Contamination by polycyclic aromatic hydrocarbons (PAHs) has been observed at high elevation environments; however, the occurrence and spatial variation of PAHs in alpine lakes of China is not well understood. We measured 15 priority PAHs in the sediments of Lake Qinghai in the Qinghai-Tibet Plateau, and assessed their distribution, source, and ecological risks. The total PAH concentration ranged from 30.4 to 125.2 ng g⁻¹. Low molecular weight PAHs were dominant in the sediments, suggesting a local source for the emissions. Sediment sites closer to local settlements and rivers had higher concentration of PAHs. The concentration of PAHs was significantly correlated with pH, probably as a result of the high salinity of the lake, while it was not significantly correlated with organic matter content. Molecular diagnostic ratio analysis indicated that PAHs were derived mainly from coal and biomass combustion. Specifically, the positive matrix factorization model showed that petrogenic sources, vehicular emissions, biomass combustion, and coal combustion contributed for 11.6, 16.3, 23.6, and 48.5% of the PAHs, respectively. The risk quotient method was used to assess ecological risk of PAHs individually. The results indicate that indeno[1,2,3-cd]pyrene, benzo[b]fluoranthene, benzo[a]pyrene, phenanthrene, and anthracene would produce moderate ecological risks in 5, 20, 65, 100, and 100% of the sediment sites, respectively, while the other 10 PAH homologues would scarcely produce any serious ecological risk. We used the hierarchical Archimedean copula integral assessment model to evaluate the integral risk of PAHs. The result showed that 10, 40, and 50% of the sediment sites belong to mid-high, low, and mid-low risk levels, respectively. The current concentration and risk levels of PAHs in this study might be used as a baseline to assess the influence of future anthropogenic activities.

Phytoextraction using Celosia argentea Linn. can potentially decontaminate Cd-contaminated soils. However, most earlier studies have been conducted at laboratory scale and for a relatively short remediation period. To evaluate the phytoextraction efficiency of C. argentea combined with different soil amendments (ammonium chloride, Bacillus megaterium, and citric acid), an 18-month field experiment was carried out in a farmland soil contaminated with 3.68 mg kg⁻¹ Cd by mine tailings in southern China. Soil Cd concentrations were decreased by 6.34 ± 0.73% after the three harvestings (with no amendments), which was 2.27 times that of the no-planting control (p < 0.05). Application of ammonium chloride, B. megaterium, and citric acid increased the overall Cd reduction rate in soil by 40.5%, 46.1%, and 105%, respectively. The application of citric acid decreased total Cd in soil by up to 16.9% in the rhizosphere soil and 13.0% in the bulk soil. The highest annual shoot biomass yield and Cd extraction amount reached 8.79 t ha⁻¹ and 273 g ha⁻¹. Acid-soluble Cd fraction in the rhizosphere was significantly lower compared to that in the bulk soil (p < 0.05), which indicates that mobile Cd in the rhizosphere was taken up by the roots vastly. C. argentea phytoextraction also improved soil metabolic functions by increasing the activities of soil enzymes (urease, invertase, phosphatase, and catalase). These findings demonstrate that Cd phytoextraction using C. argentea with the application of soil amendments can greatly improve the quality of Cd-contaminated soils.

The use of pesticides has historically helped improve agricultural productivity, although their continued use may have unforeseen effects upon the natural environment when not applied appropriately. Metaldehyde is a commercial pesticide widely used to reduce crop losses resulting from terrestrial mollusc damage. However, following precipitation and runoff it frequently enters waterbodies with largely unknown consequences for aquatic fauna. This study represents one of the first attempts to examine its potential effects on aquatic macroinvertebrate communities at sites known to have experienced elevated metaldehyde concentrations alongside unaffected control sites. In addition, a series of laboratory exposures specifically examined the effects of metaldehyde on the survivorship of non-target aquatic mollusc species. When the entire aquatic macroinvertebrate community and aquatic mollusc community were considered, limited differences were observed between metaldehyde affected and control sites based on field data. Laboratory exposures highlighted that for the molluscs examined, gastropods (Bithynia tentaculata, Planorbis planorbis, Radix balthica and Potamopyrgus antipodarum) had a greater tolerance to metaldehyde than bivalves (Sphaerium corneum and Corbicula fluminea). However, the concentrations required to reduce survivorship of all species were much greater than those ever recorded historically under field conditions. The results suggest that the differences in the community composition recorded between sites exposed to elevated metaldehyde concentrations and control sites were probably due to nutrient loading (N and P from agricultural fertilizers) rather than metaldehyde. However, these results do not negate wider concerns regarding metaldehyde use, particularly issues caused when ingested by vertebrate wildlife, livestock or children and pets in domestic settings.

