Lead (Pb) is a non-threshold toxin capable of inducing toxic effects at any blood level but availability of soil screening criteria for assessing potential health risks is limited. The oral bioaccessibility of Pb in 163 soil samples was attributed to sources through solubility estimation and domain identification. Samples were extracted following the Unified BARGE Method. Urban, mineralisation, peat and granite domains accounted for elevated Pb concentrations compared to rural samples. High Pb solubility explained moderate-high gastric (G) bioaccessible fractions throughout the study area. Higher maximum G concentrations were measured in urban (97.6 mg kg−1) and mineralisation (199.8 mg kg−1) domains. Higher average G concentrations occurred in mineralisation (36.4 mg kg−1) and granite (36.0 mg kg−1) domains. Findings suggest diffuse anthropogenic and widespread geogenic contamination could be capable of presenting health risks, having implications for land management decisions in jurisdictions where guidance advises these forms of pollution should not be regarded as contaminated land.

In recent decades, significant advances have been made in understanding the generation, fates and consequences of water quality pollutants in the Great Barrier Reef ecosystem. However, skepticism and lack of trust in water quality science by farming stakeholders has emerged as a significant challenge. The ongoing failures of both compulsory and particularly voluntary practices to improve land management and reduce diffuse agricultural pollution from the Great Barrier Reef catchment underlines the need for more effective communication of water quality issues at appropriate decision-making scales to landholders. Using recent Great Barrier Reef catchment experiences as examples, we highlight several emerging themes and opportunities in using technology to better communicate land use-water quality impacts and delivery of actionable knowledge to farmers, specifically supporting decision-making, behavior change, and the spatial identification of nutrient generation ‘hotspots’ in intensive agriculture catchments. We also make recommendations for co-designed monitoring-extension platforms involving farmers, governments, researchers, and related agencies, to cut across stakeholder skepticism, and achieve desired water quality and ecosystem outcomes.

To protect and improve water quality in the Great Barrier Reef, the Queensland Government's Reef 2050 Water Quality Improvement Plan targets that 90% of sugarcane, horticulture, cropping and grazing lands in priority areas be managed using best management practices for sediment, nutrient and pesticides by 2025. Progress towards this target is insufficient and variable across catchments and industries. The motivation to adopt improvements in management practices is heavily influenced by social, economic, cultural and institutional dimensions. In this paper we synthesise the literature on how these human dimensions influence decision making for land management practice and highlight where future investment could be focussed. We highlight that focussing on —1) investigating systems to support landholder decision making under climate uncertainty (risk); 2) generating a better understanding of the extent and drivers of landholder transaction cost; 3) understanding if there are competing ‘right’ ways to farm; and 4) improving understanding of the social processes, trust and power dynamics within GBR industries and what these means for practice change— could improve practice change uptake in the future.

We examined the effects of an amended mixture of three pesticides, atrazine (72.7 g), S-metolachlor (54.5 g), and permethrin (both cis and trans isomers; 11.4 g), on 10-day sediment toxicity to Hyalella azteca in a managed natural backwater wetland after a simulated agricultural runoff event. Sediment samples were collected at 10, 40, 100, 300, and 500 m from inflow 13 days prior to amendment and 1, 5, 12, 22, and 36 days post-amendment. Background pesticide concentrations ranged from <1 to 977, <1 to 119, and <1 to 2 μg kg⁻¹, for atrazine, S-metolachlor, and permethrin, respectively. Average post-amendment atrazine and S-metolachlor were 2,915–3,927 and 3–20 μg kg⁻¹, respectively at 10–40 m and 538–872 and <1 μg kg⁻¹, respectively at 300–500 m. Average post-amendment permethrin was 65–200 μg kg⁻¹ at 10–40 m and 1–10 μg kg⁻¹ at 300–500 m. H. azteca 10-day survival varied spatially and temporally up to 100 m from inflow. Animal growth, independent of survival, was reduced 40 and 100 m from inflow on day 36, showing continued sediment toxicity of up to 100 m from inflow more than 1 month after amendment. Animal survival and growth were unaffected at 300 and 500 m from inflow throughout the study period. Correlations of pesticide concentrations and H. azteca responses indicated that observed sediment toxicity was primarily from permethrin with potential additional synergistic toxicity from atrazine and methyl parathion. Study results indicate that natural backwater wetlands can be managed to ameliorate pesticide mixture 10-day sediment toxicity to H. azteca within 300 m of inflow and smaller wetlands (≤100 m) may require several months of effluent retention to mitigate effects.

