The expressions of 26 genes related to oxidative stress, cellular apoptosis, immune system, hypothalamic-pituitary-thyroid and hypothalamic-pituitary-gonadal axis at the mRNA level revealed that zebrafish embryos were affected by the individual or joint pesticides, and greater changes in the expressions of six genes (Mn-sod, CXCL-CIC, Dio1, Dio2, tsh and vtg1) were observed when exposed to joint pesticides compared with their individual pesticides. Taken together, the synergistic effects indicated that it was highly important to incorporate joint toxicity studies, especially at low concentrations, when assessing the risk of pesticides.

Excessive use of antibiotics in breeding industry leads to accumulation of antibiotic residuals and antibiotic resistance genes (ARGs) in environment from improperly treated livestock excrements. Four commonly used veterinary antibiotics including chlortetracycline (CTC), sulfamerazine (SMZ), enrofloxacin (ENR) and erythromycin (ERY) were monitored in the swine manure composting. Co-resistance and cross-resistance effects among relative ARGs, correlations between ARGs and bacterial community under multiple antibiotics residual during the composting were investigated in this research. With CTC addition up to 20 mg/kg, more than 99% of CTC removal was achieved after composting, and most of the other antibiotics can be thoroughly removed as well. The variations in ARGs during the composting were strongly correlated to the compositions of the microbial community, Bacteroides and Sporosarcina were main ARGs carriers in the thermophlic phase. Clostridium Ⅺ, Clostridium sensu stricto, and Pseudoxanthomonas, might spread ARGs in cooling and maturing stage. Most of the tested ARGs in swine manure can be effectively reduced through composting, thus makes the compost products safe for soil fertilization.