Atmospheric heavy metal contamination is becoming a serious threat to environmental and human health in Chinese megacities. This study evaluated the concentrations of arsenic (As), cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) and Pb isotopic compositions in herbarium and native bryophytes collected from Guangzhou from 1932 to 2018. Relatively low mean metal concentrations were measured for bryophytes collected in the 1930s. The highest mean concentrations of Cd (0.72 ± 0.32 mg/kg), Cu (28.1 ± 9.8 mg/kg), Pb (125.9 ± 62.4 mg/kg) and Zn (273 ± 130 mg/kg) were found in the bryophytes from 1979 to 2000, following the commencement of the Reform and Opening-Up Program in 1978. The mean Pb concentrations (74.7 ± 6.3 mg/kg) decreased sharply from 2001 onwards, following the cessation of leaded petrol across the Chinese mainland in 2000. However, these values are still higher than those in 1950–1978, corresponding to a significant increase in atmospheric Pb emissions from coal combustion, nonferrous metal smelting and motor vehicle petrol consumption in China in the 2000s. The lead isotopic ratios of bryophyte archives (²⁰⁶Pb/²⁰⁷Pb 1.141–1.229, ²⁰⁸Pb/²⁰⁷Pb 2.376–2.482) indicate that lithogenic input and anthropogenic input arising from leaded petrol and industrial emissions have been the main sources of atmospheric heavy metal deposition in the city of Guangzhou over the past 85 years. Herbarium bryophyte can be utilised to reconstruct temporal and spatial shifts in atmospheric heavy metal deposition to better understand and manage the current air quality in Chinese megacities.

The residual characteristics and the adsorption-desorption behaviors of azoxystrobin (AZO) as well as the soil ecological effects in the individual repeated treatments of AZO and its combination with chlorothalonil (CTL), chlortetracycline (CTC) and ciprofloxacin (CIP) were systematically studied in organic manure (OM)-amended soil under laboratory conditions. The presence of CTL, CTC, and CIP, both individually and combined, decreased the sorption affinity of AZO with the Freundlich adsorption and desorption coefficient decreasing by 0.3–24.2%, and CTC and CIP exhibited greater adverse effects than CTL. AZO dissipated slowly and the residues significantly accumulated during ten repeated treatments. The dissipation of AZO was inhibited to different degrees in the combined treatments. Biolog analysis revealed that the soil microbial functional diversity in the OM-soil + AZO and OM-soil + AZO + CTL treatments was higher than that in the OM-soil treatment during the former three repeated treatments, but which was inhibited during the latter seven repeated treatments. The soil microbial functional diversity in the OM-soil + AZO + CTC, OM-soil + AZO + CIP and OM-soil + AZO + CTL + CTC + CIP treatments was inhibited during the ten repeated treatments compared with OM-soil treatment. Metagenomic results showed that all repeated treatments significantly increased the relative abundance of Actinobacteria, but significantly decreased that of Proteobacteria and Firmicutes during the ten repeated treatments. Furthermore, the relative abundance of soil dominant bacterial genera Rhodococcus, Mycobacterium and Arthrobacter in all the repeated treatments significantly increased by 1.5–1283.9% compared with the OM-soil treatment. It is concluded that coexistence of CTL, CTC and CIP, both individually and combined, with AZO can inhibit the dissipation of AZO, reduce the adsorption affinity of AZO on soil, and alter the soil microbial community structure and functional diversity.

The specific activities of natural (²¹⁰Pb, ²²⁶Ra, and ²³²Th) and artificial (¹³⁷Cs, ²³⁹,²⁴⁰Pu, and ²⁴¹Am) radionuclides in the sediments of two North Caucasus lakes were determined. The two lakes, Lake Khuko and Lake Donguz-Orun, differ in their sedimentation conditions. Based on the use of unsupported ²¹⁰Pbₑₓ and both Chernobyl-derived and bomb-derived ¹³⁷Cs as chronological markers, it was established that the sedimentation rates in Lake Khuko over the past 55–60 y did not exceed 0.017 cm y⁻¹. Sedimentation rates in Lake Donguz-Orun were found to be more than an order of magnitude higher. In the latter case, the sedimentation rates for the period from 1986 to the present were over 1.5 times higher than they were for the period 1963–1986. The differences in sedimentation rates were due to differences in the rates of denudation of their respective catchment areas. The specific activities of artificial radionuclides (¹³⁷Cs, 2600 Bq kg⁻¹; ²³⁹,²⁴⁰Pu, 162 Bq kg⁻¹; and ²⁴¹Am, 36 Bq kg⁻¹) and their ratios in the sediments of Lake Khuko show that their deposition was mainly due to global stratospheric fallout of technogenic radionuclides associated with nuclear bomb testing during 1954–1963—rather than fallout from the Chernobyl accident. Several factors, including the mode of precipitation, features of the surface runoff, and location of Lake Khuko, were responsible for the accumulation of artificial radionuclides.