Over the past couple of decades, the world has witnessed a rise in greenhouse gas (GHG) emissions and rising income inequality that threatens human well-being. Addressing these challenges and ensuring sustainable development become a pressing issue for policymakers. This paper investigates the impact of GHG emissions on income inequality in Africa. The study uses a panel data set from 49 countries from 1981 to 2015 and shows that GHG emission widens income inequality. The result is robust for alternative emission indicators. A direct implication is that climate change policy should be designed to narrow income inequality. It is emphasized that mitigation actions should focus on the agriculture sector. Hence, intervention towards energy-smart agriculture, land conservation practices, exploiting the job creation potential, and strengthening value addition in the agricultural sector is decisive. Reforming agriculture reduces emission, narrows income inequality, and realizes sustainable development on the continent.

Changes in land management and climate alter vegetation dynamics; however, the factors driving vegetation changes remain elusive at multiple spatiotemporal levels. Here, we assess the drivers of changes in greenness from 2000 to 2015 in Northwest China (NW China). We used multiple stepwise linear regression (MSLR), redundancy analysis (RDA), and 12 other models to quantify the impacts of precipitation and temperature metrics, gross domestic product (GDP), population, and grazing intensity on the normalized difference vegetation index (NDVI) at three administrative levels (county, town, and village), four temporal levels (yearly, May, July, and September), two vegetation types (woodland and grassland), and at annual precipitation gradients of <200, 200–400, and >400 mm. The results suggest that NW China underwent vegetation greening from 2000 to 2015. Precipitation and temperature were the most influential factors contributing to the NDVI change. Population was the main determinant of NDVI under the precipitation gradient of <200 mm, and the effect of GDP on NDVI was moderate. On the temporal scale, annual precipitation, precipitation before the previous year, and precipitation in the current year determined the NDVI in May, July, and September, respectively, for both woodland and grassland. At multiple scales, climate change was the primary driver of vegetation change in NW China, rather than human disturbance. These findings expand our understanding on drivers of NDVI at multiple levels over a long period. Measures to manage decreasing vegetation coverage may be more effective and could be implemented sooner based on predicted climate change in drylands worldwide.

The accumulation of potential toxic elements (PTEs) in soils is usually conditioned by parental material or anthropogenic sources. To achieve correct land management and land degradation neutrality, it is necessary to spatially detect them. However, there are several areas over the world with high concentrations of PTE but without efficient maps and tools to correctly find solutions and apply control measures. The current study attempts to identify the concentrations, sources, and spatial distributions of the main PTEs such as As, Cd, Cr, Cu, Ni, Pb, and Zn in a non-explored area combining fieldwork and geostatistical analysis. In order to accomplish this goal, a total of 90 soil samples were collected in agricultural and natural areas in the Piedemonte Llanero, Colombia. The chemical analysis was conducted by acid digestion and determined through ICP-OES. Then, ordinary kriging was applied to spatially analyze the most vulnerable areas. Our results demonstrated the effectiveness of these techniques and it is noted that the agricultural areas presented the highest concentrations and represented the potential source of PTEs. On the other hand, the natural areas presented the following concentrations of PTEs Cr (17.10 mg/kg), As (2.92 mg/kg), Cu (7.57 mg/kg), Ni (8.63 mg/kg), Cd (0.17 mg/kg), Pb (8.80 mg/kg), and Zn (27.57 mg/kg) lower than agricultural soils. This information was a key first step to be presented to the policymakers and stakeholders to organize soil sustainable management plans for the Piedemonte Llanero in Colombia.