It is well known that sediment internal loading can worsen lake water quality for many years even if effective measures have been taken to control external loading. In this study, a 12-month field study was carried out to reveal the relationship between sediment phosphorus (P) and nitrogen (N) forms as well as their fluxes across sediment-water interface from the most polluted area of Lake Chaohu, a large shallow eutrophication lake in China. The possible contribution of mobile fraction of P and N to lake eutrophication is also analyzed. The results indicate that the content of total P and N and their forms in water and sediment were rather dynamic during the year-long field investigation. Low concentrations of P and N from sediment and overlying water were observed in the winter but increased sharply in summer. The phosphate and ammonium fluxes showed evident seasonal variation, and higher fluxes can be observed in warmer seasons especially during the period of algal bloom with high sedimentation. The reduction of ferric iron and degradation of organic matter could be responsible for the increased P flux from sediment in algal bloom seasons, which is consistent with the seasonal variation of P forms in sediment. A comparison of the mole ratio of P flux:N flux to both the P:N mole ratio in sediments and the Redfield ratio was used to further distinguish the dominant sediment P forms’ release during seasonal variation. Moreover, the anoxic condition and enhanced microbial activity in warmer seasons contribute a lot to the ammonium release from sediment. Consequently, the nutrient fluxes seasonally influence their corresponding nutrient concentrations in the overlying water. The results of this study indicate that sediment internal loading plays an important role in the eutrophication of Lake Chaohu.

Artificial light at night (ALAN) changes the natural rhythm of light and darkness and can impair the biorhythms of animals, for example the nocturnal melatonin production of vertebrates, which serves as a proxy for daily physiological rhythms. Freshwater fish are exposed to ALAN in large urban and suburban areas in the form of direct light or in the form of skyglow, a diffuse brightening of the night sky through the scattered light reflected by clouds, atmospheric molecules, and particles in the air. However, investigations on the sensitivity of melatonin production of fish towards low intensities of ALAN in the range of typical skyglow are rare. Therefore, we exposed Eurasian perch (Perca fluviatilis) to nocturnal illumination levels of 0.01 lx, 0.1 lx and 1 lx and a control group with dark nights and daylight intensities of 2900 lx in all groups. After ten days of exposure to the experimental conditions, tank water was non-invasively sampled every 3 h over a 24 h period and melatonin was measured by ELISA. Melatonin was gradually reduced in all treatments with increasing intensity of ALAN whereas rhythmicity was maintained in all treatment groups although at 1 lx not all evaluated parameters confirmed rhythmicity. These results show a high sensitivity of Eurasian perch towards ALAN indicating that low light intensities of 0.01 lx and 0.1 lx as they occur in urban and suburban areas in the form of skyglow can affect the physiology of Eurasian perch. Furthermore, we highlight how this may impact perch in their sensitivity towards lunar rhythms and the role of skyglow for biorhythms of temperate freshwater fish.

The purpose of this long-term experiment was on gaining more insights into the environmental behaviour of veterinary antibiotics in the subsurface after application with manure. Therefore, manure spiked with a bromide tracer and eight antibiotics (enrofloxacin, lincomycin, sulfadiazine, sulfamethazine, tetracycline, tiamulin, tilmicosin and tylosin) in concentrations of milligrams per litre were applied at an experimental field site. Their pathway was tracked by continuous extraction of soil pore water at different depths and systematic sampling of groundwater for a period of two years. Seven target compounds were detected in soil pore water of which four leached into groundwater. Concentrations of the detected target compounds were, with few exceptions, in the range of nanograms per litre. It was concluded that a large fraction of the investigated antibiotics sorbed or degraded already within the first meter of the soil. Further, it was inferred from the data that long and warm dry periods cause attenuation of the target compounds through increased degradation or sorption occurring in the soil. In addition, the comprehensive data-set allowed to estimate a retardation factor between 1.1 and 2.0 for sulfamethazine in a Plaggic Anthrosol soil, and to classify the individual compounds by environmental relevance based on transport behaviour and persistence. According to the distribution of resistant genes in the environment, sulfamethazine was found to be the most mobile and persistent substance.

Manganese (Mn) transporter OsNRAMP5 was widely reported to regulate cadmium (Cd) uptake in rice. However, the relationship between OsNRAMP5 expression level and Cd accumulation, impacts of external ion activities on OsNRAMP5 expression level and Cd accumulation are still unclear. Investigations of the relationship between OsNRAMP5 expression level and Cd accumulation in three indica rice genotypes were conducted under various external Mn²⁺ activities ranging from Mn deficiency to toxicity in EGTA-buffered nutrient solution. Results in this work indicated that OsNRAMP5 expression level in roots significantly up-regulated at Mn phytotoxicity compared to that at Mn deficiency, which may stimulate by the increasing uptake of Mn. Our work also demonstrated that root Cd concentration of all the tested rice decreased notably when external Mn²⁺ activity reached the level of toxicity. This may explain by the increasing competition between the excess Mn²⁺ and Cd²⁺ as well as the disorder of element absorption caused by root damage at Mn toxicity. Our work also revealed that the relationship between OsNRAMP5 expression level in roots and Cd accumulation in roots was insignificant for all the tested genotypes. Besides, OsNRAMP5 expression level in roots seemed more related to root Mn accumulation. The fact that function of OsNRAMP5 mainly focuses on Mn uptake, together with the fact that many transporter genes involved in Cd uptake might result in the insignificant correlation between OsNRAMP5 expression level and Cd accumulation in roots. At last, multi-level regulating and processing of the process from gene expression to protein translation might account for the inconsistent relationship between root OsNRAMP5 expression level and Cd accumulation in roots.