The enrichment of cadmium (Cd) in black shale–derived soils is of increasing concern due to its wide occurrence, high Cd concentrations, and potential risks. However, characteristics of enrichment and environmental availability of Cd in these soils are not well understood, which has restricted pollution control and land management. In this study, agricultural soils with elevated Cd concentrations resulting from weathering of Cd-bearing black shale in southwestern China were collected and analyzed. The results showed that Cd could be retained in soils through mechanical inheritance and/or associated with secondary minerals and organic materials. Cd concentrations in soils of the study area ranged between 0.83 and 21.6 mg/kg (average of 5.20 mg/kg), exceeding the risk screening value for agricultural land in China. The heterogeneity of Cd in these soils was highly related to geochemical composition of parent rock and other natural factors. The 0.01 M CaCl₂ and 0.05 M EDTA extraction showed that Cd in these soils had high environmental availability and potential risks. Mobile Cd pool (CaCl₂ extractable Cd, average: 0.24 mg/kg) accounted for 0.07–38.9% of the total Cd, depending on soil pH. Mobilizable Cd pool (EDTA extractable Cd, average: 2.18 mg/kg) accounted for 22.0–100%. These results showed the significance of geochemical background on enrichment of Cd in soils, documented high environmental availability of Cd in black shale–derived soils, and influence of soil pH.

In this review, we explore the concept, approach, and future research of hydrological connectivity and its assessment at multiscales, because according to the literature, an integrated review upon hydrological connectivity is lack. Systematic studies illustrate the effects of (i) human activities (i.e., dam construction, groundwater extraction, water flow regulation and diversion, and land management) and (ii) natural factors (i.e., climate, soil characteristics, vegetation, and topography) on hydrological connectivity. Approaches (i.e., soil water content patterns, runoff patterns and processes, numerical models, and index of hydrological connectivity) applied to evaluate hydrological connectivity are examined in detail. Lastly, hydrological connectivity at multiscales is indicated. This review concludes with a discussion of potential research trends that can improve understanding of hydrological connectivity. Reported records showed that few studies were published on hydrological connectivity from 1980 to 2003, whereas the evolution of these studies is temporally promising since 2003. We cannot define a standard concept of hydrological connectivity that works in all environments. We desire to show different concepts of hydrological connectivity in different environments. The degree and nature of hydrological connectivity are not static due to the influences of human activities and changes of natural factors. The index of hydrological connectivity and numerical models are the most significant approaches to assess the changes in hydrological connectivity. This study showed that considering hydrological connectivity in social-economical-ecological-hydrological frameworks can prevent its negative effects on surface or subsurface water quantity and quality and is beneficial for sound water sources management.

The contents of total arsenic (tAs), inorganic arsenic (iAs), Cd, Cr, Cu, Mn, Ni, Pb, Sb, and Zn in 135 rice grain samples from Zijiang River basin were determined, and the probabilistic distribution of noncarcinogenic and carcinogenic risks associated with ingesting locally produced rice was determined by Monte Carlo simulation. Further, multivariate statistical analysis was used to analyze the potential sources of the heavy metals in rice grains. The average concentrations of the heavy metals in rice grains were ranked as follows: Mn (17.314 mg/kg) > Zn (16.043 mg/kg) > Cu (2.013 mg/kg) > Ni (1.332 mg/kg) > Cr (0.571 mg/kg) > Cd (0.283 mg/kg) > tAs (0.241 mg/kg) > Pb (0.145 mg/kg) > Sb (0.027 mg/kg). These heavy metals were significantly enriched in some rice grain samples. The analysis of potential sources indicated that As, Pb, Sb, and Zn were mainly derived from mining and smelting and agricultural activities; Cd, Cu, Mn, and Ni were mainly derived from the agricultural activities; Cr were mainly derived from the natural source. The results of Monte Carlo simulation indicated that ingestion of rice grown in the area may pose health risks for children, adult males, and adult females. The noncarcinogenic risks were mainly from As, Cd, Mn, Ni, and Sb, and the carcinogenic risk was mainly from As, Cd, and Ni. This study could provide basic information for land management and rice intake in the study area.